The effect of viscous soluble dietary fiber on nutrient digestion and metabolic responses Ⅰ: In vitro digestion process

Optimization of Enzymolysis Modification Conditions of Dietary Fiber from Bayberry Pomace and Its Structural Characteristics and Physicochemical and Functional Properties

Bayberry pomace, a nutrient-rich material abundant in dietary fiber (DF), has historically been underutilized due to a lack of thorough research. This study aimed to investigate the physicochemical and functional properties of the DF. Ultrasonic enzymatic treatment was performed to extract the total DF, which was then optimized to produce modified soluble dietary fiber (MSDF) and insoluble dietary fiber (MIDF). The optimized conditions yielded 15.14% of MSDF with a water-holding capacity (WHC) of 54.13 g/g. The DFs were evaluated for their structural, physicochemical, and functional properties. The MSDF showed a higher (p < 0.05) WHC, oil-holding capacity (OHC), swelling capacity (SC), cation exchange capacity (CEC), and glucose adsorption capacity (GAC) (about 14.15, 0.88, 1.23, 1.22, and 0.34 times) compared to the DF. Additionally, the MSDF showed strong, superior radical scavenging and blood sugar-lowering capabilities, with a more porous surface morphology. A Fourier-transform infrared (FT-IR) spectroscopy analysis indicated that enzymatic modification degraded the cellulose and hemicellulose, reducing the DF crystallinity. Overall, the results demonstrated that cellulase hydrolysis could effectively improve the physicochemical and functional properties of DF, thereby paving the way for its development into functional food products.

Relationship between microstructure formation and in vitro starch digestibility in baked gluten-starch matrices

Increased prevalence of diabetes prompts the development of foods with reduced starch digestibility. This study analyzed the impact of adding soluble dietary fiber (inulin-IN; polydextrose-PD) to baked gluten-starch matrices (7.5-13%) on microstructure formation and in vitro starch digestibility. IN and PD enhanced water-holding capacity, the hardness of baked matrices, and lowered water activity in the formulated matrices, potentially explaining the reduced starch gelatinization degree as IN or PD concentration increased. A maximum gelatinization decrease (26%) occurred in formulations with 13% IN. Micro-CT analysis showed a reduction in total and open porosity, which, along with the lower gelatinization degree, may account for the reduced in vitro starch digestibility. Samples with 13% IN exhibited a significantly lower rapidly available glucose fraction (8.56 g/100 g) and higher unavailable glucose fraction (87.76 g/100 g) compared to the control (34.85 g/100 g and 47.59 g/100 g, respectively). These findings suggest the potential for developing healthier, starch-rich baked foods with a reduced glycemic impact.

Effects of dietary fibre on metabolic health and obesity

Obesity and metabolic syndrome represent a growing epidemic worldwide. Body weight is regulated through complex interactions between hormonal, neural and metabolic pathways and is influenced by numerous environmental factors. Imbalances between energy intake and expenditure can occur due to several factors, including alterations in eating behaviours, abnormal satiation and satiety, and low energy expenditure. The gut microbiota profoundly affects all aspects of energy homeostasis through diverse mechanisms involving effects on mucosal and systemic immune, hormonal and neural systems. The benefits of dietary fibre on metabolism and obesity have been demonstrated through mechanistic studies and clinical trials, but many questions remain as to how different fibres are best utilized in managing obesity. In this Review, we discuss the physiochemical properties of different fibres, current findings on how fibre and the gut microbiota interact to regulate body weight homeostasis, and knowledge gaps related to using dietary fibres as a complementary strategy. Precision medicine approaches that utilize baseline microbiota and clinical characteristics to predict individual responses to fibre supplementation represent a new paradigm with great potential to enhance weight management efficacy, but many challenges remain before these approaches can be fully implemented.

