Investigating the Impact of Moisture Levels on Structural Alterations and Physicochemical Properties of Cassava Flour through Extrusion: A Comprehensive Study.

The extrusion process, a vital technique for starch modification, is notably influenced by the moisture content (MC). This study aimed to elucidate the effect of varying MC levels (18, 22, 26, and 30%) on the structural and physicochemical characteristics of cassava flour during extrusion. Extrusion resulted in the fraction of degree of polymerization 13‒24, degree of branching, and molecular weight increased with increasing MC, with values of above indexes being 32.29%, 1.05%, and 1.21 × 105 g/mol, respectively, at a MC of 18%. This suggested that the degradation of amylopectin and amylose. Additionally, there was an increase in rapidly digestible starch (RDS) and a decrease in slowly digestible starch (SDS) in the extrudates in comparison to the native cassava flour. The extrusion of cassava flour at 18% MC exhibited the highest levels of RDS and SDS, reaching 64.52% and 4.06%, respectively. These findings indicated that low moisture extrusion could be a more effective method for disrupting the structure of cassava starch and enhancing the digestibility of cassava flour, offering valuable insights for the optimized use of cassava extrudates in various applications.

Optimizing planting density enhances the multi-scale structural characteristics and in vitro digestibility of maize starch via modulating the size distribution of granules.

The modification of starch through agricultural practices is becoming increasingly significant for producing healthy foodstuffs and raw materials for industrial applications, consequently gaining momentum in academic research. This study examined how three different planting densities influenced the distribution of granule sizes, multi-scale structural characteristics, and in vitro digestibility of maize starch. The results showed that planting density significantly enhanced grain yield and relative crystallinity, and significant increases were also observed in the contents of both rapidly and slowly digestible starch. The surface- and volume-weighted mean diameter of granules significantly increased under the medium level (6.75 × 104 plants ha-1), and then decreased under high planting density level. As planting density level increased, the amylose content, peak viscosity, and hardness varied from 23.3 to 26.4 %, from 1962 to 2659 mPa·s, and from 129.3 to 307.6 g, respectively. However, no change was found in crystalline structure of maize starch. These results indicated that optimizing planting density could effectively improve grain yield and starch characteristics of maize, with the best effect under the level of 6.75 × 104 plants ha-1.

Starch-related structural basis and enzymatic mechanism of the different appearances of soft rice.

To investigate the fine starch structure characteristics and formation mechanism of high-quality appearance soft rice, two high-quality and low-quality soft rice varieties (HA-SR and LA-SR, respectively) were selected. Differences in appearance quality, fine starch structure, and activity of key enzymes involved in starch synthesis during the grain-filling stage were compared. The results showed that compared with LA-SR, HA-SR were less chalky, more transparent, had larger starch grains, a lower content of shorter chains (DP 6-24), a higher content of longer chains (DP ≥ 25), lower relative crystallinity, fewer ordered structures, more amorphous structures and larger thicknesses of semi-crystalline lamellae. In terms of amylase activity during the grain-filling stage, the AGPase and GBSS activities of HA-SR were higher, and the SBE activity of HA-SR was lower compared to LA-SR. In conclusion, higher AGPase activity can produce a higher filling rate resulting in fuller starch grain in soft rice. Fuller starch grains reduce the chalkiness of soft rice. Higher AGPase and GBSS activities and lower SBE activity can result in soft rice with more long-branched and less short-branched amylopectin. Thus, soft rice has lower relative crystallinity and less ordered structure. These structures may facilitate reduce grain chalkiness and improve grain transparency.

Optimization of Heat-Moisture Treatment Conditions for High-Amylose Starch and Its Application in High-Resistant Starch Triticale Noodles.

Heat-moisture treatment (HMT) is a widely used method for modifying starch properties with the potential to reduce the digestibility of high-amylose starch (HAS). This study aimed to optimize the HMT conditions for HAS and apply the resulting HMT-HAS to triticale noodles to develop low-glycemic-index products. HMT significantly increased the resistant starch (RS) content and decreased the rapidly digestible starch (RDS) content of HAS. The treatment conditions-temperature, heating time, and moisture content-were found to significantly influence the starch composition. Optimal HMT conditions were determined using response surface methodology: a temperature of 108 °C, a heating time of 5.8 h, and a moisture content of 25.50%. Under these conditions, the RS content of HMT-HAS was 60.23%, nearly double that of the untreated sample. Increasing the level of HMT-HAS in triticale noodles led to significant decreases in short-range order, relative crystallinity, and viscosities, while the RS content increased from 12.08% to 34.41%. These findings suggest that incorporating HMT-HAS into triticale noodles effectively enhances starch digestive resistance, supporting the development of functional, low-glycemic-index triticale-based foods.

