Whole grain cereal fibers and their support of the gut commensal Clostridia for health

Protein combined with certain dietary fibers increases butyrate production in gut microbiota fermentation

The modern diet delivers nearly equal amounts of carbohydrates and protein into the colon representing an important protein increase compared to past higher fiber diets. At the same time, plant-based protein foods have become increasingly popular, and these sources of protein are generally less digestible than animal protein sources. As a result, a significant amount of protein is expected to reach the colon and be available for fermentation by gut microbiota. While studies on diet-microbiota interventions have mainly focused on carbohydrate fermentation, limited attention has been given to the role of protein or protein-fiber mixtures as fermentation substrates for the colonic microbiota. In this study, we aimed to investigate: (1) how changing the ratio of protein to fiber substrates affects the types and quantities of gut microbial metabolites and bacteria; and (2) how the specific fermentation characteristics of different types of fiber might influence the utilization of protein by gut microbes to produce beneficial short chain fatty acids. Our results revealed that protein fermentation in the gut plays a crucial role in shaping the overall composition of microbiota communities and their metabolic outputs. Surprisingly, butyrate production was maintained or increased when fiber and protein were combined, and even when pure protein samples were used as substrates. These findings suggest that indigestible protein in fiber-rich substrates may promote the production of microbial butyrate perhaps including the later stages of fermentation in the large intestine.

Comparison Study of Nontreated and Fermented Wheat Varieties 'Ada', 'Sarta', and New Breed Blue and Purple Wheat Lines Wholemeal Flour

The aim of this study was to analyze and compare the acidity, microbiological, and chromaticity parameters; fatty acid (FA) and volatile compound (VC) profiles; and biogenic amine (BA), macro- and microelement, and mycotoxin concentrations in nontreated ‘Ada’, ‘Sarta’, and new breed blue (DS8472-5) and purple (DS8526-2) wheat lines wholemeal (WW) with those fermented with lactic acid bacteria (LAB) possessing antimicrobial/antifungal properties, isolated from spontaneous sourdough: Pediococcus acidilactici-LUHS29, Liquorilactobacillus uvarum-LUHS245, Lactiplantibacillus plantarum-LUHS122). All the fermented WW showed >8.0 log10 CFU/g of LAB count, and the type of LAB was a significant factor in the WW acidity parameters. Phenylethylamine was the predominant BA in WW, and the wheat variety (WV), the type of LAB, and their interaction were significant factors on the BA formation. Despite the fact that some differences in trace element concentrations in WW were obtained, in most of the cases fermentation was not a significant factor in their content. The main FAs in WW were palmitic acid, all-cis,trans-octadecenoic acid, and linoleic acid. Fermented WW showed a more diverse VC profile; however, the influence of fermentation on deoxynivalenol in WW was varied. Finally, further studies are needed to indicate the technological parameters that would be the most effective for each WV, including the lowest BA formation and mycotoxin degradation.

Matched whole grain wheat and refined wheat milled products do not differ in glycemic response or gastric emptying in a randomized, crossover trial

BACKGROUND

Epidemiologic and some clinical studies support the view that whole grain foods have lower glycemic response than refined grain foods. However, from the perspective of food material properties, it is not clear why whole grain cereals containing mostly insoluble and nonviscous dietary fibers (e.g., wheat) would reduce postprandial glycemia.

OBJECTIVES

We hypothesized that glycemic response for whole grain wheat milled products would not differ from that of refined wheat when potentially confounding variables (wheat source, food form, particle size, viscosity) were matched. Our objective was to study the effect of whole grain wheat compared with refined wheat milled products on postprandial glycemia, gastric emptying, and subjective appetite.

METHODS

Using a randomized crossover design, healthy participants (n = 16) consumed 6 different medium-viscosity porridges made from whole grain wheat or refined wheat milled products, all from the same grain source and mill: whole wheat flour, refined wheat flour, cracked wheat, semolina, reconstituted wheat flour with fine bran, and reconstituted wheat flour with coarse bran. Postprandial glycemia, gastric emptying, and appetitive response were measured using continuous glucose monitors, the 13C-octanoic acid (8:0) breath test, and visual analog scale (VAS) ratings. Bayes factors were implemented to draw inferences about null effects.

