Understanding Starch Structure: Recent Progress

Protein targeting to Starch 2 and the plastidial phosphorylase 1 revealed protein-protein interactions with photosynthesis proteins in yeast two-hybrid screenings

Starch metabolism in plants involves a complex network of interacting proteins that work together to ensure the efficient synthesis and degradation of starch. These interactions are crucial for regulating the balance between energy storage and release, adapting to the plant's developmental stage and environmental conditions. Several studies have been performed to investigate protein-protein interactions (PPIs) in starch metabolism complexes, yet it remains impossible to unveil all of the PPIs in this highly regulated process. This study uses yeast-two-hybrid (Y2H) screening against the Arabidopsis leaf cDNA library to explore PPIs, focusing on the starch-granule-initiating protein named Protein Targeting to Starch 2 (PTST2, At1g27070) and the protein involved in starch and maltodextrin metabolism, namely, plastidial phosphorylase 1 (PHS1, EC 2.4.1.1). More than 100 positive interactions were sequenced, and we found chloroplastidial proteins to be putative interacting partners of PTST2 and PHS1. Among them, photosynthetic proteins were discovered. These novel interactions could reveal new roles of PTST2 and PHS1 in the connection between starch metabolism and photosynthesis. This dynamic interplay between starch metabolism and other chloroplast functions highlights the importance of starch as both an energy reservoir and a regulatory component in the broader context of plant physiology and adaptation.

New insights into cold plasma-induced starch modification: A comparative analysis of microstructure and physicochemical properties in A-type and B-type starches

With the growing demand for clean labeling in food products, cold plasma (CP) has gained attention as an eco-friendly method for starch modification. This study evaluated various effects of CP treatment on A- and B-type starches by comparing their microstructure and physicochemical properties. CP treatment caused the deposition of precipitates on the starch surfaces. While it did not alter the crystalline type, it reduced the relative crystallinity, particularly in potato starch (PS), with a 6.5 % decrease. Amylopectin chain length analysis showed depolymerization as the dominant effect in PS, while corn starh (CS) experienced cross-linking and degradation. Furthermore, the formation of smaller particles through CP enhanced water-holding capacity. CP treatment induced lower digestibility in both raw and cooked starches, especially uncooked PS showed slowly-digestible and resistant starch content with 11.59 % and 59.69 %. These effects are linked to differences in crystal cell arrangement, offering potential for CP-modified starches with tailored industrial applications.

Biopolymers to composite adsorbents for sulfate removal: From conventional to sustainable systems

Addressing elevated water salinity is a global water security issue listed among the UN's Sustainable Development Goals (UN-SDGs). Sulfate is a contributor to water salinity due to its high solubility and is a pollutant of increasing global concern. While various water treatment technologies are currently available, the high capital infrastructure and operational costs of such advanced methods have sustainability limits for their widespread adoption. By contrast, adsorption science and technology offers facile treatment and a sustainable mitigation strategy for the removal of oxyanions such as sulfate. A key challenge in adsorption science and technology relates to the molecular selective uptake of sulfate. This has catalysed significant effort towards achieving improved adsorption properties and the development of sustainable adsorbent technology. This review provides coverage of recent literature on synthetic adsorbents to current research on biosorbents that contain chitosan due to its multifunctional colloid and interface properties. The shift from conventional synthesis to green synthetic strategies are highlighted by the preparation of advanced biocomposite materials with unique sulfate adsorption properties. Diverse types of materials from inorganic minerals to polymer-based adsorbents (e.g., polycaprolactones, waste-based materials from fly ash, etc.) is described to highlight their sulfate adsorption properties. Specifically, chitosan and agricultural biomass waste in the form of lignocellulose materials are abundant and promising renewable platforms for the preparation of sulfate adsorbents. In particular, the adsorption properties of chitosan biocomposites are highlighted by its efficacy for adsorption-based remediation of sulfate oxyanions that reveal its promising utility as sulfate adsorbents with unique colloidal and interface properties.

Phthalate esters decreased nutritional value of rice grains via redirecting glycolytic carbon flow from grain quality formation toward antioxidative defense

The prevalence and persistence of phthalate esters (PAEs) in agricultural soils has garnered global attention. Assessing their potential impacts on crop yield and quality necessitates a thorough understanding of their risks. In this study, we elucidated the carbon flow-dependent mechanisms of the decreased grain quality upon exposure to PAEs through a soil-based rice cultivation experiment. Combining metabolomics and transcriptomics methods, our findings revealed that the glycolytic intermediates derived from sucrose breakdown preferentially flowed towards amino acid synthesis, rather than starch and fatty acid synthesis under exposure to dibutyl phthalate (DBP) or di(2-ethylhexyl) phthalate (DEHP). This redirection led to decreased levels of starch (by 14-23 %) and fatty acids (by 10-40 %) in the grains. Notably, the increased amino acids primarily served as antioxidants to mitigate DBP and DEHP stresses, rather than enhancing protein quality. Consequently, a reduction in protein levels by 5.7-38 % was observed. Moreover, our study pinpointed glucose-6-phosphate, a common precursor for amino acids, fatty acids, and starch synthesis, as the crucial branching node in glycolysis that redirected this carbon flow. This study offers a new perspective for evaluating the ecological risks associated with PAEs, paving the way for future research and interventions to mitigate their adverse effects on crops.

Status, development and potential of starch-based analogue cheese: A review

The development of alternative processed cheese formulation which are shelf stable, longer shelf-life, having lower shipping costs and mimic similar mouth feel is an emerging field. Starch based analogues cheese (AC) present a potential alternative that can incorporate casein, whey, or plant-based proteins along with water, oils/fats, emulsifying salts and additional ingredients by heat and mechanical agitation to achieve cheese-like properties. Owing to their hydration and gelatinization properties, starches serve as effective texturizing agents. Research suggests that starch could be a cost-effective and promising ingredient for developing AC. Although there are reviews on plant-based AC, no dedicated review specifically focused on starch-based analogous has been identified. In this review aims to explore existing studies on starch-based AC and investigate whether starch is truly a sustainable ingredient to meet the growing demand for AC. This review comprehensively explores the current status of starch-based AC, their development process and their effect on functional, rheological and textural properties. It also highlights current limitations, research gaps and emerging technologies relevant to the development of AC.

Natural polysaccharides-based smart sensors for health monitoring, diagnosis and rehabilitation: A review

With the rapid growth of multi-level health needs, precise and real-time health sensing systems have become increasingly pivotal in personal health management and disease prevention. Natural polysaccharides demonstrate immense potential in healthcare sensors by leveraging their superior biocompatibility, biodegradability, environmental sustainability, as well as diverse structural designs and surface functionalities. This review begins by introducing a variety of natural polysaccharides, including cellulose, alginates, chitosan, hyaluronic acid, and starch, and analyzing their structural and functional distinctions, which offer extensive possibilities for sensor design and construction. Further, we summarize several principal sensing mechanisms, such as piezoresistivity, piezoelectricity, capacitance, triboelectricity, and hygroelectricity, which provide a theoretical and technological foundation for developing high-performance healthcare sensing devices. Additionally, the review discusses the most recent applications of natural polysaccharide-based sensors in diverse healthcare contexts, including human body motion tracking, respiratory and heartbeat monitoring, electrophysiological signal recording, body temperature variation detection, and biomarker analysis. Finally, prospective development directions are proposed, such as the integration of artificial intelligence for real-time data analysis, the design of multifunctional devices that combine sensing with therapeutic functionalities, and advancements in remote monitoring and smart wearable technologies. This review aims to provide valuable insights into the development of next-generation healthcare sensors and propose novel research directions for personalized medicine and remote health management.