The mechanism of purple sweet potato anthocyanin extract to reduce the digestion rate and improve the starch digestion characteristics based on dough system.

Current studies have predominantly focused on the in vitro interactions between starch and anthocyanins, neglecting the complexity of actual food composition systems. In this study, purple sweet potato anthocyanin extract (PSPAE)-dough mixture was constructed with the aim of refining the mechanism by which anthocyanins improved starch digestive properties. Animal experiments demonstrated that the dough containing PSPAE (250 mg/kg) significantly reduced peak blood glucose levels in mice by 39.69 %. Further analysis of the dough mixture properties-including texture, particle size, pasting characteristics, microstructure, infrared spectrum, and crystallinity-helped elucidate how PSPAE impedes starch digestion. The incorporation of 600 mg of PSPAE into the dough led to a 40.45 % reduction in the volume mean diameter compared to the blank dough. Textural and microstructural examinations suggested that PSPAE obstruct the interaction forces between starch molecules by filling gluten protein pores or wrapping starch molecules. This denser microstructure likely contributes to enhanced starch resistance. Additionally, alterations in dough crystallinity revealed that PSPAE encourages the reorganization of linear starch molecules, boosting the content of resistant starch and thereby reducing starch digestibility. This study enriches the mechanism of PSPAE in ameliorating diabetes symptoms and provides theoretical insights for the development of functional foods aimed at diabetes management.

Exploring the remarkable effects of microwave treatment on starch modification: From structural evolution to changed physicochemical and digestive properties.

As one of the crucial components of the food system, starch can be hydrolyzed into glucose after gastrointestinal digestion, so regulating its digestive properties is vital for maintaining health. Microwaves can promote the rearrangement of intramolecular structure of starch, thus improving its physicochemical properties, enhancing its slowly digestible features, and expanding its scope of application. This review zooms in describing recent research results concerning the effects of microwave treatment on the multi-scale structure and physicochemical properties of starch and summarizing the patterns of these changes. Furthermore, the changes in starch structure, resistant starch content, and glycemic index after digestion are pointed out to gain an insight into the enhancement of starch slowly digestible properties by microwave treatment. The resistance of starch to enzymatic digestion may largely hinge on the specific structures formed during microwave treatment. The multi-level structural evolutions of starch during digestion endow it with the power to resist digestion and lower the glycemic index. The properties of starch dictate its application, and these properties are highly associated with its structure. Consequently, understanding the structural changes of microwave-modified starch helps to prepare modified starch with diversified varieties and functional composites.

Experimental Warming Increased Cooked Rice Stickiness and Rice Thermal Stability in Three Major Chinese Rice Cropping Systems.

Climate warming is a critical environmental issue affecting rice production. However, its effects on cooked rice texture and rice thermal properties remain unstudied in China. To address this gap, we conducted a two-year multi-site field warming experiment using free-air temperature increase facilities across three major Chinese rice cropping systems. Interestingly, warming had a minimal impact on the hardness of cooked rice, while it significantly increased stickiness by an average of 16.3% under warming conditions. Moreover, compared to control treatments, rice flour exhibited a significant increase in gelatinization enthalpy, onset, peak, and conclusion temperatures under warming conditions, with average increments of 8.7%, 1.00 °C, 1.05 °C, and 1.17 °C, respectively. In addition, warming significantly declined the amylose content, remarkedly elevated the protein content and relative crystallinity, and altered the weight distribution of the debranched starch. Correlation analysis revealed significant relationships between cooked rice stickiness, rice flour thermal properties, amylose content, protein content, and partial starch structures. Therefore, warming-induced alterations in rice composition and starch structure collectively enhanced cooked rice stickiness and rice thermal stability.

Structural and physicochemical properties of rice starch from a variety with high resistant starch and low amylose content.

Research on the physicochemical properties of rice-derived endo-sperm high resistant starch (RS) with low amylose content (AC) is limited. In this study, we evaluated the physicochemical characteristics of such a starch variety and revealed that the starch granules exhibit a smoother, more refined surface with distinct edges, increased compactness, higher order of surface, and fewer cavities compared to those of a low RS rice variety. The starch crystal was classified as an A-type, which may be connected to the high amylose-lipid complex content. The branched internal long chains (B2 + B3) were abundant, allowing for easy entanglement with other molecular chains and a compact structure. Differential scanning calorimetry revealed the need for high temperature and energy to disrupt the double helix structure within the crystallization region of starch. Furthermore, starch viscosity analysis revealed a high cold paste viscosity, consistency, and setback value, with recrystallization yielding a stable structure, increased viscosity, and enhanced hydrolysis resistance to enzymes.

