Impact of molecular and crystalline structures on in vitro digestibility of waxy rice starches

Dynamic development of changes in multi-scale structure during grain filling affect gelatinization properties of rice starch

Rice was collected over the entire grain filling period (about 40 days) to explore the multi-structure evolution and gelatinization behavior changes of starch. During the early stage (DAA 6-14), the significant reduction in lamellar repeat distance (10.04 to 9.68 nm) and relative crystallinity (26.6 % to 22.7 %) was due to initial rapid accumulation of amylose (from 9.38 % to 14.05 %) and short amylopectin chains. Meanwhile, the decreased proportion of aggregation structure resulted in a decrease in the gelatinization temperature and a narrowed range of gelatinization temperature also indicated an increase in homogeneity as starch matured. Gelatinization enthalpy was mainly controlled by aggregation structure, which was negatively and positively related to the amylose content and the degree of order respectively. Peak viscosity of starch pasting increased and reached a maximum (924 cP) at DAA-21 due to larger granule size. Amylose and short amylopectin chains with degree of polymerization 6-12 showed positive and negative correlation with short-term retrogradation ability (setback value) respectively. The dynamics of different scale structure during grain filling had varying degrees of impact on gelatinization properties.

Glass bead system to study mycotoxin production of Aspergillus spp. on corn and rice starches

Mycotoxin production by aflatoxin B1 (AFB1) -producing Aspergillus flavus Zt41 and sterigmatocystin (ST) -hyperproducer Aspergillus creber 2663 mold strains on corn and rice starch, both of high purity and nearly identical amylose-amylopectin composition, as the only source of carbon, was studied. Scanning electron microscopy revealed average starch particle sizes of 4.54 ± 0.635 µm and 10.9 ± 2.78 µm, corresponding to surface area to volume ratios of 127 1/µm for rice starch and 0.49 1/µm for corn starch. Thus, a 2.5-fold difference in particle size correlated to a larger, 259-fold difference in surface area. To allow starch, a water-absorbing powder, to be used as a sole food source for Aspergillus strains, a special glass bead system was applied. AFB1 production of A. flavus Zt41 was determined to be 437.6 ± 128.4 ng/g and 90.0 ± 44.8 ng/g on rice and corn starch, respectively, while corresponding ST production levels by A. creber 2663 were 72.8 ± 10.0 µg/g and 26.8 ± 11.6 µg/g, indicating 3-fivefold higher mycotoxin levels on rice starch than on corn starch as sole carbon and energy sources. KEY POINTS: • A glass bead system ensuring the flow of air when studying powders was developed. • AFB1 and ST production of A. flavus and A. creber on rice and corn starches were studied. • 3-fivefold higher mycotoxin levels on rice starch than on corn starch were detected.

Optimization of the morphological, structural, and physicochemical properties of maize starch using straw returning and nitrogen fertilization in Northeast China

The combination of straw returning and nitrogen (N) fertilization is a popular tillage mode and essential strategy for achieving stable yield and high quality. However, the optimal combination strategy and the influence of tillage mode on the morphological, crystalline, and molecular structures of maize starch remain unclear. We conducted a long-term field experiment over 7 years in Northeast China using two tillage modes, rotary tillage with straw returning (RTS) and plow tillage with straw returning (PTS), and four N application rates. The relative crystallinity, 1045/1022 cm-1 value, and B2 and B3 chains of maize starch were higher under RTS than under PTS, resulting in increased stability of starch and improvements in gelatinization enthalpy and temperature. The surface of the starch granules induced by N fertilizer was smoother than that under the N0 (0 kg N ha-1) treatment. The proportion of amylose content, solubility, swelling power, and light transmittance increased under N2 (262 kg N ha-1) treatment, along with improvement in starch pasting properties. These results suggest that RTS combined with N2 treatment can regulate the morphological, structural, and physicochemical characteristics of maize starch, providing an essential reference for improving the quality of maize starch from an agronomic point of view.

Physicochemical changes and in vitro digestibility of three banana starches at different maturity stages

This study aimed to compare the changes in physicochemical properties of the starch isolated from three banana cultivars (Musa AAA group, Cavendish subgroup; Musa ABB group, Pisang Awak subgroup; Musa AA group, Huangdijiao subgroup) at five different maturity stages. The results revealed both similarities and significant differences in micromorphology and physicochemical characteristics of the three banana varieties during different growth stages. Apparent amylose content and particle size of the three starches increased with the ripeness of banana. Light microscopy and scanning electron microscopy revealed that starch particles of the three starches had different microscopic characteristics, and that banana starch morphology was basically unchanged at various growth stages. Moreover, the pasting and thermal properties of the banana starches were significantly different at various growth stages. The resistant starch content of the three banana cultivars was about 80% at all growth stages. Musa AAA group, Cavendish subgroup had the highest resistant starch content at stage Ⅴ. This study provides insights into the starch changes of three banana cultivars during ripening.

