Enzymatic Modification of Corn Starch Influences Human Fecal Fermentation Profiles

Effect of anthocyanins on the in vitro fermentation of high-amylose starch

Resistant starch provides beneficial metabolites through gut microbiota fermentation, and the gut microbiota is modulated by the gut redox status. However, the impact of redox status on high-amylose maize starch (HAMS) fermentation metabolism remains uncertain. Anthocyanins (AC) are dietary antioxidants that modulate the redox status. The effect of antioxidant AC on the fermentation metabolism of HAMS was examined using an in vitro fermentation system. AC lowers the system redox potential. The antioxidant AC and fermentation substrate HAMS (HAMS-AC) synergistically increased gas production and short-chain fatty acids and reduced the pH compared to the individual components. AC promotes HAMS fermentation metabolism to produce butyric acid. HAMS-AC also influences gut microbiota composition and metabolic functions. It facilitated beneficial bacteria proliferation, including Collinsella, Faecalibacterium, Agathobacter, Ruminococcus, and Megasphaera, and suppressed harmful bacteria proliferation, including Desulfovibrio, Barnesiella, Alistipes, Parabacteroides, Dorea, Colidextribacter, and Bilophila. HAMS-AC facilitates amino acid and protein synthesis and metabolism, sugar, nucleotide, energy metabolism, and transport. Overall, the antioxidant AC, by lowering the redox potential of the fermentation system, affects the gut microbiota structure and metabolic function and contributes to HAMS metabolism to produce butyric acid. This provides a novel approach for the modulation of intestinal homeostasis and organismal health.

Modulation of Gut Microbiota by the Complex of Caffeic Acid and Corn Starch

To understand the impact of different types of polyphenol-starch complexes on digestibility and gut microbiota, caffeic acid (CA) and corn starch (CS) complexes were prepared by coheating and high-pressure homogenization. The resistant starch content in CS coheated with CA (HCS-CA) and HCS-CA after high-pressure homogenization (HCS-CA-HPH) was 47.75 and 56.65%, respectively. Fourier transform infrared spectroscopy and X-ray diffraction analysis revealed hydrogen bonding in coheated samples and enhanced V-complex formation with high-pressure homogenization. The in vitro-digested complexes were of the B + V type, with higher relative crystallinity and short-range ordering of HCS-CA-HPH. Fermentation of the digested complex with human feces increased the yield of acetate, butyrate, and total short-chain fatty acids (SCFAs), which was more pronounced for HCS-CA-HPH. HCS-CA increased torques-Ruminococcaceae abundance, while HCS-CA-HPH boosted Prevotella, Roseburia, Lachnospiraceae, and Lachnospiraceae-NK4A136. Overall, CA and CS complexes enhanced beneficial bacteria and increased SCFA production.

Structural and Functional Properties of Porous Corn Starch Obtained by Treating Raw Starch with AmyM

Porous starch is attracting considerable attention for its high surface area and shielding ability, properties which are useful in many food applications. In this study, native corn starch with 15, 25, and 45% degrees of hydrolysis (DH-15, DH-25, and DH-45) were prepared using a special raw starch-digesting amylase, AmyM, and their structural and functional properties were evaluated. DH-15, DH-25, and DH-45 exhibited porous surface morphologies, diverse pore size distributions and pore areas, and their adsorptive capacities were significantly enhanced by improved molecular interactions. Structural measures showed that the relative crystallinity decreased as the DH increased, while the depolymerization of starch double helix chains promoted interactions involving disordered chains, followed by chain rearrangement and the formation of sub-microcrystalline structures. In addition, DH-15, DH-25, and DH-45 displayed lower hydrolysis rates, and DH-45 showed a decreased C∞ value of 18.9% with higher resistant starch (RS) content and lower glucose release. Our results indicate that AmyM-mediated hydrolysis is an efficient pathway for the preparation of porous starches with different functionalities which can be used for a range of applications.

In vitro digestibility and fermentability profiles of wheat starch modified by chlorogenic acid

This study was designed to investigate the effect of chlorogenic acid (CA) on starch digestibility and fermentability in vitro. Compared with wheat starch (WS), WS-CA complexes exhibited a looser porous gel matrix, and higher solubility and swelling power with the addition of different proportion of CA. The WS-CA complexes significantly reduced the digestive rate of the gelatinized WS, and increased the proportion of resistant starch (RS) ranging from 31.70 % to 69.63 % much higher than that in the gelatinized WS (26.34 %). The residual WS-CA complexes after 24 h of fermentation with human feces induced the production of short-chain fatty acid, as well as the proliferation of gut microbiota such as genera Megamonas and Parabacteroides positively associated with the improvement of human health. The results suggest that complex of starch and CA could be a promising method for developing starchy foods with lower starch hydrolysis and promoting the growth of probiotics.

Estimation of viscosity and hydrolysis kinetics of corn starch gels based on microstructural features using a simplified model

Viscosity is an important rheological property, which may have impact on the glycemic response of starchy foods. However, the relationship between starch gels viscosity on its hydrolysis has not been elucidated. The aim of this work was to assess the effect of gels viscosity on the microstructure, and the kinetics of enzymatic hydrolysis of starch. Corn starch gels were prepared from starch:water ratios varying from 1:4 to 1:16. A structural model was proposed that correlated (R-square = 0.98) the porous structure (cavity sizes, thickness walls) of gels and its viscosity. Kinetics constants of hydrolysis decreased with increasing starch content and consequently with gel viscosity. Relationships of viscosity with the microstructural features of gels suggested that enzyme diffusion into the gel was hindered, with the subsequent impact on the hydrolysis kinetics. Therefore, starch digestibility could be governed by starch gels viscosity, which also affected their microstructure.

