High Resistant Starch Research Articles

Comparing physico‐chemical characteristics, antioxidant properties, glycemic response, and volatile profiles of eleven banana varieties

SummaryBanana with different genomic groups has a greater varietal diversity. New varieties are also developed which have unique tastes, and tolerance to biotic or abiotic stresses. Eleven varieties belonging to different genomic groups are evaluated for their nutrients, secondary metabolites, techno‐functional characteristics, antioxidant activities, glycemic indices, and shelf life. Bioactive profiling was also carried out using Gas Chromatography–Mass Spectroscopy (GCMS). Results revealed that plantain and cooking bananas recorded higher fruit weight than dessert bananas. Pulp to peel ratio was higher in the dessert variety Ney Poovan and dual‐purpose variety Popoulu compared to cooking varieties indicating the presence of a thicker skin. Higher resistant starch (39% dry weight) and lower glycemic index (45%–50%) were observed in Kaveri Saba and Monthan. Total phenolics in ripe bananas were significantly higher than in unripe stages. GCMS results showed the predominance of esters and hydrocarbons among banana varieties and the presence of unique volatiles like linoelaidic acid, 9,12‐octadecadienoic acid in Kaveri Sugantham. PCA and cluster analysis indicated that the biochemical parameters also varied with the genomic groups. The study creates new business opportunities for varieties beyond cv. Grand Naine both in the domestic and export markets.

Physicochemical characterizations of five Dioscorea alata L. starches from China

D. alata is an important edible and medicinal plant in China. Its tuber is rich in starch but the understanding of the physiochemical properties of D. alata starch is limited. In order to explore the processing and application potential of different D. alata accessions in China, five kinds of D. alata starch (LY, WC, XT, GZ, SM) were isolated and characterized. The study showed that D. alata tubers contained abundant starch, enriched in amylose and resistant starch (RS). D. alata starches showed B-type or C-type diffraction pattern, had higher RS content and gelatinization temperature (GT), lower fa and viscosity when compared to D. opposita, D. esculenta, and D. nipponica. Among D. alata starches, D. alata (SM) showing the C-type diffraction pattern, had the lowest proportion of fa with 10.18 %, the highest amylose, RS2 and RS3 content of 40.24 %, 84.17 % and 10.48 % respectively, and the highest GT and viscosity. The results indicated that D. alata tubers are potential sources for novel starch with high amylose and RS content, and provided a theoretical basis for further utilizations of D. alata starch in food processing and industry application.

Functional properties and in vitro starch digestibility of infrared-treated (micronized) green banana flour.

The consumption of green banana flour (GBF) products has been linked to reduced glycemic index (GI) and low risk of type 2 diabetes and obesity. The purpose of this study was to investigate the effect of micronization (high-intensity infrared heating method) on the molecular, microstructure and in vitro starch digestibility of five GBF cultivars grown in South Africa. The GBF was micronized at three surface temperatures (90, 120 and 150 °C for 30 min) and the in vitro starch digestibility was determined with Megazyme kits. Micronization at the highest temperature (150 °C) increased the swelling power by 6.00% in all five GBF cultivars when compared to control (unmicronized GBF). Micronization slightly reduced the resistant starch (RS) of the GBF cultivars by up to 8.63%. The FHIA-01 cultivar showed the highest RS (86.50%), whereas Grande Naine-150 °C cultivar had the lowest RS (76.00%). Both micronized and control GBF exhibited similar X-ray diffraction patterns with all cultivars and at all micronization temperatures. Similarly, the functional properties of the GBF were not altered by micronization when observed with Fourier transform infrared spectroscopy. Scanning electron microscopy showed changes in the surface morphology of starch granules after micronization and these were dependent on temperature. Overall, micronization at 120 °C showed the best improvement in functional properties of GBF and this makes it suitable for potential application for the manufacture of instant breakfast products, baked goods and pasta. In addition, the micronized GBF cultivars retained high RS, suggesting potential health benefits for people with diabetes and obesity. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Arepas Made from High Amylose Corn Flour Produce Favorably Low Glucose and Insulin Responses in Healthy Humans

