Effect of storage on resistant starch content and in vitro starch digestibility of some pressure‐cooked cereals and legumes commonly used in India

Resistant starch (RS) is that fraction of starch, which escapes enzymic hydrolysis in the small intestine and passes in the colon. Effect of storage time (12 and 24 h) and temperature (4 °C and 25 °C) was studied on RS content of the pressure‐cooked cereal and legume grains/seeds and their flours. RS content was observed to increase in the stored cereals and legumes, with more enhanced increase in the flour samples stored at refrigeration temperature for longer duration (41.4% in wheat flour and 85.4% in pea flour). Significant positive correlations were observed between RS content (4 °C, 24 h) and amylose (y = 0.388 × –5.948, r = 0.840, P ≤ 0.05, n = 7) as well as between % increase in insoluble dietary fibre content (4 °⁰C, 24 h) and amylose (y = 2.257 × –27.724, r = 0.971, P ≤ 0.05, n = 7). Reduced in vitro starch digestibility of the cooked/stored samples (4 °C, 24 h) was observed when compared to freshly cooked samples.     

Date flesh: Chemical composition and characteristics of the dietary fibre

The date by-products of two date palm (Phoenix dactylifera L.) cultivars, Deglet-Nour and Allig, from the Degach region (Tunisia), were analysed for their main chemical composition. Studies were also conducted on the physicochemical properties (colour, water and oil-holding capacity and rheological behaviour) of dietary fibre (DF) extracted from date flesh. The following values (on a dry matter basis: DM) were obtained for fleshes of Deglet-Nour and Allig cultivars, respectively: sucrose 52.7% and 13.9%, glucose 13.7% and 29.9%, fructose 12.6% and 29.0%, total dietary fibre 14.4% and 18.4%, protein 2.1% and 3%, ash 2.5% and 2.52%. Insoluble DF, the major fraction of total DF, constituted 9.19–11.7% DM for Deglet-Nour and Allig, respectively. The elaboration of DF concentrates from date fleshes was characterised by an extraction yield of 67%. The chemical composition of these DF concentrates showed high total DF contents (between 88% and 92.4% DM) and low protein and ash contents (8.98–9.12% and 2.0–2.1% DM, respectively). The DF concentrates showed a high water-holding capacity (∼15.5 g water/g sample) and oil-holding capacity (∼9.7 g oil/g sample) and pseudoplasticity behaviour of their suspensions. Thus, date DF concentrates may not only be an excellent source of DF but an ingredient for the food industry.     

Chemical composition of dehulled seeds of selected lupin cultivars in comparison to pea and soya bean

With the objective of promoting the cultivation, usage, and consumption of lupin, in the present study, the chemical and fibre composition of dehulled seeds of seven cultivars of different lupin species (Lupinus angustifolius, Lupinus albus and Lupinus luteus) was determined in comparison to pea (Pisum sativum) and soya bean (Glycine max).     

几种薯类与豆类抗性淀粉的抗消化性及其益生效应

采用压热法制备了木薯、红薯、马铃薯、豌豆和绿豆5种抗性淀粉,研究了它们对人工胃液和人工肠液的抗消化性,以及它们对肠道益生菌生长的影响。结果表明:人工胃液对木薯、红薯、马铃薯、豌豆和绿豆抗性淀粉的消化作用很小,人工肠液对它们有明显的消化作用;经人工胃液和人工肠液先后作用,它们的消化率都比单独人工肠液处理后的要高;各种抗性淀粉对双歧杆菌、嗜酸乳杆菌、保加利亚乳杆菌、乳链球菌都有不同程度的增殖作用。综合分析可知,对肠道益生菌增殖作用最强的是豌豆抗性淀粉,其次是红薯和绿豆抗性淀粉,再次是马铃薯抗性淀粉,最差的是木薯抗性淀粉。     

Physicochemical properties and in vitro digestibility of resistant starch from mung bean (Phaseolus radiatus) starch

RS from mung bean starch was prepared by autoclaving, pullulanase debranching, and retrogradation. Physicochemical properties, crystalline structure, and in vitro digestibility of selected RS samples with different RS content were investigated. Compared to native starch, AAM content of RS increased but MW decreased greatly. SEM clearly showed RS samples exhibited irregular shaped fragments with compact structure. XRD pattern indicated that RS samples had typical B‐type pattern with sharp peaks at 17.0°, 22.2°, and 23.9° 2θ. The relative crystallinity, gelatinization temperatures, and enthalpy increased with increasing RS content. The α‐amylase digestibility of RS was lower than that of native starch. The results suggested that the decrease in enzymatic digestion of RS might due to compact and ordered crystalline structures after debranching and recrystallization.     