Deacetylated Konjac Glucomannan with a Slower Hydration Rate Delays Rice Digestion and Weakens Appetite Response

The physical characteristics of chyme during gastrointestinal digestion are considered to significantly affect nutrient digestion and absorption (such as glucose diffusion), which has an impact on postprandial satiety. The present study aims to analyze the hydration rate (HR) and rheological properties of deacetylated konjac glucomannan (DKGM) at different degrees and then explore their effects on rice texture, digestive properties, and the subjects' post-meal appetite. The present results show that, as the deacetylation degree (DD) of KGM increased, the intersection point of the viscoelastic modulus shifted to a high shear rate frequency, and as the swelling time of the DKGM was prolonged, its HR decreased significantly. The results of the in vitro gastrointestinal digestion tests show that the hardness and chewability of the rice in the fast-hydration group (MK1) were remarkably reduced. In contrast, the slow-hydration group (MK5) exhibited an outstanding ability to resist digestion. The kinetics of starch hydrolysis revealed that the HR of the rice in the fast-hydration group was 1.8 times faster than that of the slow-hydration group. Moreover, it was found that the subjects' appetite after the meal was highly related to the HR of the MK. Their hunger (p < 0.001), desire to eat (p < 0.001), and prospective food consumption (p < 0.001) were significantly inhibited in the slow-hydration group (MK5) compared to the control. This study explored the nutritional effects of the hydration properties derived from the DKGM, which may contribute to modifying the high glycemic index food and provide ideas for the fabrication of food with enhanced satiating capacity.

New Horizons in Probiotics: Unraveling the Potential of Edible Microbial Polysaccharides through In Vitro Digestion Models

In vitro digestion models, as innovative assessment tools, possess advantages such as speed, high throughput, low cost, and high repeatability. They have been widely applied to the investigation of food digestion behavior and its potential impact on health. In recent years, research on edible polysaccharides in the field of intestinal health has been increasing. However, there is still a lack of systematic reviews on the application of microbial-derived edible polysaccharides in in vitro intestinal models. This review thoroughly discusses the limitations and challenges of static and dynamic in vitro digestion experiments, while providing an in-depth introduction to several typical in vitro digestion models. In light of this, we focus on the degradability of microbial polysaccharides and oligosaccharides, with a particular emphasis on edible microbial polysaccharides typically utilized in the food industry, such as xanthan gum and gellan gum, and their potential impacts on intestinal health. Through this review, a more comprehensive understanding of the latest developments in microbial polysaccharides, regarding probiotic delivery, immobilization, and probiotic potential, is expected, thus providing an expanded and deepened perspective for their application in functional foods.

Diabetes-Specific Complete Smoothie Formulas Improve Postprandial Glycemic Response in Obese Type 2 Diabetic Individuals: A Randomized Crossover Trial

This study aimed to compare newly developed diabetes-specific complete smoothie formulas with a standard diabetes-specific nutritional formula (DSNF) regarding their effects on glucose homeostasis, insulin levels, and lipid metabolism in obese type 2 diabetes (T2DM) patients. We conducted a randomized, double-blind, crossover study with 41 obese T2DM participants to compare two developed diabetes-specific complete smoothie formulas, a soy-based regular smoothie (SM) and a smoothie with modified carbohydrate content (SMMC), with the standard DSNF, Glucerna. Glycemic and insulin responses were assessed after the participants randomly consumed 300 kilocalories of each formulation on three separate days with a 7-day gap between. Postprandial effects on glycemic control, insulin levels, and lipid metabolism were measured. SMMC resulted in a significantly lower glucose area under the curve (AUC0-240) compared to Glucerna and SM (p < 0.05 for both). Insulin AUC0-240 after SMMC was significantly lower than that after SM and Glucerna (p < 0.05). During the diets, the suppression of NEFA was more augmented on SM, resulting in a less total AUC0-240 of NEFA compared to the SMMC diet (p < 0.05). C-peptide AUC0-240 after SMMC was significantly lower than that after Glucerna (p < 0.001). Conversely, glucagon AUC0-240 after SMMC was significantly higher than that after SM and Glucerna (p < 0.05). These results highlight SMMC as the better insulin-sensitive formula, potentially achieved through increased insulin secretion or a direct reduction in glucose absorption. The unique composition of carbohydrates, amino acids, and fats from natural ingredients in the smoothies may contribute to these positive effects, making them promising functional foods for managing diabetes and obesity.

