Confocal imaging to reveal the microstructure of soybean processing materials

Saline as solvent and ethanol-based purification process for the extraction of proteins and isoflavones from wet okara

Okara, the solid byproduct of water-soluble soybean extract production, is a potential source of proteins and isoflavones. This study investigated different experimental configurations for extracting these compounds from wet okara, including lipid removal with ethanol at different stages of the recovery process, sequential crosscurrent extraction, and using a saline MgCl2 solution as the solvent. Three washes with a 60:40 ethanol:water (w/w) solution after isoelectric precipitation significantly increased protein content by reducing lipid content (60 %). The crosscurrent approach using 0.05 M MgCl2 yielded okara proteinaceous material with 248 µg/g daidzein and 236 µg/g genistein, along with a 3 % increase in protein content, attributed to enhanced extraction of 7S globulins. These configurations notably affected the functional properties of the protein materials. Overall, this research provides detailed insights into the composition and properties of proteins extracted from wet okara, facilitating their specialized application in food products.

Spatial activity mapping of ß-mannanase on soybean seeds

For farm animals the supplementation of exogenous enzymes, like ß-mannanase, to soybean-based diets is beneficial to improve feed digestibility. In order to unravel the effect of ß-mannanase on soybean meal's cell structure, a novel imaging concept was developed which allows visualizing the spatial activity pattern of ß-mannanase with high sensitivity by fluorescence microscopy before any visible degradation of the cellular structure occurs. It is based on fluorescence labeling of newly formed reducing ends of ß-mannanase-hydrolyzed polysaccharides after the native reducing ends of all polysaccharides present were chemically reduced. It was revealed that ß-mannanase is not only active at the cell wall but also at previously unknown sites, like the middle lamella and, most prominently, at an intracellular matrix enclosing the protein storage vacuoles. Based on these findings it can be hypothesized that the evaluated ß-mannanase can degrade the enclosing matrix of encapsulated proteins and the cell wall structure and thereby improves efficiency of feed utilization.

Unprecedented Fluorophore Photostability Enabled by Low-Loss Organic Hyperbolic Materials

The dynamics of photons in fluorescent molecules plays a key role in fluorescence imaging, optical sensing, organic photovoltaics, and displays. Photobleaching is an irreversible photodegradation process of fluorophores, representing a fundamental limitation in relevant optical applications. Chemical reagents are used to suppress the photobleaching rate but with exceptionally high specificity for each type of fluorophore. Here, using organic hyperbolic materials (OHMs), an optical platform to achieve unprecedented fluorophore photostability without any chemical specificity is demonstrated. A more than 500-fold lengthening of the photobleaching lifetime and a 230-fold increase in the total emitted photon counts are observed simultaneously. These exceptional improvements solely come from the low-loss hyperbolic dispersion of OHM films and the large resultant Purcell effect in the visible spectral range. The demonstrated OHM platform may open up a new paradigm in nanophotonics and organic plasmonics for super-resolution imaging and the engineering of light-matter interactions at the nanoscale.

Bioconversion and bioaccessibility of isoflavones from sogurt during in vitro digestion

This study investigated the bioconversion and bioaccessibility of soy isoflavones produced in sogurt fermented with S. thermophilus and L. bulgaricus during in vitro digestion. The highest survivability of S. thermophilus (6.49 log cfu/mL) and L. bulgaricus (6.48 log cfu/mL) was in oral phase. In gastric phase, the total aglycones of sogurt (26.73 g/L) increased up to 20 times than control (1.21 g/L), with a significant increase in daidzein (17.05 g/L) and genistein (9.68 g/L). Addition of 8U of β-glucosidase into soymilk significantly increased the conversion of isoflavone in ENTII (daidzein: 0.46 g/L; genistein: 0.18 g/L) than in ENTI (daidzein: 0.33 g/L; genistein: 0.20 g/L). The particle size analysis and confocal micrographs of digesta also suggest the size of fat and protein in gastric phase to be smaller than in intestinal phase. The results indicate the prospective to develop soy-based fermented products capable of releasing high isoflavone in the digestive system.

Enzymatic pretreatment in the extraction process of soybean to improve protein and isoflavone recovery and to favor aglycone formation

This research aimed to evaluate the pretreatment of soybean with the carbohydrase multi-enzyme complex "Viscozyme L", during the extraction process; in order to improve the recovery of proteins and isoflavones in soybase, and reduce the loss of these compounds through the okara residue. Three concentrations of enzyme were studied at 50 °C, along with an experiment carried out without enzyme addition (control experiment). The results were also evaluated in relation to standard soybase processing. In comparison to the standard and control processes, the enzymatic pretreatment reduced up to 85% the total amount of okara residue. Due to the action of the multi-enzyme complex, protein and total isoflavone recovery increased from 42% to 83% and from 59% to 93%, respectively. The application of Viscozyme L also favored the conversion of conjugated forms of isoflavone to aglycone in the soybase, representing up to 50% of the total isoflavones. The enzymatic pretreatment of soybean with carbohydrase improved the nutritional quality of the soybase, while at the same time reducing residue generation; showing that the proposed food process can be considered environmentally friendly method.

