Reduced Starch Digestibility Research Articles

Granular morphology, molecular structure and thermal stability of infrared heat-moisture treated maize starch with added lipids

The thermal and structural changes of infrared heat-moisture treated (IR-HMT) maize starch with added stearic acid (SA) (1.5% w/w) were investigated. Scanning electron microscopy showed more protrusion and fewer pores on the starch granular surface for maize starch with IR-HMT plus SA. Transmission electron microscopy showed that IR-HMT promoted more interactions between starch blocklets and resulted in a more fused blocklet organisation. IR-HMT seemed to increase hydrogen bonding between starch polymeric chains. These interactions are shown by the increased relative crystallinity shown by crystalline peak area calculated from X-ray diffraction and the higher 1047/1022 cm−1 band ratio from FTIR at a molecular level. In addition, at a molecular level, dynamic mechanical thermal analysis and differential scanning calorimetry showed evidence of amylose–lipid complexes in IR-HMT starch with SA. These changes can be related to already reported functionality such as reduced starch digestibility of IR-HMT maize starch with stearic acid IR-HMT.

Effect of processing treatments on digestibility and physicochemical properties of ready‐to‐cook breakfast mixes

Increasing metabolic disorders and changing lifestyles have created an increased demand for healthy convenience food, especially breakfast. The study aims to identify an ideal processing method to formulate a Ready-to-Cook savory wheat (Dalia) porridge with reduced starch digestibility and enriched protein and fiber content. Pressure-cooking (WP), autoclaving (WA), drum-drying (WD), flaking (WF) and toasting (WT) were adopted for instantization. The energy distribution was as per the guidelines of the American Diabetes Association. Processing resulted in reduced cooking time, changes in color parameters, increased water absorption and solubility. Complete gelatinization of starch was observed in all samples except WA and WT. Resistant starch content increased in all samples (8.95-16.70 g/100 g) except WD and WT. The estimated glycemic Index (eGI) ranged from 65.8-54.8, with maximum eGI shown by WD and minimum by WA. Increased in vitro protein digestibility 5-10% was observed. All the porridge showed good sensory characteristics and acceptability.

Effects of different polyphenol-rich herbal teas on reducing predicted glycemic index

The purpose of this study was to investigate the effects of different polyphenol-rich herbal teas on reducing the in vitro starch digestibility of white bread and evaluation of predicted glycemic indexes. Generally, except for the goji berry treatment, all herbal teas reduced the starch digestibility and predicted glycemic index of white bread. Compared to untreated white bread, the rapidly digestible starch levels were decreased by 10% and 12% in the turmeric tea treatment. In addition, hydrolysis indexes were decreased by 12% and 10% in the black tea treatment compared to untreated white bread. The turmeric treatment on white bread reduced the predicted glycemic index more than other teas. It is thought that the curcumin in turmeric has more inhibitory effects on α-amylase activity than other teas. We also demonstrated that dietary polyphenols such as anthocyanins and catechins found in herbal teas might reduce starch digestion by inhibiting α-amylase and α-glucosidase thereby lowering the glycemic index of foods.

Effect of parboiling on starch digestibility and mineral bioavailability in rice (Oryza sativa L.)

Parboiled rice is preferably consumed in many countries due to its nutritional superiority and lower starch digestibility. Parboiling affects rice cooking quality, starch digestibility and phytic acid which affects minerals bioavailability. Cooking quality was improved in parboiled brown (PB) and parboiled milled (PM) rice. Parboiling has significantly (P < 0.05) reduced glycemic index in both PB and PM rice with a proportionately increase in resistant starch. After milling, the phytic acid (PA) and Fe were reduced significantly (P < 0.05), however, parboiling further reduced PA but increased Fe content and bioavailability in PM rice due to its inward diffusion. Zn content was lower in PB and PM rice due to its outward movement during parboiling. The impact of Zn retention on its bioavailability was insignificant in parboiled rice as non-parboiled rice. This study provides better insights on rice parboiling as a method to reduce starch digestibility and improve mineral bioavailability which could be beneficial for diabetics and malnourished population.