Ultraprocessed plant-based foods: Designing the next generation of healthy and sustainable alternatives to animal-based foods

Numerous examples of next-generation plant-based foods, such as meat, seafood, egg, and dairy analogs, are commercially available. These products are usually designed to have physicochemical properties, sensory attributes, and functional behaviors that match those of the animal-sourced products they are designed to replace. However, there has been concern about the potential negative impacts of these foods on human nutrition and health. In particular, many of these products have been criticized for being ultraprocessed foods that contain numerous ingredients and are manufactured using harsh processing operations. In this article, the concept of ultraprocessed foods is introduced and its relevance to describe the properties of next-generation plant-based foods is discussed. Most commercial plant-based meat, seafood, egg, and dairy analogs currently available do fall into this category, and so can be classified as ultraprocessed plant-based (UPB) foods. The nutrient content, digestibility, bioavailability, and gut microbiome effects of UPB foods are compared to those of animal-based foods, and the potential consequences of any differences on human health are discussed. Some commercial UPB foods would not be considered healthy based on their nutrient profiles, especially those plant-based cheeses that contain low levels of protein and high levels of fat, starch, and salt. However, it is argued that UPB foods can be designed to have good nutritional profiles and beneficial health effects. Finally, areas where further research are still needed to create a more healthy and sustainable food supply are discussed.

Food biopolymer behaviors in the digestive tract: implications for nutrient delivery

Biopolymers are prevalent in both natural and processed foods, serving as thickeners, emulsifiers, and stabilizers. Although specific biopolymers are known to affect digestion, the mechanisms behind their influence on the nutrient absorption and bioavailability in processed foods are not yet fully understood. The aim of this review is to elucidate the complex interplay between biopolymers and their behavior in vivo, and to provide insights into the possible physiological consequences of their consumption. The colloidization process of biopolymer in various phases of digestion was analyzed and its impact on nutrition absorption and gastrointestinal tract was summarized. Furthermore, the review discusses the methodologies used to assess colloidization and emphasizes the need for more realistic models to overcome challenges in practical applications. By controlling macronutrient bioavailability using biopolymers, it is possible to enhance health benefits, such as improving gut health, aiding in weight management, and regulating blood sugar levels. The physiological effect of extracted biopolymers utilized in modern food structuring technology cannot be predicted solely based on their inherent functionality. It is essential to account for factors such as their initial consuming state and interactions with other food components to better understand the potential health benefits of biopolymers.

Therapeutic potential of non-starch polysaccharides on type 2 diabetes: from hypoglycemic mechanism to clinical trials

Non-starch polysaccharides (NSPs) have been reported to exert therapeutic potential on managing type 2 diabetes mellitus (T2DM). Various mechanisms have been proposed; however, several studies have not considered the correlations between the anti-T2DM activity of NSPs and their molecular structure. Moreover, the current understanding of the role of NSPs in T2DM treatment is mainly based on in vitro and in vivo data, and more human clinical trials are required to verify the actual efficacy in treating T2DM. The related anti-T2DM mechanisms of NSPs, including regulating insulin action, promoting glucose metabolism and regulating postprandial blood glucose level, anti-inflammatory and regulating gut microbiota (GM), are reviewed. The structure-function relationships are summarized, and the relationships between NSPs structure and anti-T2DM activity from clinical trials are highlighted. The development of anti-T2DM medication or dietary supplements of NSPs could be promoted with an in-depth understanding of the multiple regulatory effects in the treatment/intervention of T2DM.

