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Colored brown rice shows better health benefits than polished rice, and there is great interest in the design of demanded cooking manners for brown rice. This investigation concerns how the change of cooking mode can slow starch digestion of colored brown rice by inspecting mainly starch structural changes during cooking. Compared to cooking Mode 1, the soaking of Mode 2, at higher temperature, probably enhanced water diffusion into rice matrices, thus strengthening starch lamellae without apparently altering rice morphology and ordered structures such as starch polymorphs and helices. The followed heating of Mode 2, with reduced time, more sufficiently disrupted rice structures, causing less prominent nonperiodic molecular organizations. At the final cooking stage, the braising of Mode 2, having faster temperature reduction for prolonged time, leading to similar rice morphology, reduced molecular orders (e.g., helices) and probably denser amorphous regions of nonperiodic organizations. Such features tended to increase packing density of molecular chains (mainly starch) in rice matrices, thus slowing the enzyme diffusion in rice matrices and associated binding and catalysis events. In this way, a reduced starch digestion rate and increased resistant starch (RS) and slowly digestible starch (SDS) were seen for the rice following Mode 2 cooking.

The functionalities of gluten-free rice noodles are significantly affected by starch hierarchical structures. Identifying the structures that synergistically determine noodle integrated functionalities is vital to designing health-promoting starchy foods with desirable consumer sensory and nutritional qualities. This study reports on the changes in starch structures and functionalities (starch digestibility, texture, and flavor) of rice noodles during household cooking processes (steaming, boiling, and stir-frying), and describes an underlying structure-functionality relationship. Results show that all the cooking processes examined increased starch reassembled ordered structures, especially short-range ordered structures, helical and crystalline structures, and ordered aggregate structures. Steaming and boiling led to a decrease in rapidly digestible starch (RDS) and an increase in slowly digestible starch, while stir-frying yielded a reduction in RDS content and an increase in resistant starch in rice noodles. Steaming and boiling decreased while stir-frying increased the flavor variety of noodles. All cooking processes examined altered noodle textures, with a significant increase in hardness, gumminess, and chewiness. Structure-functionality relationships suggested short-range ordered structures, crystalline structures, and the ordered molecular and aggregate structures of noodles synergistically determined starch digestion, texture, and flavor. By structuring such key structures, the digestion, texture, and flavor of rice noodles can thus be reasonably controlled.

The effects of the dry heat treatment (DHT) temperature (20, 50, 100, 150, 200 °C) on the structure of wheat flour and on the texture and in vitro starch digestibility of breads were investigated. X-ray diffraction and FTIR showed that increasing temperatures produced reduction of the hydrated starch structures, increased crystallinity and molecular order of starch chains, and had important effects on the gluten secondary structure. High treatment temperatures produced significant reductions in rapidly digestible starch (RDS) (53.21% at 20 °C, 22.24% at 200 °C), and the slowly digestible starch fraction tended to increase (26.12% at 20 °C, 31.48% at 200 °C). On the other hand, bread hardness showed a significant increase from 11.25 N at 20 °C to 49.53 N at 200 °C, the latter value being similar to that reported for bread crusts. Principal component analysis results showed that the flour and bread characteristics were drastically changed by the DHT, with 100 °C representing a critical temperature. Below 100 °C, breads showed textural characteristics close to that of the control bread, with reduced RDS fractions, while at temperatures above 100 °C, hardness was boosted.

Changes in the properties of cooked rice under various cooking conditions were investigated. Waxy, low-, and high-amylose rice were subjected to treatment with different cooking temperatures (50, 70, 90 °C) for different cooking times (15, 30, 45 min). The results showed that cooking greatly increased the swelling behavior of waxy rice but decreased the swelling behavior and amylose leaching of low- and high-amylose rice. As the cooking temperature increased, rapidly digestible starch increased significantly for all rice products, whereas slowly digestible starch and resistant starch had a certain degree of reduction. Variation in the cooking time produced little effects on starch digestibility. Gelatinization temperature was positively correlated with temperature and time, whereas gelatinization enthalpy was negatively correlated with temperature and time. Pasting properties of all rice products decreased significantly as cooking temperature and time increased. The study showed that both cooking temperature and cooking time had significant impacts on the physicochemical properties and starch digestibility of waxy, low-, and high-amylose rice to various extents. Temperature had a more pronounced impact on the extent of change to the in vitro digestibility than did cooking time.

Starch digestibility is the dominant factor affecting the nutrition of starchy food. Starch with different digestibility can be obtained through tailoring the starch multi-scale structures by controlling the crop growth period. Here, the multi-scale structure and digestibility of cassava starch obtained from different cassava growth periods were investigated, and the structure-digestibility relationships were revealed. The results indicated that the cassava starch synthesized during different growth periods showed differences in digestibility. The combined total content of slowly digestible starch (SDS) and resistant starch (RS) was highest at the growth period of 7 months, and the individual content of SDS and RS was highest at the growth periods of 10 and 11 months, respectively. The multi-scale structure changes during different growth periods demonstrated that smaller weight-average molecular molar mass, larger molecular density, more ordered short-range structure, and thinner amorphous lamellae decreased starch digestion, while higher amylose content and B2 chain ratio, longer average chain length, thicker crystalline lamellae, and repeated semicrystalline lamellae contributed the formation of RS fractions. Hence, specific starch structures can be tailored by simply controlling the growth period for obtaining slow and resistant digestible cassava starch to improve its nutritional value.

In this study, waxy or normal potato starches (WPS or NPS) were blended with waxy, low-amylose or high-amylose rice starch (WRS, LARS or HARS) in different ratios (100:0, 80:20, 60:40, 40:60, 20:80 and 0:100). Pasting profiles of blends were additively between those of the component starches separately except for some mixtures of WRS and potato starches. Twin or even three gelatinization peaks were observed for potato-WRS or potato-HARS blend, while only one peak was observed in potato-LARS blend. Addition of WRS enhanced the nutritional profile of blends containing WPS by decreasing the rapidly digestible starch level. Microscopy revealed that addition of WRS was beneficial for the development of dense and compact structure of gels of blends compared with their counterparts, which may be because few amylose chains leached to inhibit the interaction between swollen potato and rice starch granules. Besides, peak, trough, breakdown and final viscosity as well as gelatinization enthalpy showed significantly negative correlations with amylose leaching. Non-additive behaviours were observed for properties, but more independent behaviour was observed between potato starch and LARS or HARS. Results suggested that properties of blends of potato and rice starches differing in amylose content varied through different extents of amylose leaching.