Starch phosphorylation - A new perspective: A review

The phosphorylation of the storage carbohydrates, starch and glycogen, is a process that is fundamental to their physicochemical properties and their turnover. Therefore, the interest utilising phosphorylation as a biotechnological tool to customize polysaccharides has risen permanently. Today, the phosphoesterification of both carbohydrate forms is much better understood. In recent years, important new insights have been gained into the molecular mechanism of starch phosphoesterification and its effects. In the following, the current state of knowledge on starch phosphorylation is briefly summarized. In addition, protein structure predictions for GWD are presented and considered for the first time in the context of recently published analyses of starch phosphorylation, which have opened up novel perspectives on this process. Therefore, we focus on a detailed discussion of the molecular events that occur at the surface of starch granules and enable a revised and in-depth understanding of starch granule phosphorylation.

From nature to nanotech: Harnessing the power of electrospun polysaccharide-based nanofibers as sustainable packaging

Today, the applications of natural polysaccharide-based nanofibers are growing in drug delivery and food industries. They also showed their capability as packaging due to biodegradability, mechanical strength, barrier properties, thermal stability, antioxidant, and antimicrobial features. Natural polysaccharides come from different sources, such as plants, microbes, and animals. Natural polysaccharide-based nanofibers can be considered sustainable packaging in contrast to plastic packaging due to their safety and biodegradability. Smart packaging is a new trend in packaging materials, and natural polysaccharides can be applied as smart packaging. They can work as an indicator that confirms food health in food packaging. Electrospinning is one of the most used methods for the fabrication of nanofibers, and it can also be used for the fabrication of natural polysaccharide nanofibers. This method can be scaled up and used to fabricate nanofibers on a large scale. This paper will review recent studies on natural polysaccharide-based nanofiber as packaging materials and their benefits. We also discuss the challenges and limitations of their scale-up and electrospinning process. Furthermore, we will discuss the future perspective of natural polysaccharide-based nanofiber as a new sustainable packaging.

Facile and eco-friendly method of starch nanocrystals esterified with oleic acid using natural clay as a catalyst: Synthesis, Box-Behnken optimization, characterization and analysis of thermal and antioxidant properties

This study investigates the synthesis of corn starch nanocrystals (SNCs) via sulfuric acid hydrolysis. Esterification of oleic acid (OA) with SNCs was carried out using Maghnite-H+ as a catalyst, a non-polluting, eco-friendly proton-exchanged montmorillonite-based green catalyst suitable for various chemical processes. Optimization of synthesis parameters, including reaction temperature, duration, and catalyst quantity, was conducted using response surface methodology (RSM) with a central composite design incorporating three factors and three levels. Optimal conditions for achieving a high degree of substitution (DS) were determined as follows: 21.27 h reaction time, 106.39 °C temperature, and 15.17 % (by weight of starch) Maghnite-H+ catalyst, with a molar ratio of OA to anhydrous glucose units of 3:1. Characterization of the esterification product was performed using FTIR spectroscopy, while electron microscopy (SEM) and X-ray diffraction (XRD) analyses revealed significant changes in appearance and internal structure post-esterification. Thermal analysis indicated lower heat resistance for SNCs-OA compared to native starch and SNCs. Furthermore, both esterified and unmodified SNCs exhibited antioxidant properties, with activity comparable to standard antioxidant vitamin C (ascorbic acid), as measured by their ability to neutralize free radicals, which increased with SNCs concentration. This comprehensive study offers valuable insights into the synthesis, characterization, and functional properties of SNCs-OA.

The Effect of Protein-Starch Interaction on the Structure and Properties of Starch, and Its Application in Flour Products

Grains are an energy source for human beings, and the two main components-starch and protein-determine the application of grains in food. The structure and properties of starch play a decisive role in determining processing characteristics, nutritional properties, and application in grain-based foods. The interaction of proteins with starch greatly affects the structure, physicochemical, and digestive properties of the starch matrix. Scientists have tried to apply this effect to create foods tailored to specific needs. Therefore, studying the effect of protein on the structure and properties of starch in the starch-protein complexes will help in designing personalized and improved starch-based food. This paper reviews the latest research about the effects of endogenous and exogenous proteins on the structure and properties of starch, as well as factors influencing the interaction between protein and starch. This includes investigations of the chain and aggregation structure of proteins with starch, as well as assessments of impacts on thermal properties, rheology, gel texture properties, hydration properties, aging, and digestion. In addition, particular examples illustrating the effects of protein-starch interaction on starch properties in various foods are discussed, providing a reference for designing starch-protein foods that are rich in terms of nutrition and easier to process.

Sustainable water treatment using oats-based nano-starch and acetylated nano-starch for uranium removal

Present study aims at oats-based biosorbents for uranium sequestration. Nano-starch extracted from oats was acetylated using 10 % acetic anhydride of nano-starch. Comparative study of nano-starch and acetylated nano-starch for uranium removal was carried-out. Removal efficiencies observed was 97 % and 99 % for nano-starch and acetylated nano-starch under optimal conditions: initial U(VI) ion concentration = 30 ppb, reaction time = 30 min, temperature = 50 °C, and pH = 7.0. Optimum adsorbent dose of nano-starch was 0.75 g/25 mL and that of acetylated nano-starch was 1.00 g/25 mL. Structural and morphological analyses were carried-out using FTIR, XRD, and SEM-EDS. Nano-starch exhibited higher thermal stability with a Final Decomposition Temperature (FDT) of 620 °C. Adsorption data followed the Langmuir isotherm with adsorption capacity = 1.48 μg/g for 60 ppb initial concentration of U(VI) and pseudo-second-order kinetics (R2 = 0.99). The reusability of both biosorbents is excellent, with nano-starch retaining ~80 % efficiency and acetylated nano-starch ~84 % over five cycles, presenting an effective solution for U(VI) removal from wastewater.

Kinetics of Structural Changes in Starch Retrogradation Observed by Simultaneous SANS/FTIR-ATR Measurements

Because of the complicated hierarchical structure of starch, starch retrogradation is usually evaluated by combining several structural analysis methods covering various spatial scales. However, structural analyses are typically performed individually, making correlating the structural changes at different spatial scales challenging. Therefore, this study used a simultaneous measurement system comprising small-angle neutron scattering (SANS)/Fourier-transform infrared (FTIR)-attenuated total reflection (ATR) to record multiple structural changes in potato starch during retrogradation. In the SANS patterns, the shoulder-like peak became more pronounced with time. The peak intensity, I max, representing the amount of ordered semicrystalline structures, increased over time, revealing the orderly reassembly of starch on the nanoscale upon retrogradation. In the FTIR-ATR spectra, the ratio of absorptions (R 1042/1016) at 1,042 and 1,016 cm-1, indicating the short-range ordered structure in starch, increased during retrogradation. Therefore, the double-helix structures were reformed during retrogradation. The rate constant of the kinetic change for R 1042/1016 was larger than for I max; thus, changes in the short-range ordered structure of starch converged before the changes in the semicrystalline structure. These results suggest that the formation of double-helix structures of the amylopectin side chain and the structural change of its ordered arrangement could occur in stages during retrogradation.

A novel isolation technique for sweetpotato starch and its application in thermal property characterization

BACKGROUND

The utilization of sweetpotato starch in the food industry is significantly influenced by the granule size of the starch. To isolate sweetpotato starch fractions with different sizes, an efficient isolation method is in demand. The differences in thermal properties of starch fractions with different sizes from various sweetpotato varieties were revealed insufficiently.

