A review of structural transformations and properties changes in starch during thermal processing of foods

The mechanisms of thermal processing techniques on modifying structural, functional and flour-processing properties of whole-grain highland barley

The mechanisms underlying three thermal processing methods, namely hot-air drying, microwave irradiation, and heat fluidization, were systematically investigated to evaluate their effects on the structural, functional, and flour-processing properties of whole-grain highland barley. Starch granules were partially damaged when treated with hot-air drying and microwave irradiation. However, these granules were predominantly aggregated or encapsulated in proteins following heat fluidization. Accordingly, flour produced through heat fluidization exhibited the lowest relative crystallinity of 3.43 % and the greatest α → β shifts in secondary protein structures, compared to other treatments. These structural changes led to improved water/oil holding capacity, enhanced elastic property, reduced enthalpy of 4430 J/kg and breakdown viscosity of 0.24 Pa·s. Moreover, fresh noodles made from heat fluidization-treated highland barley exhibited superior textural features. Overall, heat fluidization could be a more effective method to modify the flour-processing properties of whole highland barley flour and enhance its applicability in the food industry.

Fish collagen mediated alteration of wheat starch thermal properties during multi-species co-fermentation

This study explores the impact of multi-species co-fermentation on the thermal properties of wheat starch, emphasizing the innovative use of fish collagen as an additive. The effects of adding different levels of fish collagen (0 %, 3 %, 6 %, 9 %, 12 %, and 15 %) on the thermal properties of starch were investigated during co-fermentation with Lactobacillus plantarum and Saccharomyces cerevisiae. Utilizing analytical techniques such as X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR), we observed a significant increase in the degree of order from 1.32 to 1.55 and a notable decrease in double helix formation from 1.51 to 0.80 (p < 0.05). The introduction of collagen induced the aggregation of B-starch granules, forming aggregates approximately 16 μm in diameter. Meanwhile, collagen addition shifted the peak thermal impact by +0.91 °C and elevated the maximum mass loss rate temperature from 309.33 °C to 317.09 °C (p < 0.05). Furthermore, a decrease in peak viscosity from 4321 cp to 3123 cp and final viscosity from 4143 cp to 3171 cp (p < 0.05), along with a 3 °C increase in pasting temperature. The results suggest that fish collagen is a potential quality improver for traditional fermented starch-based foods.

Effect of NaCl stress germination on microstructure and physicochemical properties of wheat starch

Germination can enhance the nutritional properties of wheat and improve its bioavailability, while simultaneously altering the microstructure of wheat starch, which further impacts its physicochemical characteristics. This work investigated the synergistic effects of germination and NaCl on the microstructure and physicochemical properties of wheat starch by applying a 60 mmol/L NaCl solution. The results indicated that germination significantly influenced both the chemical composition and microstructure of wheat starch, as evidenced by cracks and pores, variations in size, crystallinity, lamellar order, hydrogen bond disruption, branching degree, and molecular weight distribution. These changes affected the pasting and gel properties of the starch. The NaCl treatment enhanced enzyme activity, resulting in a higher phenolic content (4.70 mg GAE/g DW) at 48 h, rougher and irregular surfaces, smaller dimensions (D10 from 3.87 to 2.20 μm), and increased degree of heterogeneity. Over time, the NaCl-induced treatment led to a greater structural disruption, including reduced crystallinity (from 17.93 % to 14.95 %), damage the lamellar structure, and the breaking of hydrogen and glycosidic bonds. The germinated starch exhibited improved solubility and swelling power, thereby altering its pasting, gel, and thermal properties. Overall, this study provides valuable insights for the application of germinated wheat in food.

New insights into influencing the extraction efficiency of tigernut oil: Impact of heat on oil absorption and enzymatic hydrolysis of tigernut starch in a starch-protein-oil model system

Tigernut is a potential source of valuable edible oil; however, current oil extraction techniques are inefficient. We assessed high temperature-induced variations in oil absorption and enzymatic hydrolysis of tigernut starch (TS) in the presence of protein to explore the intrinsic reasons for the low oil extraction from tigernut. The results showed that, due to high temperature and the presence of protein, an increase in the volume mean diameters and agglomeration of TS granules occurred. As the temperature increased (80-140 °C), the relative crystallinity (19.09 %-24.40 %) of the long-range ordered structure and the orderliness of the short-range ordered structure increased, the total oil absorption (TOA: 0.25-0.19 g oil/g sample) decreased, and the starch-lipid complex index (2.56 %-24.61 %) increased. With increasing temperature in the range of 170-200 °C, the short-range ordered structure of TS became more compact, and the TOA (0.18-0.14 g oil/g sample) and the starch-lipid complex index (24.61 %-5.64 %) decreased. Changes in the structure of TS led to an increase and then a decrease in its thermal stability, an enhancement of the gel network structure, and a weakening of enzymatic hydrolysis. Results can help reveal the oil absorption mechanism of TS and regulate its physicochemical properties for the efficient extraction of tigernut oil.

Preparation and functional characteristics of starch-lipid complexes with different oleic acid-rich glycerolipids

Starch-lipid complexes with functional properties have gained extensive attention; however, little attention has been paid to how oleic acid-based lipid types and thermomechanical treatment affect the functional characteristics of starch. This study investigated the effects of five oleic acid-based lipids (oleic acid, monoolein, diolein, triolein, and rapeseed oil) and thermomechanical treatment on the structural and physicochemical properties of wheat starch. The crystal patterns and complexing indices showed that thermomechanical treatment promoted the formation of oleic acid, monoolein, and diolein V-type starch-lipid complexes with an intact granular structure, whereas triolein and rapeseed oil formed complexes with starch. Moreover, oleic acid, monoolein, and diolein significantly altered starch gelatinisation, retrogradation behaviour, more resistant starch formed in their complexes and thus decreased its digestibility. Rheological analyses indicated that the formation of lipid complexes increased the viscoelastic modulus of starch. Our results deepen understanding of the key role of oleic acid-rich lipids in starch-based foods.

