Physicochemical and functional property changes in soy protein isolates stored under high relative humidity and temperature

A review of alternative proteins for vegan diets: Sources, physico-chemical properties, nutritional equivalency, and consumer acceptance

Alternate proteins are gaining popularity as a more sustainable and environmentally friendly alternative to animal-based proteins. These proteins are often considered healthier and are suitable for people following a vegetarian or vegan diet. Alternative proteins can be recovered from natural sources like legumes, grains, nuts, and seeds, while single cell proteins (mycoproteins), and algal proteins are being developed using cutting-edge technology to grow fungus, yeast and algal cells in a controlled environment, creating a more sustainable source of protein. Although, the demand for alternative protein products is increasing, there still happens to be a large gap in use among the general consumers mainly stemming from its lower bioavailability, lack of nutritional equivalency and reduced digestibility compared to animal proteins. The focus of the review is to emphasize on various sources and technologies for recovering alternative proteins for vegan diets. The review discusses physicochemical properties of alternative proteins and emphasise on the role of various processing technologies that can change the digestibility and bioavailability of these proteins. It further accentuates the nutritional equivalency and environmental sustainability of alternative protein against the conventional proteins from animals. The food laws surrounding alternative proteins as well as the commercial potential and consumer acceptance of alternative protein products are also highlighted. Finally, key challenges to improve the consumer acceptability and market value of plant-based proteins would be in achieving nutrient equivalency and enhance bioavailability and digestibility while maintaining the same physicochemical properties, taste, texture, as animal proteins, has also been highlighted.

Evaluation of nutritional characteristics and consumers’ acceptance of gluten-free sweet biscuits made from rice-based pregelatinized composite flours containing orange pomace and soy protein isolate

Gluten-free bakery products are usually deficient in dietary fiber and inferior sources of protein. Studies that have assessed sensory characterization of products prepared with orange pomace are scarce. This study evaluated the employment of 30% of rice-based pregelatinized composite flours (containing 15, 25 or 35% orange pomace blended with 5% soy protein isolate) on gluten-free biscuits. The target was the investigation of the nutritional profile and consumer’s acceptance of three short dough sweet biscuit samples. Thermoplastic extrusion was an efficient unit operation for the elaboration of a new gluten-free ingredient in which a by-product rich in total dietary fiber and a component with a high level of protein were employed. All pregelatinized composite flours in this study can be labeled as protein sources and can be claimed as high in total dietary fiber content, as well as two biscuit samples that can be labeled as total dietary fiber source. Also, all pregelatinized composite flours and biscuits presented low moisture and water activity, being microbiologically stable to room temperature (25 ± 2 °C). Complementarily, the results of the microbiological evaluations [(coagulase-positive Staphylococcus, thermotolerant coliform (45 °C) and Salmonella sp. (absence in 25 g)] of the biscuits and their comparison with the Brazilian microbiological standards legislation attested their safety. Concerning the sensory analysis, adults’ results showed that the flavor attribute might be responsible for increasing the overall impression score of a sample. In contrast, children’s results showed that they did not distinguish (p ≥ 0.05) two of three samples of biscuits analyzed.

Storage stability of soy protein isolate powders containing soluble protein aggregates formed at varying pH

Soy protein is wildly used in food industry due to its high nutritional value and good functionalities. However, the poor storage stability of commercial soy protein products has puzzled both the producers and the users for a long time. The current study assessed the changes in protein solubility, aggregation, oxidation, and conformation of soy protein isolate (SPI) with various soluble aggregates formed at different pH values (pH 5-8) during storage. During storage, SPI samples showed a reduced protein solubility (p < .05), an increased protein oxidation (p < .05), and an attenuated conformational enthalpy (∆H). SPI with a higher pH produced more disulfide-mediated aggregates at the expense of sulfhydryl groups and experienced greater losses of protein tertiary structure and a faster reduction in solubility. Yet, all samples nearly shared similar rising trend during 8-week storage, which indicated the production of protein carbonyls was insensitive to pH. Soluble aggregates present in fresh SPI samples appeared to induce instability of SPI during storage. These findings suggested SPI prepared at pH 6 was in favor of its storage stability, and soluble aggregates presented in fresh samples should be paid more attention for further study of storage stability kinetics.

