Effects of phytase-assisted processing method on physicochemical and functional properties of soy protein isolate

A comparative study on the protein digestion of four different soy beverages: effects of the composition, microstructure, and protein digestibility evaluation method

The increased consumption of soy-based products leads to the incentive for more sustainable soybean processing and more accurate nutritional evaluation. The protein structures and aggregation states of different components vary with different soy products, but their relationship with digestibility is unclear. In order to study the digestion of soy protein in complex food matrices, four soy-based beverages were carefully prepared, including whole component soy beverage (WS), soy beverage with insoluble soybean residue removed (DO-WS), soy beverage with lipids removed (DL-WS), and soy protein isolate beverage (HSPI). During digestion, the microstructure revealed that particles of all soy beverages were reduced and more evenly distributed, but striated fibres (in WS and DL-WS) still remained after digestion. Tricine-SDS-PAGE profiles showed that after in vitro gastrointestinal digestion of the four beverages, almost all the bands corresponding to the complete proteins from soy disappeared, leaving fewer visible bands with a low MW - below 12 kDa. In vitro protein digestibility analyzed by TCA precipitation (strategy B), which ranged from 64.24% to 68.70%, was more accurate, with peptides of MW <1 kDa accounting for over 84% for all the four digested fractions. Moreover, the highest values of in vitro DIAAS (96/80) and digestible protein (29.40/24.41 g per 100 g of soybeans) were achieved by WS. Characterization of the insoluble digesta further elucidated that peptides with a smaller MW (below 12 kDa) and a higher amount of hydrophobic amino acids aggregated more easily, resulting in the occurrence of precipitates and the relatively lower in vitro protein digestibility. This research contributes to the understanding of protein digestibility in whole legume-based diets, which in turn could aid in the development of new whole legume products and more efficient utilization of proteins.

Study on gastric digestion behavior of phytase-treated soybean protein: A semi-dynamic digestion method

The digestive characteristics of plant proteins are crucial for their nutritional value and utilization efficiency. In this study, an in vitro semi-dynamic digestion model was employed to investigate the gastric digestion process of soybean protein after treatment with phytase. The results found that phytase treatment reduced the phytate content in soybean proteins (22.83 ± 0.09 to 8.72 ± 0.07 mg/g), shifted its isoelectric point towards the alkaline range by 1 pH unit, and significantly improved its solubility at pH 4.0. Particularly for protein sample treated with phytase after acid precipitation, the formation of aggregates during digestion was weakened, resulting in a significantly higher digestion rate compared to untreated SPI, with digestion being at least 15 min faster than SPI. This study provides a strategy for preparing soybean protein with faster digestion and weaker clot-forming ability during digestion, which offers insights for the application of soybean protein in clinical nutrition products and specialized medical foods.

Improvement of the emulsifying properties of Zanthoxylum seed protein by ultrasonic modification

The influence of ultrasonic treatment (100-500 W, 30 min) on the molecular structures and emulsifying properties of Zanthoxylum seed protein (ZSP) was explored for the first time in this work. Research results indicated that the all ultrasonic treatments at different power levels decreased the particle size but increased the surface charge of ZSP. In addition, the ultrasonic treatments induced the structural unfolding of the ZAP, as indicated by the increase in α-helix, ultraviolet-visible absorbance, surface hydrophobicity and the amount of surface free sulfhydryl groups, as well as the decrease in β-sheet and intrinsic fluorescence intensity. As a result, the significantly (p < 0.05) increased emulsifying activity index (EAI) and emulsion stability index (ESI) of ZSP were observed after ultrasonic treatment. In addition, the emulsion prepared by ultrasonically treated ZSP exhibited the smaller and more uniform droplets with significantly improved stability against environmental stress (temperature, salt concentration, pH), creaming and oxidation due to the increased ratio of interfacially adsorbed ZSP. Furthermore, ultrasonic treatment at 400 W was found to be the optimum condition for modification. These findings will provide a theoretical foundation for the utilization of ultrasound in enhancing the emulsifying properties of ZSP and promoting its application in the field of food processing.