Characterization of green banana starch from "Songkibab" species cultivated in the southern part of Korea

Resistant starch (RS) has advantages for regulating the colon health as prebiotics and dietary fibers, and green banana has interested due to containing high amounts of RS. Here, the structural, physicochemical, and digestible characteristics of green banana starch from newly bred Songkibab (SB) were determined to evaluate its suitability for application as a new crop in response to global warming and for obtaining genetic diversity. SB starch has structural similarities to the Cavendish (CD) banana, which is widely consumed in Southeast Asia, in its ratio of B3-chains (in high amounts), flattened shapes of smooth surfaces, and B-type crystallinity. Physiochemically, SB shows comparable swelling power, amylose content, and viscosity pattern but a higher RS content. Conclusively, this study suggests that SB banana may be a good resource for replacing CD species with novel varieties in East Asia because of the high degree of similarity in the various characteristics.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01331-z.

Effects of exogenous salicylic acid on starch physicochemical properties and in vitro digestion under heat stress during the grain-filling stage in waxy maize

Waxy maize starch serves as a pivotal component in global food processing and industrial applications, while high temperature (HT) during the grain-filling stage seriously affects its quality. Salicylic acid (SA) has been recognized for its role in enhancing plant heat resistance. Nonetheless, its regulatory effect on the quality of waxy maize starch under HT conditions remains unclear. In this study, two waxy maize varieties, JKN2000 (heat-tolerant) and SYN5 (heat-sensitive) were treated with SA after pollination and then subjected to HT during the grain-filling stage to explore the effect of SA on grain yield and starch quality. The results indicate that exogenous SA under HT treatment led to an increase in kernel weight and starch content in both varieties. Moreover, SA reduced the HT-induced holes on the surfaces of starch granules, enlarged the starch granule size, elevated the amylopectin branching degree, and reduced amylopectin average chain length. Consequently, improvements of pasting viscosity and the decrease of retrogradation percentage of starch were observed with SA under HT. Exogenous SA reduced HT-induced rapidly digestible starch content in SYN5, but had no significant effect on that in JKN2000. In summary, SA pretreatment effectively alleviated the detrimental effects of HT on starch pasting and thermal properties of waxy maize.

Avocado seed starch: Effect of the variety on molecular, physicochemical, and digestibility characteristics

Agro-industrial residues can increase environmental pollution owing to poor knowledge of the use of some components, such as dietary fiber, protein, starch, minerals, and bioactive compounds, which can be used in the food industry. This study compared the molecular, physicochemical, and digestibility characteristics of three avocado seed starches (Criolla, Fuerte, and Hass). Starch was extracted through successive washing and sedimentation. The morphology, size distribution, thermal properties, pasting properties, infrared spectra with Fourier transform, size distribution of amylopectin chains, and digestibility of the three avocado seed strains were analyzed. The starch grains were oval and spherical in shape. The average size of Criolla avocado starch (24.55 μm) was the largest, followed by Hass and Fuerte starches (21.37 μm). Higher gelatinization enthalpy (8.55 J/g), gelatinization temperature (75.28 °C), and pasting temperature (75.57 °C) were observed for Fuerte avocado starch, followed by Hass and Criolla starches. Hass avocado starch exhibited higher maximum (836.27 mPa.s), final (1407.37 mPa.s), setback (588.78 mPa.s), and breakdown (17.68 mPa.s) viscosities than Criolla and Fuerte avocado starches. In addition, the probed avocado starches exhibited high content of resistant starch (60.06-68.90%). Therefore, it was demonstrated that differences in the chemical composition and structure of avocado starch can affect the digestibility of native starch.

Structure and physicochemical properties of low digestible Euryale ferox Salisb. seed starch

BACKGROUND

Euryale ferox Salisb. is widely grown in China and Southeast Asia as a grain crop and medicinal plant. The composition, morphology, structure, physicochemical properties, thermal properties, and in vitro digestibility of North Euryale ferox seeds starch (NEFS), hybrid Euryale ferox seeds starch (HEFS), and South Euryale ferox seeds starch (SEFS) were studied.