This study aimed to investigate functional and thermal properties and digestibility of grass pea starch, and provide information on the effect of hydrothermal modifications - annealing (ANN) and heat-moisture treatment (HMT) on the physico-chemical characteristics of the starch and digestibility, especially after processing (cooking, storage after cooking and freezing). After heat treatment, especially after cooking and storage at a temperature of −18 °C, the total content of slowly digestible starch and resistant starch in grass pea starch was high, which may indicate its great tendency for retrogradation. The HMT and ANN modifications of grass pea starch caused changes in its crystalline structure and increased integrity of its granules, which in turn resulted in a lower swelling power and amylose leaching, however this effect was more pronounced upon HMT which contributed to starch polymorphic type transformation from C to A. Despite greater resistance of granules of modified starches to swelling during cooking their suspensions, after cooking these starches were characterized by a higher predicted glycemic index than the non-modified ones. A similar content of resistant starch determined in modified and non-modified gelatinized starches stored at lowered temperatures indicates that starch modifications, HMT in particular, cause no changes in its susceptibility to retrogradation.

The objective of this study is to investigate the change in physicochemical properties and digestibility of starches isolated from colored sweet potato varieties under heat-moisture treatment (HMT) or annealing treatment (ANN). The results showed that morphology and X-ray diffraction patterns of the sweet potato starches remained unchanged after the HMT or ANN. The HMT significantly reduced peak viscosity, breakdown and setback and significantly increased pasting temperature, trough and final viscosities of the sweet potato starches. The swelling powers and solubility of the heat-moisture treated starches were significantly lower than those of the native or annealed starches. The decreased rapid digestible starch and the increased slowly digestible and resistant starch contents of the sweet potato starches after HMT or ANN as compared to those of the native starches were observed. The resistant starch (RS) contents of the heat-moisture treated sweet potato starches were in a range of 30.6-39.3%, significantly higher than those of the annealed starches (28.8-32.0%). The strong impact of the HMT on physicochemical properties and RS formation of the sweet potato starches compared to the ANN might be due to the high stability of the occurred interactions between starch molecules and amylopectin chains during treatment.

Waxy rice starch slurry (10%, w/w) was treated with high hydrostatic pressure (HHP) (100–600 MPa) for 20 min and morphology, gelatinization property, X-ray diffraction pattern, semi-crystalline structure, and in vitro digestibility was determined. The morphology analysis showed that HHP treatment significantly affected the shape of starch granules. The thermal properties indicated an increase in gelatinization temperature s and decreased enthalpy with increasing pressure. However, compared with lower pressure, a complete gelatinization of starch was induced by 600 MPa. The lamellar repeat distance increased with increased pressure, while scattering peak disappeared at 600 MPa as a result of starch gelatinization. Based on the in vitro digestibility results of slowly digestible starch, HHP treatment at 400 MPa could be beneficial for improving the functionality of the waxy rice starch.

Impact of heat-moisture treatment (HMT) on nutritional properties of normal maize starch (NMS) under various reaction conditions was investigated. NMS was adjusted to moisture levels of 20%, 25%, 30% and 35% and heated at 80, 100, 120 and 140°C for 4, 8, 12 and 16h. Response surface methodology (RSM) based on Box-Behnken design (BBD) was employed to obtain the optimal combination of moisture level (X1: 20-30%), length of heating (X2: 4-12h), and temperature (X3: 100-140°C). The optimum reaction condition decreased rapidly digestible starch (RDS) from 87.10% to 82.21%, when NMS was subjected to HMT at 23.6% moisture content and heated at 114.8°C for 9.04h. The ANOVA measurement and confirmation experiments were performed to verify the predictive value and the RSM model, indicating that temperature was the main factor to determine the digestion rate of HMT NMS. The results suggested that RDS was not correlated to heating length but positively correlated to temperature and moisture content. Reaction condition had no correlations with slowly digestible starch (SDS) and resistant starch (RS). This study could provide more information for producing low-glycemic index products.

The influence of dry heat treatment (DHT) of high amylose rice starch was investigated on starch digestibility and physical properties and their characteristics were compared through the PCA analysis. High amylose rice starch was prepared by DHT under different temperatures (110, 130, and 150°C) and times (0, 1, 2, and 4h). The gelatinization temperature and enthalpy decreased as temperature and time increased, revealing the change of semi-crystalline region. There were significant increases in gel strength and pasting viscosity above 130°C, whereas gel strength and pasting viscosity were reduced with increasing heating time. On in vitro starch digestibility of DHT starch gel, the rapidly digestible starch and predicted glycemic index of DHT starches were lower than those of native starch. Both the lowest predicted glycemic index and the highest gel strength was observed at 130°C for 1h. In the results of PCA analysis, the heating temperature was negatively correlated with in vitro starch digestibility as well as pasting viscosity and gel strength. These results demonstrated that DHT could be useful of enhancing the physical and nutritional properties of high amylose rice starch.

Changes in the physicochemical properties and starch digestibility of white salted noodles (WSN) at different cooking stage were investigated. The noodles were dried in fresh air and then cooked for 2-12 min by boiling in distilled water to determine the properties of cooking quality, textural properties and optical characteristic. For starch digestibility, dry noodles were milled and sieved into various particle size classes ranging from 0.5 mm to 5.0 mm, and hydrolyzed by porcine pancreatic α-amylase. The optimal cooking time of WSN determined by squeezing between glasses was 6 min. The results showed that the kinetics of solvation of starch and protein molecules were responsible for changes of the physicochemical properties of WSN during cooking. The susceptibility of starch to α-amylase was influenced by the cooking time, particle size and enzyme treatment. The greater value of rapidly digestible starch (RDS) and lower value of slowly digestible starch (SDS) and resistant starch (RS) were reached at the optimal cooking stage ranging between 63.14-71.97%, 2.47-10.74% and 23.94-26.88%, respectively, indicating the susceptibility on hydrolysis by enzyme was important in defining the cooked stage. The study suggested that cooking quality and digestibility were not correlated but the texture greatly controls the digestibility of the noodles.