Impacts and Industrial Applications of Phytic Acid and Phytase

Phytic acid is an antinutritional compound that chelates P and essential divalent cations such as Fe, Ca, and Zn in cereals and major staple crops such as wheat, maize, rice, and sorghum. As a result, these cations cannot be absorbed by monogastric animals or humans: phytic acid has an inhibitory effect on nutrient uptake and its levels are negatively correlated with protein and starch digestibility. However, phytic acid can be degraded by the action of the enzyme phytase. Phytase plays important roles in the degradation of phytic acid and in increasing the nutritional quality of staple foods. Microbial phytase is a versatile enzyme that is beneficial for humans, animals, the environment, and the industry. In this review, we summarise the interaction of phytic acid with micronutrients, various approaches to enhancing the nutritional profile of staple foods by reducing the phytic acid content, and current knowledge of microbial-based phytase as a potential reducer of phytic acid.

Impact of Phytase Treatment and Calcium Addition on Gelation of a Protein-Enriched Rapeseed Fraction

Rapeseed press cake was upcycled as a protein-enriched ingredient through dry fractionation. The protein-enriched fraction contained higher amounts of phytic acid compared to press cake, and phytase treatment was applied to decrease the phytic acid content from 6.8 to 0.5%. The effect of phytase treatment leading to the release of cations was also mimicked by extrinsic calcium addition. Both phytase treatment and calcium addition significantly improved the heat-induced gel properties but had a minor effect on protein solubility and dispersion stability at pH 8. Water and protein holding capacities of the gels were the highest for the phytase-treated sample (91 and 97%, respectively), followed by the sample with added calcium (86 and 94%, respectively) and control sample (60 and 86%, respectively). Gel firmness followed the same pattern. Scanning electron microscopy images revealed an interconnected structured network in the phytase-treated gel, while in the control gel, a more rigid and open structure was observed. The improved gelation properties resulting from the phytase treatment suggest that the protein and soluble dietary fibre-enriched rapeseed press cake ingredient serve as a promising raw material for gelled food systems. The positive effect of calcium addition on gel properties proposes that part of the improvement observed after phytase treatment may be caused by cations released from phytate.

Effect of Fractionation and Processing Conditions on the Digestibility of Plant Proteins as Food Ingredients

Plant protein concentrates and isolates are used to produce alternatives to meat, dairy and eggs. Fractionation of ingredients and subsequent processing into food products modify the techno-functional and nutritional properties of proteins. The differences in composition and structure of plant proteins, in addition to the wide range of processing steps and conditions, can have ambivalent effects on protein digestibility. The objective of this review is to assess the current knowledge on the effect of processing of plant protein-rich ingredients on their digestibility. We obtained data on various fractionation conditions and processing after fractionation, including enzymatic hydrolysis, alkaline treatment, heating, high pressure, fermentation, complexation, extrusion, gelation, as well as oxidation and interactions with starch or fibre. We provide an overview of the effect of some processing steps for protein-rich ingredients from different crops, such as soybean, yellow pea, and lentil, among others. Some studies explored the effect of processing on the presence of antinutritional factors. A certain degree, and type, of processing can improve protein digestibility, while more extensive processing can be detrimental. We argue that processing, protein bioavailability and the digestibility of plant-based foods must be addressed in combination to truly improve the sustainability of the current food system.

Improving the color and functional properties of seabuckthorn seed protein with phytase treatment combined with alkaline solubilization and isoelectric precipitation

BACKGROUND

Reducing anti-nutritional factors like phytates in seed protein products requires an ongoing effort. This study was the first to investigate the phytic acid content in seabuckthorn seed protein (SSP) and its reduction by an exogenous phytase during protein isolation from seabuckthorn seed meal through the common alkaline solubilization-isoelectric precipitation process.

RESULTS

The additional phytase treatment could reduce the content of phytic acid from 22.46 to 13.27 g kg^-1 , leading to SSP products with lighter color (lower ΔE^* ), higher protein solubility, higher in vitro digestibility, but lower phenolic antioxidant content (including flavonoids and procyanidins) and some beneficial ions like Ca, Fe, Mg, and Zn. The Fourier transform infrared (FTIR) results indicated that the secondary structure of protein changed under the treatment with phytase. Correlation analysis showed that L* was significantly negatively correlated with TP, TPC and TF (P < 0.001), while a* and b* were significantly positively correlated with them (P < 0.001).