Customizing fracture properties of pea-based snacks using 3D printing by varying composition and processing parameters

Customized textures can be achieved using extrusion-based 3D food printing by varying composition and processing parameters, e.g., printing designs and post-processing conditions. This study aims to design textural properties of customized pea-based snacks by investigating the effects of composition and multiple processing parameters on fracture behavior. Macronutrient composition of printing materials (i.e. starch-to-protein ratio), geometric design, and post-processing conditions (i.e. steaming or baking time) were systematically varied. The fracture behavior of freshly printed and post processed structures were analyzed. Samples showed elastic deformation and plastic deformation after steaming and baking, respectively. This difference in fracture behavior could be linked to microstructural changes indicated by confocal laser scanning microscopic imaging. Starch-to-protein ratio of the printing material and the geometric design also influenced the fracture behavior, but to a relatively minor extent. Moreover, fracture stress and Young's modulus were strongly influenced by the dry matter content of the samples. Statistical analysis using ANOVA was performed to establish the significance of the effect of composition and processing parameters on Young's modulus and dry matter content of samples. Based on this understanding, we propose different strategies to effectively design textural properties of snacks using 3D printing. By considering multiple factors, this study provides valuable insights into designing healthy snacks with customized textures using 3D food printing.

Using gas-assisted electrospinning to design rod-shaped particles from starch for thickening agents and Pickering emulsifiers

Starch's large particle size and compact semi-crystalline structure limit its effectiveness as an emulsifier and shear-reversible thickener. To address this, we used gas-assisted electrospinning to convert large starch granules into thin fibers and then into rod-shaped particles for use as starch-based thickeners and emulsifiers. Manipulating the starch concentration in formic acid, and the electrospinning parameters, caused the jetted polymers to form different shapes. At low starch content (<5 w/w%), electrospraying produced smaller particles (0.4-3.0 μm diameter). At higher concentrations, the polymers tangled and favored the formation of fibers (0.5-3.9 μm diameter). The starch's morphological behavior was fine-tuned by adjusting flow rate, coaxial airflow pressure, voltage, needle gauge, and jetting distance. Extensive formic acid treatment (> 4 days) caused a fiber-to-bead transition. Fiber suspensions exhibited ∼106-times higher viscosity (3215 Pa·s at a shear rate of 0.002 s-1) than unmodified starch. High-shear and ultrasonication were used post-spin to chop the fibers into rod-shaped particles (4, 6 and 8 μm length), which were used as effective emulsifiers. The longest rods (8 μm) stabilized emulsions with the smallest droplets (12 μm). Using food-safe polymers, this study demonstrated that the shape of particles plays important roles in modulating the material functionalities.

Structural evolution of maize starches with different amylose content during pasting and gelation as evidenced by Rapid Visco Analyser

This study examined multi-scale structural alterations of maize starches varying in amylose content during pasting and gelation, using Rapid Visco Analyser (RVA). At 50 °C, starch granules maintained their morphology with low viscosity. As the temperature increased to 95 °C, helical and crystal structures were destroyed, leading to granule swelling, distortion and porosity, as identified by Wide Angle X-ray Scattering and Fourier Transforms Infrared measurements at 90% moisture. This resulted in increased viscosity and the formation of a loose gel network structure. Subsequently, maintaining the temperature at 95 °C caused a decrease in viscosity as most granules disappeared, forming a reorganized flaky gel structure with larger pores. As the temperature decreased, gel porosity reduced. In high amylose content starch, the viscosity remained low and granules were partially gelatinized since the heating temperature was below the gelatinization temperature. This study is the first to detail starch multilevel structural dynamics during RVA gelatinization.

Effects of Fermentation Modification and Combined Modification with Heat-Moisture Treatment on the Multiscale Structure, Physical and Chemical Properties of Corn Flour and the Quality of Traditional Fermented Corn Noodles

This study investigates the effects of fermentation modification and combined modification with heat-moisture treatment (HMT) on the multiscale structure, physical and chemical properties, and quality of corn flour in the production of traditional fermented corn noodles (TFCNs). The results indicate that after fermentation modification, the starch granule size decreased while the amylopectin proportion increased. Fermentation also enhanced the relative crystallinity and short-range order of the starch, along with an increase in resistant digestion components and ester content in the noodles. After combined modification with HMT, starch granules lost their spherical, intact structure, underwent melting and reorganization, and displayed an increase in particle size. These changes led to a significant improvement in the thermal stability and textural properties of corn flour, resulting in noodles with enhanced cooking quality. Furthermore, the combined modification significantly increased the contents of flavor compounds such as aldehydes, acids, and alcohols in the noodles while reducing olefin and alkane levels, thus contributing to improved flavor development. These findings demonstrate that fermentation modification and combined modification with HMT play a crucial role in enhancing the multiscale structure and physical and chemical properties of corn starch, thereby improving the quality of TFCN.

Rheological, textural, and pasting properties of A- and B-type wheat starches in relation to their molecular structures

A- and B-type wheat starches have significant differences in rheological, textural, and pasting properties; however, the structure-property relationship is not fully revealed. Herein, the physicochemical characteristics and molecular structures of A- and B-type starches isolated from three wheat varieties with different apparent amylose contents (2.41%-27.93%) were investigated. A-type starches exhibited higher pasting viscosities, relative crystallinity, onset gelatinization temperatures, and enthalpies, while B-type starches had wide gelatinization temperature ranges. B-type starches had lower resistant starch contents than their A-type counterparts, but B-type starches formed more stable gels and had a lower tendency to retrograde, resulting in lower hardness, storage (G') and loss (G'') moduli but higher tan δ values. A-type starches had lower contents of short amylose (100 ≤ X < 1000) and amylopectin chains (DP 6-12) than B-type. These findings elucidated the differences in molecular structures between A- and B-type starches, which can contribute to their effective application.

Impact of Cooking on Tuber Color, Texture, and Metabolites in Different Potato Varieties

Potatoes are a globally important crop with high nutritional value. Different potato varieties display notable variations in color, texture, and nutrient composition. However, the influence of cooking on tuber color, texture, and metabolites has not been comprehensively explored. This study evaluated the color and texture of five potato varieties before and after cooking. Cooking significantly altered tuber color, decreased hardness and adhesiveness, and increased springiness, particularly after steaming. The metabolomic analysis of Zhongshu 49 (ZS49) and Shishu 3 (SH3) tubers was conducted using gas chromatography-mass spectrometry (GC-MS) and ultra-high performance liquid chromatography (UHPLC)-MS/MS. GC-MS identified 122 volatile metabolites, with 42 significantly varying between cooking treatments, while UHPLC-MS/MS detected 755 nonvolatile metabolites, 445 of which showed significant differences. Compared to ZS49, SH3 exhibited a marked increase in umami- and flavor-related metabolites, especially after cooking. This study provides new insights into how cooking affects the quality, texture, and metabolite profiles of potato tubers.