RESULT

Of the varieties that were studied, the amylose content of NEFS (23.03%) was the highest. Starch granules of each variety were smooth, sharp, small, and had an average diameter of 2 μm. All three varieties were A-type crystals with crystallinity ranging from 26.42% to 28.17%. The degree of double helix and the short-range order ranged from 1.9006 to 2.5324 and 1.4294 to 1.6006, respectively. The high proportion of C1 region in NEFS (17.74%) and HEFS (17.66%) were found. Thermodynamic properties in North Euryale ferox seeds included the highest onset temperature (T_o ) (71.43 °C), peak temperature (T_p ) (76.60 °C), conclusion temperature (T_c ) (82.77 °C), enthalpy of gelatinization (ΔH) (12.64 J g^-1 ), and peak viscosity (1514 mPa·s). All three varieties maintained a low level of in vitro digestibility, with the highest resistant starch (RS) content (29.57%), the lowest rapidly digestible starch (RDS) content (27.07%), and the slowest hydrolysis kinetic constant (0.0303) in NEFS.

CONCLUSION

The results revealed that the low digestibility of NEFS was attributable to compact granules, high crystallinity, high degree of order, and strong thermal stability. These digestive, physicochemical, and thermodynamic properties provide information for the future application of Euryale ferox seed starch in the food industry. © 2022 Society of Chemical Industry.

Meta-analysis reveals gut microbiome and functional pathway alterations in response to resistant starch

Resistant starch (RS) has the ability to improve the structure of the gut microbiota, regulate glucolipid metabolism and maintain the health of the human body, and has been extensively studied by many scholars in recent years. However, previous studies have provided a wide range of results on the differences in the gut microbiota after RS intake. In this article, we performed a meta-analysis of a total of 955 samples of 248 individuals from the seven studies included to compare the gut microbiota of the baseline and the end-point of RS intake. At the end-point, RS intake was related to a lower gut microbial α-diversity and higher relative abundance of Ruminococcus, Agathobacter, Faecalibacterium and Bifidobacterium, and the functional pathways of the gut microbiota related to the carbohydrate metabolism, lipid metabolism, amino acid metabolism and genetic information processing were higher. Different types of resistant starch and different populations led to varied responses on the gut microbiome. The altered gut microbiome may contribute to improve the blood glucose level and insulin resistance, which may be a potential treatment route for diabetes, obesity and other metabolic diseases.

Physicochemical Characterizations, Digestibility, and Lipolysis Inhibitory Effects of Highland Barley Resistant Starches Prepared by Physical and Enzymatic Methods

This study aimed to investigate the differences in the physicochemical and structural characteristics, digestibility, and lipolysis inhibitory potential in vitro of highland barley resistant starches (HBRSs) prepared by autoclaving (HBSA), microwave-assisted autoclaving (HBSM), isoamylase (HBSI) and pullulanase (HBSP) debranching modifications. Results revealed that the resistant starch content of native starch was significantly elevated after modifications. HBSA and HBSM showed distinctly higher swelling power and water-binding capacities along with lower amylose amounts and solubilities than those of HBSI and HBSP (p < 0.05). Fourier transform infrared spectroscopy and X-ray diffraction exhibited that HBSP displayed the highest degree of the ordered crystalline region and crystallinity with a mixture of C_B- and V-type polymorphs. Meanwhile, HBSA and HBSM were characterized by their high degree of the amorphous region with a mixture of B- and V-type polymorphs. Physical and enzymatic modifications resulted in different functionalities of HBRSs, among which HBSP showed the lowest digestibility and HBSM exhibited the highest inhibitory activity on lipolysis due to their structure and structure-based morphology and particle size. This study provided significant insights into the development of native starch from highland barley as an alternative functional food.

Physicochemical, Morphological, and Functional Properties of Starches Isolated from Avocado Seeds, a Potential Source for Resistant Starch

This study compared the physicochemical and functional properties of starches from eight cultivars of avocado seeds. Amylose content, morphology, crystalline structure, swelling power, solubility, thermal and pasting properties, and in vitro digestibility were investigated. The results revealed that the apparent amylose content of starches from avocado seeds varied with different varieties. Light microscopic and scanning electron microscopic examination demonstrated that the eight starches differed slightly in terms of morphology and granule size. The X-ray diffraction and Fourier transform infrared spectroscopy analyses showed that the crystal structure and chemical linkage of the avocado seed starches were similar. However, the pasting, water solubility, and thermal properties of the eight avocado seed starches differed. Importantly, all the starches had high resistant starch content (>60%), with the highest found in Hass seeds (77.83%). To conclude, starch from avocado seeds has a high potential for use in the production of resistant starch.