Alkaline hydrogen peroxide improves physical, chemical, and techno-functional properties of okara

The objective was to evaluate the effect of modifying okara with alkaline hydrogen peroxide at different H2O2 concentrations and treatment temperatures on its soluble fiber content, water absorption and holding capacity, swelling capacity, and protein solubility in water. Multi-response optimization and characterization of physical, chemical, and techno-functional properties of unmodified and modified okara under optimal condition were performed. Treatment under optimal condition (2% H2O2 and 42 °C for 5 h) resulted in a 601% increase in soluble fiber content, a 26% increase in water absorption and holding capacity and swelling capacity, and a 609% increase in soluble protein. Scanning electron micrographs revealed that modified okara particles had a more fragmented structure and a rougher surface than control. Alkaline hydrogen peroxide treatment altered the color, chemical composition, and techno-functional properties of okara. The modification method has potential to add value to okara and contribute to the use of agro-industrial residues.

Plant-based Milks: A Review of the Science Underpinning Their Design, Fabrication, and Performance

Many consumers are interested in decreasing their consumption of animal products, such as bovine milk, because of health, environmental, and ethical reasons. The food industry is therefore developing a range of plant-based milk alternatives. These milk substitutes should be affordable, convenient, desirable, nutritional, and sustainable. This article reviews our current understanding of the development of plant-based milks. Initially, an overview of the composition, structure, properties, and nutritional profile of conventional bovine milk is given, because the development of successful alternatives depends on understanding the characteristics of real milk. The two main production routes for fabricating plant-based milks are then highlighted: (i) disruption of plant materials (such as nuts, seeds, or legumes) to form aqueous suspensions of oil bodies; (ii) formation of oil-in-water emulsions by homogenization of oil, water, and emulsifiers. The roles of the different functional ingredients in plant-based milks are highlighted, including oils, emulsifiers, thickeners, antioxidants, minerals, and other additives. The physicochemical basis of the appearance, texture, and stability of plant-based milks is covered. The importance of the sensory attributes and gastrointestinal fate of bovine milk and plant-based alternatives is also highlighted. Finally, potential areas for future work are discussed.

Controlled release and macrophage polarizing activity of cold-pressed rice bran oil in a niosome system

Phytosterols, α-tocopherol and γ-oryzanol are scientifically recognized as major health promoting compounds found in cold-pressed rice bran oil (CRBO).

Food matrix and processing modulate in vitro protein digestibility in soybeans

Soybeans represent the largest source of plant proteins on the planet but their proteins are associated with low digestibility. Although several studies addressed the limiting factors affecting the rate and extent of soy protein digestion, the net effect of the food matrix, especially of an intact cell wall, has been poorly investigated so far. The purpose of the present study was to examine the relationship between the cell matrix and protein hydrolysis during simulated in vitro digestion of soybean particles of different sizes prepared from unheated and boiled cotyledons. In addition, intact cells were isolated from unheated and autoclaved cotyledons and then digested with and without lipase inhibitors to understand the impact of an intact cell wall and the presence of oil bodies on soybean protein digestibility. Protein digestibility was the highest in the particles prepared after boiling of previously milled cotyledons compared to particles of the same size obtained by milling previously cooked cotyledons as well as of uncooked cotyledons. Protein digestibility in isolated intact cells was lower than that of extracted proteins regardless of the thermal load applied whereas inhibition of pancreatic lipase reduces protein digestibility only slightly. The data indicated that the cell wall could contribute to limit protein digestion in soybean tissues; however, it is not an absolute barrier to pancreatic proteases. An accurate design of the milling and cooking process could be instrumental to modulate the digestion kinetics of soybean proteins.

Action of multi-enzyme complex on protein extraction to obtain a protein concentrate from okara

The objective of this study was to optimize the extraction of protein by applying a multi-enzymatic pretreatment to okara, a byproduct from soymilk processing. The multi-enzyme complex Viscozyme, containing a variety of carbohydrases, was used to hydrolyze the okara cell walls and facilitate extraction of proteins. Enzyme-assisted extraction was carried out under different temperatures (37-53 °C), enzyme concentrations (1.5-4%) and pH values (5.5-6.5) according to a central composite rotatable design. After extraction, the protein was concentrated by isoelectric precipitation. The optimal conditions for maximum protein content and recovery in protein concentrate were 53 °C, pH 6.2 and 4% of enzyme concentration. Under these conditions, protein content of 56% (dry weight basis) and a recovery of 28% were obtained, representing an increase of 17 and 86%, respectively, compared to the sample with no enzymatic pretreatment. The multi-enzyme complex Viscozyme hydrolyzed the structural cell wall polysaccharides, improving extraction and obtaining protein concentrate from the okara. An electrophoretic profile of the protein concentrate showed two distinct bands, corresponding to the acidic and basic subunits of the protein glycinin. There were no limiting amino acids in the protein concentrate, which had a greater content of arginine.