RESULTS

In this study, we devised a time-saving isolation technique to effectively isolate sweetpotato starch fractions based on granule sizes. The new technique was proved applicable for sweetpotato varieties with different flesh colors. The amylose contents of the isolated starch fractions were in the range 16.49-23.27%. A positive association was observed between amylose content, relative crystallinity of starch fractions and their granule size. Conversely, both the swelling power and water solubility at 95 °C displayed a consistent decline from more than 30 g g-1 to lower than 20 g g-1 as the granule size increased. Tp, To and Tc decreased gradually with an increase of starch granule size, while the medium- or small-sized starch fractions showed higher ΔH. In the first stage of thermogravimetric analysis curves, the weight of the small-sized starch fractions decreased the slowest, but no definite pattern was detected in the second or third stage.

CONCLUSION

Therefore, the newly established technique and the results of this study will help better understand the properties of sweetpotato starch fractions with different sizes and certainly provide guidelines for the utilization of sweetpotato starch in food processing and product development. © 2024 Society of Chemical Industry.

Combined effects of particle dosing rate and airflow rate on triboelectric charging of wheat and yellow pea protein and starch

The dry and chemical-free tribo-electrostatic separation (TES) process fractionates food particles while maintaining their functionality. Its mechanism relies on the pneumatic transfer of particles within a tribo-charger tube, wherein inter-particle and particle-wall collisions induce distinct charges on particles before being exposed to an external electric field for electrostatic separation. This study assessed the relative chargeability of protein and starch single components of yellow pea and wheat using various conductor and insulator tribo-charger tubes via online charge analysis while investigating the simultaneous impacts of particle dosing rates (g/h) and airflow rates. Accordingly, the triboelectric series was determined as (+) nylon > yellow pea protein > wheat gluten > polyvinylchloride (PVC) > wheat starch > yellow pea starch > polytetrafluoroethylene (PTFE) > copper alloy (-). The PTFE tribo-charger tube was quickly saturated with charged particles through their repetitive continuous collisions, thereby limiting effective charge transfer over time, making the impacts of tube length and airflow rate negligible on particles' chargeability across all particle dosing rates. However, for the PVC, copper alloy, and nylon tribo-chargers, the use of longer tubes and turbulent airflow at low particle dosing rates (<200 g/h for starch and <500 g/h for protein) maximized specific charge (nC/g) acquisition for all protein and starch particles. All protein and starch particles charged with PVC, copper alloy, and nylon exhibited significantly higher specific charges (nC/g) at lower dosing rates compared to higher particle dosing rates, regardless of the airflow rate. This suggests that particle-particle collisions play a more significant role in charge acquisition than particle-wall collisions in concentrated particle flow. Yellow pea and wheat protein particles achieved higher specific charges with increasing airflow rate (7-14 LPM) than tube length (50-150 cm), a pattern not seen with starch particles. These fundamental findings regarding the charging behavior of protein and starch components at different airflow and particle dosing rates can help researchers gain a better understanding of the separation behavior of milled legumes and cereals, as well as protein-starch binary mixtures during TES.

Mechanism of maltogenic α-amylase modification on barley granular starches spanning the full range of amylose

Amylopectin (AP)-only (APBS), normal (NBS), and amylose (AM) only (AOBS) barley starches were selected here to investigate catalysis pattern of maltogenic α-amylase (MA) on hydrolyzing AP and AM granular starches. MA shortened starch side chains with degree of polymerization (DP) 11-30. MA-treated APBS exhibited porous granular structures and dramatically increased degree of branching (DB, 17-20 %), and reduced ordered degrees, suggesting high hydrolysis and transglycosylation activities of MA. MA-treated NBS showed less pronounced porous structures and slightly increased DB (2-4 %), indicating high hydrolysis but low transglycosylation activities. AOBS displayed minimal changes in DB (0.2-0.3 %) and starch structures, implying low hydrolysis and transglycosylation activities. Therefore, MA preferred to attack the AP molecules with abundant glucan substrates with DP 11-30, while AM restricted MA activity likely by creating ineffective binding sites and undergoing rapid reorganization. These findings deepened the understanding of the mechanisms of MA in modifying granular starches with varying AM content.

Applying the Sabatier Principle to Decipher the Surface-Structure-Dependent Catalysis of Different Starch Granules by Pullulanase

Interfacial enzyme catalysis is widespread in both nature and industry. Granular starch is a sustainable and abundant raw material for which a rigorous correlation of the surface structure with enzymatic degradation is lacking. Here pullulanase-catalyzed debranching of 12 granular starches varying in amylopectin contents and branch chain contents and lengths is shown to present a biphasic relationship characteristic of the Sabatier principle. Introducing normalization of the specific rate (v 0/E 0) by a substrate-dependent constant C, related to the Arrhenius prefactor of k cat, reveals that optimal activity according to the Sabatier principle occurs at moderate substrate binding strength. The density of pullulanase attack sites (kinΓmax), determined using combined conventional and inverse Michaelis-Menten kinetics, was increased by branching enzyme treatment. Medium kinΓmax and branch chain length conferred the highest activity depending on substrate load. Correlation analysis demonstrated that starch granular crystallinity, surface order, and average branch chain length influence the enzymatic degradation by affecting the C constant. Therefore, C should be considered together with the enzyme binding strength to understand the degradation of starch granules. The Sabatier principle could serve as a diagnostic tool to characterize enzyme performance on substrates having different surface structures and guide rational modification of granular starches for specific purposes.

Encapsulation of Fatty Acids Using Linear Dextrin from Waxy Potato Starch: Effect of Debranching Time and Degree of Unsaturation

This study investigates the effects of the debranching time of waxy potato starch using pullulanase and recrystallization on particle morphology, debranching degree, and crystal structure. The results demonstrated that after gelatinization and debranching, the surface of the starch crystals became rough and uneven due to hydrolysis, with most particles showing a fragmented surface. The crystalline state was not significantly changed with debranching time. X-ray diffraction analysis revealed no significant differences in the patterns of recrystallized linear dextrin (LD) after various debranching times. Notably, the short-range ordered structure of LD after debranching and recrystallization was more organized than that of the original or gelatinized starch. Additionally, polarized light microscopy showed that the birefringent pattern disappeared as a result of debranching and recrystallization, indicating the breakdown of particle structure, although the overall particle morphology did not change significantly with varying debranching times. Furthermore, linear dextrin derived from starch debranched for 6 h (with pullulanase at 15 μg/g) successfully embedded stearic acid, oleic acid, and linoleic acid, forming a VI-type starch-fatty acid complex.

Relationship Between Physical Characteristics of Cereal Polysaccharides and Soft Tribology-The Importance of Grain Source and Malting Modification

Starch and non-starch polysaccharides ((N)SPs) are relevant in cereal-based beverages. Although their molar mass and conformation are important to the sensory characteristics of beer and non-alcoholic beer, their triggering mechanism in the mouth is not fully understood. Soft tribology has emerged as a tool to mimic oral processing (drinking). The contribution of each (N)SPs to the friction coefficient can be determined when they are enzymatically isolated and characterized by chromatography techniques. Thus, this work aimed to study the relationship between the physical characteristics of isolated (N)SPs and their possible contribution to oral processing through soft tribology (friction). To accomplish this, this research analyzes the effect of grain source (barley, wheat, and oats) and its modification (by steeping degree at two levels) to the (N)SPs´ physical characteristics in wort produced on a laboratory scale. Different characteristics were present in the (N)SPs due to the grain source and the degree of modification. When comparing the impact of the grain source, the malted oats showed the highest molar masses. A higher modification degree produced smaller and more compact structures except for wheat's arabinoxylans and dextrins. The conformation ratio (r rms / r hyd ) values indicate the existence of sphere and micro-gel structures within each (N)SPs, with branches in arabinoxylans and dextrins. Subsequently, soft tribology was measured on all the worts and their correlation to the (N)SPs' data was performed by multivariate analysis. The wort produced with high modification grains generated higher friction responses. However, this was only statistically significant in barley samples. The multivariate analysis showed that within the mouth (tongue) velocity, the apparent density of the (N)SPs, and the molar mass of arabinoxylans and β-glucans may influence the friction response and, hence, the oral processing in the mouth during oral processing (drinking).