Development of low glycemic index instant Phirni (pudding) mix-its visco-thermal, morphological and rheological characterization

High amylose rice (HAR) and carboxymethyl cellulose (CMC) are the preferred choices for enhancement of resistant starch content and lowering of glycemic index in dairy desserts. The effects of different levels of skimmed milk powder (SMP): HAR flour (45:55 to 75:25) and CMC (0.1 to 1%) were investigated on physical characteristics of dry-mix and on texture profile parameters, resistant starch (RS), predicted glycemic index (pGI), glycemic load (GL) and overall acceptability of phirni (a traditional milk pudding). Design expert predicted SMP (70): HAR (30) and CMC (0.8%) as optimum levels for reducing the pGI and maximizing the RS content and other quality characteristics in phirni. RS content of phirni (4.38%) prepared from optimized dry-mix (ODM) was higher while pGI (48.12) and GL (7.50) were lower as compared to phirni prepared from market dry-mix (MDM). The visco-thermal properties of ODM and MDM also showed significant variations. Storage modulus (Gʹ) and loss modulus (Gʹʹ) indicated that ODM phirni was less solid than MDM phirni. Scanning electron micrographs showed fused structures in ODM, while coarse sheet like structures were observed across the surface of MDM. Thus, ODM can be a promising substitute for the available milk desserts for diabetic patients.

In vitro digestion of designed emulsions based on milk protein and guar gum systems

There is a growing interest in designing novel food microstructures that can control nutrient digestion and provide satiety for tackling obesity. In this study, phase separated microstructures of skimmed milk powder (SMP) and guar gum (GG) were the main focus, and these can be considered as water-in-water (W/W) emulsions. Through the incorporation of oil into these systems, it was possible to form model systems of SMP-GG-OIL, showing the lipid phase within the protein phase within the polysaccharide phase. The in vitro digestibility of such phase separated model systems of SMP-GG-OIL with different microstructures was investigated using a pH stat method. Confocal laser scanning microscopy also revealed structural changes that occurred to the emulsified lipid droplets as they passed through a gastrointestinal (GI) model. The microstructures were created based on the tie-lines on a previously established phase diagram of SMP-GG, and shown to be able to control lipid digestion. For a selected tie-line, the lipolysis follows the order: protein continuous > bi-continuous > polysaccharide continuous system, at a certain level of oil addition. The mechanism involved in the lipolysis of the designed formulations/microstructures was dependent upon the protein, rather than GG, and was driven by the protein concentration. These findings provide insights for potential applications in functional food designing in the food industry.

A Study on the Skin Whitening Activity of Digesta from Edible Bird's Nest: A Mucin Glycoprotein

Edible bird’s nest (EBN) is an unusual mucin glycoprotein. In China, it is popular among consumers due to its skin whitening activity. However, the relationship between protein, sialic acid, and the whitening activity of EBN after digestion is still unclear. In the present work, the whitening activity (antioxidant activity and tyrosinase inhibitory activity) of digested EBN were studied by HepG2 and B16 cell models. The dissolution rate of protein and sialic acid was 49.59% and 46.45% after the simulated digestion, respectively. The contents of free sialic acid and glycan sialic acid in EBN digesta were 17.82% and 12.24%, respectively. HepG2 cell experiment showed that the digested EBN had significant antioxidant activity, with EC₅₀ of 1.84 mg/mL, and had a protective effect on H₂O₂-induced oxidative damage cells. The results of H₂O₂-induced oxidative damage showed that the cell survival rate increased from 40% to 57.37% when the concentration of digested EBN was 1 mg/mL. The results of the B16 cell experiment showed that the digested EBN had a significant inhibitory effect on tyrosinase activity, and the EC₅₀ value of tyrosinase activity was 7.22 mg/mL. Cell experiments showed that free sialic acid had stronger antioxidant activity and tyrosinase inhibitory activity than glycan sialic acid. The contribution rate analysis showed that protein component was the main antioxidant component in digestive products, and the contribution rate was 85.87%; free sialic acid was the main component that inhibited tyrosinase activity, accounting for 63.43%. The products of the complete digestion of EBN are suitable for the development of a new generation of whitening health products.

