Amylose crystal seeds: Preparation and their effect on starch retrogradation

Investigation of film Physical properties under various starch thermal treatments with emphasis on Retrogradation effects

This study investigated the changes in the physical properties of cornstarch-based films as they were retrogradely aged at different temperatures. Using a casting method, the films were fabricated, and their effects on the mechanical properties, thermal stability, barrier properties, and essential properties were analyzed. With prolonged aging and retrogradation periods, reductions in film thickness, solubility, water content, and water vapor permeability of 5.35%, 9.92%, 29.61%, and 20.94%, respectively, were observed. In addition, the surface roughness decreased by 44.46% for Rq (root-mean-square roughness) and 45.61% for Ra (arithmetic average roughness), while the elongation at break decreased by 72.64%. Conversely, the tensile strength, maximum degradation rate, and maximum degradation temperature increased by 116.98%, 99.5%, and 3.21%, respectively. These results provide a fundamental understanding of the changes that occur in the properties of cornstarch-based films during aging and retrogradation.

Retrogradation behaviors of damaged wheat starch with different water contents

The retrogradation behaviors of five damaged wheat starches (DS) after milling 0, 30, 60, 90, and 120 min with different water contents (33, 50, 60 %) were evaluated. Milling treatment increased DS content and developed an agglomeration of small particles. After 7 days of storage, the recrystallinity and long-range ordered structure of starch pastes were increased with the contents of DS and water. This process led to a lower setback viscosity and poor leaching of amylose. LF-NMR indicated a conversion from tightly bound water and free water to weakly bound water. During storage, DS12 with 60 % water content had the highest retrogradation tendency where the retrogradation enthalpy increased by 1.5 J/g and 2.2 J/g compared with DS0 with 60 % and DS12 with 33 % water content. DS with higher water content promoted the water mobility and made the starch molecular chains migrated conveniently. These changes facilitated the recrystallinity process during retrogradation period.

Comparison of structural and in vitro digestive properties of autoclave-microwave treated maize starch under different retrogradation temperature conditions

Retrogradation is a critical step in the physical production of resistant starch. This study aimed to examine the effects of isothermal and temperature-cycled retrogradation on the structural, physicochemical properties, and digestibility of resistant starch type-III (RS3) under various thermal conditions. To create RS3, normal maize starch (NM) and Hylon VII (HAM) were treated by autoclave-microwave and then retrograded at isothermal (4 °C) or various temperature conditions (4/10 °C, 4/20 °C, 4/30 °C, 4/40 °C, and 4/50 °C). We found that temperature-cycled retrogradation possessed greater potential than isothermal retrogradation for producing short-range ordering and crystalline structures of RS3. Also, retrograded starch prepared via temperature cycling exhibited higher double helix content, lower amorphous content, reduced swelling power, and less amylose leaching in water. Furthermore, the starch digestibility was affected by structural alterations, which were more significant in HAM-retrograded starch. While, HAM-4-40 (39.27 %) displayed the highest level of resistant starch (RS).

Synergistic modification of hot-melt extrusion and nobiletin on the multi-scale structures, interactions, thermal properties, and in vitro digestibility of rice starch

Background

Rice starch has high digestibility due to its large carbohydrate content. Synergistic modification of hot-melt extrusion (HME) and additives such as flavonoids, hydrocolloids, proteins, lipids, and other additives has the tendency to retard the rate of starch hydrolysis. Hence, the current investigation aimed to study the combined effect of the HME-assisted addition of nobiletin (NOB, 0, 2, 4, and 6%) on the multi-scale structures, interactions, thermal, and digestibility characteristics of rice starch.

Methods

The study employed density functional theory calculations and an infrared second derivative of an Fourier-transform infrared (FTIR) spectrometer to analyze the interactions between NOB and starch. The physicochemical properties of the starch extrudates were characterized by FTIR, 13C nuclear magnetic resonance, X-ray diffraction, and differential scanning calorimetry, while the digestibility was evaluated using an in vitro digestion model.