Incorporation of germinated lupin into corn-based extrudates: Focus on starch digestibility, matrix structure and physicochemical properties

The research aimed to assess the effects of incorporating germinated Lupinus angustifolius flour into corn extrudates for different periods (3, 5, and 7 days), focusing on starch digestibility, morphological structure, thermal, and pasting properties. Extrudate with germinated lupinus flour for 7 days (EG7) significantly increased the content of slowly digestible starch up to 10.56% (p < 0.05). Crystallinity increased up to 20% in extrudates with germinated flour compared to extrudates with ungerminated flour (EUG), observing changes at the molecular level by FTIR that impact the thermal and pasting properties. X-ray diffraction revealed angles of 2θ = 11.31, 16.60, 19.91, and 33.04 as a result of the germination and extrusion processes. Microstructural analysis indicated starch-protein interactions influencing changes in calorimetry, viscosity, X-ray diffraction, and digestibility. PCA allowed establishing that the addition of germinated flours significantly affected the properties and microstructural characteristics of extruded products, potentially affecting digestibility and nutritional quality.

Insights into impact of chlorogenic acid on multi-scale structure and digestive properties of lotus seed starch under autoclaving treatment

The interaction between polyphenols and starch is an important factor affecting the structure and function of starch. Here, the impact of chlorogenic acid on the multi-scale structure and digestive properties of lotus seed starch under autoclaving treatment were evaluated in this study. The results showed that lotus seed starch granules were destroyed under autoclaving treatment, and chlorogenic acid promoted the formation of loose gel structure of lotus seed starch. In particular, the long- and short-range ordered structure of lotus seed starch-chlorogenic acid complexes were reduced compared with lotus seed starch under autoclaving treatment. The relative crystallinity of A-LS-CA complexes decreased from 23.4 % to 20.3 %, the value of R1047/1022 reduced from 0.87 to 0.80, and the proportion of amorphous region increased from 10.26 % to 13.85 %. In addition, thermal stability, storage modulus and loss modulus of lotus seed starch-chlorogenic acid complexes were reduced, indicating that the viscoelasticity of lotus seed starch gel was weakened with the addition of chlorogenic acid. It is remarkable that chlorogenic acid increased the proportion of resistant starch from 58.25 ± 1.43 % to 63.85 ± 0.96 % compared with lotus seed starch under autoclaving treatment. Here, the research results provided a theoretical guidance for the development of functional foods containing lotus seed starch.

Recent advances in the impact of gelatinization degree on starch: Structure, properties and applications

During home cooking or industrial food processing operations, starch granules usually undergo a process known as gelatinization. The starch gelatinization degree (DG) influences the structural organization and properties of starch, which in turn alters the physicochemical, organoleptic, and gastrointestinal properties of starchy foods. This review summarizes methods for measuring DG, as well as the impact of DG on the starch structure, properties, and applications. Enzymatic digestion, iodine colorimetry, and differential scanning calorimetry are the most common methods for evaluating the DG. As the DG increases, the structural organization of the molecules within starch granules is progressively disrupted, the particle size of the granules is altered due to swelling and then disruption, the crystallinity is decreased, the molecular weight is reduced, and the starch-lipid complexes are formed. The impact of DG on the starch structure and properties depends on the processing method, operating conditions, and starch source. The starch DG affects the quality of many foods, including baked goods, fried foods, alcoholic beverages, emulsified foods, and edible inks. Thus, a better understanding of the changes in starch structure and function caused by gelatinization could facilitate the development of foods with novel or improved properties.

High-Resistant Starch Based on Amylopectin Cluster via Extrusion: From the Perspective of Chain-Length Distribution and Structural Formation

Resistant starch (RS) has the advantage of reshaping gut microbiota for human metabolism and health, like glycemic control, weight loss, etc. Among them, RS3 prepared from pure starch is green and safe, but it is hard to achieve structural control. Here, we regulate the crystal structure of starch with different chain-length distributions (CLDs) via extrusion at low/high shearing levels. The change in CLDs in extruded starch was obtained, and their effects on the fine structure (Dm, dBragg, dLorentz, degree of order and double helix, degree of crystal) of RS and its physicochemical properties were investigated by SAXS, FTIR, XRD and 13C NMR analyses. The results showed that the RS content under a 250 r/min extrusion condition was the highest at 61.52%. Furthermore, the crystalline system induced by high amylopectin (amylose ≤ 4.78%) and a small amount of amylose (amylose ≥ 27.97%) was favorable for obtaining a high content of RS3-modified products under the extruding environment. The control of the moderate proportion of the A chains (DP 6-12) in the starch matrix was beneficial to the formation of RS.

Impact of Processing on the Phenolic Content and Antioxidant Activity of Sorghum bicolor L. Moench

Sorghum, a cereal grain rich in nutrients, is a major source of phenolic compounds that can be altered by different processes, thereby modulating their phenolic content and antioxidant properties. Previous studies have characterised phenolic compounds from pigmented and non-pigmented varieties. However, the impact of processing via the cooking and fermentation of these varieties remains unknown. Wholegrain flour samples of Liberty (WhiteLi1 and WhiteLi2), Bazley (RedBa1 and RedBa2), Buster (RedBu1 and RedBu2), Shawaya black (BlackSb), and Shawaya short black 1 (BlackSs) were cooked, fermented, or both then extracted using acidified acetone. The polyphenol profiles were analysed using a UHPLC-Online ABTS and QTOF LC-MS system. The results demonstrated that combining the fermentation and cooking of the BlackSs and BlackSb varieties led to a significant increase (p < 0.05) in total phenolic content (TPC) and antioxidant activities, as determined through DPPH, FRAP, and ABTS assays. The 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity of WhiteLi1, BlackSb, RedBu2, and BlackSs increased by 46%, 32%, 25%, and 10%, respectively, post fermentation and cooking. Conversely, fermentation only or cooking generally resulted in lower phenolic content and antioxidant levels than when samples were fully processed compared to raw. Notably, most of the detected antioxidant peaks (53 phenolic compounds) were only detected in fermented and cooked black and red pericarp varieties. The phenolic compounds with the highest antioxidant activities in pigmented sorghum included 3-aminobenzoic acid, 4-acetylburtyic acid, malic acid, caffeic acid, and luteolin derivative. Furthermore, the growing location of Bellata, NSW, showed more detectable phenolic compounds following processing compared to Croppa Creek, NSW. This study demonstrates that sorghum processing releases previously inaccessible polyphenols, making them available for human consumption and potentially providing added health-promoting properties.