Short-range molecular order is the driving factor for starch digestibility and texture of alginate-encapsulated rice beads.

BACKGROUND: Rice grain analogues with slow starch digestibility are commonly associated with an unsatisfactory texture, often leading to consumer dissatisfaction. Alginate encapsulation has been applied to reduce the digestibility of corn and potato starch. The fine molecular structures of rice starch can greatly determine its digestibility and texture. However, it remains unclear whether a combination of alginate encapsulation and varied starch molecular structures can be employed to create rice grain analogues that offer both slow starch digestibility and an appealing texture. RESULTS: For the first time, the present study constructed alginate-encapsulated rice beads (as a rice grain analogue). A wide range of starch digestion rates were found among alginate-encapsulated rice beads prepared with different rice varieties, and only certain rice varieties (e.g. Subei and Nanjing) were able to result in rice beads with slower starch digestibility than their parental rice kernels. More importantly, all rice beads showed a relatively softer texture compared to their parental rice kernels. Correlation analysis showed that starch digestion rate, hardness and stickiness were all positively correlated with the ratio of short-range amorphous regions in rice bead samples, as obtained from Fourier transform-infrared spectroscopy, but not with the relative crystallinity. CONCLUSION: Collectively, these results suggest that rice beads with slower starch digestion rate and softer texture could be obtained by choosing rice varieties that develop more short-range ordered structure after cooking. © 2024 Society of Chemical Industry.

Valuation of the significant hypoglycemic activity of black currant anthocyanin extract by both starch structure transformation and glycosidase activity inhibition.

The objective of this study was to investigate the impact of anthocyanin-rich black currant extract (BCE) on the structural properties of starch and the inhibition of glycosidases, gathering data and research evidence to support the use of low glycemic index (GI) foods. The BCE induced a change in the starch crystal structure from A-type to V-type, resulting in a drop in digestibility from 81.41 % to 65.57 %. Furthermore, the inhibitory effects of BCE on glycosidases activity (α-glucosidase: IC50 = 0.13 ± 0.05 mg/mL and α-amylase: IC50 = 2.67 ± 0.16 mg/mL) by inducing a change in spatial conformation were confirmed through in vitro analysis. The presence of a 5'-OH group facilitated the interaction between anthocyanins and receptors of amylose, α-amylase, and α-glucosidase. The glycosyl moiety enhanced the affinity for amylose yet lowered the inhibitory effect on α-amylase. The in vivo analysis demonstrated that BCE resulted in a reduction of 3.96 mM·h in blood glucose levels (Area Under Curve). The significant hypoglycemic activity, particularly the decrease in postprandial blood glucose levels, highlights the potential of utilizing BCE in functional foods for preventing diabetes.

Germination-induced modifications of starch structure, flour-processing characteristics, and in vitro digestive properties in maize.

Current research on maize germination suffers from long sampling intervals, and the relationship between the starch structure and the processing properties of flour in maize is still unclear. This study observed the effect of germination on the structure and composition of maize starch and the processing properties of maize flour over a 72 h period using a short interval sampling method. At 36 h, the short-range ordered structure, crystallinity, and enthalpy of starch reached the highest values of 1.02, 34.30%, and 9.90 J/g, respectively. At 72 h, the ratios of rapidly-digested starch (RDS) and slowly-digested starch (SDS) enhanced to 29.37% and 28.97%; the RS content reduced to 35.37%; and the flow properties of the starch were improved. This study enhances the understanding of the effects of germination on the processing properties of maize starch and flour, determines the appropriate application, and recommends the use of germination in the food industry.

Effect of synergistic fermentation of Saccharomyces cerevisiae and Lactobacillus plantarum on thermal properties of hyaluronic acid-wheat starch system.

Hyaluronic acid (HA), as a multifunctional hydrophilic polysaccharide, is potentially beneficial in improving the thermal stability of fermented modified starches, but relevant insights at the molecular level are lacking. The aim of this study was to investigate the effect of different levels (0 %, 3 %, 6 %, 9 %, 12 % and 15 %) of HA on the structural, thermal and pasting properties of wheat starch co-fermented with Saccharomyces cerevisiae and Lactobacillus plantarum. We found that the addition of HA increased the median particle size of fermented starch granules from 16.387 to 17.070 µm. Meanwhile, the crystallinity of fermented starch was negatively correlated with the HA content, decreasing from 14.70 % to 12.80 % (p < 0.05). Fourier transform infrared spectroscopy results confirmed that HA interacted with starch granules and water molecules mainly through hydrogen bonding. Thermal analyses showed that the thermal peak of the composite correlated with the HA concentration, reaching a maximum of 73.17 °C at 12 % HA. In addition, HA increases the pasting temperature, reduces the peak, breakdown and setback viscosities of starch. This study demonstrates the role of HA in improving the thermal stability of fermented starch, providing new insights for traditional fermented food research and the application of HA in food processing.