Characterisation of alkaline and enzymatic modified insoluble dietary fibre from Undaria pinnatifida

Undaria pinnatifida insoluble dietary fibre (UIDF) was modified by alkali (NaOH solution) and complex enzyme (xylanase and cellulase) to improve the physicochemical properties. Scanning electron microscopy revealed that the surface structure after modification was rough and loose. The characteristic absorption peaks in Fourier transfer infrared spectrometry and X-ray diffraction patterns showed that enzymes can further hydrolyse the UIDF than alkali mainly in amorphous region, and increased the soluble dietary fibre content to 16.31%. The alkaline and complex enzymatic modification both resulted in higher water retention capacity, water swelling capacity, oil absorption capacity, glucose adsorption capacity and the inhibition ability towards α-amylase. The complex enzymatic modification exhibited better features in almost all properties, and the modification did not change the inhibiting mechanism on α-amylase (non-competitive type). Overall, both two modifications could effectively improve the properties of UIDF, which may promote its use in food applications.     

In vitro measurement of resistant starch of cooked milled rice and physico-chemical characteristics affecting its formation

Resistant starch (RS) content was determined in 10 indica and japonica milled rices with different levels of amylose. The effect of microbial growth during starch digestion on the measurement of RS, and the correlation between physico-chemical characteristics and RS contents of milled rice were analysed. Results indicated a significant decrease (P < 0.01) in assay values of RS after antibiotics addition, and the markedly decreased sample pH due to fermentation might be the main reason for errors in RS determination. Correlation analyses showed that RS contents of milled rice were closely related to amylose content (r = 0.75, P < 0.05) and protein content (r = 0.78, P < 0.01). No significant correlation existed between RS content and some relatively simple physical properties, such as width, shape and elongation ratio of rice grain, which were reported to be good indictors of rate of rice starch digestion, while a significant positive correlation was found between elongation ratio and digestible starch in cooked milled rice (r = 0.67, P < 0.05).     

Influence of germination on the soluble carbohydrates and dietary fibre fractions in non-conventional legumes

Influence of light exposure during germination on structural and soluble carbohydrates including total dietary fibre (TDF), insoluble dietary fibre (IDF) and soluble (SDF) dietary fibre fractions and also raffinose family oligosaccharides (RFOs) was studied in non-conventional legumes Vigna unguiculata (cowpea), Canavalia ensiformis (jack bean), Stizolobium niveum (mucuna), and Lablab purpureus (dolichos), and compared to a well known and used Glycine max (soybean). Non-conventional legumes were rich in DF, mainly IDF, which represented 93–97% of TDF. It was relevant the proportion of protein that remained associated to the insoluble DF matrix. Non-conventional legumes exhibited important levels of RFOs but their profile was different depending on the tropical seed. The germination of seeds produced changes in the carbohydrate fraction, mainly an increase of TDF in most instances, except for soybean, and a drastic reduction of RFOs, from 98% to 63%, with the corresponding increase in the amounts of total soluble sugars.     

Effect of heat-moisture treatment on the formation and physicochemical properties of resistant starch from mung bean (Phaseolus radiatus) starch

Mung bean starch was subjected to a range of heat-moisture treatments (HMT) based on different moisture contents (15%, 20%, 25%, 30%, and 35%) all heated at 120 °C for 12 h. The impact on the yields of resistant starch (RS), and the microstructure, physicochemical and functional properties of RS was investigated. Compared to raw starch, the RS content of HMT starch increased significantly, with the starch treated at 20% moisture having the highest RS content. After HMT, birefringence remained at the periphery of the granules and was absent at the center of some granules. The shape and integrity of HMT starch granules did not change but concavity was observed under scanning electronic microscopy. Apparent amylose contents of HMT starch increased and the HMT starch was dominated by high molecular weight fraction. Both the native and HMT starches showed A-type X-ray diffraction pattern. Relative crystallinity increased after HMT. The gelatinization temperatures (To, Tp, and Tc), gelatinization temperature range (Tc–To) and enthalpies of gelatinization (ΔH) increased significantly in HMT starch compared to native starch. The solubility increased but swelling power decreased in HMT starches. This study clearly shows that the HMT exhibited thermal stability and resistance to enzymatic hydrolysis owing to stronger interactions of starch chains in granule.     