Effects of hydrocolloids on mechanical properties, viscoelastic and microstructural properties of starch-based modeling clay

The effects of various hydrocolloids (guar gum, xanthan gum, and carboxymethyl cellulose) on the texture, rheology, and microstructural properties of modeling clay prepared with cassava starch were investigated. Notably, incorporation of 3 % guar gum and 4 % xanthan gum into starch-based modeling clay resulted in enhancements of 94.12 % and 77.47 % in cohesiveness, and 64.70 % and 66.20 % in extensibility, respectively. For starch-based modeling clay with added guar gum and xanthan gum, compared to formulations without hydrocolloids, the linear viscoelastic range exceeded 0.04 %, and the frequency dependence of both maximum creep compliance (Jmax) and storage modulus (G') was significantly reduced. This indicates a more stable network structure and enhanced resistance to deformation. Results from Fourier Transform Infrared (FTIR) spectroscopy and X-ray diffraction (XRD) confirmed that the physical interactions between starch and various hydrocolloids, along with the addition of these hydrocolloids, inhibited the degradation effect of thermomechanical processing on the crystalline structure of starch. With the addition of guar gum, it is observed that a continuous and dense network structure forms within the starch-based modeling clay, and starch particles are distributed uniformly. In conclusion, hydrocolloids enhances the properties of starch-based modeling clay, introducing an innovative solution to the modeling clay sector.

Enhancing the nutritional and bioactive benefits of faba bean flour by combining preprocessing and thermoplastic extrusion: A comprehensive study on digestion-resistant peptides

This research assessed how three preprocessing techniques [soaking (S), soaking and reconstitution (SR), and soaking and dehulling (SD)] impact the protein digestibility and bioactivity of faba bean flours when combined with thermoplastic extrusion. Samples were compared against a control (C) of extruded faba bean flour without preprocessing. Applying preprocessing techniques followed by extrusion diminished antinutrient levels while enhancing protein hydrolysis and in vitro bioactivity in higher extent compared to C. Specifically, SD combined with extrusion was the most effective, achieving an 80% rate of protein hydrolysis and uniquely promoting the release of gastric digestion-resistant proteins (50-70 kDa). It also resulted in the highest release of small peptides (<3kDa, 22.51%) and free amino acids (15.50%) during intestinal digestion. Moreover, while all preprocessing techniques increased antioxidant (ABTS radical-scavenging), antidiabetic, and anti-hypertensive activities, SD extruded flour displayed the highest levels of dipeptidyl peptidase inhibition (DPP-IVi, IC50=13.20 µg/mL), pancreatic α-amylase inhibition (IC50=8.59 mg/mL), and angiotensin I-converting enzyme inhibition (ACEi, IC50=1.71 mg protein/mL). As a result, it was selected for further peptide and in silico bioactive analysis. A total of 24 bioactive peptides were identified in intestinal digests from SD extruded flour, all with potential DPP-IVi and ACEi activities, and six were also predicted as antioxidant peptides. VIPAGYPVAIK and GLTETWNPNHPEL were highlighted as resistant bioactive peptides with the highest antidiabetic and antioxidant potential. Our findings demonstrated that combining preprocessing (particularly SD) and thermoplastic extrusion enhances protein digestibility in faba beans and promotes the release of beneficial bioactive peptides in the intestine.

The effect of stir-frying on the aging of oat flour during storage: A study based on lipidomics

In this study, we used the LC-ESI-MS/MS technique to elucidate the effects of stir-frying on the lipidomics of oat flour before and after storage. We detected 1540 lipids in 54 subclasses; triglycerides were the most abundant, followed by diacylglycerol, ceramide (Cer), digalactosyldiacylglycerol, cardiolipin, and phosphatidylcholine. Principal component analysis and orthogonal least squares discriminant analysis analyses showed that oat flour lipids were significantly different before and after storage in stir-fried oat flour and raw oat flour. After oat flour was stir-fried, most of the lipid metabolites in it were significantly downregulated, and the changes in lipids during storage were reduced. Sphingolipid metabolism and ether lipid metabolism were the key metabolic pathways, and Cer, PC, and lyso-phosphatidylcholine were the key lipid metabolites identified in the related metabolic pathways during oat flour storage. Frying inhibits lipid metabolic pathways during storage of oat flour, thereby improving lipid stability and quality during storage. This study laid the foundation for further investigating quality control and the mechanism of changes in lipids during the storage of oat flour.

Improvement on wheat bread quality by in situ produced dextran-A comprehensive review from the viewpoint of starch and gluten

Deterioration of bread quality, characterized by the staling of bread crumb, the softening of bread crust and the loss of aroma, has caused a huge food waste and economic loss, which is a bottleneck restriction to the development of the breadmaking industry. Various bread improvers have been widely used to alleviate the issue. However, it is noteworthy that the sourdough technology has emerged as a pivotal factor in this regard. In sourdough, the metabolic breakdown of carbohydrates, proteins, and lipids leads to the production of exopolysaccharides, organic acids, aroma compounds, or prebiotics, which contributes to the preeminent ability of sourdough to enhance bread attributes. Moreover, sourdough exhibits a "green-label" feature, which satisfies the consumers' increasing demand for additive-free food products. In the past two decades, there has been a significant focus on sourdough with in situ produced dextran due to its exceptional performance. In this review, the behaviors of bread crucial compositions (i.e., starch and gluten) during dough mixing, proofing, baking and bread storing, as well as alterations induced by the acidic environment and the presence of dextran are systemically summarized. From the viewpoint of starch and gluten, results obtained confirm the synergistic amelioration on bread quality by the coadministration of acidity and dextran, and also highlight the central role of acidification. This review contributes to establishing a theoretical foundation for more effectively enhancing the quality of wheat breads through the application of in situ produced dextran.