On the Architecture of Starch Granules Revealed by Iodine Binding and Lintnerization. Part 2: Molecular Structure of Lintnerized Starches

This investigation validated iodine binding in combination with lintnerization for studying the structural nature of the amorphous areas in starch granules. Lintners of four iodine vapor-stained and non-stained amylose-containing starches and their waxy counterparts were analyzed by high-performance anion-exchange chromatography (HPAEC). The composition of the lintners was strongly affected by the absence of amylose in barley and potato starch but not in maize and cassava starch. Iodine-stained waxy lintners possessed increased number of long B2 chains. β-Limit dextrins of the lintners were very variable in composition. Iodine inclusion complexes washed out from the granular residues in the lintners (mostly from amylose-containing barley and maize starches) were also analyzed. Acid-soluble complexes from both amylose-containing and waxy starches possessed a lot of material with a degree of polymerization (DP) around 60 and a periodicity in size of DP 8-12. Such long chains were only minor components in water-soluble complexes of amylose-containing barley and maize starch lintners, and they lacked the size periodicity. Models of the principal structure of the acid and water-soluble complexes are suggested. It is concluded that acid hydrolysis of iodine-stained starch granules is a useful tool in structural analyses of the molecular composition of amorphous parts of starch granules.

Recent Advances on Starch-Based Adsorbents for Heavy Metal and Emerging Pollutant Remediation

Starch is one of the most abundant polysaccharides in nature and has a high potential for application in several fields, including effluent treatment as an adsorbent. Starch has a unique structure, with zones of different crystallinity and a glycosidic structure containing hydroxyl groups. This configuration allows a wide range of interactions with pollutants of different degrees of hydrophilicity, which includes from hydrogen bonding to hydrophobic interactions. This review article aims to survey the use of starch in the synthesis of diverse adsorbents, in forms from nanoparticles to blends, and evaluates their performance in terms of amount of pollutant adsorbed and removal efficiency. A critical analysis of the materials developed, and the results obtained is also presented. Finally, the review provides an outlook on how this polysaccharide can be used more effectively and efficiently in remediation efforts in the near future.

Production of Starch-Based Flexible Food Packaging in Developing Countries: Analysis of the Processes, Challenges, and Requirements

Biodegradable packaging offers an affordable and sustainable solution to global pollution, particularly in developing countries with limited recycling infrastructure. Starch is well suited to develop biodegradable packages for foods due to its wide availability and simple, low-tech production process. Although the development of starch-based packaging is well documented, most studies focus on the laboratory stages of formulation and plasticization, leaving gaps in understanding key phases such as raw material conditioning, industrial-scale molding, post-production processes, and storage. This work evaluates the value chain of starch-based packaging in developing countries. It addresses the challenges, equipment, and process conditions at each stage, highlighting the critical role of moisture resistance in the final product's functionality. A particular focus is placed on replacing single-use plastic packaging, which dominates food industries in regions with agricultural economies and rich biodiversity. A comprehensive analysis of starch-based packaging production, with a detailed understanding of each stage and the overall process, should contribute to the development of more sustainable and scalable solutions, particularly for the replacement of single-use packages, helping to protect vulnerable biodiverse regions from the growing impact of plastic waste.

Understanding starch biosynthesis in potatoes for metabolic engineering to improve starch quality: A detailed review

Potato tubers accumulate substantial quantities of starch, which serves as their primary energy reserve. As the predominant component of potato tubers, starch strongly influences tuber yield, processing quality, and nutritional attributes. Potato starch is distinguished from other food starches by its unique granule morphology and compositional attributes. It possesses large, oval granules with amylose content ranging from 20 to 33 % and high phosphorus levels, which collectively determine the unique physicochemical characteristics. These physicochemical properties direct the utility of potato starch across diverse food and industrial applications. This review synthesizes current knowledge on the molecular factors controlling potato starch biosynthesis and structure-function relationships. Key topics covered are starch granule morphology, the roles and regulation of major biosynthetic enzymes, transcriptional and hormonal control, genetic engineering strategies, and opportunities to tailor starch functionality. Elucidating the contributions of different enzymes in starch biosynthesis has enabled targeted modification of potato starch composition and properties. However, realizing the full potential of this knowledge faces challenges in optimizing starch quality without compromising plant vigor and yield. Overall, integrating multi-omics datasets with advanced genetic and metabolic engineering tools can facilitate the development of elite cultivars with enhanced starch yield and tailored functionalities.

Strategies and Methodologies for Improving Toughness of Starch Films

Starch films have attracted increasing attention due to their biodegradability, edibility, and potential use as animal feed from post-products. Applications of starch-based films include food packaging, coating, and medicine capsules. However, a major drawback of starch-based films is their brittleness, particularly under dry conditions, caused by starch retrogradation and the instability of plasticizers. To address this challenge, various strategies and methodologies have been developed, including plasticization, chemical modification, and physical reinforcement. This review covers fundamental aspects, such as the microstructures, phase transitions, and compatibility of starch, as well as application-oriented techniques, including processing methods, plasticizer selection, and chemical modifications. Plasticizers play a crucial role in developing starch-based materials, as they mitigate brittleness and improve processability. Given the abundance of hydroxyl groups in starch, the plasticizers used must also contain hydroxyl or polar groups for compatibility. Chemical modification, such as esterification and etherification, effectively prevents starch recrystallization. Reinforcements, particularly with nanocellulose, significantly improved the mechanical properties of starch film. Drawing upon both the literature and our expertise, this review not only summarizes the advancements in this field but also identifies the limitations of current technologies and outlines promising research directions for future development.

Insights into Dual Self-Assembly Mechanisms in Various Artocarpus altilis (Parkinson) Fosberg Starch-Endogenous Lipid-Endogenous Protein Complexes: Interactions between Digestibility Kinetics and Multiscale Structure

Chinese seedless breadfruit is rich in starch, lipids, and protein. To explore the interactions among these macromolecules during food processing, the seedless breadfruit starch-endogenous lipid-endogenous protein complex was investigated. Native seedless breadfruit starches are categorized as low-resistant-content starch [low-resistant starch (LRS)] or high-resistant starch (HRS). After complexation, dual self-assembly mechanisms occur after complexation. Initially, for the LRS group, long chains of amylopectin and amylose participate in complexation due to the migration from the short side chain of amylopectin, leading to an increase in RS content compared to the native starch. In contrast, amylose participated in complexation in the HRS group, which showed higher digestibility than that of raw starch. According to chemometric analysis, the HRS group complex possesses a more compact external and internal nanomicrostructure, leading to its weaker digestibility kinetics compared to the LRS group complex. This study provides a fundamental basis for the comprehensive application of novel multicomponent foods.

Protein and Polysaccharide Fibers via Air Jet Spinning: Emerging Techniques for Biomedical and Sustainable Applications

Polymers play a critical role in the biomedical and sustainable materials fields, serving as key resources for both research and product development. While synthetic and natural polymers are both widely used, synthetic polymers have traditionally dominated due to their ability to meet the specific material requirements of most fiber fabrication methods. However, synthetic polymers are derived from non-renewable resources, and their production raises environmental and health concerns. Natural polymers, on the other hand, are derived from renewable biological sources and include a subset known as biopolymers, such as proteins and polysaccharides, which are produced by living organisms. These biopolymers are naturally abundant and offer benefits such as biodegradability and non-toxicity, making them especially suitable for biomedical and green applications. Recently, air jet spinning has emerged as a promising method for fabricating biopolymer fibers, valued for its simplicity, cost-effectiveness, and safety-advantages that stand out compared to the more conventional electrospinning process. This review examines the methods and mechanisms of air jet spinning, drawing on empirical studies and practical insights to highlight its advantages over traditional fiber production techniques. By assembling natural biopolymers into micro- and nanofibers, this novel fabrication method demonstrates strong potential for targeted applications, including tissue engineering, drug delivery, air filtration, food packaging, and biosensing, utilizing various protein and polysaccharide sources.