Radio frequency treatment improved the slowly digestive characteristics of rice flour

Reducing starch digestibility can be beneficial to control the increasing of postprandial blood glucose and reduce the risk of diabetes, obesity, and other related chronic diseases. In this study, the structure, digestibility and physicochemical properties of rice flour under radio frequency (RF) treatment was investigated. The structural properties of rice flour were characterized by the X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and particle size analyzer. The results showed that RF treatment caused the aggregation of starch granules, resulting in the increase of particle size. The relative crystallinity and the short-range order of rice flour were reduced following RF treatment. In vitro digestibility results showed that the resistant starch content of indica, japonica and waxy rice flour (IRF, JRF and WRF) increased from 39.04% to 42.02%, 39.95%–45.12% and 36.26%–43.61% after RF treatment, respectively. Moreover, RF treatment reduced the peak viscosity and breakdown of IRF and JRF, whereas enhanced them in WRF. After RF treatment, the G′ and G″ of all samples increased, while the tan δ displayed an opposite trend. These results suggest that RF treatment has the potential to modify rice flour for extending its application range in food industries.

Effects of psyllium and cellulose fibres on thermal, structural, and in vitro digestion behaviour of wheat starch

SummaryThe study investigated the effects of adding different types of fibre (psyllium and cellulose) on in vitro digestion behaviour of wheat starch with its thermal and structural properties. Psyllium and cellulose fibres interfered with the wheat starch differently. Psyllium fibre hindered starch gelatinisation, restricted the loss of starch crystallinity, and decreased the accessibility of enzymes to starch. In contrast, cellulose fibre had no significant effect on gelatinisation and loss of crystallinity but limited the digestive enzyme mobility. The impact of psyllium was more pronounced than cellulose on reducing starch digestibility. Rapidly digestible starch fractions of the cooked starch reduced from between 57.90 ± 0.60–69.72 ± 0.46 (% in starch) to between 28.06 ± 0.36–46.34 ± 1.10 (% in starch) and 53.23 ± 0.36–66.71 ± 0.24 (% in starch) for psyllium and cellulose fibre, respectively. This information could be helpful to design foods containing starch with reduced digestibility for a healthy diet.

In vitro α‐amylase inhibitory and antioxidant properties of soluble proteins and their peptic hydrolysates from raw and cooked commercially available oatmeal

AbstractBackground and objectivesReady‐to‐eat cereal‐based foods like quick‐cooking oatmeal are commonly available in the market often highlighting the levels of nutrients and the effects of dietary fiber. Information about the proteins in these foods is limited to content only. This study measured two health‐related bioactivities of the salt‐soluble proteins in commercially available oatmeal using in vitro assays. Soluble proteins and their peptic hydrolysates extracted from raw and cooked commercially available oatmeal were analyzed for their in vitro α‐amylase inhibitory activity and antioxidant properties in an attempt to determine the health‐promoting potential of the protein portion of oatmeal. Total soluble proteins were extracted from the raw and cooked oatmeal samples using saline solution, precipitated, and dialyzed, and their gel electrophoretic profiles were also studied.FindingsTwo major protein bands were found in both extracts with estimated molecular weight range of 22–24 and 54–56 kDa, respectively. Soluble proteins generally had low inhibitory activity toward α‐amylase (~5%) but increased when these were hydrolyzed with pepsin. The crude proteins from cooked oatmeal showed the highest α‐amylase inhibitory activity. Metal‐reducing ability was higher for the unhydrolyzed proteins from raw (48%) and cooked (32%) oatmeal than for their peptic hydrolysates (5% and 9%, respectively), while radical‐scavenging activity was higher for the peptic hydrolysates (65%–90%) than for the unhydrolyzed proteins (3%–12%).ConclusionsThe soluble proteins of commonly consumed quick‐cooking oatmeal offer health benefits such as glucose‐lowering potential via α‐amylase inhibition and antioxidant properties via metal‐reducing capacity. Their peptic hydrolysates may slightly reduce starch digestibility but showed promising radical‐scavenging potential.Significance and noveltyCurrent findings may be useful to cereals manufacturing industry and to consumers who consider other health‐related benefits of whole grain food products aside from nutrient content and beneficial effects of dietary fiber.

Effects of Auricularia auricula-judae polysaccharide on pasting, gelatinization, rheology, structural properties and in vitro digestibility of kidney bean starch

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.