Effects of cooking methods on the physical properties and in vitro digestibility of starch isolated from Chinese yam

The objective of this study was to compare the structural and functional attributes of Chinese yam starches obtained via different domestic cooking methods. Cooking changed the crystalline type from the C type to the CB type, and disrupted the short- and long-range molecular order of Chinese yam starch. The average chain length of amylopectin in BOS (boiling starch) was the smallest at 22.78, while RWS had the longest average chain length, reaching 24.24. These alterations in molecular structure resulted in variations in functional properties such as solubility, swelling power (SP), pasting characteristics, and rheological properties. Among these alterations, boiling was the most effective method for increasing the water-binding capacity and SP of starch. Specifically, its water holding capacity was 2.12 times that of RWS. In vitro digestion experiments indicated that BOS has a higher digestion rate (k = 0.0272 min-1) and lower RDS (rapidly digestible starch), which may be related to its amylopectin chain length distribution. This study can guide us to utilize yam starch through suitable cooking methods, which is relevant for the processing and application of Chinese yam starch.

Effects of frying on the surface oil absorption of wheat, potato, and pea starches

The effects of structural changes on surface oil absorption characteristics of wheat starch, pea starch and potato starch during frying under different water content (20%, 30%, 40%, 50%) were studied. Fried potato starch with a 40% water content exhibited the highest surface oil content. When the initial moisture content reached 30%, the scattering intensity of the crystal layer structure decreased for wheat and pea starches, while the scattering peak for potato starch completely disappeared. At 40% moisture content, the amorphous phase ratio values for fried potato, wheat and pea starches were 13.50%, 11.78% and 11.24%, respectively, and the nitrogen adsorption capacity of fried starch decreased in turn. These findings that the structure of potato starch was more susceptible to degradation compared to pea starch and wheat starch, resulting in higher surface oil absorbed by potato starch during frying process.

A review of the effects of fermentation on the structure, properties, and application of cereal starch in foods

Fermentation is one of the oldest food processing techniques known to humans and cereal fermentation is still widely used to create many types of foods and beverages. Starch is a major component of cereals and the changes in its structure and function during fermentation are of great importance for scientific research and industrial applications. This review summarizes the preparation of fermented cereals and the effects of fermentation on the structure, properties, and application of cereal starch in foods. The most important factors influencing cereal fermentation are pretreatment, starter culture, and fermentation conditions. Fermentation preferentially hydrolyzes the amorphous regions of starch and fermented starches have a coarser appearance and a smaller molecular weight. In addition, fermentation increases the starch gelatinization temperature and enthalpy and reduces the setback viscosity. This means that fermentation leads to a more stable and retrogradation-resistant structure, which could expand its application in products prone to staling during storage. Furthermore, fermented cereals have potential health benefits. This review may have important implications for the modulation of the quality and nutritional value of starch-based foods through fermentation.

Effects of oil and heating on the physicochemical and microstructural properties of gluten-starch dough

Oil has crucial applications for improving the quality of some wheat products during dough formation and heat-processing. Herein, the influence of oil modification and thermal-mechanical treatment on dough prepared mainly with wheat starch and gluten was investigated. Oils with different structures addition reduced the hardness but improved the tensile strength of dough and inhibited starch retrogradation. Oil also reduced the disulfide bond, hydrogen bond and hydrophobic interactions whilst changed the rheology of dough. The X-ray diffraction patterns were characterised by new weak peaks at approximately 12.9°, and 19.8°, indicating that thermal-mechanical treatment promoted the formation of V-type complexes. Oil modification impaired dough short-range ordered structure, but prevented part starch granule crystallinity degradation caused by thermal-mechanical treatment. Scanning electron microscopy revealed oil modification and thermal-mechanical treatment synergistically affected starch-gluten agglomeration. Our findings contributed to elucidate the influence of oil modification and thermal-mechanical treatment on dough functionality.

Functionality differences between esterified and pregelatinized esterified starches simultaneously prepared by octenyl succinic anhydride modification and its application in dough

Octenyl succinic anhydride (OSA)-modified starches have gained widespread interest, but the modification can produce two starches with different states ignored. Herein, the two types of starches, esterified starch (ES) and pregelatinized esterified starch (PES), prepared by OSA modification were separated, and their structural and functional characteristics were comprehensively explored. Results showed that compared with native starch (NS), ES and PES exhibited high water-holding capacity, solubility, and swelling power and significantly decreased pasting temperature and thermal stability. Dynamic rheological tests illustrated that OSA modification changed the rheological behavior of starches. Fourier transform infrared spectroscopy confirmed that PES with higher degree of substitution showed more obvious ester carbonyl and carboxylate groups than ES. Laser confocal micro-Raman spectroscopy revealed that the short-range molecular order of ES, especially PES, decreased after modification. X-ray diffraction indicated that OSA modification disrupted the crystalline structure of starch, and that more amylose-lipid complex was formed in PES. Scanning electron microscopy showed that OSA modification eroded starchs surface and reduced its smoothness, and significantly disrupted PES integrity. ES and PES could be developed as food additives for retrogradation inhibition of dough. These results provide new insights into OSA modification and expand its functional application in foods.

New Insight into the Effects of Endogenous Protein and Lipids on the Enzymatic Digestion of Starch in Sorghum Flour

The effects of endogenous lipids and protein in sorghum flour on starch digestion were studied following the depletion of lipids and/or protein and after the reconstitution of separated fractions. The removal of protein or lipids moderately increases the digestibility of starch in raw (uncooked) sorghum flour to values close to those for purified starch. Rapid Visco Analyzer data (as a model for the cooking process) show that cooked sorghum flours with lipids have a lower starch digestibility than those without lipids after RVA processing, due to the formation of starch-lipid complexes as evidenced by their higher final viscosity and larger enthalpy changes. Additionally, the formation of a starch-lipid-protein ternary complex was identified in cooked sorghum flour, rather than in a reconstituted ternary mixture, according to the unique cooling stage viscosity peak and a greater enthalpy of lipid complexes. After heating, the sorghum flour showed a lower digestibility than the depleted flours and the reconstituted flours. The results indicate that the natural organization of components in sorghum flour is an important factor in facilitating the interactions between starch, lipids, and protein during RVA processing and, in turn, reducing the starch digestion.