RESULTS

Little-to-no differences were observed in glycemic responses, with lower incremental AUC between 0 and 120 min glycemic responses only for semolina [mean difference (MD): -966 mg min/dL; 95% CI: -1775, -156 mg min/dL; P = 0.02) and cracked wheat (MD: -721 mg min/dL; 95% CI: -1426, -16 mg min/dL; P = 0.04) than for whole wheat flour porridge. Bayes factors suggested weak to strong evidence for a null effect (i.e., no effect of treatment type) in glycemic response, gastric emptying, and VAS ratings.

CONCLUSIONS

Although whole grain wheat foods provide other health benefits, they did not in their natural composition confer lower postprandial glycemia or gastric emptying than their refined wheat counterparts.This trial was registered at clinicaltrials.gov as NCT03467659.

Boosting the value of insoluble dietary fiber to increase gut fermentability through food processing

Insoluble dietary fibers are typically known to be poorly fermented in the large intestine. However, their value may be high as evidence shows that important butyrogenic bacteria preferentially utilize insoluble substrates to support their energy needs. The objective of this study was to increase fermentability of an insoluble bran fiber (pearl millet) while keeping it mostly insoluble to promote bacteria in the community that rely on fermentable insoluble dietary fibers. Following pretests with different processing methods, a combination of microwave and enzymatic treatments were applied to isolated pearl millet fiber to increase its accessibility of gut bacteria. In vitro human fecal fermentation was conducted and analyses were made for short chain fatty acids and microbiota changes. Combined microwave and enzymatic processing increased the amount of insoluble fiber fermented in vitro from 36 to 59% of total dietary fiber, with a minor increase in soluble fiber (8%). Microwave/enzymatic processing doubled butyrate production and almost tripled acetate production at 6 h fermentation compared to the native millet fiber. 16S rRNA gene sequencing showed that the processing promoted a significant increase in Firmicutes/Bacteroidetes ratio compared to the native fiber with relative abundance increases in Blautia and Copprococcus genera and a decrease in Bacteroidetes. Overall, these data show that processing techniques can be used to increase the value of insoluble fiber, presumably by increasing accessibility of the fiber to degrading bacteria, and to support Firmicutes that preferentially compete on insoluble fibers.

Co-Encapsulated Synbiotics and Immobilized Probiotics in Human Health and Gut Microbiota Modulation

Growing interest in the development of innovative functional products as ideal carriers for synbiotics, e.g., nutrient bars, yogurt, chocolate, juice, ice cream, and cheese, to ensure the daily intake of probiotics and prebiotics, which are needed to maintain a healthy gut microbiota and overall well-being, is undeniable and inevitable. This review focuses on the modern approaches that are currently being developed to modulate the gut microbiota, with an emphasis on the health benefits mediated by co-encapsulated synbiotics and immobilized probiotics. The impact of processing, storage, and simulated gastrointestinal conditions on the viability and bioactivity of probiotics together with prebiotics such as omega-3 polyunsaturated fatty acids, phytochemicals, and dietary fibers using various delivery systems are considered. Despite the proven biological properties of synbiotics, research in this area needs to be focused on the proper selection of probiotic strains, their prebiotic counterparts, and delivery systems to avoid suppression of their synergistic or complementary effect on human health. Future directions should lead to the development of functional food products containing stable synbiotics tailored for different age groups or specifically designed to fulfill the needs of adjuvant therapy.

Sourdough improves the quality of whole-wheat flour products: Mechanisms and challenges-A review

Increasing the intake of whole-wheat flour (WWF) products is one of the methods to promote health. Sourdough fermentation is increasingly being used in improving the quality of WWF products. This review aims to analyze the effect of sourdough fermentation on WWF products. The effects of sourdough on bran particles, starch, and gluten, as well as the rheology, antinutritional factors, and flavor components in WWF dough/products are comprehensively reviewed. Meanwhile, sourdough fermentation technology has a promising future in reducing anti-nutritional factors and toxic and harmful substances in WFF products. Finally, researchers are encouraged to focus on the efficient strain screening and metabolic pathway control of sourdough for WWF products, as well as the use of bran pre-fermentation and integrated biotechnology to improve the quality of whole-wheat products. This review provides a comprehensive understanding of the effect of sourdough fermentation technology on wholemeal products to promote WWF production.