Results

HME was found to disrupt the crystalline structure, helix structure, short-ordered structure, and thermal properties of starch. The interaction between NOB and starch involved hydrophobic interactions and hydrogen bonds, effectively preventing the molecular chains of starch from interacting with each other and disrupting their double helix structure. The addition of NOB led to the formation of a highly single-helical V-type crystalline structure, along with the formation of ordered structural domains. Consequently, the combined treatment significantly enhanced the ordered structure and thermal stability of starch, thus effectively leading to an increase in resistant starch and slowly digestion starch.

Discussion

The study underscores that synergistic modification of HME and NOB holds promise for enhancing both the nutritional value and functional properties of rice starch. These findings offer valuable insights for developing high-quality rice starch products with broader applications.

Effect of different starch on masking fishy odor compounds

Starch is a common ingredient to improve gel property of freshwater fish surimi, but the function of natural starch to mask fishy odor compounds in surimi products has not been investigated systematacially. Therefore, this study aimed to determine which natural starch could effectively mask fishy odor compounds and clarify their interaction by GC-MS, FT-IR spectroscopy, raman spectroscopy, X-ray diffraction, scanning electron microscopy and 13C nuclear magnetic resonance. The results showed that when the concentration, crystal type, amylose content, and dispersion degree of starch was 1 %, type C, 48 % (w/v), and 200 mesh with 0.88 span, the starch had the strongest masking effect on typical fishy odor compounds, namely hexanal, 1-Octen-3-ol, (E,E)-2,4-Heptadienal and (E)-2-Octenal. It indicated that complexation and hydrogen bonding both occurred between the fishy odor compounds and starch.

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.

Purple rice starch in wheat: Effect on retrogradation dependent on addition amount

While individual starch types may not possess the ideal gelatinization and retrogradation properties for specific applications, the amalgamation of multiple starch varieties might bestow desirable physicochemical properties upon resulting starch-based products. This study explored the impact of incorporating purple rice starch (PRS), as a novel starch variant (up to 15 % PRS), on the gelatinization and retrogradation (within 14 days) of regular wheat starch (WS). Rheological and texture assessments demonstrated that the introduction of PRS diminished the viscoelasticity and hardness of fresh WS paste. Additionally, in the case of retrograded WS pastes stored at 4 °C for 1-14 days, the incorporation of 10 % or 15 % PRS effectively retarded the reduction in transparency and significantly reduced hardness, retrogradation degree, the ratio of absorbance at 1047/1017 cm-1, and relative crystallinity. Notably, 10 % PRS results in a more pronounced effect. Conversely, 5 % PRS induced an opposing impact on retrograded WS post-storage. Moreover, scanning electron microscopy revealed that as the proportion of PRS increased, the microstructure of gelatinized WS-PRS closely resembled that of pure PRS. In conclusion, the diverse effects of varying PRS proportions on WS alter the texture and characteristics of starch-based foods, underscoring the potential of starch blending for improved applications.

Structural properties of the intra- and interhelical cavities of V6-type crystalline starches

V-type crystalline starch is known for its property to enhance aroma retention. Intra- and interhelical cavities are the first-order characteristics of V-type crystalline starch, which can affect its properties from microscopic level. This work aims to provide a detailed analysis of structural attributes of intra- and interhelical cavities and their influence on the properties of V-type crystalline starches. Helix deformation was caused due to the formation of interhelical cavities, which was reflected by the downfield shift of the signals for C1 and C4 as well as the appearance of an independent signal for C3 in 13C CP/MAS NMR spectra. Unit cell and lamellar structure formed by the aggregation of intrahelical cavities exhibited relatively low cell volume and high fractal dimension at crystal cell and lamellar levels. Toward a larger crystal, d-spacing increased with the formation of interhelical cavities, causing low-angle shifts of V-type crystalline starches in X-ray diffraction profiles. Intrahelical cavities enabled V6I-type crystalline starch to show high crystallinity per unit volume and a favorable short-range order, contributing greatly to the stable thermal properties. The flavor quality improvement in starch-based food is attributed to the structural characteristics of helical cavities and their relationship with the properties of V-type crystalline starches.