The influence of the ratio of soluble dietary fiber (SDF) and insoluble dietary fiber (IDF) on the in vitro starch digestion, predicted glycemic index (pGI), and the physicochemical properties of fiber-enriched cakes were evaluated. The hydration and pasting properties were affected by the ratio of SDF and IDF. According to the increase of IDF ratio (SDF ratio reduction) in 3 g fiber-enriched cakes, slowly digestible starch (SDS) contents increased, while the rapidly digestible starch (RDS) contents decreased. The pGI values were significantly different with control in 3 g fiber-enriched cake containing more than 50% IDF contents (p

The temperature-cycled retrogradation conditions were optimized for producing slowly digestible starch (SDS) products in this study. The present data showed that the following conditions (temperature cycle, 4/25 °C; temperature-cycled time, 14 d; temperature-cycled time interval, 24 h; and ratio of starch to water, 1:2) were available for increasing the SDS yield of the products. The maximum yield reached 54.5%, while the SDS products were prepared under the optimum conditions. The results also indicated that temperature-cycled retrogradation significantly increased the slow digestibility of the SDS products. This was probably attributed to many solid blocks remaining after the hydrolysis of the SDS products by the enzymes for 60 min and 120 min. The solid blocks may comprise of more imperfect crystallites and part of amorphous non-digestible starch. These results suggest that the optimum conditions obtained are suited for preparing SDS products in food and pharmaceutical industries.

Fucoidans (FC) have a variety of biological activities, and it can also affect the functionality and nutritional characteristics of starch-based food products. However, there are few studies on the structural and digestive properties of starch - fucoidans blends. The effect of FC at different concentrations (0, 0.6 %, 0.8 %, 1.0 %, w/v) on the structural properties and digestibility properties of A-type wheat starch (AS) and B-type wheat starch (BS) subjected to autoclave treatment were investigated. The results show that compared with native wheat starch, AS with FC displayed higher crystallinity as well as the structural ordering, but the crystallinity and degree of order of BS with FC decreased, which was proposed due to AS interact with FC in crystalline region but BS reacts with FC in the amorphous region. With the interaction of FC with AS and BS, granules compactness of AS and BS were enhanced. The addition of FC delayed digestion in vitro of AS and BS, the rapidly digestible starch content was obviously lower than native one, and the proportion of slowly digestible starch raise markedly. This study might broaden the recognition of wheat starch with different proportion of AS and BS, and provide a theoretical basis for the potential utilization of FC in carbohydrate based food industry.

The effects of repeated retrogradation (RR, range from 1 to 3 times) at different temperatures (4 °C; 4/25 °C, with a 24 h interval; 25 °C) on the in vitro digestibility and structures of Tartary buckwheat starch (TS) were investigated in this study. Results demonstrated that TS treated by RR for 1 time under 4/25 °C contained the maximum content of slowly digestible starch (SDS, 35.25%); TS treated by RR for 3 times under 25 °C contained the maximum content of resistant starch (RS, 54.92%). As the increase of RR cycle times, the value of relative crystallinity, the ratios of 1047/1022 cm−1 and 995/1022 cm−1 increased, the starch pore wall thickened, and more smooth fragments appeared (observed by scanning electron microscope), while the value of melting temperature range trended to decrease. The crystallization type of TS changed from type “A” to a mixture of “B + V” after retrogradation treatment. Pearson correlation analysis revealed that the content of rapidly digestible starch (RDS) was negatively correlated with the ratio of 995/1022 cm−1, transition temperatures, and enthalpy (P

Microwave radiation (MW) is an environment-friendly technology used to physically modify flours. Rice flour was MW-treated at different moisture content (MC) (3 %, 8 %, 13 %, 15 %, 20 % and 30 %). In vitro starch digestibility was determined and related to the changes caused by MW treatment to flours' structure and thermal properties, which were influenced by MC. A reduction of 49 % and 65 % in the gelatinization enthalpy of samples treated at 20 % and 30 % MC denoted a partial gelatinization. A loss of granular crystallinity in treated samples was confirmed by XR-diffraction and FTIR, particularly at 15 %, 20 % and 30 % MC. MW promoted the formation of random-coil, α-helix and β-turn protein structure, and the disappearance of LF-β-sheet. Morphological differences were found between samples treated at 8 % MC (loss of polygonal structure, protein layer covering granules' surface and small holes) and 30 % MC (rounded and aggregated granules, covered with exudate amylose). In vitro starch digestibility revealed that samples treated at 20 % and 30 % MC showed 40 % and 47 % higher rapidly digestible starch, 48 % and 70 % lower slowly digestible starch and 90 % lower resistant starch than the untreated flour. Flour MC in MW-treatment allowed the modulation of structural and thermal characteristics of rice flour and consequently its starch hydrolysis rate.

The objective of this study was to evaluate the impact of sprouting (0, 12, 24, 36, 48 hr) on enzyme activity, protein solubility, dough mixing behavior, anti-nutritional components and in vitro starch and protein digestibility of minor millets. Sprouting decreased starch, fat, protein and ash contents while the dietary fiber content, amylase and protease activity significantly (p 0.05) increased. Sprouting promoted a significant (p 0.05) decrease in anti-nutritonal components like phytic acid and condensed tannin. The protein solubility enhanced that also resulted in improved protein digestibility (in vitro) of sprouted millets. Sprouting exerted a significant (p 0.05) effect on mixolab dough rheology indicating a decrease in dough consistency (C1), peak and final viscosity whilst protein weakening and breakdown increased (p 0.05). This process produced an increase in free glucose thereby improving rapidly digestible starch and increasing glycemic index. A significant (p 0.05) reduction in resistant starch along with slowly digestible starch was promoted during sprouting. In conclusion, sprouting provides millet flours with modified nutritional quality and better technofunctional properties than the raw flours that may suggest their potential utilization in complementary food formulations and baked products.