Pasting Properties of Various Waxy Rice Flours: Effect of α-Amylase Activity, Protein, and Amylopectin

Waxy rice has a long history of being cultivated and consumed in China. In this study, the effect of different factors including α-amylase activity, protein, and amylopectin structure on the pasting properties of four waxy rice varieties were investigated. Rice flours were divided into four groups (Vietnam indica (VI), Jiangxi indica (JI), Anhui japonica (AJ), and Dongbei japonica (DJ) group) and treated with AgNO3 solution, DL-dithiothreitol (DTT), or protease (n = 3). Results suggested that both α-amylase activity and protein significantly decrease the pasting viscosity of waxy rice flours. Chain length distribution of amylopectin as measured by high performance ion exchange chromatography (HPAEC-PAD) showed that starch with a higher ratio of short chain leads to a higher pasting viscosity. X-Ray diffractograms showed that the crystal type of all the four varieties of rice starches were characteristic A-type. Relative crystallinity of each rice starch was further calculated, and higher crystallization resulted in a higher viscosity. Our study would provide a fundamental knowledge of the relationship between different factors and waxy starch pasting properties, as well as be a reference for controlling the quality of waxy rice starch-based food products.

Study on the Pasting Properties of Indica and Japonica Waxy Rice

In this study, the physicochemical properties of indica (IWR) and japonica (JWR) waxy rice were investigated to find the critical factor that differentiates the pasting behaviors among the two cultivars. The results showed that the peak viscosity of 5 IWR flours was in the range of 1242 to 1371 cP, which was significantly higher than 4 JWR flours (667 to 904 cP). Correlation analysis indicated that all pasting parameters were not correlated (p < 0.05) with physicochemical properties of rice flours and the fine structure of isolated starches. The pasting profiles of IWRs were still significantly higher than those of JWRs after removing lipid, while there were no significant differences between the two cultivars after removing protein sequentially. Meanwhile, the addition of extracted protein from JWR to the isolated starch significantly decreased the viscosity compared to the addition of protein extracted from IWR. The protein composition results found that the IWR protein contained about 18% globulin and 64% glutelin, while the JWR protein contained 11% globulin and 73% glutelin. The addition of glutelin to isolated starch significantly decreased viscosity compared to the addition of globulin. Therefore, the differences in the content of globulin and glutelin might be the main reasons that differentiate the pasting behaviors of the two cultivars.

Differences in starch multi-layer structure, pasting, and rice eating quality between fresh rice and 7 years stored rice

With the continuous improvement of rice production capacity and the accumulation of reserves year by year, rice sometimes has to be stored for a long time. However, long-term storage of rice has poor sensory properties, which may be related to the structural changes of starch. Different from the previous studies on short-term storage of rice (often 3–12 months), the focus of this study was to understand the differences in starch multi-layer structure, pasting, and rice eating quality between 7 years stored rice and fresh rice. Our research indicated that 7 years stored rice showed higher hardness and lower stickiness compared to fresh rice, which ultimately led to poorer eating quality. These bad changes were related to differences in starch multi-layer structure. The 7 years stored rice had lower amylose content, a lower thickness of crystalline lamellae and short-range ordered structure of starch, and more large starch granules. In particular, the volume mean diameter of 7 years starch was more than 4 times that of fresh starch. 7 years stored rice had more large granular starch and unstable crystal structure, which led to the increase of pasting temperature and the decrease of gelatinization enthalpy during starch gelatinization, and ultimately reduced the eating quality of the rice.

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7 years stored rice had higher hardness and poorer eating quality.

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Volume mean diameter of 7 years stored starch was 4 times larger than fresh starch.

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7 years stored rice had lower short-range order structure of starch.

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The pasting temperature of 7 years stored starch was higher than fresh starch.

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Higher pasting temperature and lower gelatinization enthalpy reduced the eating quality.