Fabrication and Enhanced Flexibility of Starch-Based Cross-Linked Films

The development of sustainable materials has driven significant interest in starch as a renewable and biodegradable polymer. However, the inherent brittleness, hydrophilicity, and lack of thermoplasticity of native starch limit its application in material science. This study addresses the limitations of native starch by converting it to dialdehyde starch (DAS) and cross-linking with polyether diamines via imine bonds. The effects of Jeffamine molecular weights (D-2000, D-400, and D-230) and mole ratios on the mechanical, thermal, and structural properties of starch-based films were examined. The cross-linked DAS/Js films exhibited significant enhancements in flexibility and toughness. Specifically, DAS/J2000 at a 0.03 mol ratio achieved a tensile strength of 62.9 MPa. In comparison, DAS/J400 at a 0.5 mol ratio demonstrated 126.2% elongation at break, indicating the balance between cross-linking density and chain mobility. X-ray diffraction (XRD) analysis revealed reduced crystallinity and tighter molecular packing with increased cross-linking. Dynamic mechanical analysis (DMA) indicated a decrease in Tg with an increasing mole ratio, reflecting enhanced molecular mobility. The results underscore the potential of optimized cross-linking conditions to produce starch-based films with properties that contribute to developing sustainable biopolymer materials.

Structural disorganization and orientation of high-amylose maize starch with improved oil absorption capacity: Effects of water-ionic liquid ratios

Due to the structural compactness of high-amylose maize starch (HAMS), the full gelatinization of starch granules is challenging below 100 °C. In this work, we explored the potential of water-ionic liquid (IL, 1-allyl-3-methylimidazolium chloride, [AMIM]Cl) mixtures to promote the structural disorganization of HAMS during heating. Phase transition results indicated that when the water-IL ratio changed from 10:0 to 7:3 (w/w), the peak temperature of HAMS increased from 95.17 °C to 102.04 °C, and as the water-IL ratio dropped further to 2:8 (w/w), the peak temperature decreased markedly to 55.82 °C. Similar trends were observed in morphology, pasting, and rheological behavior analysis, confirming that HAMS was substantially destroyed and that a solution-like homogeneous fluid was generated after heating in a water-IL (2:8, w/w) mixture. SEM, XRD, and 13C solid-state NMR spectroscopy analysis suggested that the regenerated HAMS exhibited a porous reticular microstructure and V-type conformation, and it displayed improved complexation ability and an excellent oil absorption capacity of 3.55 ± 0.15 g/g. These results showed that an appropriate concentration of water-IL mixtures provided a prerequisite for remodeling the starch chains of HAMS. Therefore, this work proposed an efficient way for disorganizing HAMS and regenerating starch to achieve desired oil-absorbing properties.

Effect of Rice Protein on the Gelatinization and Retrogradation of Rice Starch with Different Moisture Content

Rice protein and moisture content are pivotal in the gelatinization and retrogradation processes of rice starch. This study aimed to explore the influence of rice protein on these processes by preparing rice starch gels with varying moisture levels and incorporating rice protein. At a high moisture content of 1:6, rice protein exhibited a minimal effect on the gelatinization properties of rice starch but significantly retarded the retrogradation of the starch gel. At intermediate moisture levels of 1:4 and 1:2, the rice starch gels showed pronounced retrogradation. However, rice protein was effective in inhibiting this retrogradation at a 1:4 moisture content, while its inhibitory effect diminished at a 1:2 moisture content. Under low moisture conditions of 1:1, the gelatinization of rice starch was markedly constrained by the limited water availability, but rice protein mitigated this constraint. Conversely, at this moisture level, rice protein promoted the retrogradation of the rice starch gel during the retrogradation process. The findings of this study offer a theoretical foundation that could inform the production of rice-based products.

Enhancing thermal stability and mechanical resilience in gelatin/starch composites through polyvinyl alcohol integration

In practical scenarios, destabilizing the physical attributes of natural polymers such as gelatin and starch occurs readily when exposed to specific moisture levels and heat. In this context, this work was carried out to assess the impact of PVA addition (up to 13 wt%) on the structure and physical properties of a 6:4 (w/w) gelatin/starch blend. The inclusion of PVA unfolded the molecular chains of gelatin and starch, thereby disrupting gelatin α-helices and impeding biopolymer crystallization. This facilitated hydrogen-bonding interaction between PVA and the two biopolymers, enhancing the stability of the molecular network structure. Rheological results indicate that composites (added with 4 % or 7 % PVA) with good compatibility exhibited excellent mechanical properties and deformation resistance. The addition of PVA elevated the gelling temperature (Tgel) of the composites from 41.31 °C to 80.33 °C; the tensile strength and elongation at break were increased from 2.89 MPa to 3.40 MPa and 341.62 % to 367.56 %, respectively; and the thermal stability was also apparently improved, signifying the effective enhancement of the physical properties of gelatin/starch-based composites and the broadening of their application scope. This work could provide insights into the development of biodegradable natural/synthetic polymer composites with application-beneficial characteristics.

On the architecture of starch granules revealed by iodine vapor binding and lintnerization. Part 1: Microscopic examinations

Structural nature of glucan chains in the amorphous part of granular starch was examined by iodine vapor treatment and lintnerization. Four iodine-stained amylose-containing normal starches and their waxy counterparts were examined under a microscope before, during, and after lintnerization. The presence of amylose retarded the lintnerization rate. The degree of retardation correlated with the structural type of the amylopectin component, suggesting that potato amylopectin (type 4 structure) interacts with amylose in the granules, whereas in barley granules (type 1 structure) the interaction is very weak. The inclusion complexes with iodine were not degraded by the acid treatment. Therefore, the iodine-glucan chain complex formation could be used to study the structural nature of the flexible, amorphous parts of the starch granules. Indeed, at the end of lintnerization, when 20%-30% of the granules remained, substantial amounts of blue-stained complexes were washed out from the granules especially from amylose-containing barley and maize starch, but also from both normal and waxy cassava and potato starch. The complexation with iodine did not affect the rate of lintnerization. This suggested that single helical structures were present during lintnerization also in the absence of iodine and this conformation was the reason for the acid resistance.

A comparison of the physicochemical properties, digestibility, and expression patterns of starch-related genes of two supersweet corn hybrids (F1) and their parents

The quality difference of corn largely depends on parental selection. Herein, the structure, digestive characteristics, and expression patterns of starch-related genes of two supersweet maize hybrids and their parents were studied. The structural analysis revealed that the starch of supersweet corn is round or oval, and the particles are smaller compared to those of normal corn. Hybridization changed the grain morphology, crystal, and helical structure of starch. Parents had a significantly different influence on supersweet corn. Notably, hybridization improved the setback value and digestibility of Shantian1500F1 and Shantian2000F1 compared to that of the parents. ZmBEI, ZmPHOH, and ZmAGPL2 genes had a consistent high expression throughout the whole grain formation phase. The results of this study expand our understanding of the breeding of supersweet corn hybrids and the effect of parents on the new strand. These results provide a useful reference for further breeding and studies of supersweet corn for starch production in corn.