Effects of degree of milling on starch digestibility of cooked rice during (in vitro) small intestine digestion were investigated. By fitting starch digestograms to the logarithm of slope plot and combination of parallel and sequential digestion kinetics model, two starch fractions with distinct digestion rate constants were identified. Results from scanning electronic microscope and confocal laser scanning microscope showed that the rapidly digestible starch fraction (RDF) was mainly composed of gelatinized starch, while the slowly digestible starch fraction (SDF) was consisted of relatively intact starch granules, protein matrix encapsulated starch and starch-protein binary complex. The cooked rice with milling treatment had more loosely packed and larger network cells compared to that for brown rice. Consequentially, the RDF content was decreased, while that for SDF was increased by the milling treatment. These results could help the rice processing industry to develop healthy rice products with desirable starch digestibility.

Using restructuring technology, A- or B-type crystalline granular potato starch was produced from amorphous granular potato starch (AGPS). AGPS was prepared using ethanol-heat processing, and hydrothermal treatments were performed with different moisture contents (18, 29, 200% d.b.) and temperatures (4, 25, 40, 60, 80 °C) for 3 weeks. AGPS showed no endothermic peak in a DSC thermogram, while hydrothermally treated AGPS (HAGPS) revealed endothermic peaks. In X-ray diffraction, AGPS displayed an amorphous pattern, and HAGPS displayed A- or B-type crystalline patterns depending on treatment temperature and moisture content. Neither AGPS nor HAGPS had typical RVA pasting curves, and their viscosities gradually increased. Raman spectroscopy and FT-IR confirmed that ordered structure and crystalline regions increased in HAGPS. Resistant starch (RS) and slowly digestible starch (SDS) contents of HAGPS increased but rapidly digestible starch (RDS) content decreased compared to AGPS. These results elucidated that hydrothermal treatment could change the physicochemical properties of AGPS and produce an identical material, such as granular potato starch with A-type and B-type crystalline granular potato starch.

The endogenous rutin-degrading enzymes (RDEs) in Tartary buckwheat (TB) considerably limit the development of TB functional foods. In this study, three thermal treatments, including superheated steam (SS), saturated steam (ST), and far-infrared drying (FID), were used to inactivate RDEs in TB. Results showed that SS and ST could efficiently inactivate RDEs, whereas FID could not. The extractable rutin contents in TB were increased by 52.3% and 12.3% by SS and ST, respectively, with 90 s of treatment time. Furthermore, the properties of phenolics and starch were used to evaluate the influence of thermal inactivation on TB. Results showed that the soluble phenolic compounds contents in TB were significantly improved (p 0.05) by SS. The bound phenolic compounds contents were decreased after SS and ST treatments. The change in antioxidant properties was consistent with that of phenolics and flavonoids. Besides, the starch in SS- and ST-treated TB achenes had higher relative crystallinity, setback, transition temperatures, rapidly digestible starch, and slowly digestible starch contents, but a lower ratio of 1047 cm

Amino acids are the structural units (monomers) that make up proteins and play many critical roles in human diets with or without food processing. In this study, corn starch (CS) mixed with Lys, Ser, Ala, or Asp were subjected to heat moisture treatment (HMT) or annealing (ANN). We evaluated the morphological properties, swelling power, pasting properties, thermal properties, crystallinity structure, and in vitro digestibility of CS and CS-AA complexes. HMT increased the gelatinization temperatures and retarded the retrogradation for CS with or without AAs, while ANN had little impact on gelatinization temperature and promoted the recrystallization. Generally, HMT samples were more enzyme resistant than the ANN samples. For the uncooked samples, the addition of Ser, Ala, and Asp decreased rapidly digestible starch (RDS) and slowly digestible starch (SDS) contents, but increased resistant starch (RS) content. Compared with the control (CS without AA), CS-AA complexes had lower contents of RDS following HMT. Under ANN, CS-AAs had higher content of RDS compared with the control. In all groups (physically mixed, HMT, and ANN) with cooked samples, the addition of different AAs decreased the contents of RDS and increased RS contents to varying degrees.

Aqueous dispersions of normal and waxy corn starch (3% w/w) were mixed with Tween 80 (0, 7.5, 15, 22.5 and 30 g/100 g of starch), and gelatinized (90 °C, 20 min). Optical microscopy of the gelatinized starch dispersions (GSDx; x = Tween 80 concentration) revealed that the microstructure was characterized by a continuous phase of leached amylose and amylopectin entangled chains, and a dispersed phase of insoluble remnants, called ghosts, on whose surface small granules were observed, imputed to Tween 80. The apparent viscosity of the GSDx decreased as the concentration of Tween 80 increased (up to about 70-90%). FTIR analysis of dried GSDx indicated that Tween 80 addition decreased short-range ordering. The content of rapidly digestible starch (RDS) and resistant starch (RS) fractions tended to increase significantly, at the expense of a significant decrease of slowly digestible starch (SDS) fraction, an effect that may be attributed to the increase of amorphous structures and starch chain-surfactant complexes. The RDS and RS increase was more pronounced for normal than for waxy corn starch, and the significance of the increase was dependent on Tween 80 concentration. Overall, the results showed that surfactant can affect largely the digestibility of starch chains.

The pasting and digestibility of a red adzuki bean starch were simultaneously modulated by heat-moisture treatment (HMT) through altering the multi-scale structure. HMT, especially at high moisture content, could disrupt the granule integrity, semicrystalline lamellae, molecular order (crystallites) and molecular chains. Also, certain rearrangement of starch molecules occurred to form ordered structures with increased thermal stability as shown by DSC. This concomitant disordering and reassembly in the multi-scale structure converted the fractions of resistant starch (RS) and rapidly digestible starch (RDS) into that of slowly digestible starch (SDS). Furthermore, the emergence of thermally-stable orders increased the pasting temperature but suppressed the swelling of granules during heating. Hence, HMT-modified red adzuki starch may serve as a potential thickener/gelling agent with slow digestion rate for various foods.

Effect of acid hydrolysis on the morphology, structure and digestion property of starch from Cynanchum auriculatum Royle ex Wight was investigated in this study. The hydrolysis degree of C. auriculatum starch rapidly increased to 63.69% after 4days and reached 78.67% at the end of 9days. Morphology observation showed that the starch granules remained intact during the first 4days of hydrolysis. However, serious erosion phenomenon was observed after 5days and starch granules completely fell into pieces after 7days. During acid hydrolysis process, the crystal type of hydrolyzed starch changed from original CB-type to final A-type. Small-angle X-ray scattering patterns showed the semi-crystalline growth rings started to be hydrolyzed after 4days. The proportions of single helix and amorphous components as well as amylose content in starch gradually decreased, whereas the proportion of double helix components continuously increased during acid hydrolysis. However, the contents of rapidly digestible starch, slowly digestible starch and resistant starch were almost constant during acid hydrolysis process, indicating the in vitro digestion property of C. auriculatum starch was not affected by acid hydrolysis. Our results provided novel information on the inner structure of C. auriculatum starch granules.