Improvement of in vitro digestibility and thermostability of debranched waxy maize starch by sequential ethanol fractionation

This study aimed to improve the in vitro digestibility and thermostability of debranched waxy maize starch (DWMS) by sequential fractionation. Waxy maize starch was debranched by pullulanase, followed by sequential precipitation through controlling the ratio of starch supernatants to ethanol at 1:0.5, 1:1, and 1:1.5 (v/v). Subsequently the structural, thermal, in vitro digestive properties of DWMS were investigated. In vitro digestion results showed that the secondary ethanol fractionation of 1:1 on the basis of the initial fractionation (1:0.5) induced a significant higher amount of slowly digestive starch (SDS, 30.0 %) and resistant starch (RS, 58.6 %) amongst all three fractions, along with the highest peak temperature (Tp, 106.4 °C) and the highest decomposition value (Td, 310.0 °C) in calorimetric (DSC) and thermogravimetry (TGA) measurements. Chain length distribution, surface morphology, and laser confocal micro-Raman spectroscopy (LCM-Raman) analyses revealed that medium (degree of polymerization, DP 13- 36) and long chains (DP ≥37) respectively constituting 72.0 % and 10.2 % of DWMS resulted in the formation of spheroidal crystallites with higher homogeneity and more ordered short-range structures. Overall, this work confirmed that ethanol fractionation is an efficient method for improving the in vitro digestibility and heat stability of waxy maize starch.

Starch ordered structures control starch reassembly behaviors during heat-moisture treatment for modulating its digestibility

This study investigated the effect of starch crystallinity on starch reassembly behaviors during the heat-moisture treatment (HMT) using starches with A-type crystal content of 0.00%-19.03%. The results showed that HMT reduced the native starch crystal content from 19.03% to 15.02% and increased starch thermostability, leading to a decrease in rapidly digestible starch (RDS) content from 86.91% to 76.71%. Moreover, starches containing a crystal content of 2.51%-8.11% exhibited significant reassembly during the HMT, and the resulting modified starches had more crystals and less RDS of 63.43%-69.31%. Interestingly, starches lacked A-type crystals but had some helical structures exhibiting A-type crystalline structures and lower digestibility after HMT. These findings verified that starch could significantly reassemble to form crystalline structures during the HMT. Controlling the crystal content of starch granules, particularly between 2.51% and 8.11%, was a promising approach for promoting starch reassembly during HMT and reducing starch digestibility.

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.

A novel method for obtaining high amylose starch fractions from debranched starch

High amylose starch shows wide applications in food and non-food-based industries. Traditional complex-precipitation approach for the amylose fractionation required a large volume of organic reagents and was possibly risky for food safety. The object of this work was to establish a novel method to obtain starch fractions rich in amylose from debranch starch through repeated short-term retrogradation and centrifugation. Four starch fractions were obtained with the amylose content of 52.08% (C1), 62.28% (C2), 63.58% (C3), and 64.74% (C4). The thermograms of samples displayed that multiple endothermic peaks were detected in C1 and C2 and only one endothermic peak with melting temperature over 120 °C were observed in C3 and C4, indicating their differences in retrogradation behavior. The chain length distribution results of sample exhibited that C1 and C2 contained more short chains (DP ≤ 24), while C3 and C4 consisted of mainly long chains (DP ≥ 25). Accordingly, the differences in fine structures could provide more choices for these fractionated high amylose starch to utilize in practical applications.

Effect of hydroxypropyl distarch phosphate on the retrogradation properties of sterilized pea starch jelly and its possible mechanism

Due to the high content of amylose in pea starch (PS), PS jelly is prone to retrogradation during storage and its quality reduces subsequently. Hydroxypropyl distarch phosphate (HPDSP) shows a potential inhibitory effect on the retrogradation of starch gel. Based on this, five retrograded PS-HPDSP blends containing 1 %, 2 %, 3 %, 4 % and 5 % (w/w, based on the weight of PS) of HPDSP were prepared, and their long-range, short-range ordered structure and retrogradation properties, and the possible interaction between PS and HPDSP were investigated. The addition of HPDSP significantly reduced the hardness of PS jelly and maintained its springiness during cold storage, and this effect was enhanced with HPDSP dosage being from 1 % to 4 %. The presence of HPDSP destroyed both short-range ordered structure and long-range ordered structure. Rheological results indicated that all the gelatinized samples were typical non-Newtonian fluids with shear-thinning characteristics and HPDSP increased their viscoelasticity in a dose-dependent manner. In conclusion, HPDSP delays the retrogradation of PS jelly mainly by combining with amylose in PS through hydrogen bonds and steric hindrance.