Relation between textural attributes and surface leachate structural and compositional characteristics of cooked rice.

The objective of this study was to evaluate the leachate and textural characteristics of cooked rice, and the correlations between the leachate properties and texture attributes were also investigated. Cooked waxy rice had much higher total solids and amylopectin amount in leachate than the normal and high-amylose rice. For all varieties, the amylopectin chain length of the leachate was similar, excluding Dodam cultivar. The rheological characteristics of the leachate solutions were highly dependent on the amylopectin amount of the leachate. Regarding the textural characteristics, Dodam had the highest hardness and the lowest adhesiveness. The principal component analysis showed substantial differences in leachate and textural characteristics of Korean cooked rice according to its amylose content. The adhesiveness was positively and negatively correlated with amylopectin amount of leachate and the proportion of long amylopectin chains, respectively. These results indicated that the leachate characteristics of cooked rice significantly influenced its textural attributes. Supplementary Information: The online version contains supplementary material available at 10.1007/s10068-023-01446-3.

Correlation between in vitro starch digestibility and starch structure/physicochemical properties in rice.

Natural resistant starch (RS) in rice provides human health benefits, and its concentration in rice is influenced by the structure and physicochemical properties of starch. The native starch structures and physicochemical properties of three rice varieties, QR, BR58, and BR50, and their relationships to in vitro digestibility were studied. The starch granules in all three varieties were irregular or polyhedral in shape. There were a few oval granules and a few pinhole structures in QR, no oval granules but a higher number of pinholes in BR58, and no oval granules and pinholes in BR50. QR is a low-amylose (13.8 %), low-RS (0.2 %) variety. BR58 is a low-amylose (15.3 %), high-RS (6.5 %) variety. BR50 is a high-amylose (26.7 %), high-RS (8.3 %) variety. All three starches exhibited typical A-type diffraction patterns. Starch molecular weight, chain length distribution, starch branching degree, pasting capabilities, and thermal properties differed considerably between the rice starches. The RS contents of the rice starch varieties were positively correlated with AAC, Mw/Mn, Mz/Mn, peak 3, B, PTime, and Tp and negatively correlated with Mn, peak 2, DB, PV, and BD, according to Pearson's correlation analysis. These findings may be helpful for the breeding and development of high-RS rice varieties.

Comparative analysis of granular starch hydrolysis and multi-structural changes by diverse α-amylases sources: Insights from waxy rice starch.

Three cultivars of waxy rice starch with different multi-scale structures were subjected to α-amylase hydrolysis to determine amylopectin fine structure, production of oligosaccharides, morphology, and crystallinity of the partially hydrolyzed starch granules. α-amylases hydrolyzed the amylopectin B2 chain during the initial stage of hydrolysis, suggesting that it is primarily located in the outer shell of the granules. For waxy rice starch with loose structure, α-amylases attacked the crystalline and amorphous regions simultaneously in the initial stage, while for starch granules with compact structure, the outer shell blocklet (crystalline structure) can be a hurdle for α-amylases to proceed to hydrolysis of the internal granule structure. The ability of α-amylases from porcine pancreatic α-amylases to attack the outer shell crystalline structure was lower than that of α-amylases from Bacillus amyloliquefaciens and Aspergillus oryzae. These results show that α-amylase source and rice cultivar combinations can be used to generate diverse structures in degraded waxy rice starch.

Characterization of the starch molecular structure of wheat varying in the content of resistant starch.

Resistant starch (RS) is the total amount of starch that is incompletely or not digested and absorbed in the small intestine. It plays a role similar to dietary fibre with beneficial effects for human health. In this study, the RS content of 129 wheat accessions was determined, and the relationship between the several starch physical properties and resistant starch content were analyzed. By comparing the total starch content, amylose starch content, starch chain length distribution, starch crystallization type, starch branching degree, and starch granule morphology between the high RS and low RS content wheat accessions, it was found that the amylose content and RS content were significantly positively correlated. However, in the range of chain length fb 3 (DP ≥ 37), there was a significant negative correlation between amylopectin content and RS content. The surface of starch granules became increasingly smooth as the content of RS increased.

Exploring the effects of enzymatic and thermal treatments on banana starch characteristics.