A nonthermal processing technology, high hydrostatic pressure (HHP) treatment, was investigated to assess its influence on the physicochemical properties and in vitro digestibility of sorghum starch (SS). There was no change in the ‘A’-type crystalline pattern of SS after the pressure treatments at 120–480 MPa. However, treatment at 600 MPa produced a pattern similar to ‘B’-type crystalline. HHP treatment also resulted in SS granules with rough surfaces. Measured amylose content, water absorption capacity, alkaline water retention, pasting temperature and thermostability increased with increasing pressure levels, while the oil absorption capacity, swelling power, relative crystallinity and viscosity decreased. Compared with native starch, HHP-modified SS samples had lower in vitro hydrolysis, reduced amount of rapidly digestible starch, as well as increased levels of slowly digestible starch and resistant starch. These results indicate that HHP treatment is an effective modification method for altering in vitro digestibility and physicochemical properties of SS.

This work concerns different cultivars of waxy maize starch (WMS), from which a significant correlation between the multi-scale structure and the digestibility has been identified. WMSs show a typical A-type crystalline polymorph. The surface porosity of WMS granules facilitates their digestibility. In contrast, the in vitro digestion results indicate that the resistant starch (RS) content increased with higher contents of amylose, single helices, and surface short-range ordered structures. Resistant starch (RS) was found to be made up of single helices and perfect crystallites formed by the fraction of chains with a degree of polymerization (DP) between 13 and 24. Slowly digestible starch (SDS) consists of single helices. Rapidly digestible starch (RDS) is mainly composed of disordered molecular chains in the amorphous regions of starch. This work reveals the relationship between the multiscale structure and digestibility of different WMSs and can provide guidance for the application of WMSs in food or non-food fields.\ud \ud

Annealing effects on the structure characteristics and the digestibility of corn starch (CS)/corn oil (oil)/lysine mixture were investigated. The objective of this study was to provide guidance for designing higher slowly digestible starch. Confocal laser confirmed that lysine adhered to granules surface. The interactions among starch, corn oil and lysine were further investigated by using X-ray diffraction (XRD), differential scanning calorimetry (DSC) and rapid visco analyzer (RVA). After annealing treatment, in vitro digestion studies showed that the content of slowly digestible starch increased in the mixture blended with corn oil and lysine. The physical barrier of lysine, amylose-lipid complex and starch-oil-lysine three-dimensional network can provide resistance to digestive enzymes. Annealing with corn oil and lysine can be a good prospect for the efficient modification of in vitro digestibility of starch.

The combined effects of extrusion (ET) and heat-moisture treatments (EHMT) on the physicochemical properties and in vitro digestibility of corn starch were investigated. Extrusion played a dominant role in reducing relative crystallinity and resistant starch (RS) content, but the swelling power, solubility, rapidly digestible starch (RDS) and slowly digestible starch (SDS) content were increased compared to native starch. EHMT resulted in a decreased swelling power, solubility and a transition in the X-ray diffraction from V- to V+A-type pattern, indicating a structural transformation toward an increased thermodynamic stability. The gelatinization temperatures shifted to higher values while the enthalpy was increased from 1.556 J/g in ET to 3.542 J/g in EHMT. The SDS and RS contents of starch granules were significantly increased, with the latter being increased from 63.03% in ET starch to 71.48% in EHMT starch.

The effect of improved extrusion cooking technology (IECT) on jackfruit seed starch (JFSS) digestion properties was investigated by the in vitro starch hydrolysis, hydrolysis index (HI) and glycaemic index (GI). The IECT markedly increased the content of rapidly digestible starch (RDS), slowly digestible starch (SDS), equilibrium concentration (C∞), HI, GI, and the rate of starch digestion but decreased in resistant starch (RS). Increasing the temperature and screw speed resulted in significant increases in SDS, C∞, HI, GI, and decreases in RDS, RS content. The scanning electron microscope demonstrated the digestion result that the JFSS changed from more compact structure to more loose polyhedral and from fewer pits to number of hollows. However, the opposite results were observed for increasing moisture content. All these results suggested that the in vitro digestibility of the high amylose and small granules JFSS can be efficiently enhanced by the improved extrusion cooking treatment.

This study presents the effects of dry heat (DH) assisted by pre-and post-electron beam (EB) treatment on buckwheat starch's multiscale structural, physicochemical, and digestive properties. The granule integrity and crystal shape were not affected by the investigated treatments. However, DH and EB treatments decreased amylose content, crystallinity, molecular weight, swelling power, thermal transition temperatures and gelatinization enthalpy while increasing solubility and the content of A chain, B1 chain, and resistant starch. EB application to DH starch promoted subsequent structural changes and enhanced starch properties compared to samples DH-processed alone. In addition, EB-induced starch chain depolymerization and structural rearrangement had sequential effects. EB pre-treatment reduced DH starch's amylose content, molecular weight, and swelling power while enhancing the content of A- chain, rapidly digestible starch, and resistant starch compared with EB post-treatment. This innovative study provides a theoretical basis for the potential applicability of EB irradiation in modifying the properties of DH starch.

Normal rice starches were isolated from six different rice varieties grown in Korea and their molecular structure, crystalline structure, and in vitro digestibility were investigated. Apparent amylose content was the highest in starch from Junam cultivar (25.5%) and lowest in Hopum (22.4%). Starch from Hiami cultivar had the lowest molecular weights of amylose and amylopectin, average amylopectin chain length, proportion of short chains (DP 6–12), and proportion of long chains (DP ≥ 37) among the tested rice starches. The relative crystallinity and ratio of 1047/1022 ranged from 30.2 to 36.7% and from 0.638 to 0.652, respectively. Hiami had the lowest gelatinization temperatures and the highest gelatinization enthalpy. Hiami had the highest pasting temperature (92.1 °C), the lowest setback (515 cP) and final viscosity (876 cP), whereas Hanareum had the lowest pasting temperature (82.7 °C), the highest setback (1002 cP), and final viscosity (1580 cP). The rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) content ranged from 43.9–53.5%, 35.5–52.6%, and 0.5–15.6%, respectively. The Junam cultivar had the lowest RDS content, whereas Hiami had the highest RDS content. The RS content of Hanareum (16.2%) and Boramchan (14.5%) was significantly higher than that of other normal rice cultivars (3.0–6.5%).