Importance of amylose chain-length distribution in determining starch gelatinization and retrogradation property of wheat flour in the presence of different salts

Although starch gelatinization and retrogradation properties of wheat flour have been studied with respect to their relations to starch structures, it remains less understood how starch structure and salt (a common food additive) together determine these properties. Gelatinization and retrogradation properties of seven wheat flours with distinct starch structures were thus investigated after adding different salts. NaCl most efficiently increased starch gelatinization temperatures, while KCl showed highest efficiency in retarding the retrogradation degree. Both gelatinization and retrogradation parameters were significantly affected by amylose structural parameters and types of salts. E.g., wheat flours with longer amylose long chains had more heterogeneous amylopectin double helices during gelatinization, while this relationship disappeared after adding NaCl. More amylose short chains increased the heterogeneity of retrograded short-range starch double helices, while the relationship was opposite after adding NaCl. These results help a better understanding of the complex relationship between starch structure and physicochemical property.

Starch-based controlled release fertilizers: A review

Starch, as a widely available renewable resource, has the potential to be used in the production of controlled-release fertilizers (CRFs) that support sustainable agriculture. These CRFs can be formed by incorporating nutrients through coating or absorption, or by chemically modifying the starch to enhance its ability to carry and interact with nutrients. This review examines the various methods of creating starch-based CRFs, including coating, chemical modification, and grafting with other polymers. In addition, the mechanisms of controlled release in starch-based CRFs are discussed. Overall, the potential benefits of using starch-based CRFs in terms of resource efficiency and environmental protection are highlighted.

Effects of Konjac Glucomannan on Retrogradation of Amylose

The effect of konjac glucomannan (KGM) on the retrogradation of amylose was explored during storage. The color, rheological properties, texture, water-holding capacity (WHC), low-field nuclear magnetic resonance (LF-NMR), and X-ray diffraction (XRD) were investigated. Results of color and rheological measurements showed that with the increasing amount of KGM, the L value of the system decreased, but the elastic modulus, viscous modulus, and tangent value of loss angle increased. The textural result presented that KGM obviously inhibited the growth rate of gel strength of amylose. Results from WHC and XRD suggested after 14 days of storage, when the concentration of KGM increased from zero to 0.3% in the mixture, the WHC grew from 80% to 95% and the crystallinity degree declined from 35.3% to 25.6%. The LF-NMR result revealed that KGM limited the conversion of free water to bound water in the system. In general, a small amount of KGM in a mixed system could inhibit the short-term and long-term retrogradation of amylose. This research could provide a theoretical reference for the influence of hydrophilic colloids on the retrogradation of starch, and it could also provide support for the processing and production of starch-based food.

Starch crystal seed tailors starch recrystallization for slowing starch digestion

Crystal seed significantly affected polymers homogeneous or heterogeneous crystallization. However, how starch crystal seed affected recrystallization of gelatinized starch and in turn digestibility were not clearly understood. Herein, effects of endogenous crystal seed on starch recrystallization and digestibility were herein investigated. Structures of retrograded starches characterized by Fourier transform infrared spectroscopy and X-ray diffraction indicated that endogenous A-type crystal seed significantly promoted starch reassociation to form well-defined crystalline structure. Notably, starch crystal seed-mediated retrograded starch contained more compact structures after cooking in comparison with that of retrograded starch mediation without the crystal seed, and therefore the crystal seed-mediated retrograded starch exhibited a lower digestibility. This study preliminarily indicated starch endogenous crystal seed significantly modulate starch retrogradation and digestibility, nevertheless, how recrystallization temperature, the content and crystalline structure of the crystal seed affect recrystallization behaviors of crystal seed-containing starch are part of future work.

High-amylose starch: Structure, functionality and applications

Starch with a high amylose (AM) content (high AM starch, HAS) has attracted increasing research attention due to its industrial application potential, such as functional foods and biodegradable packaging. In the past two decades, HAS structure, functionality, and applications have been the research hotspots. However, a review that comprehensively summarizes these areas is lacking, making it difficult for interested readers to keep track of past and recent advances. In this review, we highlight studies that benefited from rapidly developing techniques, and systematically review the structure, functionality, and applications of HAS. We particularly emphasize the relationships between HAS molecular structure and physicochemical properties.