Structure and Properties of Octenyl Succinic Anhydride-Modified High-Amylose Japonica Rice Starches

Starches rich in amylose are promising functional ingredients for calory-reduced foods. In this research, a high-amylose Japonica rice starch (amylose content 33.3%) was esterified with octenyl succinic anhydride (OSA) to improve the functional properties. The OSA-modified derivatives were evaluated for structure and functional properties, with OSA-modified normal Japonica rice starch (amylose content 18.8%) used as control. Fourier transform infrared spectra confirmed the introduction of OSA groups to starch. OSA modification made little change to morphology and particle size of high-amylose starch, but decreased the relative crystallinity and pasting temperature and increased the pasting viscosity, swelling power, emulsifying stability, and resistant starch (RS) content. The changes of properties were related to the degree of substitution (DS). Typically, OSA-modified high-amylose starch at DS of 0.0285 shows polyhedral-shape granules, with a volume-average particle diameter of 8.87 μm, peak viscosity of 5730 cp, and RS content of 35.45%. OSA-modified high-amylose starch had greater peak viscosity and RS content and lower swelling power than OSA-modified normal starch of similar DS, but the two kinds of derivatives did not have a significant difference in emulsifying stability. The OSA-modified high-amylose Japonica rice starch could be used as an emulsifier, thickener, and fat replacer in food systems.

Isolation, modification, and characterization of rice starch with emphasis on functional properties and industrial application: a review

Starch is one of the organic compounds after cellulose found most abundantly in nature. Starch significantly varies in their different properties like physical, chemical, thermal, morphological and functional. Therefore, starch is modified to increase the beneficial characteristics and remove the shortcomings issues of native starches. The modification methods can change the extremely flexible polymer of starch with their modified physical and chemical properties. These altered structural attributes are of great technological values which have a wide industrial potential in food and non-food. Among them, the production of novel starches is mainly one that evolves with new value-added and functional properties is on high industrial demands. This paper provides an overview of the rice starch components and their effect on the technological and physicochemical properties of obtained starch. Besides, the tuned techno-functional properties of the modified starches through chemical modification means are highlighted.HighlightsNative and modified starches varies largely in physicochemical and functional traits.Modified physical and chemical properties of starch can change the extremely flexible polymer of starch.Techno-functional properties of the modified starches through chemical modification means are highlighted.Dual modification improves the starch functionality and increases the industrial applications.Production of novel starches is on high industrial demands because it mainly evolves with new value added and functional properties.

Effects of physicochemical and structural properties of single and double feedstuffs derived from different botanic sources on in vitro starch digestion and glucose release kinetics

Starch is the largest constituent in animal diets. The aims of this study were as follows: (a) to assess the variability of basic physicochemical properties and in vitro starch digestion of starchy feedstuffs and investigate relationship between physicochemical properties and starch digestion of the feedstuffs, and (b) to explore the effects of different sources of starchy feedstuffs on starch digestion and glucose release. In this study, we determined the inherent molecular structure and granular structure of starch and chemical compositions of seven starchy feedstuffs, as well as starch digestion in single feedstuff and different feedstuffs combined with corn. Scanning electron microscope (SEM) results revealed significant difference between granule shape and size of starch of different feedstuffs. Fourier transforms infrared (FTIR) spectra for barley and wheat had lower (p < 0.05) absorbance band at areas A_860 and A_928 than other feedstuffs, yet rice starch had the lowest value for ratio (R) (1047/1022). Moreover, digestion rate ranged from 0.0157/min for resistant starch (sorghum) to 0.029/min for rapidly starch (broken rice). The principle component analysis (PCA) showed that predicted glycaemic index (pGI) was positively related to A_1022, glucose and rapidly (RDS) content and negatively related to A_995, A_1047, R (1047/1022), resistant starch (RS) and amylose content. Most of the feedstufss with corn combination had no effect on rate of starch digestion. In addition, different starchy feeds and corn combination changed the rate of starch digestion, when barley, however, sorghum combined with corn seemed to affect rate of starch digestion. To sum up, different sources differed in basic physicochemical and structural properties, which would influence the digestion rate of starch and the release of glucose. Combination of different feedstuffs particular sorghum with corn has interactive effect on starch digestion and the release of glucose.

Starch in aquafeeds: the benefits of a high amylose to amylopectin ratio and resistant starch content in diets for the carnivorous fish, largemouth bass (Micropterus salmoides)