This study aimed to understand effects of adding corn oil (CO) and soy protein (SP) to corn starch on the physicochemical properties and digestive rates of annealed starch complex and mechanisms of interactions between corn starch (CS), CO and SP. Binary and ternary blends were prepared using CS mixed with CO (10%, dsb) and/or SP (10%, dsb) and incubated in a water bath at 50°C for 14h. Results showed that more agglomerates of the granules were in the ternary blends. With the addition of CO and/or SP, the CS displayed a decreased pasting temperature, an increased peak viscosity and a decreased enthalpy change of amylose-lipid complex dissociation. The CO can reinforce but SP hinder the annealing phenomenon. Results also showed that CO decreased retrogradation of CS, whereas SP increased it. The digestibility studies showed that the addition of CO and SP decreased the content of rapidly digestible starch and increased the sum of slowly digestible starch and resistant starch contents. SP displayed more impact on the digestibility of the ternary blends than CO. The physical barrier of CO, and amylose-lipid complex and protein-starch matrix can provide resistance to starch digestion.

This study investigated structural, in vitro digestion and physicochemical properties of normal rice starch (NRS)/flour (NRF) complexed with maize oil (MO) through heat-moisture treatment (HMT). The NRS-/NRF-MO complex displayed an increased pasting temperature and a decreased peak viscosity. After HMT, less ordered Maltese and more granule fragments were observed for NRS-/NRF-MO complex. Meanwhile, more aggregation was observed in the HMT samples with higher moisture contents. We found that higher onset temperature, lower enthalpy change and relative crystallinity of the NRS-/NRF-MO complex were associated with a higher moisture content of HMT samples. The higher moisture content of HMT was also favorable for the amylose-lipid complex formation. Differences in starch digestion properties were found for NRS-MO and NRF-MO complex. All of the NRS/NRF complexed MO after cooking showed lower rapidly digestible starch (RDS) contents compared with the control sample, therein NRS-/NRF- MO 20% exhibited the highest sum of the slowly digestible starch and resistant starch contents. In general, HMT had a greater impact on the in vitro digestion and physicochemical properties of flour samples compared with starch counterparts.

Pearl millet is a nutrient dense and gluten free cereal, however it's flour remains underutilized due to the onset of rancidity during its storage. To the best of our knowledge, processing methods, which could significantly reduce the rancidity of the pearl millet flour during storage, are non-existent. In this study, pearl millet grains were subjected to a preliminary hydro-treatment (HT). Subsequently, the hydrated grain-wet flour have undergone individual and combined thermal treatments viz., hydrothermal (HTh) and thermal near infrared rays (thNIR). Effects of these thermal treatments on the biochemical process of hydrolytic and oxidative rancidity were analyzed in stored flour. A significant (p 0.05) decrease in the enzyme activities of lipase (47.8%), lipoxygenase (84.8%), peroxidase (98.1%) and polyphenol oxidase (100%) in HT-HTh-thNIR treated flour compared to the individual treatments was documented. Upon storage (90 days), decline of 67.84% and 66.4% of free fatty acid and peroxide contents were observed in flour under HT-HTh-thNIR treatment without altering starch and protein digestibility properties. HT-HTh treated flour exhibited the highest (7.6%) rapidly digestible starch, decreased viscosity and increased starch digestibility (67.17%). FTIR analysis of HT-HTh treated flour divulged destabilization of short-range ordered crystalline structure and altered protein structures with decreased in vitro digestibility of protein. Overall, these results demonstrated the effectiveness of combined thermal treatment of HT-HTh-thNIR in reducing rancidity and preserving the functional properties of the stored flour.

The influence of inulin (IN) on pasting, thermal, rheological properties, and in vitro digestibility of pea starch gel was investigated. Results showed that as the concentration of IN in PS increased, the pasting temperature of PS gradually increased, while the value of peak viscosity, breakdown, and setback decreased. Rheological test suggested that all PS-IN gels were typical non-Newtonian fluids and exhibited a solid-like behavior. With the increased concentration of IN, hardness, chewiness, and gumminess of PS-IN gels significantly declined, in which the minimum value was at addition level of 20%. The presence of IN increased the gelatinization temperatures of PS-IN gels, while decreased the gelatinization enthalpy. Fourier-transform infrared spectroscopy (FT-IR) results indicated that no covalent bonding but intermolecular hydrogen bonding occurred between PS and IN. No influence of IN on the diffraction peak of PS after pasting was confirmed by X-ray diffraction analysis. In addition, IN decreased the content of rapidly and slowly digestible starch of PS, while increasing the content of resistant starch. These results will expand the application range of PS, and also provide a theoretical basis for the development of inulin-starch based products.

Auricularia auricula-judae polysaccharide (AP) has unique molecular structures and multiple bioactivities with excellent gel-forming property and thermal tolerance. However, few researches focus on the interactions between AP and legume starches. In this study, the effects of AP on the pasting, gelatinization, rheology, microstructure, and in vitro digestibility of kidney bean starch (KBST) were evaluated. The pasting, gelling and structural properties of AP-KBST mixtures were characterized by rapid visco analyzer, rheometry, texture analyzer, laser particle analyzer, low-field nuclear magnetic resonance, Fourier transform infrared spectroscopy and scanning electron microscopy, respectively. And an in vitro method was employed to measure the digestibility of AP-KBST composites. The pasting viscosity, swelling degree of starch granules, viscoelasticity, gel strength, cold storage stability and water-retention capacity of KBST were enhanced with increasing AP concentration. The combination of AP and KBST exhibited a higher short-range ordered and a firmer and denser structure than that of KBST alone. Moreover, AP increased the contents of resistant starch and slowly digestible starch, which were positively correlated with the storage modulus and the degree of order, thereby suggesting that the formation of strong and ordered gel network structure by synergistic interactions between AP and KBST was responsible for the reduced starch digestibility.