Evaluation of dual modification by high hydrostatic pressure and annealing on the physicochemical properties of bean starch

This study investigated the physical modifications by high hydrostatic pressure (HHP) at 600 MPa for 30 min/30 °C, annealing (AN) at 50 °C/24 h and the combination of both (HHP + AN and AN + HHP) applied to yellow bean starch to verify changes in morphology, X-ray diffraction, molecular order, thermal properties and pasting properties of native (NS) and modified starches. Morphological analysis showed loss of sphericity and increase in diameter with the appearance of pores on the surface after application of treatments. The AN starch showed lower values of syneresis, degree of double helix (DD), order (DO), and viscosity of the paste obtained by RVA. It exhibited a Vh-type classification with the appearance of the amylose-lipid complex. However, the gelatinization temperatures, as well as the enthalpy of gelatinization, were significantly higher. On the other hand, the starch treated with HHP showed a higher Setback (SB) value. The greatest modifications were found for the starches subjected to the combined treatments (AN + HHP) and (HHP + AN), where the order of the treatments was significant for the morpho-structural changes of yellow bean starch. According to the micrographs, the surface aspect was altered, with AN + HHP showing greater irregularities and flat yet irregular faces, as well as a larger granule diameter (147.05). The X-ray diffractogram showed a reduction in crystallinity from 28.14 % (NS) to 18.09 % (AN + HHP) and classified the starch as type "A". The double modification (HHP + AN and AN + HHP) reduced the gelatinization temperature and the enthalpy of gelatinization but had no effect on the bands of the FT-IR spectrum. There was only a reduction in the degree of order and the double helix. Finally, the treatment with AN + HHP is more effective as the gelatinization with AN facilitates the application of HHP. Both methods used are classified as physical (thermal and non-thermal), aiming to minimize environmental impacts and achieve faster and safer morpho-structural modification without leaving chemical residues in the products.

Effect of Konjac Glucomannan on Structure, Physicochemical Properties, and In Vitro Digestibility of Yam Starch during Extrusion

In this study, the effect of konjac glucomannan (KGM, 0-5%) on the structure, physicochemical properties, and in vitro digestibility of extruded yam starch (EYS) was investigated. The EYS became rougher on the surface and the particle size increased as observed using scanning electron microscopy and particle size analysis. X-ray diffraction and Raman results revealed that the relative crystallinity (18.30% to 22.30%) of EYS increased, and the full width at half maxima at 480 cm-1 decreased with increasing KGM content, indicating the increment of long-range and short-range ordered structure. Differential scanning calorimetry and rheological results demonstrated that KGM enhanced thermal stability and the gel strength of EYS due to enhanced interaction between KGM and YS molecules. Additionally, a decrease in the swelling power and viscosity of EYS was observed with increased KGM content. The inclusion of KGM in the EYS increased the resistant starch content from 11.89% to 43.51%. This study provides a dual-modified method using extrusion and KGM for modified YS with high thermal stability, gel strength, and resistance to digestion.

Oil structuring from porous starch to powdered oil: Role of multi-scale structure in the oil adsorption and distribution

Oil structuring from porous starch is a potential alternative for the industrial production of powdered oil, but their relationship between starch multi-scale structure and oil adsorption characteristics was not clear. This study compared the role of multi-scale structure of porous starch (PS) prepared by normal and waxy maize starch in the oil adsorption. Waxy maize porous starch exhibited higher oil adsorption capacity (32.43 %-98.71 %) and more oil distributed on the surface of granules than normal maize porous starch, resulting from the more pores, larger specific surface area (1.01-1.53 m2/g), and pore size (8.45-9.32 nm). The enzymolysis time of native starch dominated oil distribution, leading to different granule adhesion and aggregation state. Pearson correlation analysis further showed oil adsorption capacity was negatively correlated with particle size, but positively correlated with enzymolysis rate and specific surface area of PS. The formation of powdered oil was mainly through the physical adsorption, including surface adsorption and pore adsorption. These findings could provide a promising route for the preparation of powdered oil with controlled multi-scale structure of PS.

A comprehensive review on starch: Structure, modification, and applications in slow/controlled-release fertilizers in agriculture

This comprehensive review thoroughly examines starch's structure, modifications, and applications in slow/controlled-release fertilizers (SRFs) for agricultural purposes. The review begins by exploring starch's unique structure and properties, providing insights into its molecular arrangement and physicochemical characteristics. Various methods of modifying starch, including physical, chemical, and enzymatic techniques, are discussed, highlighting their ability to impart desirable properties such as controlled release and improved stability. The review then focuses on the applications of starch in the development of SRFs. It emphasizes the role of starch-based hydrogels as effective nutrient carriers, enabling their sustained release to plants over extended periods. Additionally, incorporating starch-based hydrogel nano-composites are explored, highlighting their potential in optimizing nutrient release profiles and promoting plant growth. Furthermore, the review highlights the benefits of starch-based fertilizers in enhancing plant growth and crop yield while minimizing nutrient losses. It presents case studies and field trials demonstrating starch-based formulations' efficacy in promoting sustainable agricultural practices. Overall, this review consolidates current knowledge on starch, its modifications, and its applications in SRFs, providing valuable insights into the potential of starch-based formulations to improve nutrient management, boost crop productivity, and support sustainable agriculture.

Structural changes of thermally treated starch during digestion and the impact on postprandial glucose homeostasis

Intake of foods upon thermal treatment is typically associated with an elevated postprandial glycemic response, which is one of the risk factors for type 2 diabetes development and progression. In this study, rice starch was thermally treated using aqueous phase (boil), air phase (bake), and lipid phase (fry). Peak blood glucose levels in C57 mice increased by 16.94 %, 12.60 %, and 8.1 % after ingestion of thermally treated starch (20.23, 19.48, and 18.70 mmol/L), compared with raw starch (17.30 mmol/L). The insulin response to the intake of thermally treated starch increased (4.73 %-6.83 % higher than the control), whereas the concentration of GLP-1, a hormone used to promote insulin secretion, decreased (1.54 %-8.56 % lower than the control). Furthermore, thermally treated starch accelerated food absorption by enhancing gastrointestinal digestion, exacerbating postprandial glucose fluctuation at the next meal. Structural characterization showed thermal treatment reduced starch branching density and degree of structure order, which were not conducive to preventing the attack of enzymes. During digestion, they were highly hydrolyzed into low-molecular-weight fragments, and the proportion of ultrashort chains substantially increased. These findings provide a better understanding of the fine structure of starch that promotes hypoglycemia and initially explain how diets high in thermally treated starch impair glucose balance.

