Brewers’ spent grain (BSG) is the main side-stream of the brewing industry with an annual production of 40 million tons of wet weight. BSG has a protein content of 15-30 % dry basis, which makes it an interesting material for protein extraction. Normally, extraction is performed under high temperatures or high alkaline conditions. In this study, microwave-assisted extraction, pulsed electric field, ultrasound, and ohmic heating were tested to extract proteins from BSG without pH adjustment (pH 6) or at pH 9. The extracts were further tested for their emulsifying activity. The results obtained showed that the use of ultrasound at pH 9 resulted in the highest protein content and protein recovery of 24.1 % and 58.6 %, respectively. Extracts produced from microwave-assisted extraction and ohmic heating could produce the smallest emulsion droplets; however, the stability of all emulsions was low. The present study highlights the potential of emerging technologies as an alternative to harsh solvent usage in order to extract BSG proteins.

This study investigated the formation and characterization of aerogels from soy protein isolate (SPI) at different pHs (6-10) using supercritical carbon dioxide (SC-CO2) drying. The extraction yield of proteins was 33% with 92% purity. The formed SPI hydrogels and aerogels were characterized for their rheological properties, textural properties, morphology, crystallinity, chemical structure, thermal stability, and solubility. The gels formed at pH values of 7.0-10.0 were able to form strong gels, where all the gels showed a shear-thinning behavior. The hardness of the gels increased with the increase in pH from 7.0 to 10.0. The resulting SPI aerogels upon SC-CO2 drying showed outstanding properties, such as surface areas of 222-278 m²/g, pore sizes of 8-11 nm, and pore volumes of 1.88-3.13 cm3/g. Their densities were ~0.21 g/cm3 with high porosities of ~83%. Further, SEM images of aerogels showed three-dimensional open porous structures, where the structures were more heterogeneous at higher pH values, leading to a higher surface area. XRD and FTIR data provided information about the crystallinity and changes in the chemical structure of proteins, respectively. The main thermal degradation peak for aerogels was ~295 °C, which was slightly lower than that for SPI powder at 303 °C. The water solubility of SPI powder increased with the formation of aerogels from 17-19% to 30-36%. Overall, this study provides one of the first reports on generating SPI aerogels with high surface areas for their potential use in food, pharmaceutical, and biomaterial industries.

The dominance of pulses in plant-based protein foods necessitates an investigation into their organoleptic properties. Taste, aroma, flavor, and trigeminal attribute intensities of purees obtained from pressure-cooked black bean, chickpea, faba bean, green lentil, pinto bean, and yellow pea were assessed using a trained panel. All pulse purees had similar dry matter content and relatively similar particle size distribution profiles; thus, these factors would not influence the intensities of the sensory attributes. The pulse-like attribute was consistently rated highly across all the pulse purees. The black, pinto, and faba bean purees mostly exhibited similar characteristics whilst chickpea and yellow pea purees behaved similarly. For example, the dry beans and faba bean purees had higher intensities for the bitter, earthy, and metallic aromas and lower intensities for the green, floury/starchy, sweet, and nutty aromas than those for the chickpea and yellow pea purees. Interestingly, green lentil puree largely exhibited intensities that were typical of dry bean purees. Some attributes were perceived to be more intense when assessed as tastes than aromas or vice versa. The same was also observed for attributes that were assessed as both aroma and flavor. It was found that the sensitivity of the mode of perception on the perceived intensity of an attribute may depend on the type of pulse. The similarities in sensory profiles of the pulses can be useful to first, the food industry to expand on ingredients in formulations without drastic effects on the sensory quality and second, the consumers who are neophobic.

Food proteins, essential ingredients in food products, extend product structuring and health-promoting benefits. The objective of the current study is to improve the bio- and techno-functionalities of food proteins simultaneously through non-thermal plasma exposure. Four different food proteins (pea, rice, wheat gluten, and milk proteins) were exposed to plasma at voltage 240V, frequency 1.5 kHz, and 30 min exposure time. The structural, digestibility, bioactivity, and techno-functional properties were analyzed. Plasma treatment alters the secondary structure of proteins by increasing β-structures and random coils by 3-4 times while decreasing α-helices by half, reducing surface hydrophobicity. The study found that longer treatment times and higher voltage intensities enhance protein digestibility and increase amino acid release, with gluten showing the highest improvement in both digestibility and free amino acid content among the proteins examined. The proteins also showed a loss of radical scavenging capacity after treatment due to oxidation reactions. Cold plasma treatment improved protein solubility but reduced emulsifying and foaming properties. The enhancements in digestibility and bioactivity can be attributed to structural unfolding and the exposure of reactive sites on the proteins. In summary, the effects of cold plasma treatment depend on the specific protein, treatment parameters, and the degree of oxidation.