Incomplete filling in the basal region of maize endosperm: timing of development of starch synthesis and cell vitality

Starch synthesis in maize endosperm adheres to the basipetal sequence from the apex downwards. However, the mechanism underlying nonuniformity among regions of the endosperm in starch accumulation and its significance is poorly understood. Here, we examined the spatiotemporal transcriptomes and starch accumulation dynamics in apical (AE), middle (ME), and basal (BE) regions of endosperm throughout the filling stage. Results demonstrated that the BE had lower levels of gene transcripts and enzymes facilitating starch synthesis, corresponding to incomplete starch storage at maturity, compared with AE and ME. Contrarily, the BE showed abundant gene expression for genetic processing and slow progress in physiological development (quantified by an index calculated from the expression values of development progress marker genes), revealing a sustained cell vitality of the BE. Further analysis demonstrated a significant parabolic correlation between starch synthesis and physiological development. An in-depth examination showed that the BE had more active signaling pathways of IAA and ABA than the AE throughout the filling stage, while ethylene showed the opposite pattern. Besides, SNF1-related protein kinase1 (SnRK1) activity, a regulator for starch synthesis modulated by trehalose-6-phosphate (T6P) signaling, was kept at a lower level in the BE than the AE and ME, corresponding to the distinct gene expression in the T6P pathway in starch synthesis regulation. Collectively, the findings support an improved understanding of the timing of starch synthesis and cell vitality in regions of the endosperm during development, and potential regulation from hormone signaling and T6P/SnRK1 signaling.

Influence of crystalline properties on starch functionalization from the perspective of various physical modifications: A review

The relationship between structural properties and functional characteristics of starch remains a hot subject among researchers. The crystalline property is a substantial characteristic of starch granules, undergoing different changes during modification techniques. These changes are closely related to the functional properties of modified starches. Physical modifications are eco-friendly techniques and are widely adopted for starch modifications. Therefore, understanding the impact of changes in crystalline properties during different physical modifications on starch functionality is the ultimate way to improve their industrial utilization. However, the existing literature still lacks the elucidation of changes in functional properties of starch in accordance with its crystalline properties during different physical treatments. Hence, this review summarizes the effects of the most important and widely used physical modifications on starch crystalline properties, highlighting the alterations in various functional properties such as hydration, pasting, gelatinization, and in vitro digestibility resulting from changes in crystalline characteristics in a single comprehensive discussion. Furthermore, the current review gives direction for envisaging the functionalization of starches based on deviations in the crystalline properties during several physical treatments.

Effects of amylose and amylopectin fine structure on the thermal, mechanical and hydrophobic properties of starch films

The fine structures of pumpkin, potato, wheat, cassava, and pea starches were determined, followed by an evaluation of how these structures affected the properties of starch films. The structures significantly influenced film properties. Starches with larger molecular weights exhibited greater thermal stability. The tensile strength of starch film was negatively associated with the amylose chain length (r = -0.88, p < 0.05). The chain length distributions of amylose and amylopectin affected the mechanical properties of starch films by influencing structure ordering, supported by the positive correlation between the double helix content and the tensile strength (r = 0.95, p < 0.05). The amylopectin B1, B2, and B3 chains increased film mechanical strength. Conversely, amylopectin A-chains reduced the mechanical strength. The water contact angle was negatively correlated with the B3 chain proportion (r = -0.93, p < 0.05). The pumpkin starch exhibited the highest tensile strength (14.29 MPa), while the wheat starch film showed the highest water contact angle (112°). This study offers valuable insights into the structure-function relationships of starch films, thereby facilitating the acquisition of starch films with enhanced strength and stability through screening or designing starch structures. Consequently, this will expand the application of starch films as packaging materials in various food products.

Effect of plasma-activated water on the supramolecular structure and techno-functional properties of starch: A review

This review discusses the changes in the multi-scale structure and functionality of starch after its hydrothermal modification using plasma-activated water (PAW). PAW contains reactive species that decrease the pH of the water and increase the oxidation-reduction potential, which promotes the oxidation and degradation of the surface of the starch granules to varying extents, depending on the botanical source and treatment conditions. In this article, we compile the information published so far on the effects of using PAW during heat-moisture and annealing treatments and discuss the results of the substitution of water with PAW on the long and short-range crystallinity, helical order, thermal behavior, functional properties, and digestibility. Additionally, we highlighted the possible application of PAW-modified starches. Finally, we provided an overview of future challenges, suggesting several potential directions to understand the mechanisms behind PAW use for developing sustainable modified starches for the food industry.

Biofortification of potato nutrition

BACKGROUND

Potato (Solanum tuberosum L.) is the fourth most important food crop after rice, wheat and maize in the world with the potential to feed the world's population, and potato is a major staple food in many countries. Currently, potato is grown in more than 100 countries and is consumed by more than 1 billion people worldwide, and the global annual output exceeds 300 million tons. With the rapid increase in the global population, potato will play a key role in food supply. These aspects have driven scientists to genetically engineer potato for yield and nutrition improvement.

AIM OF REVIEW

Potato is an excellent source of carbohydrates, rich in vitamins, phenols and minerals. At present, the nutritional fortification of potato has made remarkable progress, and the biomass and nutrient compositions of potato have been significantly improved through agronomic operation and genetic improvement. This review aims to summarize recent advances in the nutritional fortification of potato protein, lipid and vitamin, and provides new insights for future potato research.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review comprehensively summarizes the biofortification of potato five nutrients from protein, lipid, starch, vitamin to mineral. Meanwhile, we also discuss the multilayered insights in the prospects of edible potato fruit, vaccines and high-value products synthesis, and diploid potato seeds reproduction.

Comparative efficiency of Geotrichum candidum microcapsules prepared with alginate and in combination with other polymers: In vitro evaluation

Microencapsulation is utilized to protect probiotics, such as Geotrichum candidum, ensuring their survival, stability, and targeted release. The encapsulation efficiency depends on factors such as the type and concentration of the polymers and the encapsulation method. In this study, G. candidum was encapsulated using alginate (Alg) combined with starch (AlgS) or xanthan (Alg-X) and coated with chitosan aand chitosan nanoparticles (AlgC, Alg-S-C, Alg-X-C, Alg-CN, Alg-S-CN, and Alg-X-CN) using a simple extrusion technique. The structural characteristics and surface morphology of the microcapsules were analyzed using Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). Encapsulation efficiency (EE) and pH and temperature tolerances were assessed using in vitro assays. SEM results showed that the Alg-CN microcapsules were notably spherical and smooth, in contrast to the irregular and rough textures of the uncoated forms. Notably, Alg-CN exhibited the highest EE (99.3 %), followed by Alg-C (96.6 %) and Alg-X-CN (96.03 %). Moreover, chitosan-coated microcapsules, particularly Alg-CN, demonstrated superior viability at various pH levels and after exposure to 60 °C, along with extended shelf life at room temperature and 4 °C. These findings suggest that a 2 % alginate and 0.4 % chitosan combination is optimal for preserving G. candidum's viability in various applications.

Indole-3-Acetic Acid Esterified with Waxy, Normal, and High-Amylose Maize Starches: Comparative Study on Colon-Targeted Delivery and Intestinal Health Impact

Background: Accumulating research suggests that metabolites produced by gut microbiota are essential for maintaining a balanced gut and immune system. Indole-3-acetic acid (IAA), one of tryptophan metabolites from gut microbiota, is critical for gut health through mechanisms such as activating aryl hydrocarbon receptor. Delivery of IAA to colon is beneficial for treatment of gastrointestinal diseases, and one promising strategy is IAA esterified starch, which is digested by gut microbes in colon and releases loaded IAA. Amylose content is a key structural characteristic that controls the physicochemical properties and digestibility of starch.

METHODS

In the current study, IAA was esterified with three typical starches with distinct amylose content to obtain indolyl acetylated waxy maize starch (WMSIAA), indolyl acetylated normal maize starch (NMSIAA), and indolyl acetylated high-amylose maize starch (HAMSIAA). The study comparatively analyzed their respective physicochemical properties, how they behave under in vitro digestion conditions, their ability to deliver IAA directly to the colon, and their effects on the properties of the gut microbiota.