Electron beam irradiation modification of ultra-high pressure treated broad bean starch: Improvement of multi-scale structure and functional properties

To investigate the synergistic effect of electron beam irradiation (EBI) on the ultra-high pressure (UHP) modification of broad bean starch, various pressures (200, 400, 600 MPa) combined with different irradiation doses (3, 6, 12 kGy) were used to modify the structure-properties of broad bean starch in this study. The results showed that both UHP and EBI induced a reduction of amylopectin molecular weight (Mw) and depolymerization of long chains, caused the loss of short-range ordered structure and imperfection of crystal structure, and improved starch viscosity, solubility and enzyme sensitivity. Furthermore, the applied pressure causes changes in starch granule structure, upon which EBI promotes further degradation and depolymerization of starch by affecting the crystalline and amorphous regions. Hence, appropriate doses of EBI treatment can impart more desirable processing properties to UHP-modified starches, and EBI can be used as a promising way to promote starch modification further.

A Review on Isolation, Characterization, Modification, and Applications of Proso Millet Starch

Proso millet starch (PMS) as an unconventional and underutilized millet starch is becoming increasingly popular worldwide due to its health-promoting properties. This review summarizes research progress in the isolation, characterization, modification, and applications of PMS. PMS can be isolated from proso millet grains by acidic, alkaline, or enzymatic extraction. PMS exhibits typical A-type polymorphic diffraction patterns and shows polygonal and spherical granular structures with a granule size of 0.3-17 µm. PMS is modified by chemical, physical, and biological methods. The native and modified PMS are analyzed for swelling power, solubility, pasting properties, thermal properties, retrogradation, freeze-thaw stability, and in vitro digestibility. The improved physicochemical, structural, and functional properties and digestibility of modified PMS are discussed in terms of their suitability for specific applications. The potential applications of native and modified PMS in food and nonfood products are presented. Future prospects for research and commercial use of PMS in the food industry are also highlighted.

Physicochemical and In Vitro Starch Residual Digestion Structures of Extruded Maize and Sorghum Starches Added with Sodium Stearoyl Lactylate

This research aimed to characterize the physicochemical, in vitro digestion, and structural features of digestion residues of maize and sorghum starches subjected to thermoplastic extrusion, along with the influence of Sodium Stearoyl Lactylate (SSL), to obtain improved starches for food applications and to understand their behavior when consumed as a food ingredient. The morphology of the extruded materials showed remanent starch granules when SSL was used. A higher amount of medium and large linear glucan chains were found in these particles, influencing higher thermal stability (ΔH ≈ 4 J/g) and a residual crystallinity arrangement varying from 7 to 17% in the extrudates. Such structural features were correlated with their digestibility, where slowly digestible starch (SDS) and resistant starch (RS) fractions ranged widely (from 18.28 to 27.88% and from 0.13 to 21.41%, respectively). By analyzing the data with a Principal component analysis (PCA), we found strong influences of B2 and B3 type chains on the thermal stability of the extrudates. The amylose and smaller glucan chains (A and B1) also significantly affected the emulsifying and foam stability properties. This research contributes to the molecular knowledge of starch in extruded products with broad food applications.

Effect of Storage Time and Temperature on Digestibility, Thermal, and Rheological Properties of Retrograded Rice

Retrogradation is defined as the recrystallization or realignment of amylose and amylopectin chains upon cooling of gelatinization starch gels. The storage conditions such as the storage time and temperature are crucial factors that influence and govern the degree of retrogradation and in turn, affect the formation of resistant starch and alteration of thermal and rheological properties. This article investigates the effect of storage time and temperature on the properties of retrograded rice starch. Rice kernels of five different indigenous varieties, namely Diasang lahi, Khaju lahi, Dhusuri bao, Omkar, and Bili rajamudi were cooked by boiling in water and stored at 4 °C and -20 °C for 6 and 12 h, respectively. Differential scanning calorimetry (DSC) studies revealed in raw form that Bili rajamudi exhibited the highest peak gelatinization temperature (T_p, °C) at 79.05 °C whereas Diasang lahi showed the least T_p at 56.12 °C. Further, it was indicated that the T_p and degree of retrogradation (DR%) also increase with increasing time and decreasing temperature of storage. All samples stored at -20 °C for 12 h exhibited the highest degree of retrogradation DR%. Amongst all five varieties stored at -20 °C for 12 h, Omkar exhibited the highest %DR, followed by Bili rajamudi, Khaju lahi, Dhusuri bao, and Diasang lahi. A negative correlation was also established between T_p and resistant starch content (RS%). It was also observed that the resistant starch (RS%) content increased with the increasing time and decreasing temperature of storage. A strong negative correlation was observed between RS% and non-resistant starch (NRS%). Further, rheological studies indicated that retrogradation also affects the viscosity and dynamic rheological properties of starch. In this study, it was evident that extending storage duration from 6 to 12 h and lowering temperature from 4 to -20 °C impact retrogradation of rice starch, which in turn affects the starch's gelatinization, digestibility, and rheology. Rice starch retrograded at lower temperatures for a longer period could prove to be extremely beneficial for development of food products with better textural properties and high RS content or low glycemic index.

Impact of starch-lipid complexes on oil absorption of starch and its mechanism

BACKGROUND

Worldwide, fried food has a huge demand and good development prospects. Low oil in foods is the standard that everyone is now pursuing for a healthy diet.

RESULTS

The oil absorption behavior of rice starch during frying was investigated in the presence or absence of fatty acids or fatty acid esters with different carbon chain lengths. The complex formed between starch and fatty acids or fatty acid esters was dependent on lipid chain length, which was confirmed by X-ray diffraction and complexing index. The formation of starch-lipid complexes could significantly reduce the oil absorption of starch, and the complexes with higher complexing index had lower oil absorption. The starch-palmitic acid complex showed the lowest oil absorption after frying, which was 14.06 g per 100 g lower than that of gelatinized starch. This was attributed to the ability of the palmitic acid to increase the density of starch crystalline polymorphs as well as their ability to complex with the amylose spiral cavity.