Insights into the proteomic profile of newly harvested corn and metagenomic analysis of the broiler intestinal microbiota

Background

The use of newly harvested corn in feed causes wet droppings in broilers and increased feed cost which was termed as “new season grain problem”. The present study was conducted to evaluate the proteomic profile of newly harvested corn and the subsequent influence on intestinal microbiol community for broiler chickens.

Methods

Newly harvested corn stored for either half a month (HM) or two months (TM) was used, and the pasting properties, total soluble sugars, and proteomic analysis technology was used to explore the influence of storage on natural aging corn properties. Additionally, seventy-two 7-day-old Ross 308 male broiler chicken were fed with different stored corn. Apparent metabolizable energy (AME), digesta viscosity, intestinal morphology and microbiota were examined to explore the influence of feed corn storage on broiler chickens.

Results

Pasting properties in the TM corn exhibited decreased viscoelastic properties. Proteomic studies found a total of 26 proteins that were differentially expressed between the two treatment groups. Proteins involved in starch and polysaccharides biosynthesis were upregulated in TM compared with HM. Chickens fed on TM diet had higher relative energy utilization compared to the HM birds. With increased corn storage, the relative digesta viscosity decreased significantly (P ≤ 0.05). The total number of goblet cells and lymphocytes was lower in chickens fed the TM diet. The microbiota data showed that the TM chickens had decreased abundance of diarrheal bacteria such as Hungatella hathewayi and Bacteroides fragilis, and increased butyrate-producing bacteria such as Alistipes compared to the HM chickens.

Conclusions

Storage of newly harvested corn induced the synthetic reaction of large molecules and changed the solubility of starch and protein with increasing soluble sugars and decreasing pasting properties that may improve the fermentation of intestinal microbiota, improve the energy utilization and protect gut health without the risk of diarrhea.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40104-021-00656-1.

Contribution of starch to the flavor of rice-based instant foods

Increased consumption of instant foods has led to research attention, especially rice-based instant foods. Starch, one of the most important components of rice, significantly affects food quality. However, the mechanisms by which starch contributes to rice-based instant foods flavor are poorly understood in many cases. The review aims to describe the common mechanisms by which starch contributes to food flavor, including participating in flavor formation, and affecting flavor release throughout starch multiscale structure: particle morphology, crystal structure, molecular structure. Five specific examples of rice-based instant foods were further analyzed to summarize the specific contribution of starch to flavor, including instant rice, fermented rice cake, rice noodles, fried rice, and rice dumplings. During foods processing, reducing sugars produced by heating or enzymatic hydrolysis of starch participate in Maillard reaction, caramelization and thermal degradation, which directly or indirectly affect the formation of flavor compounds. In addition, adsorption by granules, encapsulation by retrograded V-type crystal, and controlled release by starch gel all contribute to rice-based instant food flavor qualities. These mechanisms jointly contribute to flavor compounds formation and release. Proper theoretical application and improved processing methods are needed to promote the high-quality, mechanization, and automation of rice-based instant foods production.

Effects of different storage temperatures on the intra- and intermolecular retrogradation and digestibility of sago starch

Three different storage temperatures including room temperature (RT), 4 °C and -20 °C were investigated in this study, with respects to their effects on the retrogradation property and in vitro digestibility of gelatinized sago starch. Storage at -20 °C resulted in the highest amount of both intra- and intermolecular double helices and a fracture-like structure under scanning electron microscopy (SEM). These crystallites were more homogenous while less thermally stable than that from RT and 4 °C storage conditions. Storage at RT significantly increased the stability and heterogeneity of the formed crystallites, resulting in a sponge-like structure under SEM. Causally, the digestion rate of retrograded sago starch by α-amylase was significantly lowered after storage at -20 °C compared to that at RT and 4 °C. The crystallite heterogeneity, thermal stability, and ratio of inter- to intramolecular double helices were possibly the main driven factors for the observed digestion rates instead of the amount and micro-morphology of the crystallites. These results supply potential tools for the manufacture of food products with slower starch digestibility.