Aquafeeds for carnivorous species face a nutritional-technological conundrum: containing sufficient starch to meet specific manufacturing requirements for binding, extrusion and expansion, but ideally containing as little starch as possible owing to their limited ability to utilise carbohydrates. The present study evaluated the effects of dietary starch with different amylose to amylopectin ratios and resistant starch contents on growth performance, hepatic glycogen accumulation and glucose metabolism of an important cultured carnivorous finfish, largemouth bass (Micropterus salmoides). A common starch source (α-cassava starch (CS)) was tested as is or after being enzymatically de-branched at three different inclusion levels in diets for largemouth bass. Results showed that the increased dietary starch levels compromised performance and high dietary α-CS content led to obvious liver damage. However, the growth performances of fish fed the diets with de-branched starch (DS) were improved, and no manifest liver damages were observed even at the higher inclusion level. The increasing dietary starch contents significantly increased hepatic glycogen accumulation, but not when DS was used. High dietary starch content, without regard to starch sources, had no effect on the expression of glucose metabolism-related genes, except for down-regulation of insulin receptor expression. However, the use of dietary DS promoted the expression of genes involved in the insulin pathway and glycolysis. In conclusion, this study showed that the use of starch sources with a high amylose to amylopectin ratio and resistant starch in the feed for cultured carnivorous finfish could alleviate the hepatic glycogen deposition through regulating the insulin pathway and glycolysis.

Starch digestibility: past, present, and future

In the last century, starch present in foods was considered to be completely digested. However, during the 1980s, studies on starch digestion started to show that besides digestible starch, which could be rapidly or slowly hydrolysed, there was a variable fraction that resisted hydrolysis by digestive enzymes. That fraction was named resistant starch (RS) and it encompasses those forms of starch that are not accessible to human digestive enzymes but can be fermented by the colonic microbiota, producing short-chain fatty acids. RS has been classified into five types, depending on the mechanism governing its resistance to enzymatic hydrolysis. Early research on RS was focused on the methods to determine its content in foods and its physiological effects, including fermentability in the large intestine. Later on, due to the interest of the food industry, methods to increase the RS content of isolated starches were developed. Nowadays, the influence of RS on the gut microbiota is a relevant research topic owing to its potential health-related benefits. This review summarizes over 30 years of investigation on starch digestibility, its relationship with human health, the methods to produce RS and its impact on the microbiome. © 2018 Society of Chemical Industry.

Physicochemical Characteristics of Starch in Sweet Potato Cultivars Grown in Korea

The objective of this study was to investigate the structural and physicochemical properties of starch from seven sweet potato cultivars (Shinyulmi, Sinjami, Hogammi, Jeonmi, Jinyulmi, Juhwangmi, and Pungwonmi). Jeonmi and Jinyulmi had amylose contents of 40.04% and 37.39%, respectively, whereas Juhwangmi and Pungwonmihad amylose contents of 30.95% and 32.37%, respectively. As a result of amylopectin polymerization, the seven cultivars were found to have high (>48%) contents of the degree of polymerization (DP) 13∼24 fraction, whereas the DP≥37 fraction content was <3.45%. The level of resistant starch was highest in Jeonmi (>30%) and lowest in Pungwonmi (<5%). The in vitro digestibility of Pungwonmi was greater than that of the other cultivars. Starch X-ray patterns did not differ among the cultivars. The results of this study provide useful information for the food industry regarding the application of sweet potato starches.

Reducing the glycemic impact of carbohydrates on foods and meals: Strategies for the food industry and consumers with special focus on Asia

Type 2 diabetes is increasingly prevalent in Asia, which can be attributed to a carbohydrate-rich diet, consisting of foods in the form of grains, for example, rice, or a food product made from flours or isolated starch, for example, noodles. Carbohydrates become a health issue when they are digested and absorbed rapidly (high glycemic index), and more so when they are consumed in large quantities (high glycemic load). The principal strategies of glycemic control should thus aim to reduce the amount of carbohydrate available for digestion, reduce the rate of digestion of the food, reduce the rate of glucose absorption, and increase the rate of glucose removal from blood. From a food perspective, the composition and structure of the food can be modified to reduce the amount of carbohydrates or alter starch digestibility and glucose absorption rates via using different food ingredients and processing methods. From a human perspective, eating behavior and food choices surrounding a meal can also affect glycemic response. This review therefore identifies actionable strategies and opportunities across foods and meals that can be considered by food manufacturers or consumers. They are (a) using alternative ingredients, (b) adding functional ingredients, and (c) changing processing methods and parameters for foods, and optimizing (a) eating behavior, (b) preloading or co-ingestion of other macronutrients, and (c) meal sequence and history. The effectiveness of a strategy would depend on consumer acceptance, compatibility of the strategy with an existing food product, and whether it is economically or technologically feasible. A combination of two or more strategies is recommended for greater effectiveness and flexibility.