CONCLUSION

These results may be useful for development of healthier fried starch-based foods with reduced oil contents. © 2022 Society of Chemical Industry.

Formation of Starch-Lipid Complexes during the Deep-Frying Process and Its Effects on Lipid Oxidation

In the present study, maize starch (MS), potato starch (PS), high-amylose maize starch (HAMS), and wheat starch (WS) were deep-fried in soybean oil that was continuously heated for 40 h under 180 °C. The thermodynamic and pasting properties of deep-fried starch samples were determined. The results suggested that starch−lipid complexes formed with the extension of frying oils’ usage; however, their number was not dependent on the frying oils’ life cycle. Importantly, the results of pasting properties revealed the following strength of intermolecular force in deep-fried starch samples: PS > MS > HAMS > WS. The results of XRD and FTIR analysis confirmed the formation of starch−lipid complexes during the deep-frying process. Furthermore, the results of the in vitro digestibility of deep-fried starch revealed that the formation of starch−lipid complexes inhibited the swelling of starch granules and prevented the entrance of amylase into the interior. Additionally, the results of the oxidation stability of deep-frying oil indicated that the formation of starch−lipid complexes did not alter the trend of lipid oxidation as an effect of the limited number of starch−lipid complexes. These results could have critical implications for the development of healthier deep-fried foods.

Study on adsorption of low-concentration methyl mercaptan by starch-based activated carbon

The development of a low-concentration methyl mercaptan adsorbing material for an efficient decontamination has become a hot research topic. In this study, carbonization activation was employed with starch and urea as carbon and nitrogen sources, respectively, to prepare a type of starch-based activated carbon. Subsequently, the product was used to adsorb low-concentration methyl mercaptan. Based on sorption experiments and molecular simulations, the underlying mechanism of the adsorption effect of the adsorbent's pore structure and surface oxygen- and nitrogen-containing functional groups on methyl mercaptan molecules were discussed. The results indicated that when the methyl mercaptan equilibrium concentration was 0.197 mg/L, the adsorption capacity of SUAC-16-2 for methyl mercaptan was 78.16 mg/g. Its adsorption performance was better than that of its previously reported counterparts. The well-developed microporous structure of SUAC-16-2 promoted the adsorption of methyl mercaptan. In addition, methyl mercaptan molecules could be broken down to produce CH₃S^- and H⁺ by the effect of the surface functional groups. Adjacent carbon atoms containing nitrogen and oxygen functional groups could better adsorb CH₃S^- and H⁺, and further strengthen the methyl mercaptan adsorption performance of activated carbon. The study could help to develop new technology for treatment of low concentration of methyl mercaptan in the air.

Effects of Extrusion on Starch Molecular Degradation, Order-Disorder Structural Transition and Digestibility-A Review

Extrusion is a thermomechanical technology that has been widely used in the production of various starch-based foods and can transform raw materials into edible products with unique nutritional characteristics. Starch digestibility is a crucial nutritional factor that can largely determine the human postprandial glycemic response, and frequent consumption of foods with rapid starch digestibility is related to the occurrence of type 2 diabetes. The extrusion process involves starch degradation and order-disorder structural transition, which could result in large variance in starch digestibility in these foods depending on the raw material properties and processing conditions. It provides opportunities to modify starch digestibility by selecting a desirable combination of raw food materials and extrusion settings. This review firstly introduces the application of extrusion techniques in starch-based food production, while, more importantly, it discusses the effects of extrusion on the alteration of starch structures and consequentially starch digestibility in various foods. This review contains important information to generate a new generation of foods with slow starch digestibility by the extrusion technique.

Effect and mechanism of glycerol monostearate dimer (GMS-D) and baking-treatment on the structure, in vitro digestion of gelatinized potato starch-GMS-D

With the increasing progress of society and in-depth scientific research, dietary regulations, especially sustained glucose releases, are regarded as an effective and significant way to lighten or even cut the emergence of diabetes. In this research, the starch-lipid complex gelatinized potato starch-glycerol monostearate dimer (GPS-GMS-D) was developed to provide a low-glycemic index functional food component for type 2 diabetes. Briefly, the higher complexation index (CI, 71.02%), lower rapidly digestible starch (RDS, 35.57%), and lower estimated glycemic index (eGI, 52.34%) were referred to as GPS-GMS-D. It was assumed that the solid V-type crystal structure, induced with the helix between GMS-D and GPS due to high amylose, high saturation, and low steric hindrance, contributed to the lower digestibility. In addition, baking treatment for 5 min was systematically exerted to improve the flavor of GPS-GMS-D with a relatively high CI (59.98%) and low eGI (54.15%). It was believed that rapid dehydration and close interaction during baking treatment could slow down the decomposition of GPS-GMS-D and conversions of starch fractions. Therefore, these results suggested that the as-developed GPS-GMS-D was a promising low GI functional dietary food component for diabetes mellitus, and a suitable baking post-thermal treatment was successfully proposed to enhance the flavor of GPS-GMS-D. PRACTICAL APPLICATION: The higher amylose and solid V-type crystal structure in gelatinized potato starch-glycerol monostearate dimer (GPS-GMS-D) would induce the formation of slowly digestive starch (SDS) and resistant starch (RS) to suppress enzymatic hydrolysis. Moreover, the flavor of GPS-GMS-D was enhanced with appropriate and moderate thermal processing (baking), which was likely to improve the quality of life of a person with diabetes. Thus, we believe that GPS-GMS-D is a promising functional food component for diabetes mellitus.

Structural transformation and oil absorption of starches with different crystal types during frying

The changes in the structure and oil absorption characteristics of three different crystalline starches under different initial moisture levels (20-50%) during frying were investigated. The granule morphology of potato starch was more severely disrupted during frying, especially under 40% moisture or higher. At 50% moisture, the crystallinity of potato starch decreased by 29.7% and the R₁ value decreased by 0.17. The effect of frying treatment on the structural properties of wheat starch and pea bean starch was less than that of potato starch. At 30% moisture, the ΔH values for wheat starch, potato starch, and pea bean starch were 7.8, 5.5, and 8.1 J/g respectively. The above results showed that B-type potato starch was more susceptible to the effects during frying than A-type wheat and C-type pea bean starch, which led to more oil absorption of B-type potato starch than A-type wheat or C-type pea bean starch.