The importance of the amylose: amylopectin ratio in the postprandial glycemic and insulinemic responses to corn was studied in food products that might realistically be consumed. Healthy subjects were given test meals in the form of arepas made from ordinary (25% amylose) or high amylose (70% amylose) corn flour. The ordinary corn meal contained 45 g of potentially available starch. To exclude the possible influence of a lowered content of potentially available starch due to formation of resistant starch in the high amylose product, this product was evaluated at two levels and included either on the basis of potentially available starch (45 g) or total starch (including resistant starch) (45 g, i.e., 29 g potentially available starch), respectively. The rate of starch hydrolysis, measured in vitro employing a method based on chewing, was studied. In addition, the content of in vitro resistant starch was analyzed in all products. The meals containing high amylose corn flour produced lower areas under the glucose and insulin response curves (57 and 42% lower, respectively) than did the meals containing ordinary cornmeal. This could not be explained by a lower amount of potentially available starch. No differences were noted when subjects consumed the two high amylose meals of arepas, despite 36% lower potentially available starch in one of the meals. The rate of starch hydrolysis measured in vitro was slower in the high amylose corn products than in the ordinary corn product. Resistant starch in the ordinary product was 3 g/100 g dry matter, vs. -20 g/100 g dry matter in the high amylose products. We concluded that high amylose corn products have a potential to promote favorably low metabolic responses and high resistant starch contents.

Effect of Calcium Hydroxide on Physicochemical and In Vitro Digestibility Properties of Tartary Buckwheat Starch-Rutin Complex Prepared by Pre-Gelatinization and Co-Gelatinization Methods

This study examined the effect of calcium hydroxide (Ca(OH)2, 0.6%, w/w) on structural, physicochemical and in vitro digestibility properties of the complexed system of Tartary buckwheat starch (TBS) and rutin (10%, w/w). The pre-gelatinization and co-gelatinization methods were also compared. SEM results showed that the presence of Ca(OH)2 promoted the connection and further strengthened the pore wall of the three-dimensional network structure of the gelatinized and retrograded TBS-rutin complex, indicating the complex possessed a more stable structure with the presence of Ca(OH)2, which were also confirmed by the results of textural analysis and TGA. Additionally, Ca(OH)2 reduced relative crystallinity (RC), degree of order (DO) and enthalpy, inhibiting their increase during storage, thereby retarding the regeneration of the TBS-rutin complex. A higher storage modulus (G') value was observed in the complexes when Ca(OH)2 was added. Results of in vitro digestion revealed that Ca(OH)2 retarded the hydrolysis of the complex, resulting in an increase in values in slow-digestible starch and resistant starch (RS). Compared with pre-gelatinization, the complex process prepared with the co-gelatinization method presented lower RC, DO, enthalpy, and higher RS. The present work indicates the potential beneficial effect of Ca(OH)2 during the preparation of starch-polyphenol complex and would be helpful to reveal the mechanism of Ca(OH)2 on improving the quality of rutin riched Tartary buckwheat products.

Resistant Starch Decreases Serum Total Cholesterol and Triacylglycerol Concentrations in Rats

Rats were meal-fed semipurified diets containing a low (0.8 g/MJ) and a high (9.6 g/MJ) amount of resistant starch (RS) or various amounts of RS (0.8 to 9.6 g/MJ) and guar gum (0 to 8.8 g/MJ). In one experiment, rats were fed the low and high RS diets in three dietary regimens (ad libitum consuming, 12 h ad libitum/12 h food deprived, and meal fed). Effects of RS and guar gum on serum postprandial and postabsorptive concentrations of total cholesterol (TC) and triacylglycerol (TAG), growth, hydrogen excretion, tissue weights and contents of small intestine and cecum, and pH of cecal contents were investigated. In addition, effects of RS on food intake, de novo hepatic synthesis of fatty acids and neutral sterols, and on lipoprotein lipase activity and weight of epididymal fat pads were investigated. Compared with feeding the low RS diet, the high RS diet reduced the serum TC and TAG concentrations, with these effects observed after 1 and 2 wk of feeding, respectively. The dietary regimen did not influence the effect of RS on the serum TC and TAG concentrations, but it did affect the serum TAG concentration. Resistant starch had no effect on the hepatic synthesis of fatty acids and neutral sterols or on the lipoprotein lipase activity in epididymal fat pads. Guar gum also reduced the serum TC concentration, but it had no effect on serum TAG concentration. The tissue weights and contents of small intestine and cecum as well as hydrogen excretion increased with increasing amounts of dietary RS and guar gum, whereas the pH of cecal contents decreased. No effects of RS on food intake and total body weight gain were found, whereas guar gum decreased weight gain. Feeding the high RS diet also led to a lower weight of the epididymal fat pads. We conclude that dietary RS can reduce serum TC and TAG concentrations and fat accretion.