Banana starch has a highly resistant starch (RS) and slow-digested starch (SDS) content, making it attractive as a functional ingredient. Unfortunately, banana starch requires modification processes due to the loss of RS and SDS during gelatinization because of its thermolabile characteristics. This study explores the effect of banana starch modification by enzymatic, heat moisture treatment (HMT) and dual modification (HMT+ enzymatic) on its nutritional (RS, SDS) and functional properties (hydration, structural, gelation, rheological). HMT and dual modifications decrease RS (from 44.62 g/100 g to 16.62 and 26.66 g/100 g, respectively) and increase SDS (from 21.72 g/100 g to 33.91 and 26.95 g/100 g, respectively) in raw starch but induce structural changes that enhance RS (from 3.10 g/100 g to 3.94 and 4.4 g/100 g, respectively) and SDS (from 2.58 g/100 g to 9.58 and 11.48 g/100 g) thermo-resistance in gelled starch. Also, changes in the functional properties of starches were evidenced, such as weaker gels (hardness < 41 g), lower water absorption (<12.35 g/g), high starch solubility (>1.77 g/100 g) and increased gelatinization temperature. Improved gelatinization temperature and RS thermostability resulted from modifications that could expand banana starch applications as a beverage and compote thickener agent.

Structural and property changes of starch derivatives under microwave field: A review.

Native starches are commonly modified for desired properties because of their limited applications. Among various modifications, microwave irradiation has been gaining strong interests and becoming a focal area to transform starch during the last few years. Such interests reside in microwave irradiation's high heating rates, lesser extent of loss in nutritional qualities, and so on when compared with other approaches. This review summaries the effects of microwave field on the structural (e.g. morphology characteristic, lamellae structure, crystallinity, and molecular structure) and physicochemical properties (e.g. pasting properties and gelatinization) of naturally existing starch derivatives. Different microwave-assisted chemical derivatizations can directly or indirectly affect starch structure from the macroscopic to the microscopic level, thereby resulting in various functionalities. Moreover, conventional starch modification processes can be optimized by applying microwave irradiation to obtain modified starch with high degree of substitution and low viscosity. The future research will help to better understand the structural changes of microwave-assisted starch chemical derivatization and thereby creating a wide range of functionalities.

Heat-moisture treatment to modify structure and functionality and reduce digestibility of wrinkled and round pea starches.

Heat-moisture treatment (HMT) was employed to modify wrinkled pea (74.2 % and 76.5 % amylose) and round pea starches (35.9 % and 34.8 % amylose) at 35.0 % moisture, 110 or 130 °C, and 6 h. HMT increased the gelatinization temperatures and decreased the gelatinization enthalpy changes, reduced the pasting viscosities and gel hardness, and enhanced the enzymatic resistance of the pea starches in comparison with the native counterparts, with greater extents of changes observed for HMT at 130 °C overall. Although HMT decreased the relative crystallinity and elevated the proportion of amorphous conformation, the remaining double-helical crystallites in the modified samples showed improved thermal stability as revealed by differential scanning calorimetry (DSC). More importantly, the HMT-modified pea starches required a higher heating temperature of 120 °C, rather than 95 °C, in Rapid Visco Analyser to provide greater pasting viscosities and develop firmer gels, suggesting that the modified samples had stronger molecular entanglement than the native counterparts. Such molecular entanglement could also reduce enzymatic digestion of HMT-modified starches after boiling in water. With more diverse functional profiles and increased resistant starch (RS) contents (particularly for the HMT-modified wrinkled pea starches having 22.7-29.9 % RS), the HMT-modified pea starches could be promising new ingredients for food applications.

Static magnetic field improvement of the quality of rice dumpling subjected to freeze-thaw cycles: Roles of phase transition of water and changes in structural and physicochemical properties of glutinous rice flour.

This study aimed to investigate the effect of static magnetic field (SMF, 0-10 mT) on the quality of rice dumplings subjected to 7, 14, 21, and 28 freeze-thaw cycles. The underlying mechanism was explored by monitoring changes in water phase transition, water distribution, and structural and physicochemical properties of rice flour. Results suggested that SMF enables the formation of small ice crystals by accelerating freezing rate, shortening phase transition time, and increasing bound water content, which attributes to reducing the mechanical damage on starch granules and thus improves the quality of frozen rice dumpling. After 7-28 freeze-thaw cycles, SMF treatment increased the whiteness by 0.08-1.58, reduced the cracking ratio by 1.67 %-8.34 %, decreased the water loss ratio by 0-0.75 %, and significantly improved the texture of cooked rice dumplings. This study confirmed the feasibility of SMF in improving the quality of rice dumpling, which contributes to expanding the applications of magnetic freezer in the preservation of starch-based foods.