RESULTS

The new characteristic peak of 1H NMR at 10.83 ppm, as well as the new characteristic peak of FTIR spectra at 1729 cm-1, represented the successful esterification of IAA on starch backbone. The following in vitro digestion study further revealed that treatment with indolyl acetylation significantly elevated the resistant starch content in the starch samples. In vivo experimental results demonstrated that WMSIAA exhibited the most significant increase in IAA levels in the stomach, whereas HAMSIAA and NMSIAA demonstrated the most remarkable increases in IAA levels in the small intestine and colon, respectively. The elevated IAA levels in the colon are conducive to promoting the growth of beneficial intestinal bacteria and significantly alleviating DSS-induced colitis.

CONCLUSIONS

This research presents innovative insights and options for the advancement of colon-specific drug delivery systems aimed at preventing and curing gastrointestinal disorders.

Photo-crosslinking methacrylated-amylopectin/polyacrylamide hydrogels loading curcumin for applications as degradable, injectable, and antibacterial wound dressings

The preparation of biodegradable and antibacterial hydrogels has important clinical value. In this work, a novel strategy has been developed to prepare degradable hydrogel dressings without chemical crosslinking agent using methacrylate anhydride (MA)-modified amylopectin (APMA) and polyacrylamide (PAM). After introducing CC bonds, APMA/PAM hydrogels can be formed under light irradiation. This strategy improves the gelling ability of AP and degradation properties of the hydrogel by avoiding the addition of crosslinking agent. The degradation rate of APMA/PAM hydrogel is 74.04 ± 0.69 % within 12 weeks, while that of APMA/PAM hydrogel containing crosslinking agent is only 38.5 ± 0.1 %. The APMA/PAM hydrogel loading curcumin (Cur) (APMA/PAM-Cur) exhibits high antibacterial efficiency of 98.29 ± 0.41 % and 97.18 ± 0.81 % against S. aureus and E. coli, respectively, with light irradiation. Animal experiments show that the APMA/PAM-Cur hydrogel reduces the infiltration of inflammatory factors, increases the density of collagen, and makes the newly formed granulation tissue thicker and tighter. This study not only proves the promising potential of the APMA/PAM-Cur hydrogel as degradable and antibacterial wound dressing for clinical treatment, but also provides a new strategy for developing low-cost, degradable, and antibacterial wound dressings and reducing antibiotic abuse and environmental pollution caused by medical waste.

Biopolymers as Sustainable and Active Packaging Materials: Fundamentals and Mechanisms of Antifungal Activities

Developing bio-based and biodegradable materials has become important to meet current market demands, government regulations, and environmental concerns. The packaging industry, particularly for food and beverages, is known to be the world's largest consumer of plastics. Therefore, the demand for sustainable alternatives in this area is needed to meet the industry's requirements. This review presents the most commonly used bio-based and biodegradable packaging materials, bio-polyesters, and polysaccharide-based polymers. At the same time, a major problem in food packaging is presented: fungal growth and, consequently, food spoilage. Different types of antifungal compounds, both natural and synthetic, are explained in terms of structure and mechanism of action. The main uses of these antifungal compounds and their degree of effectiveness are detailed. State-of-the-art studies have shown a clear trend of increasing studies on incorporating antifungals in biodegradable materials since 2000. The bibliometric networks showed studies on active packaging, biodegradable polymers, films, antimicrobial and antifungal activities, essential oils, starch and polysaccharides, nanocomposites, and nanoparticles. The combination of the development of bio-based and biodegradable materials with the ability to control fungal growth promotes both sustainability and the innovative enhancement of the packaging sector.

Perspectives on Starch Structure, Function, and Synthesis in Relation to the Backbone Model of Amylopectin

Understanding functionality of polysaccharides such as starch requires molecular representations that account for their functional characteristics, such as those related to gelatinization, gelation, and crystallization. Starch macromolecules are inherently very complex, and precise structures can only be deduced from large data sets to generate relational models. For amylopectin, the major, well-organized, branched part of starch, two main molecular representations describe its structure: the classical cluster model and the more recent backbone model. Continuously emerging data call for inspection of these models, necessary revisions, and adoption of the preferred representation. The accumulated molecular and functional data support the backbone model and it well accommodates our present knowledge related to the biosynthesis of starch. This Perspective focuses on our current knowledge of starch structure and functionality directly in relation to the backbone model of amylopectin.

The effects of chain-length distributions on starch-related properties in waxy rices

Normal rice starch consists of amylopectin and amylose, whose relative amounts and chain-length distributions (CLDs) are major determinants of the digestibility and rheology of cooked rice, and are related to metabolic health and consumer preference. Here, the mechanism of how molecular structural features of pure amylopectin (waxy) starches affect starch properties was explored. Following debranching, chain-length distributions of seven waxy varieties were measured using size-exclusion chromatography, and parameterized using biosynthesis-based models, which involve breaking up the chain-length distribution into contributions from five enzyme sets covering overlapping ranges of chain length; structure-property correlations involving the fifth set were found to be statistically significant. Digestibility was measured in vitro, and parameters for the slower and longer digestion phase quantified using non-linear least-squares fitting. The coefficient for the significant correlation involving amylopectin fine structure for the fifth set was -0.903, while the amounts of amylopectin short and long chains were found to dominate breakdown viscosity (correlation coefficients 0.801 and - 0.911, respectively). This provides a methodology for finding or developing healthier starch in terms of lower digestion rate, while also having acceptable palatability. As rice breeders can to some extent control CLDs, this can help the development of waxy rices with improved properties.

Sub-high amylose maize starch: an ideal substrate to generate starch with lower digestibility by fermentation of Qu

BACKGROUND

The fermentation of Qu (FQ) is a novel method to modify the properties of starch to expand its application and especially to increase the resistant starch (RS) content. Using waxy maize starch (WMS) as a fermentation substrate can increase the RS content significantly but it may be time consuming and not cost effective due to the almost negligible RS content of WMS. To solve this problem, we hypothesized that sub-high amylose starch (s-HAMS), with an amylose content close to 50% could be an ideal substrate for FQ.

RESULTS

The results showed that FQ did not change the shape and the particle size of starch granules, the gelatinization peak (Tp), or the conclusion temperature (Tc), but the slowly digested starch content declined. Rapidly digested starch content fluctuated during FQ and the amylose content decreased within 36 h and then increased. Within 24h, FQ significanlty increased these values: the RS content, relative crystallinity (RC), the ratio of FTIR absorbances at 1047/1022cm-1, the diffraction peak at 19.8° in X-ray diffraction (XRD), and the gelatinization onset temperature (To) increased significantly, within 24 h of FQ. However, after 24 h of fermentation, the RS content, RC, the ratio of FTIR absorbances at 1047/1022 cm-1, and gelatinization enthalpy (ΔH) decreased significantly.

CONCLUSION

Sub-high amylose starch is more suitable for FQ to produce low digestibility starch, and the increase in RS may be due to the formation of 'amylose-lipid' complexes (RS5). © 2024 Society of Chemical Industry.

Potato: from functional genomics to genetic improvement

Potato is the most widely grown non-grain crop and ranks as the third most significant global food crop following rice and wheat. Despite its long history of cultivation over vast areas, slow breeding progress and environmental stress have led to a scarcity of high-yielding potato varieties. Enhancing the quality and yield of potato tubers remains the ultimate objective of potato breeding. However, conventional breeding has faced challenges due to tetrasomic inheritance, high genomic heterozygosity, and inbreeding depression. Recent advancements in molecular biology and functional genomic studies of potato have provided valuable insights into the regulatory network of physiological processes and facilitated trait improvement. In this review, we present a summary of identified factors and genes governing potato growth and development, along with progress in potato genomics and the adoption of new breeding technologies for improvement. Additionally, we explore the opportunities and challenges in potato improvement, offering insights into future avenues for potato research.