Quality Improvement of Green Saba Banana Flour Steamed Cake

Gluten avoidance is becoming a popular diet trend around the world. In this study, green Saba banana flour (GSBF) was used to produce a gluten-free (GF) steamed cake. The effects of soy protein isolate (SPI) (0%, 10%, 15%) and Ovalette (0%, 3.5%, 7%) on the quality of the cake were investigated. Physicochemical properties of the flours were measured. The viscosity and specific gravity of the batters; as well as the specific volume, weight loss and texture profile of the resulting cakes were determined. Sensory evaluation was performed to compare the acceptance of the cake formulations. The macronutrient and resistant starch content of the cakes were determined. The use of an appropriate level of SPI and Ovalette was found to effectively enhance the aeration of the cake batter and improved the specific volume and weight loss of the cake. The presence of Ovalette was essential to soften the texture of the cake. GF cake supplemented with 10% SPI and 3.5% Ovalette obtained the highest sensorial acceptance. The nutritional quality of this sample was significantly improved, whereby it contained higher protein than the gluten-containing counterpart. GSBF also contributed to the high dietary fiber and resistant starch content of the cake.

Structure, thermal stability, and in vitro digestibility of rice starch–protein hydrolysate complexes prepared using different hydrothermal treatments

In this study, rice starch-protein hydrolysate (WPH-S) complexes with high resistant starch (RS) content were prepared by heat-moisture treatment (HMT) and annealing (ANN). The effects of different hydrothermal treatments on the structure and thermal stability of the WPH-S complexes and their relationship with starch digestibility were further discussed. The results showed that RS contents of ANN-WPH-S complexes (35.09–40.26 g/100 g) were higher than that of HMT-WPH-S complexes (24.15–38.74 g/100 g). Under hydrothermal treatments, WPH decreased the hydrolysis kinetic constant (k) of starch form 4.07 × 10−2–4.63 × 10−2 min−1 to 3.29 × 10−2–3.67 × 10−2 min−1. HMT and ANN promoted hydrogen bonding between WPH and starch molecules, thus increasing the molecular size of starch. In addition, the shear stability of WPH-S mixture was improved with the hysteresis loop area decreased after HMT/ANN treatments, resulting in a more stable structure. Most importantly, the hydrothermal treatment made the scatterers of WPH-S complexes denser and the surface smoother. Especially after ANN treatment, the WPH60-S complex formed a denser aggregate structure, which hindered the in vitro digestion of starch to a certain extent. These results enrich our understanding of the regulation of starch digestion by protein hydrolysates under different hydrothermal treatments and have guiding significance for the development of foods with a low glycemic index.

Preparation and characterization of type 3 resistant starch by ultrasound-assisted autoclave gelatinization and its effect on steamed bread quality.

In this study, we aimed to establish an innovative and efficient preparation method of potato resistant starch (PRS). To achieve this, we prepared type 3 resistant starch (RS3) from native potato starch (PS) using an ultrasonic method combined with autoclave gelatinization and optimized by the response surface method to study the structure and properties of potato RS3 (PRS3) and its effect on the quality of steamed bread. Under optimal treatment conditions, the PRS3 content increased from 7.5% to 15.9%. Compared with PS, the B-type crystal structure of PRS3 was destroyed, and the content of hydroxyl groups was increased, but no new chemical groups were introduced. PRS3 had a rougher surface and a lower crystallinity, gelatinization temperature, viscosity, setback value, and breakdown value. The low content (5%) of PRS3 had a stable viscosity and was easily degraded by bacteria, which can improve the quality of steamed bread to a certain extent. When the PRS3 content was over 10%, it competed with the gluten protein to absorb water, which reduced the contents of β-turn and α-helix in the dough, increased the contents of β-fold, and weakened the structure of the gluten network. It also decreased the specific volume and elasticity of the steamed bread and increased the spreading rate, hardness, and chewiness. Steamed bread prepared with a flour mixture containing 5% PRS3 was similar to the presidential acceptance of control flour. In this study, a new sustainable and efficient PRS3 preparation method was established, which has certain guiding significance for the processing of Functional steamed bread with high-resistant starch.