Waxy corn starch is widely used in food and papermaking industries due to its unique properties. In this work, the structural and functional properties of starch isolated from waxy corn at different stages of kernel growth were investigated and their relationships were clarified. The results showed that with kernel growth, the surface of starch granules became smooth gradually, and the inner growth rings and the porous structure grew and became clear. Meanwhile, the weight-average molecular mass (Mw), root mean square radius (Rg), and average particle size increased while the amylose content decreased, which should account for the decreased pasting temperature (from 71.37 to 67.44 °C) and increased peak viscosity (1574.2 to 1883.1 cp) and breakdown value observed. Besides, the contents of slowly digestible starch (SDS) and resistant starch (RS) in waxy corn starch decreased significantly (from 44.01% to 40.88% and from 16.73% to 9.80%, respectively, p < 0.05) due to decreases in the double helix content, crystallinity, and structural order, and increases in the semi-crystalline lamellae thickness and the amorphous content. This research provides basic data for the rational utilization of waxy corn starch at different stages of kernel growth.\ud \ud

Dual modification of cassava starch was carried out using ultrasonication and acetylation by acetic acid by altering the sequence. The results revealed that the type of modification and sequence of modification for dual modified starches significantly affected the properties of starch. The swelling decreased for all the modified starches whereas solubility decreased for ultrasonicated starches but increased for acetylated starch and dual modified starch where acetylation was done after ultrasonication. The paste viscosities of all the modified starches were found to be significantly lower compared to native starch and the lowest viscosities were observed for dual modified starch where ultrasonication was done after acetylation. The resistant starch and slowly digestible starch content of the modified starches were significantly higher than in native starch, and the type of modification and sequence of modification for dual modified starches seemed to affect the digestibility of starches.

Rice is sometimes fermented with microorganisms to develop health-promoting foods, but the contribution of a short-term fermentation (a necessary step for fermented rice cake-preparation) to properties of rice starch is not resolved yet. The effects of microorganism fermentation with different amount of starter cultures on multi-scale structures and digestibility of rice starch were investigated. The amount of starter cultures significantly affected structures and digestibility of fermented starch. The fermentation with a lower amount of starter cultures induced starch degradation (corrosion of starch granules, reduction of lamellar orders and compactness, decrease in crystallinity, double helix, short ranger-ordered structures, and molar mass) and a slightly reassembly, which increased the content of slowly digestible starch (SDS). While, the fermentation produced more starch fractions with Mw between 0.60 × 107 g/mol and 1.50 × 107 g/mol as the amount of starter cultures increased, and these starch molecules tended to reassemble and form more ordered multi-scale structures including double helical and short range-ordered structures, starch lamellar orders and compactness, which elevated SDS content. The SDS content of fermented starchy foods could be improved via controlling starch reassembly and multi-scale ordered structures through modulating the amount of starter cultures during fermentation.

The structure and in vitro digestibility of native waxy rice starch by the combined hydrolysis of α-amylase and hydrochloric acid were investigated in this study. The combined hydrolysis technique generated higher hydrolysis rate and extent than the enzymatic hydrolysis. The granular appearance and chromatograph profile demonstrated that α-amylase and hydrochloric acid exhibited different patterns of hydrolysis. The rise in the ratio of absorbance 1047/1022cm(-1), the melting temperature range (Tc-To), and the melting enthalpy (ΔH) were observed during the combined hydrolysis. These results suggest that α-amylase simultaneously cleaves the amorphous and crystalline regions, whereas the amorphous regions of starch granules are preferentially hydrolyzed during the acid hydrolysis. Furthermore, the combined hydrolysis increased rapidly digestible starch (RDS) while decreased slowly digestible starch (SDS) and resistant starch (RS), indicating that the hydrolysis mode affected the digestion property of native waxy rice starch.

This study investigated the effects of using infrared heat-moisture treatment (IRHMT) on the properties of maize starch paste complexed with stearic acid (SA). Scanning electron micrographs showed that starch granules ghosts from IR HMT starch with SA did not show significant granular disintegration in comparison to conventionally HMT starch paste. The resistant starch (RS) content increased with SA-IR HMT, while extended pasting increased slowly digestible starch (SDS) content in IR HMT starch alone. The V polymorphs observed in XRD and DSC, and increased crystallinity from FTIR supported the changes in the properties of IRHMT starches. To a greater extent, the SA-IRHMT exerted more changes on starch micro- and molecular structural properties, and digestibility properties compared to conventional heat-moisture treatment (CHMT).

In this study, potato and bean starches were treated by gamma-irradiation up to 50kGy. Molecular structure and physicochemical properties of irradiated potato and bean starches were investigated. Microscopic observation under scanning electron microscope (SEM) and polarized microscope showed that some of potato and bean starch granules were destroyed by gamma-irradiation and the breakage was much greater at a higher dose (50 kGy). Carboxyl content and amylose leaching increased, whereas the swelling factor and apparent amylose content decreased after irradiation in both potato and bean starches. The proportions of short (DP 6-12) and long (DP > or = 37) amylopectin chains as well as average chain length increased with increasing irradiation dose. However, the proportion of DP 13-24 decreased by irradiation. The relative crystallinity, the degree of granule surface order, and gelatinization enthalpy decreased with an increase in irradiation dose. The extent of decrease in potato starch was greater than that in bean starch. The exothermic peak around 90-110 degrees C was observed in DSC thermogram when the potato starch was irradiated at 50 kGy. The pasting viscosity significantly decreased with an increase in irradiation dose. The proportion of slowly digestible starch (SDS) decreased and resistant starch (RS) content increased by irradiation in both potato and bean starches. However, the rapidly digestible starch (RDS) of potato starch increased with increasing irradiation dose, whereas the bean starch showed the opposite trend to potato starch in RDS content.