Starch-Based Functional Films Enhanced with Bacterial Nanocellulose for Smart Packaging: Physicochemical Properties, pH Sensitivity and Colorimetric Response

Starch-based pH-sensing films with bacterial nanocellulose (BNC) and red cabbage anthocyanins (RCA) as active components were investigated in this research. Their structural, physical, surface and colorimetric properties were analyzed, mainly as a function of BNC concentration. The aim of the research was to relate the changes in the intermolecular interactions between the components of the films (starch, anthocyanins and BNC) to the physical, surface and colorimetric properties that are important for the primary intended application of the produced films as pH indicators in smart packaging. The results showed that maize starch (MS) was more suitable as a matrix for the stabilization of anthocyanins compared to potato starch (PS). PS-based films showed a lower value of water contact angle than MS-based films, indicating stronger hydrophilicity. The swelling behavior results indicate that the concentrations of BNC in MS-based films (cca 10%) and the concentration of about 50% BNC in PS-based films are required if satisfactory properties of the indicator in terms of stability in a wet environment are to be achieved. The surface free energy results of PS-based films with BNC were between 62 and 68 mJ/m2 and with BNC and RCA between 64 and 68 mJ/m2; for MS-based films, the value was about 65 mJ/m2 for all samples with BNC and about 68 mJ/m2 for all samples with BNC and RCA. The visual color changes after immersion in different buffer solutions (pH 2.0-10.5) showed a gradual transition from red/pink to purple, blue and green for the observed samples. Films immersed in different buffers showed lower values of 2 to 10 lightness points (CIE L*) for PS-based films and 10 to 30 lightness points for MS-based films after the addition of BNC. The results of this research can make an important contribution to defining the influence of intermolecular interactions and structural changes on the physical, surface and colorimetric properties of bio-based pH indicators used in smart packaging applications.

Starch Characteristics and Amylopectin Unit and Internal Chain Profiles of Indonesian Rice (Oryza sativa)

Indonesia is arguably a major player in worldwide rice production. Though white rice is the most predominantly cultivated, red, brown, and red rice are also very common. These types of rice are known to have different cooking properties that may be related to differences in their starch properties. Investigating the starch properties, especially the fine structure of their amylopectin, can help understand these differences. This study aims to investigate the starch characteristics of some Indonesian rice varieties by evaluating the starch granule morphology and size, molecular characteristics, amylopectin unit and internal chain profiles, and thermal properties. Starches were extracted from white rice (long grain (IR-64) and short grain (IR-42)), brown rice, red rice, and black rice cultivated in Java Island, Indonesia. IR-42 had the highest amylose content of 39.34% whilst the black rice had the least of 1.73%. The enthalpy of gelatinization and onset temperature of the gelatinization of starch granules were between 3.2 and 16.2 J/g and 60.1 to 73.8 °C, respectively. There were significant differences between the relative molar amounts of the internal chains of the samples. The two white rice and black rice had a significantly higher amount of A-chains, but a lower amount of B-chains and fingerprint B-chains (Bfp) than the brown and red rice. The average chain length (CL), short chain length (SCL), and external chain length (ECL) were significantly longer for the red rice and the black rice in comparison to both the white rice amylopectins. The long chain length (LCL) and internal chain length (ICL) of the sample amylopectins were similar. Rice starches were significantly different in the internal structure but not as much in their amylopectin unit chain profile. These results suggest the differences in their amylopectin clusters and building blocks.

Changes of crystalline structure and physicochemical properties of Pueraria lobata var. thomsonii starch under water deficit

Crystal type is an important physicochemical property of starch. However, it is currently unclear whether changes in crystal type affect other properties of starch. This study discovered that water deficit resulted in an increase in small starch granules and transparency in Pueraria lobata var. thomsonii, while causing a decrease in amylose content and swelling power. Additionally, the crystal type of P. Thomsonii starch changed from CB-type to CA-type under water deficit, without significantly altering the short-range ordered structure and chain length distribution of starch. This transformation in crystal type led to peak splitting in the DSC heat flow curve of starch, alterations in gelatinization behavior, and an increase in resistant starch content. These changes in crystalline structure and physicochemical properties of starch granules are considered as adaptive strategies employed by P. Thomsonii to cope with water deficit.

Insight to starch retrogradation through fine structure models: A review

The retrogradation of starch is crucial for the texture and nutritional value of starchy foods products. There is mounting evidence highlighting the significant impact of starch's fine structures on starch retrogradation. Because of the complexity of starch fine structure, it is a formidable challenge to study the structure-property relationship of starch retrogradation. Several models have been proposed over the years to facilitate understanding of starch structure. In this review, from the perspective of starch models, the intricate structure-property relationship is sorted into the correlation between different types of structural parameters and starch retrogradation performance. Amylopectin B chains with DP 24-36 and DP ≥36 exhibit a higher tendency to form ordered crystalline structures, which promotes starch retrogradation. The chains with DP 6-12 mainly inhibit starch retrogradation. Based on the building block backbone model, a longer inter-block chain length (IB-CL) enhances the realignment and reordering of starch. The mathematical parameterization model reveals a positive correlation between amylopectin medium chains, amylose short chains, and amylose long chains with starch retrogradation. The review is structured according to starch models; this contributes to a clear and comprehensive elucidation of the structure-property relationship, thereby providing valuable references for the selection and utilization of starch.

Bottom-Up Synthesized Glucan Materials: Opportunities from Applied Biocatalysis

Linear d-glucans are natural polysaccharides of simple chemical structure. They are comprised of d-glucosyl units linked by a single type of glycosidic bond. Noncovalent interactions within, and between, the d-glucan chains give rise to a broad variety of macromolecular nanostructures that can assemble into crystalline-organized materials of tunable morphology. Structure design and functionalization of d-glucans for diverse material applications largely relies on top-down processing and chemical derivatization of naturally derived starting materials. The top-down approach encounters critical limitations in efficiency, selectivity, and flexibility. Bottom-up approaches of d-glucan synthesis offer different, and often more precise, ways of polymer structure control and provide means of functional diversification widely inaccessible to top-down routes of polysaccharide material processing. Here the natural and engineered enzymes (glycosyltransferases, glycoside hydrolases and phosphorylases, glycosynthases) for d-glucan polymerization are described and the use of applied biocatalysis for the bottom-up assembly of specific d-glucan structures is shown. Advanced material applications of the resulting polymeric products are further shown and their important role in the development of sustainable macromolecular materials in a bio-based circular economy is discussed.

Bio-Sourced Flame Retardants for Textiles: Where We Are and Where We Are Going

After the period of halogenated compounds, the period of nano-structured systems, and that of phosphorus (and nitrogen)-based additives (still in progress), following the increasingly demanding circular economy concept, about ten years ago the textile flame retardant world started experiencing the design and exploitation of bio-sourced products. Indeed, since the demonstration of the potential of such bio(macro)molecules as whey proteins, milk proteins (i.e., caseins), and nucleic acids as effective flame retardants, both natural and synthetic fibers and fabrics can take advantage of the availability of several low-environmental impact/"green" compounds, often recovered from wastes or by-products, which contain all the elements that typically compose standard flame-retardant recipes. The so-treated textiles often exhibit flame-retardant features that are similar to those provided by conventional fireproof treatments. Further, the possibility of using the same deposition techniques already available in the textile industry makes these products very appealing, considering that the application methods usually do not require hazardous or toxic chemicals. This review aims to present an overview of the development of bio-sourced flame retardants, focusing attention on the latest research outcomes, and finally discussing some current challenging issues related to their efficient application, paving the way toward further future implementations.