Chemically modified resistant starch in breadmaking: Impact on bone, mineral metabolism and gut health of growing Wistar rats

Effect of resistant starch types as a prebiotic

Since the role of intestinal microbiota in metabolism was understood, the importance of dietary components such as fibres and prebiotics, which affect the modulation of microbiota, has been increasing day by day. While all prebiotic components are considered dietary fibre, not every dietary fibre is considered a prebiotic. While fructooligosaccharides, galactooligosaccharides, inulin, and galactans are considered prebiotics, other fermentable carbohydrates are considered candidate prebiotic components based on in vitro and preclinical studies. Resistant starch, one of such carbohydrates, is considered a potential prebiotic component when it is made resistant to digestion naturally or chemically. In this review, both in vitro and in vivo studies in which the prebiotic capacity of type II, type III, and type IV resistant starch isolated from food and produced commercially was assessed were analyzed. According to the results of current studies, certain types of resistant starch are thought to have a high prebiotic capacity, and they may be candidate prebiotic components although positive results have not been achieved in all studies. KEY POINTS: • Resistant starch is undigested in the small intestine and is fermented in the large intestine. • Resistant starch fermentation positively affects the growth of Bifidobacterium and Lactobacillus. • Resistant starch can be considered a prebiotic ingredient.

Insoluble dietary fibers: structure, metabolism, interactions with human microbiome, and role in gut homeostasis

Consumption of food rich in dietary fibers (DFs) has been long recognized to exert an overall beneficial effect on human health. This review aims to provide a holistic overview on how IDFs impact human gut health either directly, or through modulation of the gut microbiome. Several databases were searched for collecting papers such as PubMed, Google Scholar, Web of Science, Scopus and Reaxys from 2000 till 2022. Firstly, an overview of the chemical structure of the various IDFs and the pathways employed by gut microbiota for their degradation is provided. The impact of IDFs on microbial community structure and pathogens colonization inside the human gut was discussed. Finally, the impact of IDFs on gut homeostasis and systemic effects at the cellular level, as well as the overall immunological benefits of IDFs consumption were analyzed. IDFs viz., cellulose, hemicellulose, resistant starch, and lignin found enriched in food are discussed for these effects. IDFs were found to induce gut immunity, improve intestinal integrity and mucosal proliferation, and favor adhesion of probiotics and hence improve human health. Also, IDFs were concluded to improve the bioavailability of plant polyphenols and improve their health-related functional roles. Ultimately, dietary fibers processing by modification shows potential to enhance fibers-based functional food production, in addition to increase the economic value and usage of food-rich fibers and their by-products.

Gut Health Function of Instant Dehydrated Rice Sticks Substituted with Resistant Starch Types 2 and 4

The purpose of this study was to analyze the effects of instant dehydrated rice sticks (IDRS) which were substituted with resistant starch (RS) types 2 and 4 whose gut health function targets gut microbiota. IDRS are a type of rice noodles that were developed by two formulations. The first formulation had substitution of rice flour with 20% RS type 2 and 0.15% carboxymethyl cellulose (CMC) (RSc-2), and the second formulation had 25% RS type 4 and 0.15% CMC (RSc-4). RSc-2 and RSc-4 were investigated for gut health function by human fecal fermentation in a pH-controlled batch culture. The results of gut microbiota enumeration by fluorescent in situ hybridization confirmed that significantly (P < 0.05) higher numbers of bifidobacteria were obtained with RSc-2 (10.06 ± 0.09 log cells/mL) and RSc-4 (10.00 ± 0.06 log cells/mL) compared to the control (100% rice flour formula) at 24 h fermentation. Additionally, the prebiotic indexes of RSc-2 and RSc-4 were 3.8 and 2.8 -fold higher than that of the control at 24 h fermentation. The short-chained fatty acids, acetic, propionic and butyric acid were analyzed by gas chromatography-flame ionization detector. The butyric acids were significantly (P < 0.05) higher with RSc-2 (43.56 ± 0.01 mM) and RSc-4 (43.63 ± 0.07 mM) compared to the control at 24 h. Thus, RSc-2 and RSc-4 showed butyrogenic, bifidogenic and prebiotic potential to support gut health and could aid in prevention of colon cancer.

Insights into the structure and conformation of potato resistant starch (type 2) using asymmetrical flow field-flow fractionation coupled with multiple detectors

Insight into the structure and conformation characteristics of starch that influence its enzyme susceptibility is import for its potential application. In this study, the capacity of asymmetrical flow field-flow fractionation (AF4) coupled online with multi-angle light scatting (MALS) and differential refractive index (dRI) detectors (AF4-MALS-dRI) for monitoring of change in structure and conformation of potato starch during enzymatic hydrolysis was evaluated. The dissolution behavior of potato resistant starch (type 2) (PRS) was investigated. The effect of incubation time and amyloglucosidase concentration on the structure and conformation of potato starch was studied. The apparent density and the ratio of R_g (radius of gyration) to R_h (hydrodynamic radius) obtained from AF4-MALS-dRI were proven to be important parameters as they offer an insight into conformation of PRS at molecular level. Results suggested that gelatinization process made potato amylose molecules have a loose and random coil conformation which could contribute to an acceleration of enzymatic hydrolysis of potato starch. Furthermore, an intermediate with an elongated branched conformation was found between amylose and amylopectin populations, which may play a role in digestion property of potato starch. The results demonstrated that AF4-MALS-dRI is a powerful tool for better understanding of conformation of PRS.