Optimasi Proses Pembuatan Tepung Pisang Termodifikasi terhadap Kadar Pati Resisten, Nilai Indeks Glikemik, dan Total Kalori Snack Bar

Experimental research in the laboratory was carried out to obtain young kepok banana flour with high resistant starch which was then processed into snack bar products. Young kepok bananas obtained from Sumbawa Regency were treated with different retrogradation treatments, namely: P1 (1 time retrogradation process); P2 (2 times retrogradation process); P3 (3 times retrogradation process); and P4 (4 times the retrogradation process). The research data were analyzed using ANOVA, and each treatment that was significantly different was followed by Duncan's further test at the 5% level of confidence. Both of these analytical methods were processed using SPSS 25 software. The results showed that the retrogradation treatment (autoclaving-cooling) which was carried out repeatedly had a significant effect on increasing the resistant starch content produced in modified banana flour, with a value obtained in treatment P1 = 3.000% , treatment P2 = 4.567%, treatment P3 = 7.333%, and P4 = 11.333%. The P4 treatment was then chosen as a raw material for making snack bars because it has the highest resistant starch content. Testing the value of the glycemic index and total snack bar calories are then calculated. The glycemic index was analyzed through the ratio of area under the curve (area under curve) of food glucose response by measuring fasting blood glucose 0, and once every 30 minutes, namely 30, 60, 90, and 120 minutes after consumption of the test food (modified banana flour snack bar). ) and standard food (glucose water). The results of the Area Under Curve (AUC) for banana flour snack bars were 7.619 and the AUC for glucose was 11.841. The results of the glycemic index value of the modified banana flour snack bar were 42.2. Modified banana flour snack bar in 50 g contains a total of 89.3 Kcal calories.

Combined Effects of BEIIb and SSIIa Alleles on Amylose Contents, Starch Fine Structures and Physicochemical Properties of Indica Rice

Starch branching enzyme IIb (BEIIb) and soluble starch synthase IIa (SSIIa) play important roles in starch biosynthesis in cereals. Deficiency in the BEIIb gene produces the amylose extender (ae) mutant rice strain with increased amylose content (AC) and changes in the amylopectin structure. The SSIIa gene is responsible for the genetic control of gelatinization temperature (GT). The combined effects of BEIIb and SSIIa alleles on the AC, fine structures, and physicochemical properties of starches from 12 rice accessions including 10 recombinant inbred lines (RIL) and their two parents were examined in this study. Under the active BEIIb background, starches with the SSIIa-GC allele showed a higher GT than those with the SSIIa-TT allele, resulting from a lower proportion of A chain and a larger proportion of B1 chains in the amylopectin of SSIIa-GC. However, starch with the BEIIb mutant allele (be2b) in combination with any SSIIa genotype displayed more amylose long chains, higher amylose content, B2 and B3 chains, and molecular order, but smaller relative crystallinity and proportion of amylopectin A and B1 chains than those with BEIIb, leading to a higher GT and lower paste viscosities. These results suggest that BEIIb is more important in determining the structural and physicochemical properties than SSIIa. These results provide additional insights into the structure-function relationship in indica rice rather than that in japonica rice and are useful for breeding rice with high amylose content and high resistant starch.

Naturally cultured high resistant starch rice improved postprandial glucose levels in patients with type 2 diabetes: A randomized, double-blinded, controlled trial.

To assess the effect of a novel naturally cultured rice with high resistant starch (RS) on postprandial glycemia in patients with type 2 diabetes compared to ordinary rice. This study is a randomized, double-blinded controlled trial. Patients with type 2 diabetes were recruited, and postprandial glucose levels were measured at 5-time points after the ingestion of one of two types of cooked rice in random order. Paired t-tests were used to compare postprandial blood glucose changes and increment areas under the blood glucose curve between high-RS rice and ordinary rice. The increments of the postprandial blood glucose levels for high-RS rice were significantly lower than that for ordinary rice, i.e., 2.80 ± 1.38 mmol/L vs. 3.04 ± 1.50 mmol/L (P = 0.043) and 3.94 ± 2.25 mmol/L vs. 4.25 ± 2.29 mmol/L (P = 0.036) at 30 min and 60 min, respectively. The incremental areas under the blood glucose curve for high-RS rice were also significantly lower than that for ordinary rice, i.e., 42.04 ± 20.65 [mmol/(L·min)] vs. 45.53 ± 22.45 [mmol/(L·min)] (P = 0.043), 143.54 ±69.63 [mmol/(L·min)] vs. 155.15 ± 73.53 [mmol/(L·min)] (P = 0.026), and 354.61 ± 191.96 [mmol/(L·min)] vs. 379.78 ± 195.30 [mmol/(L·min)] (P = 0.042) at 30, 60, and 120 min, respectively. Repeated-measures ANOVA showed that postprandial glucose levels were not affected by the test order. The novel high-RS rice as a staple food when substituting for widely consumed ordinary rice may provide potential health benefits by lowering blood glucose in patients with type 2 diabetes.