The Molecular Properties of Peanut Protein: Impact of Temperature, Relative Humidity and Vacuum Packaging during Storage

This study aimed to investigate the variation of molecular functional properties of peanut protein isolate (PPI) over the storage process and reveal the correlation between the PPI secondary structure and properties in the storage procedure. After storage, the molecular properties of PPI changed significantly (p < 0.05). Extending storage time resulted in a decrease in free sulfhydryl content, fluorescence intensity, surface hydrophobicity and emulsifying properties, which was accompanied by an increase in protein particle size. The results of infrared spectroscopy suggested the content decline of α-helix and β-sheet, and the content rise of β-turn and random coil. Based on bivariate correlation analysis, it was revealed that surface hydrophobicity and emulsifying activity of PPI was significantly affected by α-helix and by β-turn (p < 0.05), respectively. This research supplied more information for the relationship between the peanut protein’s secondary structure and functional properties over the stored process.

Antimicrobial Potential of Silver Nanoparticles Synthesized Using Medicinal Herb Coptidis rhizome

Coptidisrhizome contains several alkaloids that are bioactive agents of therapeutic value. We propose an eco-friendly method to synthesize biocompatible silver nanoparticles (AgNPs) using the aqueous extract of Coptidisrhizome. Silver ions were reduced to AgNPs using the aqueous extract of Coptidisrhizome, indicating that Coptidisrhizome can be used for the biosynthesis of AgNPs. The time and the concentration required for conversion of silver ions into AgNPs was optimized using UV-absorbance spectroscopy and inductively coupled plasma spectroscopy (ICP). Biosynthesized AgNPs showed a distinct UV-Visible absorption peak at 420 nm. ICP analysis showed that the time required for the completion of biosynthesis was around 20 min. Microscopic images showed that nanoparticles synthesized were of spherical shape and the average diameter of biosynthesized AgNPs was less than 30 nm. XRD analysis also confirmed the size of AgNps and revealed their crystalline nature. The interaction of AgNPs with phytochemicals present in Coptidisrhizome extract was observed in FTIR analysis. The antimicrobial property of AgNPs was evaluated using turbidity measurements. Coptidisrhizome-mediated biosynthesized AgNPs showed significant anti-bacterial activities against Escherichia coli and Staphylococcus aureus that are commonly involved in various types of infections, indicating their potential as an effective anti-bacterial agent.

Kinetics and Characteristics of Soybean Oil and Protein Extracted by AOT Reverse Micelle Technology

The mass transfer process of soybean oil extracted by AOT reverse micelle was determined. Meanwhile, the physicochemical properties of oil and structural properties of protein were also investigated by gas chromatography (GC), Fourier infrared spectrum (FTIR), and amino acid analyzer. The results indicated that the mass transfer model can be set up as 1+2(1-x)-3(1-x)2/3=0.248•exp⁡(-720.8/T)•t. The reaction probably belongs to internal diffusion. The oil extracted by AOT reverse micelle was in better quality according to physicochemical analysis. The soybean protein almost retained its original structure in AOT reverse micelle by FTIR and amino acid analysis. Therefore, AOT reverse micelle is an attractive procedure for extracting oil and protein simultaneously.

Interactions between soy protein hydrolyzates and wheat proteins in noodle making dough

Soy protein hydrolyzate has been used as supplements in wheat flour to enhance the nutritional value of its products, but it may negatively affect the gluten properties simultaneously. In order to explore the mechanism of this effect, protein characteristics including disulfide bond, protein composition, intermolecular force of dough proteins, and atomic force microscope images of gluten were obtained. Results showed that disulfide bonds in dough increased when soy protein hydrolyzate was added, but glutenin macropolymer decreased. Atomic force microscope images showed that gluten were weakened by soy protein hydrolyzate. Based on these results, a model was developed to describe the interaction between soy protein hydrolyzates and wheat proteins: soy protein hydrolyzates linked with wheat proteins through disulfide bond, disrupted the glutenins polymerization, thus hindered gluten networks formation. The interaction between wheat proteins and soy protein hydrolyzates in noodle making dough could be described with this model reasonably.