Modulation of gelatinized wheat starch digestion and fermentation profiles by young apple polyphenols in vitro

To evaluate the effect of young apple polyphenols (YAP) on starch digestion and gut microbiota, complexes of native wheat starch (NWS) with YAP, and their main components chlorogenic acid (CA) and phlorizin (P) were fabricated and gelatinized. Through XRD and FTIR analysis, it was found that the partial crystalline structure of NWS was destroyed during gelatinization, and the addition of P decreased the extent of destruction. Then, the gelatinized starchy samples were subjected to in vitro digestion. The wheat starch (WS)-phenolic compound complexes significantly suppressed the digestion rate and increased the proportion of resistant starch (RS) in WS. Furthermore, the residual starchy components after digestion were fermented by human fecal samples for 24 h. The WS-YAP complex greatly increased the concentration of short-chain fatty acids (SCFAs), especially acetic and propionic acids, and enhanced the growth of health-promoting gut microbiota such as Prevotella. Conclusively, YAP was shown to play a positive role in maintaining blood glucose balance and intestinal health.

Green fabrication and characterization of debranched starch nanoparticles via ultrasonication combined with recrystallization

With recent advances in nanotechnology, debranched starch nanoparticle (DBS-NP) materials have attracted considerable interest from the fields of functional food, biomedicine, and material science, thanks to their small size, biodegradability, biocompatibility, sustainability, and non-hazardous effects on health and the environment. In this study, DBS-NP was fabricated using an eco-friendly method involving ultrasonication combined with recrystallization. The effects of ultrasonication and recrystallization times on the morphology, particle size, and crystal structure of the DBS-NPs were systematically investigated. Compared with the DBS-NPs prepared using ultrasonication treatment only, the DBS-NPs formed using ultrasonication combined with recrystallization were uniform in size and well distributed in aqueous solution. Moreover, the maximum encapsulation efficiency and loading capacity of the epigallocatechin gallate (EGCG) in the DBS-NPs with ultrasonication treatment reached 88.35% and 22.75%, respectively. The particle sizes of the EGCG@DBS-NP were more stable at a neutral pH (7.4) than at an acidic pH (2.1). The EGCG in the EGCG@DBS-NP displayed excellent radical scavenging activity and antibacterial effects, and cell assays demonstrated that the EGCG@DBS-NP was non-toxic and highly biocompatible.

Supplementation with Chlorella vulgaris, Chlorella protothecoides, and Schizochytrium sp. increases propionate-producing bacteria in in vitro human gut fermentation

BACKGROUND

Gut microbiota are major contributors to host metabolism and are considered as potential targets of novel therapeutics. Microalgae have a strong potential for use as prebiotics because they are a rich source of proteins, fatty acids, fiber, and minerals for nutritional supplementation in humans. Nevertheless, there has been insufficient research into the effect of microalgae on gut microbiota. To investigate the effects of three edible microalgae (Chlorella vulgaris, Chlorella protothecoides, and Schizochytrium sp.) on gut microbiota, simulated digestion and colonic fermentation were examined.

RESULTS

Following in vitro digestion, the microalgae displayed different levels of bioaccessibility and the nutrient analysis revealed that unabsorbed nutrients during the digestion process could be used for colonic fermentation. Following colonic fermentation, the control, inulin, and microalgae groups displayed different metabolite tendencies when investigated with nuclear magnetic resonance (NMR) spectroscopic analysis. In particular, microalgae supplementation increased the proportion of propionate in the colonic culture (control: 19.14%, Inulin: 18.38%, C. vulgaris: 25.80%, C. protothecoides: 25.46%, and Schizochytrium sp.: 25.56%). Microbial profiling analysis using 16S rRNA gene sequencing also disclosed that the relative abundance of Bacteroides (control: 1.91%, inulin: 2.61%, C. vulgaris: 14.77%, C. protothecoides: 11.17%, and Schizochytrium sp.: 5.51%) and Dialister (control: 0.08%, inulin: 2.06%, C. vulgaris: 6.79%, C. protothecoides: 4.45%, and Schizochytrium sp.: 4.48%), involved in propionate metabolism increased more than in the inulin group.

CONCLUSION

Our findings suggest the potential use of microalgae as a functional food to increase propionate generation because propionate has been reported to be effective in weight loss and the inhibition of pathogen infection. © 2020 Society of Chemical Industry.

Intestinal gases: influence on gut disorders and the role of dietary manipulations

The inner workings of the intestines, in which the body and microbiome intersect to influence gut function and systemic health, remain elusive. Carbon dioxide, hydrogen, methane and hydrogen sulfide, as well as a variety of trace gases, are generated by the chemical interactions and microbiota within the gut. Profiling of these intestinal gases and their responses to dietary changes can reveal the products and functions of the gut microbiota and their influence on human health. Indeed, different tools for measuring these intestinal gases have been developed, including newly developed gas-sensing capsule technology. Gases can, according to their type, concentration and volume, induce or relieve abdominal symptoms, and might also have physiological, pathogenic and therapeutic effects. Thus, profiling and modulating intestinal gases could be powerful tools for disease prevention and/or therapy. As the interactions between the microbiota, chemical constituents and fermentative substrates of the gut are principally influenced by dietary intake, altering the diet, which, in turn, changes gas profiles, is the main therapeutic approach for gastrointestinal disorders. An improved understanding of the complex interactions within the intestines that generate gases will enhance our ability to prevent, diagnose, treat and monitor many gastrointestinal disorders.