Lactic acid esterification of maize starch in solid state: Assistant effect of pullulanase modification on digestibility and physicochemical properties

The current work was the first report to prepare lactate-esterified debranched starch (LEDS) in solid state mode. Normal maize starch (NS) was initially modified by pullulanase enzyme in granule form and then esterified with lactic acid under dry heating for 3 h at 80 °C and presence of 0.2% w/w sodium hydroxide. Physicochemical properties of the treated starches by single and dual treatments were determined and compared with NS. The enzymatic modification could improve reaction efficiency of esterification process up to 75.2% through partial hydrolysis of starch chains. Compared with NS and individual modifications, the combined treatment significantly increased amylose extent, and the amount of resistant starch (RS) while decreased the freeze thaw stability, viscosity, gelatinization temperatures, paste clarity, swelling power, and relative crystallinity. The morphological examination showed dissociation and degradation of starch granules by single and dual treatments. FT-IR confirmed the introduction of ester groups onto the starch molecules through a band at 1715 cm−1. The impact of designed dual treatment on the environment was assessed by applying Eco-scale index, proving the greenness of the method (score: 75). The findings of this study will provide a theoretical background for development of high RS food products.

Body Weight Development in Adult Dogs Fed a High Level Resistant Starch Diet.

This study investigated the effect of Dodamssal rice, which has a high content of resistant starch, on obesity and hematologic properties in dogs. In Experiment 1, 24 spayed dogs were divided into three feeding groups: normal-fat basal diet (control), high-fat diet with 12% normal amylose type rice (hNAR), and high-fat diet with 12% high amylose type rice (Dodamssal rice; hHAR). In Experiment 2, 8 spayed dogs were assigned to a normal amylose type rice (NAR) group and a high amylose type rice group (HAR) with a normal-fat basal diet. After 24 weeks, an increase in weight and blood cholesterol was observed in both high-fat diet groups for Experiment 1. Specifically, an increase in serum alanine aminotransferase was observed over time in the hNAR group compared with that of the control; however, no such patterns were present in the hHAR group. Further, a significant weight-loss effect was observed in the HAR group in Experiment 2 at 4 weeks. The effect on body weight was due to the reduced digestibility of amylose and thereby lower dietary ME content. Overall, this confirmed that Dodamssal rice had a positive effect on weight loss in dogs, and these results suggest that Dodamssal rice has potential value as a raw ingredient for preventing obesity in dogs.

Chemical composition, glycaemic index, and antidiabetic property of analogue rice made from composite tubers, germinated legumes, and cereal flours

The dependence on rice as a source of carbohydrates in Indonesia is among the highest in Asia. Innovations to develop products that can be used as a carbohydrate source, and have functional values beneficial to health are currently needed. The present work thus aimed to determine the chemical composition, glycaemic index, and antidiabetic property of three analogue rice types. The formulation of three types of analogue rice was done by combining natural tuber flour, modified tuber flour, germinated cereals, and germinated legumes. The glycaemic index was assessed using experimental animal. The antidiabetic properties of three types of analogue rice were assessed by food efficiency ratio, glucose profile, lipid profile, and atherogenic index. Results showed that analogue rice had high dietary fibre, resistant starch, and protein, and low fat and carbohydrate. The three types of analogue rice were classified as low glycaemic index based on glycaemic response tests. The glycaemic index of analogue rice I, II, and III were 41.23 ± 3.39, 42.55 ± 3.21, and 40.19 ± 3.34, respectively. The ability of analogue rice to decrease glucose, triglycerides, total cholesterol, low-density lipoprotein, atherogenic index; and increase high-density lipoprotein in diabetic mice was affected by its low glycaemic index and chemical composition benefits. The ability to improve the characteristics of glucose and lipids should support the development of analogue rice as a functional food.

Starch Bio-Synthetic Pathway Genes Contribute to Resistant Starch Content Differentiation in Bread Wheat

Resistant starch (RS) is a special group of starches which are slowly degraded and rarely digested in the gastrointestinal tract. It was recognized as a new type of dietary fiber that improved cardiovascular, cerebrovascular, and intestinal health. Breeding high-RS-content wheat is one of the most efficient and convenient approaches for providing an adequate amount of RS for a healthy diet. However, studies which aim to genetically illustrate RS content in wheat are still rare. In the present study, a panel of 207 wheat varieties were collected world-wide and planted under three locations. The RS content of each variety was measured, and 14 additive genetic loci were found to stably exist under more than two environments. Meanwhile, four genes were recognized as the putative candidates with annotated functions of β-amylase, α-1,4 glucan phosphorylase, sucrose transporter, and NAC domain protein. A kompetitive allele-specific PCR (KASP) marker was developed from the SNP AX-94546744, representing the genetic locus of β-amylase located. The AX-94546744-T allele can significantly increase the RS content compared to the AX-94546744-C allele. The genetic loci and KASP marker associated with RS content may be useful for wheat germplasm cultivation and variety breeding with a high RS content, further helping to improve the nutritional quality in wheat.

