Effects of dietary fiber on the digestion and structure of gluten under different thermal processing conditions

Fully Organic Sensors for Continuous Real-Time Digestion Monitoring

Monitoring the gastric digestive function is important for the diagnosis of gastric disorders and drug development. However, there is no report on the in situ and real-time monitoring of digestive functions. Herein, we report a flexible fully organic sensor to effectively monitor protein digestion in situ in a simulated gastric environment for the first time. The sensors are made of a blend of gluten that is a protein and poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) that is a conducting polymer. During the protein digestion, the breakdown of the polypeptides increases the level of separation among the PEDOT chains, thereby increasing the resistance. The resistance variation is sensitive to various conditions, including the concentration of pepsin that is the enzyme for protein digestion, temperature, pH value, and digestive drugs. Hence, these sensors can provide real-time information about the digestion and efficacy of digestive drugs. In addition, the signals can be collected via a convenient wireless communication manner.

Combined techniques for revealing the mechanism beneath the inhibition effects of pectin on gluten digestibility using static in vitro gastro-duodenal protocols

In the current study, how pectin retards the digestibility of wheat gluten was investigated using a static in vitro gastric-duodenal model. The degree of protein hydrolysis was estimated using the o-phthaldialdehyde method, while the in vitro digestograms were mathematically fitted using a single first-order kinetics model. Peptides' profile, free amino acids compositions, gluten-pectin interactions and their effects on enzymatic activities of proteolytic enzymes as well as on the gluten secondary structures under digestive conditions were studied using combined techniques. Results showed that pectin could retard gluten digestibility through 1). preferential absorption to insoluble gluten aggregates by electrostatic interactions; 2). increasing the helix and reducing the β-sheet content of the solubilized gluten protein fractions in terms of their secondary molecular structures; 3). reducing pepsin activity by forming negatively charged pectin-gluten mixtures which then interacted with the positively charged pepsin molecules. The deeper insight into gluten-pectin interactions and their influences on gluten digestibility under gastrointestinal conditions provides important clues for developing effective forms of dietary fiber to improve the nutritional benefits of plant protein in individuals.

Textural, rheological, melting properties, particle size distribution, and NMR relaxometry of cocoa hazelnut spread with inulin-stevia addition as sugar replacer

This study investigated the influence of substituting 60, 80, and 100% of the sugar in traditional cocoa hazelnut paste (control) formulation with inulin-stevia (90:10, w/w) mixture on textural and rheological characteristics, melting behavior, water activity (aw), particle size distribution (PSD), and color. Textural, rheological, melting properties, and color of samples were analyzed after 1, 2, and 3 months of storage at 11°C. Nuclear magnetic resonance (NMR) relaxometry experiments were also performed to understand the interaction of new ingredients with oil. Replacement of sugar with inulin-stevia gave darker color, reduced Casson yield stress, and changed the textural parameters and melting profile of the samples depending on the level but did not create a remarkable effect on PSD and Casson plastic viscosity. Increasing inulin-stevia content yielded lower aw and higher T2a values indicating decreased mobility of water. Complete removal of sugar caused low spreadability. The results showed that an 80% replacement level yielded a product with similar textural parameters and fat-melting mouth feeling compared to control sample. Cocoa hazelnut spreads prepared with inulin and stevia showed good textural stability during storage.

Interaction of wheat bran dietary fiber-gluten protein affects dough product: A critical review

Wheat bran dietary fiber (WBDF) is an emerging food additive used for improving the nutritional value of dough products, albeit its adverse effects cannot be ignored. The dilution effect, mechanical shear effect, competitive water absorption, and steric hindrance of WBDF, as well as the non-covalent binding between WBDF and gluten protein, are considered the key mechanisms underlying the WBDF-gluten protein interaction. However, current studies on the interaction are mostly limited to the impact of the interaction on gluten protein and are rarely focused on the quality of products. Therefore, the effects of the interaction on the structural characteristics and aggregation behavior of gluten protein and multiple involved mechanisms are discussed in this review. On this basis, these changes are systematically related to the gluten network structure, dough properties, and product quality. Mitigation measures corresponding to negative impacts also need to be elaborated to guide and standardize the production and development of dough products containing WBDF.

Interaction with wheat starch affect the aggregation behavior and digestibility of gluten proteins

Understanding the interplay between gluten and wheat starch is crucial for elucidating the digestibility mechanism of gluten in wheat-based products. However, this mechanism remains under-investigated. This study sought to elucidate the influence of starch-induced protein structural modifications on gluten digestion. Our findings revealed that starch considerably enhanced gluten digestion. In the presence of starch, gluten protein digestibility increased from 10.91 % (in the control group with a gluten-to-starch ratio of 1:0) to 14.40 % (in the complex with a gluten-to-corn starch ratio of 1:1). The diminished gluten protein digestibility due to starch may be ascribed to modifications in protein configuration and aggregation behavior. Morphological studies suggested that starch not only functioned as filler particles but also diluted the gluten matrix. A protein network assessment further affirmed that both the junction density and branching rate of gluten proteins decreased notably by 29.9 % and 25.1 %, respectively. Conversely, lacunarity increased by 1.92-fold, compromising the cohesiveness and connectivity of the gluten matrix. Elevated starch concentrations suppressed the formation of disulfide bonds, impeding gluten protein aggregation. Concurrently, gluten-starch interactions were governed by hydrogen bonds and hydrophobic associations. In summary, starch augmented gluten protein digestibility by curtailing their polymerization. This revelation might offer novel perspectives on optimizing gluten protein digestion and utilization.