CONCLUSIONS

There may be a trade-off between protein functionalities and other health-promoting components when a phytase treatment is included in SSP isolation. © 2021 Society of Chemical Industry.

Impact of Fermentation and Phytase Treatment of Pea-Oat Protein Blend on Physicochemical, Sensory, and Nutritional Properties of Extruded Meat Analogs

Plant materials that are used for the production of extruded meat analogs are often nutritionally incomplete and also contain antinutrients, thus there is a need to explore alternative plant proteins and pre-treatments. This study demonstrates application of phytase and fermentation to a pea-oat protein blend with a good essential amino acid profile and subsequent texturization using extrusion cooking. Enzymatic treatment reduced the content of antinutrient phytic acid by 32%. Extrusion also degraded phytic acid by up to 18%, but the effect depended on the material. Differences in physicochemical, sensorial, and textural properties between untreated and phytase-treated extruded meat analogs were small. In contrast, fermented material was more difficult to texturize due to degradation of macromolecules; physicochemical and textural properties of extrudates were markedly different; sensory analysis showed enhancement of flavor, but also detected an increase in some unwanted taste attributes (bitterness, cereal and off-taste). Phytic acid was not degraded by fermentation. Analysis of volatile compounds showed extrusion eliminated volatiles from the raw material but introduced Maillard reaction products. Overall, phytase treatment and fermentation demonstrated the potential for application in extruded meat analogs but also highlighted the necessity of optimization of process conditions.

Seeds

A wide variety of plant species provide edible seeds. Seeds are the dominant source of human calories and protein. The most important and popular seed food sources are cereals, followed by legumes and nuts. Their nutritional content of fiber, protein, and monounsaturated/polyunsaturated fats make them extremely nutritious. They are important additions to our daily food consumption. When consumed as part of a healthy diet, seeds can help reduce blood sugar, cholesterol, and blood pressure.

Effect of extrusion pretreatment on the physical and chemical properties of broad bean and its relationship to koji preparation

The physicochemical properties of broad bean paste koji made from extruded and traditional steam-cooked raw materials were investigated by scanning electron micrographs (SEM), confocal laser scanning micrographs (CLSM), circular dichroism (CD) and Molecular weight (Mw) analysis. The results showed that the protease activity of koji made from the extruded materials was higher than that of the traditional cooking method. A network porous structure in the extruded samples was observed by SEM. Furthermore, the CLSM results showed that the starch of the extrudate was embedded well in its protein network. CD spectroscopy implied that the α-helix decreased while the β-turn and random coil increased after both treatments. Mw analysis determined that the starch molecules were degraded during extrusion, the proportion of micromolecules was more in the extruded samples than in the steam-cooked samples. However, the chain length distribution of starch exhibited no significant difference between the extruded and steam-cooked broad beans.

Effect of Anadenanthera colubrina protease inhibitors as an antiinflamatory mediator

This work aimed to obtain and characterize protease inhibitors from A. colubrina leaves and evaluate their potential as inflammatory mediator and cell viability. The protein extract was analyzed and characterized by SDS-PAGE, RP-HPLC-PDA, MALDI-TOF/MS and Zeta potential. Bioassays were conducted in order to evaluate the cell viability in RAW 264.7, in vitro (NO and TNF-α production inhibition) and in vivo anti-inflammatory potential, inhibition rate of trypsin and hemagglutination activity from protein extract. The results revealed the presence of bands at 14, 21 and 30 kDa in SDS-PAGE, the RP-HPLC-PDA analysis showed peaks at 12, 13, 28 and 40 minutes and MALDI-TOF/MS showed peaks with 3.4, 4.7, 5.6, 9.4 and 11.2 kDa. The protein extracts presented enzymatic activity inhibition of trypsin (IC₅₀ 59.2 μgmL^-1), did not show any cytotoxicity to RAW264.7 cells, hemagglutination 8HU and insignificant reduction in NO and TNF-α production and reduced anti-inflammatory potential in vivo compared to dexamethasone.