Resistant starch and potential glycaemic index of raw and cooked legumes (lentils, chickpeas and beans)

 The amount of resistant starch (RS) in raw and processed legumes, lentils, chickpeas and beans was analysed. In addition, the effect of cooking on the availability of legume starches to enzymes, which may influence the glycaemic response, was studied. Raw legumes were found to have higher RS values (16–21%) than retrograded or cooked ones (4–8%). Cooling increased RS yields, whereas reheating maintained or decreased the value depending on the sample. On the other hand, the kinetics of starch hydrolysis revealed that the rate of digestion was higher for cooked seeds and retrograded flours (15–21% of total starch digested) than for raw flours (5–8% of total starch digested). The estimated glycaemic indices (GIs), i.e. GI₁ from the Hydrolysis Index (HI) and GI₂ from the percentage of hydrolysis within 90 min (H ₉₀), were well correlated with the reported GI values (r = 0.96 and r = 0.95 respectively, P≤ 0.05). Received: 22 September 1997 / Revised version: 24 November 1997     

A critical review on anti-diabetic and anti-obesity effects of dietary resistant starch

abstract

“Diabesity” is the term to illustrate the interdependent relationship between obesity and diabetes. About 80% of the diabetic patients are diagnosed with obesity. Diabesity can be prevented by dietary interventions, especially by incorporating sufficient amount of resistant starch (RS). In the past few decades, RS has inspired the researchers due to its various health benefits. Differing from digestible starch, RS remains undigested in the small intestine, but in the large intestine, it is subjected to fermentation. This review intends to encapsulate the current information related to the dietary RS on diabetes and obesity. RS attenuate hyperglycemic, hyperinsulinemic and hyperlipidemic response in various subjects by restricting gluconeogenesis, bolstering glycogenesis, maintaining glucose and lipid homeostasis and ameliorating pancreatic dysfunction. Various food products were fortified with RS to enhance its dietary intake and were found to exhibit positive impact on human and animal models. This review identified and summarized the research gaps in the available literature.     

Effects of cellulosic fibre on physical and rheological properties of starch,gluten and wheat flour

In this study, we report on the effects of cellulose fibres of different particle size on changes to dough water absorption and rheology; and on effects of fibre on starch and gluten, separately, at different levels of fibre incorporation (0.1–10%). Water absorption and dough‐mixing properties were affected with fibre incorporation, with 40‐μm fibre incorporation resulting in greater absorption values. Dough stickiness and extensibility were affected by cellulose fibre particle size, and decreased with increasing fibre addition. Flour or starch and fibre mixtures were evaluated using a Micro ViscoAmlyoGraph (MVAG), and the resulting gel firmness was measured using a texture analyzer. MVAG peak and final viscosities of flour samples decreased with increasing fibre content. Starch–fibre interactions followed a similar trend as flour–fibre treatments. Gluten–fibre interactions were also measured using a Gluten Peak Tester on flour–fibre and gluten–fibre mixtures. Cellulose fibre enhanced the kinetics of gluten aggregation.     

Bread fortified with dietary fibre extracted from culinary banana bract: its quality attributes and in vitro starch digestibility

The effect of fortification of dietary fibre (DF) on dough rheology, quality characteristics and in vitro starch digestibility of bread was studied. Bread was prepared incorporating DF (2–4 g per 100 g of flour mixture). Rheological study of dough showed an increase in dough stiffness and elasticity with higher incorporation of the DF. The results of chemical composition revealed that addition of DF increased total DF (19.65 g per 100 g) content of bread. However, incorporation of 2 g per 100 g DF of flour mixture with 66 g per 100 g moisture showed higher water retention and specific volume of 86.76% and 5.83 cm³ g⁻¹, respectively, which was close to control bread. Improved textural property with acceptable sensory attributes was observed for bread fortified with 2 g per 100 g DF of flour mixture and 66 g per 100 g moisture content. Incorporation of DF (2–4 g per 100 g of flour mixture) showed a decrease in rapidly digestible starch (RDS) and an increase in slowly digestible starch (SDS) content with lower predicted glycaemic index (pGI) than control bread.     

