The Preparation and Characterization of Quinoa Protein Gels and Application in Eggless Bread.

The properties of xanthan gum protein gels composed of quinoa protein (XG-QPG) and ultrasound-treated quinoa protein (XG-UQPG) were compared for the preparation of high-quality quinoa protein gels. The gel qualities at different pH values were compared. The gels were used to produce eggless bread. Microscopically, the secondary structure of the proteins in XG-QPG (pH 7.0) was mainly α-helix, followed by random coiling. In contrast, the content of ß-sheet in XG-UQPG was higher, relative to the viscoelastic properties of the gel. Moreover, the free sulfhydryl groups and disulfide bonds of XG-QPG (pH 7.0) were 48.30 and 38.17 µmol/g, while XG-UQPG (pH 7.0) was 31.95 and 61.58 µmol/g, respectively. A high disulfide bond content was related to the formation of gel networks. From a macroscopic perspective, XG-QPG (pH 7.0) exhibited different pore sizes, XG-UQPG (pH 7.0) displayed a loose structure with uniform pores, and XG-UQPG (pH 4.5) exhibited a dense structure with small pores. These findings suggest that ultrasound can promote the formation of a gel by XG-UQPG (pH 7.0) that has a loose structure and high water-holding capacity and that XG-UQPG (pH 4.5) forms a gel with a dense structure and pronounced hardness. Furthermore, the addition of the disulfide bond-rich XG-UQPG (pH 7.0) to bread promoted the formation of gel networks, resulting in elastic, soft bread. In contrast, XG-UQPG (pH 4.5) resulted in firm bread. These findings broaden the applications of quinoa in food and provide a good egg substitute for quinoa protein gels.

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.

Food biopolymers (FBP) impact nutrient distribution differently in various digestion phases.FBP application can help tailor nutritional values for personalized dietary plans.FBP colloidization under complex interactions results challenges in practical applications.Accurate assessment of FBP colloidization requires combination of methodologies.Dietary FBP additives benefits and safety warrant investigation in real food matrix.

Ultrasonic treatment influences the compactness of quinoa protein microstructure and improves the structural integrity of quinoa protein at the interfaces of high internal phase emulsion.

For native quinoa protein with a loose disordered structure and low structural integrity, once the protein is absorbed to the oil-water interface, the stress of interfacial tension and hydrophobic interaction can easily trigger the conformation change and denaturation of quinoa protein, leading to the instability of high internal phase emulsion (HIPE). Ultrasonic treatment can induce the refolding and self-assembling of quinoa protein microstructure, which is expected to frustrate the disruption of protein microstructure. The particle size, tertiary structure, and secondary structure of quinoa protein isolate particle (QPI) were investigated by multi-spectroscopic technology. The study demonstrates that QPIs prepared with ultrasonic treatment of 5 kJ/mL exhibit more robust structural integrity compared with native QPIs. The relatively loose structure (random coil, 28.15 ± 1.06 %∼25.10 ± 0.28 %) transformed to a more ordered and compact form (α-helix, 5.65 ± 0.07 %∼6.80 ± 0.28 %). Through the addition of QPI-based HIPE as an alternative for commercial shortening, the specific volume of white bread was increased (2.74 ± 0.35 âˆ¼ 3.58 ± 0.04 cm3/g).

High internal phase emulsions stabilized solely by sonicated quinoa protein isolate at various pH values and concentrations.

In this study, stable high internal phase emulsions (HIPEs) constructed solely by sonicated quinoa protein isolate (QPI) at various pH values and protein concentrations (c) were constructed, and differences of HIPE microstructures at these conditions were discussed. HIPEs stabilized by QPI at pH 7.0, 9.0 possessed smaller droplet size (14-24 µm), smoother appearance, and higher physical stability which were caused by polyhedral framework microstructure. However, at acidic conditions, QPI aggregates filled in the gaps between droplets (30-52 µm) instead of adsorbing to oil-water interface, which decreased the stability. The solid-like viscoelasticity of HIPEs were enhanced when the c increased while the increment of pH value had the significant opposite effect (decreased from about G' 1000 Pa, G″ 280 Pa to G' 350 Pa, G″ 50 Pa) due to the microstructure difference. This study broadens the commercial applications of quinoa protein in novel food products like fat substitutes.

Rice peptide nanoparticle as a bifunctional food-grade Pickering stabilizer prepared by ultrasonication: Structural characteristics, antioxidant activity, and emulsifying properties.

In this study, a novel food-grade Pickering stabilizer was fabricated from insoluble rice peptide aggregates that are considered undesirable and formed during the hydrolysis of rice protein using ultrasonication. The results confirmed that ultrasonication was effective in fabricating rice peptide nanoparticles (RPNs) with a spherical appearance, and the particle size was reduced with ultrasonic time, reaching a minimum size of 357.8 nm in 30 min. Moreover, ultrasonic treatment could improve the antioxidant activity of RPNs by promoting the DPPH scavenging (3.5-fold increase) and Fe2+ chelating activity (3.8-fold increase). Notably, the bioactive RPNs could form stable Pickering emulsions that possess both physical and oxidative stability during storage, which might be due to the antioxidative physical barrier formed by RPNs. These findings suggest a new approach for the effective utilization of insoluble aggregates produced during protein hydrolysis as well as provide a novel bifunctional Pickering stabilizer with intrinsic antioxidant properties.