The impact of incorporating coarse wheat farina containing intact endosperm cells in a bread recipe on bread characteristics and starch digestibility

Intact or broken wheat kernels containing clusters of intact cells can be used in wheat bread recipes to lower starch digestibility but result in very dense bread crumb. We hypothesized that a smaller wheat milling fraction [i.e. coarse farina (CF; average diameter 705 μm)] that still contains intact cells can result in lower starch digestibility without a substantial deleterious effect on bread quality. We thus studied the impact of different levels of CF incorporation on bread characteristics and starch digestibility. A portion of the CF cell walls seemingly retained integrity throughout the bread making process. Bread volume and crumb softness linearly decreased with increasing levels of CF, yet remained acceptable. Unexpectedly, the extent and rate of in vitro starch digestion were not influenced by CF incorporation. In the complex bread crumb matrix, the reduced starch digestibility as a result of the inclusion of intact CF cells in the recipe may well be counterbalanced by increased starch digestibility as a result of the presence of a less elaborated gluten network and thus weaker gluten-starch interactions. Overall, modulation of starch digestibility in wheat bread is an inherently difficult task and incorporation of clusters of intact cells only appears effective at reducing starch digestibility when very large particles at plant tissue level are added.

Effects of red lentil protein addition on textural quality and starch digestibility of brown rice noodles

SummaryIn this study, the additions of red lentil, rice protein and lentil protein on the quality of brown rice (BR) noodles were investigated, aiming to develop nutritionally fortified noodles with both desirable textural quality and lower starch digestibility. The results showed that the additives reduced the hardness, cohesiveness and chewiness, and increased cooking loss and turbidity of rice noodles. The addition of lentil protein had less effect on the texture quality of rice noodles when compared with the red lentil and rice protein. Lentil protein decreased the starch digestibility of BR noodles, thereby reducing the estimated glycemic index (eGI) from 70.48 to 65.33. XRD and FTIR revealed that lentil protein increased the relative crystallinity and 1047/1022 cm−1 ratio. Ordered structure could effectively limit the interaction between amylase and starch, and reduce its digestibility. Therefore, lentil protein was more suitable to be added in BR noodles to reduce starch digestibility.

Effect of protein enrichment on quality characteristics and glycemic index of gluten free sweet potato (Ipomoea batatas L.) spaghetti.

The aim of present investigation was justifying the suitability of sweet potato flour for development of gluten free spaghetti with reduced starch digestibility and to enhance protein content by fortification of whey protein concentrate (WPC) and chickpea flour (CPF) at the rate of 5%, 10%, and 15% respectively along with control. The effect of fortification in spaghetti was assessed for its glycemic index, physical, nutritional, and sensory properties. The data revealed that increase in the level of fortification of WPC and CPF resulted with increase in optimum cooking time, weight and volume without affecting cooking loss as compared to control sample. The percent increase in protein content of spaghetti fortified with WPC and CPF found as 192.20% and 150.08% respectively in comparison with control. However, spaghetti fortified with 15% CPF and 15% WPC showed lowest starch digestibility with reduced glycemic index to 59.43 and 58.73 respectively. The spaghetti fortified with 10% WPC and 10% CPF was found overall acceptable by panelists. Moreover, the fortification of spaghetti with WPC and CPF could significantly increase the protein content along with overall acceptability and functional characteristics.

Evolutions of rheology, microstructure and starch hydrolysis of pumpkin‐enriched bread during simulated gastrointestinal digestion

AbstractIn this study, the influences of pumpkin flour additions to breadmaking on evolutions of microstructure, rheology and starch hydrolysis during simulated gastrointestinal digestion were investigated. Compared to white bread (PB0), the bread supplemented with 20% pumpkin flour (PB20) showed more continuous and fibrous gel network structure with most starch granules encapsulated in the network throughout the in vitro digestion. Due to the dilution of digestive fluids and enzymatic hydrolysis, the digesta moduli and viscosity remarkably decreased as time progressed, but PB20 presented significantly higher rheology compared to PB0 in each digestion phase. At the end of intestinal phase, the in vitro starch digestibility was 69.9% for PB0, significantly higher than that for PB20 (55.4%). This is presumably attributed to the abundant dietary fibre in pumpkin flour, contributing to the increased digesta viscosity and the formation of more compact and stable gel networks that would hinder the contact of starch granules with α‐amylase. In addition, the pumpkin‐added breads gave satisfactory results in terms of sensory acceptability. This study has suggested promising potential of incorporating pumpkin flour in the production of functional bakery products with reduced starch digestibility while maintaining good sensory characteristics.