Characterisation of flour, starch and fibre obtained from sweet potato (kumara) tubers, and their utilisation in biscuit production

Sweet potato (kumara) tubers of differing colours (orange, red and white) were used to produce tuber flour, a purified starch fraction and an isolated fibre extract. The fractions from each tuber colour were added into a biscuit mixture, and the effects of tuber source and fraction composition were observed in relation to the physico-chemical characteristics of biscuits. Addition of sweet potato flour and fibre fractions to white wheat flour significantly reduced the pasting properties (peak and final viscosity) of the resulting gels by up to seven-fold compared with the control wheat flour gel (as determined by the Rapid Visco Analyser). The addition of sweet potato starch affected the pasting properties of wheat flour–sweet potato starch mixes to a lesser extent. Biscuit texture (force required to cause a biscuit to fracture) was significantly reduced with the incorporation of sweet potato fibre into the biscuit dough preparation, this was linked to a reduction in biscuit thickness and spread ratio. However, the addition of sweet potato flour and starch resulted in biscuits of similar firmness as the control biscuits.     

Effect of raw and cooked onion dietary fibre on the antioxidant activity of ascorbic acid and quercetin

The effect of cell walls (dietary fibre) from raw and cooked onions (Allium cepa L. red skinned variety) on two dietary antioxidants, l-ascorbic acid (AA) and quercetin, was investigated. Cell walls isolated from onion parenchyma tissues were incubated with AA or quercetin in HEPES buffer at pH 6.5 and 37 °C for 2 h. The resulting supernatants were analysed by the ferric reducing antioxidant power (FRAP) assay and cyclic voltammetry (CV). Results show that onion cell walls effectively reduced AA degradation, but provided no protective effect against quercetin degradation, and may increase the degradation. This suggests some type of favourable interaction of the cell wall components with AA but not with quercetin. Cooking facilitates the extraction of cell wall polysaccharides and hence influences the extent of interaction of cell wall components and antioxidants. The redox behaviour of the antioxidants, the polysaccharide components of cell walls, and their relative extractabilities all appear to have important influences on the interactions.     

The effect of chemically‐modified resistant starch,RS type‐4, on body weight and blood lipid profiles of high fat diet‐induced obese mice

This study was conducted to investigate the effects of feeding chemically‐modified resistant starch type‐4 (RS4) of normal (NCS) and high‐amylose corn starch (HACS) on weight gain and plasma and liver lipid profiles of mice fed a high‐fat diet (HFD). The experimental four groups were, respectively, fed following diets: A 40% HFD with NCS, HACS, NCS‐ and HACS‐RS4. A normal diet (ND) group of mice fed the standard diet was also used as control. In order to produce RS4 by chemical modification, corn starches were treated with STMP/STPP. Total RS (TRS) and total dietary fiber (TDF) levels of chemically‐modified NCS were 26.4 and 44.0%, respectively, while TRS and TDF levels in chemically‐modified HACS were 78.1 and 78.5%, respectively. Onset gelatinization temperatures of both modified corn starches clearly shifted to higher temperatures after STMP/STPP treatment. At the end of the diet trial, the mice on the HACS diet decreased body weight gain compared to the NCS‐fed mice. Adding NCS‐ and HACS‐RS4 to the diet significantly reduced the weight gain relative to NCS and HACS groups. Both RS4 diets were effective in improving the lipid profile compared to their respective controls. They significantly reduced the level of total lipid and total cholesterol.     

Chemical Composition,Starch Bioavailability and Indigestible fraction of Common Beans (Phaseolus Vulgaris L.)

In Mexico, consumption of beans represents 15% of the normal diet of the population in rural zones. Four common bean varieties cultivated in Mexico were studied regarding their chemical composition, starch digestibility and indigestible fraction. The protein level in the samples Huasteco, Tacana and TLP 19 was not different (α = 0.05), but Veracruz cultivar had the highest protein and ash content, and the lowest lipid level. Differences in chemical composition were determined in the cultivars studied. Total starch (TS) ranged between 33.6 and 36.7%, and the cultivars Tacana, TLP 19 and Veracruz were not different in starch content (α = 0.05). The available starch (AS) determined represented between 74 and 87% of TS, due to the resistant starch content and perhaps some complex formed between starch and protein or starch and polyphenols, by the high level of the indigestible fraction determined in the beans. The in vitro α‐amylolysis rate was similar for the different varieties, except for Veracruz cultivar which presented a slightly lower hydrolysis rate.