Cellulose is a major component of dietary fiber and it is proved to influence starch digestibility. The effects of native cellulose (NC), microcrystalline cellulose (MC), soluble cellodextrin (SC) on starch digestion have not been clearly elucidated. In this study, three types of cellulose with representative molecular weights (NC, 422500 Da; MC, 27750 Da; SC, 2202 Da) were prepared and their effects on starch digestion, glucose diffusion, α-amylase and amyloglucosidase activity were compared. The results suggested SC inhibited starch digestibility to a greater degree than those of NC and MC. When addition of SC reached 3 %, rapidly digestible starch proportion decreased from 31.2 % to 11.3 % and resistant starch proportion increased from 15.0 % to 58.0 %. Notably, hindrance effects of SC on glucose diffusion were higher than those of NC and MC. Moreover, SC reduced activity of α-amylase and amyloglucosidase to a larger extent than those of MC and NC. With the effect of starch digestion inhibition, NC, MC and SC could be utilized as functional food ingredients. Especially, the soluble property and the highest starch digestion inhibition ability of SC favors its application in food industry.

With the advent of modern technology, the utilization of residues obtained after food processing are being largely explored for commercialization. Semolina, a starch rich food ingredient is one of such byproducts of food processing that has not been yet vividly studied, although it is profusely used as an important ingredient in Indian cuisines. Rapid digestibility of most starch rich foods boosts up the blood glucose level. Thus, the present study put forward an attempt to curtail the rapid digestibility of starch rich semolina flour by increasing its resistant starch content through enzymatic process. The enzymatically modified semolina flour (MS) was compared with its native counterpart (NS) on grounds of their digestibility pattern, biochemical and functional properties. A rise in resistant starch content by 9.3 ± 1.6 %, amylose content by 10.9 ± 1.2 %, crystallinity by 10.4 % and the drop in readily digestible starch by 11.9 ± 1.4 % and oil absorption by 2.1 ± 0.3 g/g were observed in MS. These initial findings of the present study are interesting as the results showed elevated potential of the modified semolina flour to be used as functional ingredient in cuisines worldwide.

Large and small wheat starch granules were modified by conventional and pulsed electric fields (PEF)-assisted dual esterification methods. Due to the assistance of PEF, the degree of substitution (DS) of AS and BS increased by 0.0159 and 0.0066, respectively, while the crystallinity of them decreased by 1.7% and 1.2%. An increase in diffraction intensity at q = 0.68 nm−1 was observed in dual modified starch compared to conventional method. The DS of A-type starch (AS) were more sensitive than B-type starch (BS) and the thermal stability of AS was decreased obviously than that of BS. It was found that esterified starch exhibited superior freeze-thaw stability than native starch, especially for the PEF-assisted esterification of AS rather than BS. The resistant starch of esterified BS was increased while the slowly digestible starch was decreased, especially for the assistance of PEF.

In this study, proso millet starch was isolated and subjected to treatment with ultra-high pressure (UHP), cold plasma (CP), or their combination to modify its functional properties. The changes in structural, physicochemical, and digestive properties of proso millet starch after these treatments were investigated. The proso millet native starch granules showed irregular and polygonal shapes with a smooth surface. Treatments with CP or UHP at low pressures did not change the morphological properties or crystalline structure type of proso millet starch granules, while the treatment with UHP at 600 MPa and CP resulted in a complete gelatinization of starch. Also, UHP treatment at high pressure, followed by CP treatment, destroyed the partial crystalline region and reduced the short-range order of proso millet starch. Besides, a combination of UHP and CP treatment promoted the depolymerization of long chains in proso millet starch. Moreover, the combined treatments could enhance the resistance to high temperature and shearing and improve the pasting stability of starch. Furthermore, the combined treatment could increase the slowly digestible starch content. Therefore, the combination of UHP and CP treatment can be suggested for modifying the functional properties of proso millet starch and promoting its industrial applications.

The dough characteristics and flat bread quality parameters were studied on replacing a part of wheat flour with different minor millets (finger, foxtail, barnyard, kodo, little, proso) in the proportion 3:1. The dietary fiber and phytic acid increased while damaged starch decreased on replacing wheat flour with millet flour. The millet flours lowered water absorption and dough stability however protein weakening, gelatinization temperature and peak viscosity during heating increased. Flat breads prepared from wheat millet composite flour displayed more shrinkage and bake loss and reduced puffing and starch retrogradation. Rapidly digestible starch and glycemic index lowered while slowly digestible and resistant starch increased significantly (p 0.05) as a consequence of millet flour addition to wheat flour. Millets as whole flour can be utilized in formulation of food products having higher neutraceutical value by replacing a part of wheat flour with millet flours.

Cold-chain cooked rice is a widely-consumed instant food. While the quality of cooked rice as affected by processing has been widely studied, it remains largely unexplored how concurrent cold-chain conditions (e.g., refrigeration time with specific water contents) tailor the structure and starch digestibility of cooked rice. Here, as shown by combined techniques (e.g., scanning electron microscopy and small angle X-ray scattering), the cold storage (1 to 3 days) of cooked rice at 1.1:1 w/w water-to-rice ratio increased the uniformity of the rice matrix, strengthened the nonperiodic structure, and allowed more B-type starch crystallites and short-range orders. This induced an increase in the slowly digestible starch (SDS) content (from ca. 33.7% to 38.5%) as the refrigeration time rose. In contrast, for cooked rice with 1.5:1 w/w water-to-rice ratio, the cold storage (mainly 1 day) strengthened the matrix uniformity and the nonperiodic structure, and eventually increased the resistant starch (RS) content from ca. 10.3% to 17.7%. The present data could facilitate the design of cold-chain cooked rice with tailored starch digestibility.

The role of endogenous/exogenous rice protein and its hydrolysates in the enzymatic hydrolysis resistance of rice starch was investigated. Scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM) and Fourier transform infrared spectroscopy (FTIR) results showed that different types of rice endogenous proteins retarded the digestion of rice starch by the same way. Exogenous addition of protein hydrolysates was more effective than protein for impeding starch digestion. FTIR results indicated that rice protein hydrolysates were bound to starch granules through hydrogen bonds, and their interaction strengthened the ordered structure of the starch. Further, the intensity of the starch V- type peak was enhanced after the addition of protein hydrolysates, indicating that some peptides or free amino acids released by the protein formed complexes with the starch, thereby contributing to high slowly-digestible starch content. These findings provide a theoretical basis for the preparation of low glycemic index starch-based foods.