Evolutions of rheology, microstructure and digestibility of parboiled rice during simulated semi-dynamic gastrointestinal digestion

Despite the general recognition about the beneficial effects of parboiled rice in lowering glycemic response, there are contradictory studies regarding the negligible effect of parboiling treatment on digestive behaviour of rice and its glycemic index (GI) value. In this study, the rheology, microstructure, particle size distribution, and starch hydrolysis before and within semi-dynamic in vitro gastrointestinal digestion were measured and compared between the cooked parboiled and non-parboiled (control) rice. The protein content was significantly increased from 4.04 to 5.26 g/100 g, while the fat and moisture contents were slightly decreased after parboiling. The apparent viscosity and moduli of parboiled rice were higher than that of the control rice before and during the in vitro digestive phases. Optical and confocal microstructures showed denser gel-networks with less disrupted granules or clusters in the parboiled rice during digestion. At the end of digestion, parboiled rice had a starch digestibility of around 74 g/100 g whereas it was 85 g/100 g for the control. The reduced starch digestibility of parboiled rice was supported by its higher digesta rheology and more compact microstructure during digestion. This work suggests that parboiling is a promising and practical approach to producing healthier cooked rice with lower starch digestibility.

Two 1,4-α-glucan branching enzymes successively rearrange glycosidic bonds: A novel synergistic approach for reducing starch digestibility

Enzymatically rearranging α-1,4 and α-1,6 glycosidic bonds in starch is a green approach to regulating its digestibility. A two-step modification process successively catalyzed by 1,4-α-glucan branching enzymes (GBEs) from Rhodothermus obamensi STB05 (Ro-GBE) and Geobacillus thermoglucosidans STB02 (Gt-GBE) was investigated as a strategy to reduce the digestibility of corn starch. This dual GBE modification process caused a reduction of 25.8 % in rapidly digestible starch fraction in corn starch, which were more effective than single GBE-catalyzed modification with the same duration. Structural analysis indicated that the dual GBE modified product contained higher branching density, more abundant short branches, and shorter external chains than those in single GBE-modified product. These results demonstrated that a moderate Ro-GBE treatment prior to starch gelatinization caused several suitable alterations in starch molecules, which promoted the transglycosylation efficiency of the following Gt-GBE treatment. This dual GBE-catalyzed modification process offered an efficient strategy for regulating starch digestibility.

Potential health benefits of garden pea seeds and pods: A review

AbstractPea (Pisum sativum L.) is a nutritious pulse crop belonging to the leguminous family, and widely cultivated. In recent time, health and nutritional benefits of the pea and its by‐products enriched with biomolecules, which have gained significant attention to the researchers and consumers. Peas are known for its pivotal nutritional value with high‐quality proteins, dietary fibres, starch, carbohydrates and micronutrients including vitamins and minerals. It is also enriched with phytochemicals, antioxidants, flavonoids, tannins and other phenolic compounds under non‐nutritional category. Dietary fibre extracted from its cotyledon of the cell wall, seed coats and pods proved to accelerate the gastrointestinal activity by developing intestinal microflora. Intermediate amylose maintains blood glucose level by lowering the glycaemic index and reducing starch digestibility of peas. Pea proteins derived peptides have opportunities in nutraceuticals. Furthermore, pea‐derived non‐α‐galactooligosaccharides could mitigate the gas production by colonic bacteria during the fermentation. Anti‐acetylcholinesterase (anti‐AChE) was also traced in the pea pod with some antioxidant properties. The focus of this review paper is to provide a comprehensive profiling of chemical compositions and bioactives of fresh mature peas (specifically garden or field pea seeds) and by‐products of pea processing (pods and peels) that sets a foundation for assessment of their health benefits.

Faba bean meal, starch or protein fortification of durum wheat pasta differentially influence noodle composition, starch structure and in vitro digestibility

Faba bean (Vicia faba L.) flour, starch concentrate (60% starch), protein concentrate (~60% protein) and protein isolate (~85% protein) were added to replace one-quarter of durum wheat semolina to enrich the nutritional quality and physiological functions of durum wheat (Triticum turgidum L.) pasta. The raw pasta samples prepared with protein concentrate or isolate had higher (p ≤ 0.001) protein and lower (p ≤ 0.001) total starch concentrations, along with increased total dietary fiber and slowly digestible starch (p ≤ 0.001) than durum wheat semolina control or those with added whole faba-bean flour or isolated starch. The faba bean fortified pasta had altered starch with increased proportion of medium B-type glucan chains and long C-type glucan chains, reduced starch digestibility and were associated with glycaemia related effects in the human diet. The faba bean fortified pasta had increased protein and dietary fiber that influenced food intake and satiety. The results suggest differential contributions of food ingredients in human health outcomes.