Study on crystalline, gelatinization and rheological properties of japonica rice flour as affected by starch fine structure

Although many researches have investigated the effects of starch characteristics on its functional properties to evaluate rice quality, few studies were carried out the correlations between starch molecular structure and rice processing properties. In this study, eight varieties of japonica rice with similar content of protein and lipid and less variant content of amylose (12.12-18.19%) were elaborately selected. The result showed that crystalline and pasting parameters were mainly reliant on the differences in chain length distribution of amylopectin. Amylose content and chain length distribution, especially for average exterior chain length (ECL) and interior chain length (ICL) and their entanglement, showed significant correlation on rheological parameters. Swelling power of rice flour showed negative correlation with amylose content. Furthermore, in temperature-reduction process when the temperature is lower gelatinization temperature of amylopectin, the variation of loss modulus was affected by amylopectin. In addition, the PCA plot clearly revealed the interrelationship of all parameters.

Textural Properties, Resistant Starch, and in Vitro Starch Digestibility as Affected by Parboiling of Brown Glutinous Rice in a Retort Pouch

The effects that two preparation methods (parboiling with different degrees of gelatinization and parboiling with enzymatic hydrolysis) have on the qualities of brown glutinous rice were investigated in order to optimize the pretreatment conditions of brown glutinous rice for the ready-to-eat product in retort pouch. The brown glutinous rice was parboiled at various temperatures (50, 70 and 90C) and steamed at atmospheric pressure until the gelatinize level of 60, 80 and 100%. For the parboiling with enzymatic hydrolysis, the brown glutinous rice was immersed in xylanase before steamed. Results showed that parboiling not only affected the nutritional composition, color, and texture of glutinous rice but also decreased the Glycemic index (GI) to 61.3 ± 0.03 and raised the Resistance starch (RS) to 2.9 ± 0.02. There was interaction among RS, GI, and the amylopectin content of brown glutinous rice during parboiling without enzymatic hydrolysis. Amylopectin is directly proportional to GI but inversely proportional to RS. Enzymatic hydrolysis improved both the texture and the physical and chemical properties. In addition, the GI value of enzyme treated samples decreased to 62.7 ± 0.24 and the RS increased to 2.9 ± 0.05. The highest overall preference score was attained by parboiled rice which was soaked in water at 90°C and then steamed until 100%gelatinization.

Understanding the multi-scale structural changes in starch and its physicochemical properties during the processing of chickpea, navy bean, and yellow field pea seeds

This study aimed to isolate starch from three types of untreated and autoclaved pulse seeds including chickpea, navy bean, and yellow field pea and to characterize their multi-scale structure and the associated physicochemical properties. Autoclaving of pulse seeds tended to significantly decrease the relative crystallinity, the Mw value, and degree of order of starch samples measured by X-ray diffraction, size exclusion chromatography, and FT-IR. Simultaneously, double helix content, and degree of double helix obtained from solid-state 13CNMR and FT-IR were relatively higher (P < 0.05) for autoclaved pulse seeds than their native counterparts. The structural characteristics also corroborated well with the obtained results of resistant starch content, gelatinization behavior, swelling power, solubility, and bile acid binding capacity. This research gave insights into the structural characteristics of starch from pulses and their changes that occurred following processing of seeds, aiming to provide information for the future study on their processing-structure-function relationship.

Influences of Extraction Methods on Physicochemical and Functional Characteristics of Three New Bulbil Starches from Dioscorea opposita Thunb. cv. Tiegun

Starches from the bulbils of Dioscoreae opposita Thunb. cv. Tiegun were isolated by aqueous steeping (SBS), enzyme extraction (EBS), and alkaline extraction (ABS) methods, respectively. The physicochemical, mineral composition, thermal and morphological characteristics of these starches were investigated. The starch granules were oval, spherical and kidney-shaped and its crystal type is a mixture of A-type and B-type patterns. The starches having larger average granule size showed more amylose and phosphorus contents than those with smaller average granule size. Differential scanning calorimetry (DSC) showed that the SBS had an endothermic transition ranging from 65.8 °C to 76.3 °C with an enthalpy of 2.0 J/g. The endothermic transitions of ABS and EBS showed the regions of 67.9 °C to 73.0 °C, and 66.8 °C to 82.0 °C, respectively. The gelationization enthalpies of ABS and EBS were 13.8 and 11.5 J/g, respectively. Additionally, ABS presented greater clarity in comparison with EBS and SBS. Pasting properties indicated that ABS had the highest peak viscosity, breakdown, but SBS had the lowest trough, final viscosity, setback, and pasting temperature. Generally, ABS and EBS could be used as food thickener or frozen food additives. SBS and EBS were potential technological alternatives in quality preservation of frozen starch-based products and other industrial applications.