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

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. 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 2μm. 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 inNorth Euryale ferox seeds included the highest onset temperature (To ) (71.43 °C), peak temperature (Tp ) (76.60 °C), conclusion temperature (Tc ) (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. 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.

High-amylose wheat tortillas with reduced in vitro digestion and enhanced resistant starch content

Increased nutritional functionality in bread and noodles have been reported with the incorporation of high amylose wheat flour (HAWF). Here, we broaden the application of HAWF and report structure-function-nutrition relationships for tortillas prepared with 50% and 100% incorporation of HAWF. The breaking force and extensibility of the HAWF tortillas were lower than controls resulting from incompletely gelatinized high-amylose wheat starch (HAWS). The digestion degree of tortillas was significantly reduced by increase of amylose content due to HAWS structural features and enzyme hindrance effects of greater protein content, with resistant starch (RS) content increasing from ∼3% in control (32% amylose) to ∼12% in tortillas with 71% amylose and ∼23% in tortillas with 84% amylose. In addition, tortillas showed lower starch digestion and higher RS than loaf bread or noodle counterparts. This demonstrates that wheat food in-vitro enzyme hydrolysis is not only a function of starch structure, but also the local density of the microstructure formed during food processing.

High temperature boosts resistant starch content by altering starch structure and lipid content in rice ssIIIa mutants.

High temperature (HT) during grain filling had adverse influences on starch synthesis. In this study, the influences of HT on resistant starch (RS) formation in rice were investigated. Most genes in ssIIIa mutants especially in RS4 were upregulated under Normal Temperature (NT) while downregulated under HT when compared with those of wild parent R7954. ssIIIa mutants had higher RS content, more lipid accumulation, higher proportion of short chains of DP 9-15, and less long chains of DP ≥37. ssIIIa mutation exacerbated the influences of HT on starch metabolite and caused larger declines in the expression of BEI, BEIIa, BEIIb, and SSIVb when exposed to HT. HT reduced the contents of total starch and apparent amylose significantly in wild type but not in mutants. Meanwhile, lipids were enriched in all varieties, but the amounts of starch-lipid complexes and the RS content were only heightened in mutants under HT. HT led to greatest declines in the amount of DP 9-15 and increases in the proportion of fb3 (DP ≥37); the declines and increases were all larger in mutants, which resulted in varied starch crystallinity. The increased long-chain amylopectin and lipids may be the major contributor for the elevated RS content in mutants under HT through forming more starch-lipid complexes (RSV).

Functional, Thermal and Structural Properties of Green Banana Flour (cv. Giant Cavendish) by De-astringency, Enzymatic and Hydrothermal Treatments.

Green banana fruit with high resistant starch (RS) content has a potential to be a nutraceutical ingredient despite having an unpleasant astringency taste and is yet to be fully explored. In this study, the green banana after de-astringency treatment was employed for flour production, and the resulting flour was subjected to modification by the combined treatments of pullulanase debranching and annealing. The banana flour (BF) and the modified flour (MF) were compared with each other by evaluating their functional, thermal and structural properties. The BF showed a restricted-swelling pasting profile, behaving like a slightly chemically cross-linked starch; the MF exhibited less pronounced changes in pasting behavior with increased solubility and decreased swelling power and dispersed volume fraction at elevated temperatures. As compared with the BF, an enhanced thermal stability of the MF was observed, reflected in the endotherm shifting to higher temperatures with increased enthalpy. The BF displayed a CA-type polymorph, while the MF comprised a mixture of B- and V-type polymorphs with increased crystallinity. The MF showed an increased molecular order, reflected in an increase in short-range double helical order detected in the starch fingerprint regions of FT-IR spectra, and along with increased crystallinity, underlying its enhanced thermal stability. The modification treatment resulted in irregularly shaped flour particles with a more compact structure as revealed by morphological characters. The results of this study can provide useful information for the development of food products using the modified green banana flour with improved thermal stability and functional properties as a health-promoting ingredient.