Borate and phosphite treatments of potato plants (Solanum tuberosum L.) as a proof of concept to reinforce the cell wall structure and reduce starch digestibility

Potatoes are one of the main sources of carbohydrates in human diet, however they have a high glycaemic index (GI). Hence, developing new agricultural and industrial strategies to produce low GI potatoes represents a health priority to prevent obesity and related diseases. In this work, we investigated whether treatments of potato plants with elicitors of plant defence responses can lead to a reduction of tuber starch availability and digestibility, through the induction of cell wall remodelling and stiffening. Treatments with phosphites (KPhi) and borate were performed, as they are known to activate plant defence responses that cause modifications in the architecture and composition of the plant cell wall. Data of suberin autofluorescence demonstrated that potato plants grown in a nutrition medium supplemented with KPhi and borate produced tubers with a thicker periderm, while pectin staining demonstrated that KPhi treatment induced a reinforcement of the wall of storage parenchyma cells. Both compounds elicited the production of H2O2, which is usually involved in cell-wall remodelling and stiffening reactions while only KPhi caused an increase of the total content of phenolic compounds. A two-phase digestion in vitro assay showed that treatment with KPhi determined a significant decrease of the starch hydrolysis rate in potato tubers. This work highlights the ability of cell wall architecture in modulating starch accessibility to digestive enzymes, paving the way for new agronomic practices to produce low GI index potatoes.

Effects of Hericium erinaceus powder on the digestion, gelatinization of starch, and quality characteristics of Chinese noodles

AbstractBackground and objectivesTo improve the nutritional value and flavor of traditional Chinese noodles, Hericium erinaceus powder (HEP) was incorporated into Chinese noodles. The effects of HEP on the digestion, gelatinization of starch, and quality characteristics of Chinese noodles were analyzed.FindingsThe results showed that adding HEP could significantly reduce starch digestion rate and digestion extent in noodle, and the antioxidant capacity and gelatinization temperature were also positively related to the amount of HEP. The water absorption and cooking loss of noodles were improved by HEP, and noodle color was also impacted, showing increased L*, a* and b* values. Incorporation of HEP apparently affected texture profile analysis of noodles, resulting in increased hardness, gumminess, and chewiness. When &lt;6% of HEP was incorporated, noodle quality was not dramatically changed, although starch digestibility was significantly inhibited. More HEP could further reduce starch digestion and increase antioxidant capacity; however, noodle quality might be deteriorated.ConclusionsIn our study, it found that incorporation up to a 6% of HEP into the noodles yielded an acceptable product with improved nutraceutical properties.Significance and noveltyThe results provided guidance for the development of functional noodles and facilitated the comprehensive application of HEP.

A mechanistic model to study the effect of the cell wall on starch digestion in intact cotyledon cells

The role of the plant matrix is recognized as the main factor restricting starch digestibility in beans. Several authors have provided insights about the mechanisms behind the reduced starch digestibility in plant matrices. In this study, by means of a mathematical model, we provide a mechanistic explanation of the role played by the cell wall. It was confirmed that starch entrapped within intact cells could only be hydrolysed after α-amylase diffusion through the cell wall. This process is limited by the pores naturally present in the cell wall and the adsorption of α-amylase to the cell wall surface. These factors restrict the concentration of α-amylase available within the cells. The model assumptions are valid under controlled laboratory conditions and were validated with in-vitro digestion data giving very accurate results. The proposed approach provides new information to understand the digestibility of starch, and possibly other macronutrients, in complex food matrices.

In vitro digestion rate of fully gelatinized rice starches is driven by molecular size and amylopectin medium-long chains

In current study, the effects of starch fine molecular structures on its in vitro digestibility at fully gelatinized stage were investigated. The digestion kinetics of 15 fully gelatinized rice starches were obtained and correlated with starch chain-length distributions and molecular size distributions. Both logarithm of slopes and parallel first-order kinetic model were applied to fit the digestion curves to a few kinetics-based parameters. Result showed there were two simultaneous digestion fractions (fast versus slow) for fully gelatinized rice starches. The rate constants of slowly-digestible fraction significantly correlated with starch molecular sizes, especially with that of amylopectin molecules. Hydrodynamically larger amylopectin molecules tend to contain more shorter branches but less long chains. This slows down the starch hydrolysis by α-amylase while the action of AMG is less antagonistically hindered, increasing overall digestion rate. This study provides important information for rice breeders and manufacturers to develop rice products with reduced starch digestibility.