Physical, textural and sensory characteristics of legume-based gluten-free muffin enriched with waxy rice flour

Physical, textural, and sensory characteristics of the gluten-free muffins made of mungbean and cowpea flours enriched with waxy rice flour were investigated. Amylose content and pasting viscosity of legume-waxy rice flour blend (1:1) were lower than that of wheat flour. The number and area of gas cells of muffin containing legume flour was lower than that of control muffin with wheat flour. Legume-based muffins had low lightness value due to the presence of color components. Weight of the muffins containing legume was higher than that of control muffin, but their height and volume were lower than control. Legume-based muffins had greater crude ash and protein contents than control. Compared with control, muffin containing legume flour had significantly higher hardness and gumminess. In sensory evaluation, overall acceptance of muffin containing Okdang cultivar of cowpea was the highest among legume-based muffins, which was comparable to control muffin.

Properties and Digestibility of Octenyl Succinic Anhydride-Modified Japonica-Type Waxy and Non-Waxy Rice Starches

Waxy and non-waxy rice starches from japonica type Korean rice varieties were esterified with different levels of octenyl succinic anhydride (OSA), and the molecular structure of amylopectin (AP), digestibility, and emulsion stability were investigated. As OSA levels increased, the degree of substitution, granule size, peak and final viscosities, emulsion stability, and short chain of AP increased. However, the gelatinization temperature and enthalpy, and digestibility decreased. All OSA esterified starches showed a new band at 1723 cm-1, but maintained A-type crystallinity. The DP6-12 of AP in waxy rice starch (WRS) was higher than that in non-waxy rice starch (NRS) with increasing OSA levels. Because the amylose and long chain of AP accessed easily with OSA groups, the digestibility of NRS was lower than that of WRS. The emulsion stability was higher in WRS than in NRS. From the above results, it is suggested that amylose should have a higher affinity with OSA esterification than AP and that the emulsion stability should increase in WRS, but the digestibility should decrease in NRS after OSA modification.

The microstructure of starchy food modulates its digestibility

Starch is the main carbohydrate in human nutrition and shows a range of desired food properties. It has been demonstrated that fast digestion of starchy food can induce many health issues (e.g., hyperglycaemia, diabetes, etc.); therefore, how to modulate its digestion is an interesting topic. Previous studies have revealed that the microstructure and digestibility of starchy food of different botanical origin or from multiple processes are quite different; modulating starch digestion by retaining or altering its microstructure may be effective. In the present review, the current knowledge of the relationship between microstructural changes to starchy food and its digestibility at molecular, cell and tissue, and food processing levels is summarized. New technologies focused on microstructure studies and ways to manipulate food microstructure to modulate starch digestibility are also reviewed. In particular, some insights focusing on the future study of microstructure and the digestibility of starchy food are also suggested.

Molecular structures of rice starch to investigate the differences in the processing quality of rice flours

The molecular structures of non-waxy rice starches purified from three Korean rice cultivars, Dongjin1, Hopyeong, and Ilmi, were investigated to determine the main reasons why it is difficult to make manju with Dongjin1 flour compared to other rice flours with similar processing qualities. The molecular structural characteristics of the three rice starches were analyzed by high-performance size-exclusion chromatography and high-performance anion-exchange chromatography. The Dongjin1 starch had lower molecular weight (MW) amylose, a smaller proportion of short a chains, and higher average amylopectin branch chain length than the other two starches. These properties of Dongjin1 starch resulted in a lower water binding capacity, lower swelling power at 80 °C, and lower peak viscosity than those of the other two starches. It is suggested that the MW of amylose and degree of polymerization of amylopectin are important factors to make gluten-free bakery products using non-waxy rice flours.

Starch Structure Influences Its Digestibility: A Review

Twenty-five years ago, it was found that a significant fraction of the starch present in foods is not digested in the small intestine and continues to the large intestine, where it is fermented by the microbiota; this fraction was named resistant starch (RS). It was also reported that there is a fraction of starch that is slowly digested, sustaining a release of glucose in the small intestine. Later, health benefits were found to be associated with the consumption of this fraction, called slowly digestible starch (SDS). The authors declare both fractions to be "nutraceutical starch." An overview of the structure of both fractions (RS and SDS), as well as their nutraceutical characteristics, is presented with the objective of suggesting methods and processes that will increase both fractions in starchy foods and prevent diseases that are associated with the consumption of glycemic carbohydrates.