The impact of various exogenous type starch on the structural properties and dispersion stability of autoclaved lotus seed starch

In order to investigate the effects of exogenous V-type starch on the structural properties and dispersion stability of lotus seed starch after autoclave treatment, the crystal structure, molecular structure, and dispersion stability were analyzed and discussed, as well as compared with exogenous A-type and B-type starches. Analysis of structural properties indicated that the addition of different crystal nuclei led the crystallization of disordered helices to a specific direction. The B- and V-type starch addition increased the crystallinities of starch and enhanced the ordered arrangement of disordered helices, whereas A-type starch had no significant positive influence on the stability of starch system. The microstructure observation showed that A- and B-type starch addition led to a rough and porous morphology of starch particles; the presence of V-type starch retarded the agglomeration and retrogradation of starch after autoclaving. Analysis of contact angle and dispersion stability revealed that the addition of various exogenous starch increased the contact angle of starch particles in different extent, suggesting the enhancement of hydrophobicity. But B-type starch addition resulted in the poor dispersion stability compared to A-type starch, instead V-type starch addition improved the dispersion stability of starch in aqueous solution, allowing the particles to stay dispersed for 141.12 ± 6.52 min. These results provided a theoretical basis for the effects of exogenous type starch on original starch properties, and revealed the potential of V-type starch as dispersion stabilizer.

An overview on plasticized biodegradable corn starch-based films: the physicochemical properties and gelatinization process

With increasing awareness of environmental protection, petroleum-based raw materials are continuously decreasing, which in turn necessitated the development of eco-friendly sustainable biomaterials, as alternative strategy. Starch could be an ideal substitute. Corn starch has been used as a renewable material for development of biodegradable packaging, owing to great varieties, low cost, large-scale industrial production, and good films forming properties. Unfortunately, its poor mechanical and barrier properties have limited the application of starch-based films. Thence, plasticizers were added to overcome the aforementioned pitfalls and improve the films elongation, distribution, flexibility, elasticity, and rigidity. Addition of plasticizers can change the continuity and therefore would enhance the properties of corn starch-based films. While plasticization can improve the tensile strength and percent elongation, it can reduce the water resistance in prepared films. Herein, we focused on changes of starch granules during gelatinization process, types of biodegradable films, as well as the types of modified starch with plasticizers. Furthermore, the influence of plasticizers on corn starch-based films and the physicochemical properties of various types of corn starch-based films were also addressed.

Effect of cooling rate on long-term recrystallized crystal of rice starch in the presence of flavor compounds

This study evaluated the effect of cooling rate on starch recrystallization in the presence of 2,3-butanedione and 2-acetyl-1-pyrroline, which could form B-type and V-type complexes with starch, respectively. Rapid cooling resulted in poor perfection and high heterogeneity of both B-type and V-type recrystallized crystal. For B-type crystal, rapid cooling changed nucleation mode from instantaneous (Avrami index n < 1) to continuous mechanism (1 ≤ n ≤ 2), and decreased recrystallization rate from 0.0502 to 0.0160 d^-n, indicating the increased retention of starch on 2,3-butanedione. V-type crystal was formed at initial stages of recrystallization, and inhibited the growth of B-type crystal. The loose crystalline obtained by rapid cooling is conducive to the retention of flavor compounds for B-type complexes (especially ≤14 days) and V-type complexes (especially ≤1 day). These results could provide guidance for maintaining fragrance of instant rice during long-term storage.

Improvement of gluten-free steamed bread quality by partial substitution of rice flour with powder of Apios americana tuber

This study investigated the effect of powder made from tubers of the legume Apios americana (Apios) as a rice flour substitute in the making of gluten-free steamed bread. The carbohydrates of Apios powder were mainly starch and sucrose, and included legume-specific raffinose and stachyose. Apios powder contained almost no α-amylase but had a high level of β-amylase activity. Substitution of rice flour with Apios powder delayed the hardening of bread on storage and helped to maintain cohesiveness. Apios powder-substituted bread had higher maltose content than unsubstituted control bread due to β-amylase activity in the Apios powder. Bread substituted with 10% Apios powder had a significantly higher degree of gelatinization than the control even after storage, most likely due to lower amounts of recrystallized amylose as determined by differential scanning calorimetry. These results demonstrate Apios powder as promising a new food ingredient for improving the quality of gluten-free rice bread.