Complexation between burdock holocellulose nanocrystals and corn starch: gelatinization properties, microstructure, and digestibility in vitro

Holocellulose nanocrystals (hCNCs), with hydrodynamic diameters (D_Z) ranging from about 600 to 200 nm, were prepared by treating burdock insoluble dietary fiber (IDF) with enzymes and ultrasonic power. It was revealed that hCNCs improved the viscosity of corn starch (CS) during pasting and inhibited its short-term retrogradation. Besides, the crystallinity, short-range order of the double helix, viscoelastic properties, and microstructure compactness of CS gels improved remarkably in the presence of burdock hCNCs. These effects were both size- and dose-dependent, which primarily originated from the hydrogen bonding between hCNCs and amylopectin or leached amylose. In this regard, the digestion of CS gels containing hCNCs was remarkably retarded because of the reduced accessibility of digestive enzymes to the glycosidic bonds. Therefore, burdock hCNCs, prepared from natural resources using green techniques, hold potential applications in functional foods of a low glycemic index.

Structure, physicochemical properties and effects on nutrients digestion of modified soluble dietary fiber extracted from sweet potato residue

Alkaline hydrogen peroxide (AHP) modification increased the yield and the content of soluble dietary fiber extracted from sweet potato residue. As compared to the original sweet potato dietary fiber (O-SPDF), AHP modified SPDF (A-SPDF) had a smaller molecular weight of 69073.59 Da and a lower zeta-potential of -27 mV. Monosaccharide composition analysis revealed that A-SPDF had a higher proportion of pectin polysaccharides with homogalacturonan (HG) and rhamnogalacturonan-Ⅰ (RG-Ⅰ) backbones. Fourier transformed infrared (FT-IR), scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses were employed to determine the structural differences between A-SPDF and O-SPDF. Characterization of their rheological properties showed that A-SPDF exhibited higher viscosity than O-SPDF at concentrations of 2%, 4% and 6%, respectively. Additionally, A-SPDF had a more gel-like behavior than O-SPDF in the presence of Ca²⁺, supporting the better functional properties of A-SPDF as determined by water holding capacities (WHC), oil holding capacities (OHC), and water swelling capacities (WSC). Furthermore, A-SPDF performed significantly better in inhibiting starch hydrolysis and reducing the glucose diffusion rate using an Infogest simulated digestion model. However, SPDFs had no impact on the digestion rate of protein. Our results suggested that A-SPDF has the potential to serve as a novel food additive and functional hydrocolloid to attenuate nutrients digestion related disorders, which forms the scientific basis for the better utilization of sweet potato residue and further develop sweet potato dietary fiber (SPDF) as a functional food and/or additive in the food industry.

β-Glucan Interaction with Lentil (Lens culinaris) and Yellow Pea (Pisum sativum) Proteins Suppresses Their In Vitro Digestibility

In this study, β-glucan interaction with lentil and yellow pea proteins and the effect on in vitro protein digestibility were investigated. Proteins were mixed with β-glucan at mass ratios of 1:0.5, 1:1, and 1:2. The interaction between β-glucan and the proteins was demonstrated by the decrease in transmittance and surface charge and the increase in particle size of the complexes. Bright-field microscopy showed the formation of aggregates between the biopolymers, although increased molecular size was not observed by discontinuous native polyacrylamide gel electrophoresis. Fluorescence microscopy indicated that β-glucan formed aggregates with lentil proteins, while the interaction with yellow pea proteins appeared as distinct phases of protein within the β-glucan network. The in vitro protein digestibility of lentil and pea protein decreased by 27.3 and 34.5%, respectively, in the presence of a β-glucan mass ratio of 1:2. The findings confirm the possibility to modulate protein digestibility by changing the physical characteristics of a food matrix.