Effect of Starch on the Solubility of Quinoa Protein Isolates during Heat Treatment

There is increasing interest in developing quinoa products due to their unique nutritional value. Starch and protein are the primary components in quinoa, and the interaction between them affects the quality of quinoa products. This study extracted the starch and protein from quinoa and simulated the thermal processing of quinoa to investigate the effects of starch on the solubility and structure of quinoa protein isolates during heat treatment. The structure of quinoa protein isolates was characterized by fluorescence spectroscopy, Fourier transform infrared spectroscopy, laser particle size analysis, and scanning electron microscopy. The results showed that starch decreased protein solubility, and the maximum solubility was obtained after heating for 5 min. After starch addition during heat treatment, the surface charge distribution of protein changed, the degree of protein aggregation increased, the particle size of proteins increased, the thermal stability increased, and the β-sheet ratio of the proteins increased, suggesting that the protein structure is more ordered, which is the structural foundation of protein solubility decreasing. The research about the interaction between starch and protein and the effects on the solubility of protein could provide a reference for quinoa products processing.

The Role of Gluten in Food Products and Dietary Restriction: Exploring the Potential for Restoring Immune Tolerance

Wheat is extensively utilized in various processed foods due to unique proteins forming from the gluten network. The gluten network in food undergoes morphological and molecular structural changes during food processing, affecting the final quality and digestibility of the food. The present review introduces the formation of the gluten network and the role of gluten in the key steps of the production of several typical food products such as bread, pasta, and beer. Also, it summarizes the factors that affect the digestibility of gluten, considering that different processing conditions probably affect its structure and properties, contributing to an in-depth understanding of the digestion of gluten by the human body under various circumstances. Nevertheless, consumption of gluten protein may lead to the development of celiac disease (CD). The best way is theoretically proposed to prevent and treat CD by the inducement of oral tolerance, an immune non-response system formed by the interaction of oral food antigens with the intestinal immune system. This review proposes the restoration of oral tolerance in CD patients through adjunctive dietary therapy via gluten-encapsulated/modified dietary polyphenols. It will reduce the dietary restriction of gluten and help patients achieve a comprehensive dietary intake by better understanding the interactions between gluten and food-derived active products like polyphenols.

Influence of High-Intensity Ultrasound on Characteristics and Bioaccessibility of Pea Protein in Fiber-Enriched Suspensions

Pea protein is of high interest for the food industry owing to its low allergenicity and high nutritional value. However, it often exhibits poor functionality, such as low solubility. The presence of dietary fiber in food products is beneficial for human health but may decrease the bioaccessibility of nutrients. Ultrasound, as a promising green technology, may influence properties of fibers and proteins and, thus, bioaccessibility. Therefore, this study investigated the effects of high-intensity ultrasound on the characteristics and protein bioaccessibility of protein-fiber suspensions. Suspensions containing different fiber compounds (1 wt.%) and pea protein (5 wt.%) were homogenized using high-intensity ultrasound (amplitude 116 µm, t = 150 s, energy density = 225 kJ/L, P¯ = 325 W). Owing to sonication-induced cavitation, the dispersibility of the protein was enhanced, and the viscosity of solutions containing citrus or apple fiber was increased. FE-SEM revealed the formation of different fiber-protein networks during sonication. Even if viscosity is known to have an impact on the bioaccessibility of nutrients, no restrictions on the digestibility of protein were detected during an in vitro digestion. Thus, protein uptake is probably not affected, and ultrasound can be used to modify the technofunctionality of fibers and proteins without any nutritional disadvantages.

Digestibility of Malondialdehyde-Induced Dietary Advanced Lipoxidation End Products and Their Effects on Hepatic Lipid Accumulation in Mice

Advanced lipoxidation end products (ALEs) are formed by modifying proteins with lipid oxidation products. The health effects of ALEs formed in vivo have been extensively studied. However, the digestibility, safety, and health risk of ALEs in heat-processed foods remain unclear. This investigation was performed to determine the structure, digestibility, and effect on the mice liver of dietary ALEs. The results showed that malondialdehyde (MDA) was able to alter the structure of myofibrillar proteins (MPs) to form linear, loop, and cross-linked types of Schiff bases and dihydropyridine derivatives under simulated heat processing, leading to the intra- and intermolecular aggregation of MPs and, thus, reducing the digestibility of MPs. In addition, dietary ALE intake resulted in abnormal liver function and lipid accumulation in mice. The core reason for these adverse effects was the destructive effect of ALEs on the intestinal barrier. Because the damage to the intestinal barrier leads to an increase in lipopolysaccharide levels in the liver, it induces liver damage by modulating hepatic lipid metabolism.

Influence of pre-treated bitter orange albedo on the physicochemical, textural and sensory properties of fermented sausages (sucuk)

The aim of this study was to determine the physicochemical (pH, water activity, titratable acidity, moisture, protein, fat, colour, weight loss and oxidative stability), textural and sensory properties, and the growth of lactic acid bacteria in fermented sausages (sucuk) supplemented with different levels (0, 1, 2.5 and 5.0%) of pre-treated bitter orange (Citrus aurantium) albedo. Results indicated that adding albedo to sucuk samples increased (P < 0.01) the titratable acidity, lightness and yellowness values; while it led to a decrease (P < 0.01) in pH and weight loss values. Moreover, it was observed that there were increases (P < 0.05) in Thiobarbituric acid (TBA) values when albedo was added to the samples. The highest lactic acid bacteria count was observed in the sucuk samples supplemented with 5% albedo. Regarding textural properties, albedo addition increased (P < 0.01) hardness, springiness, gumminess and chewiness values. Lastly, sensory analysis results showed that albedo added sucuk samples generally got higher (P < 0.05) scores from panellists compared to control samples.