Grass pea (Lathyrus sativus L.) protein yield and functionality as affected by extraction method: Alkaline, ultrasound‐assisted, and ultrasound pretreatment extraction

Abstract

Background and Objectives Plant protein products are now considered sustainable substitutes for animal proteins in new product formulations, and various methods such as ultrasound have been used to improve their properties. The aim of this study was to investigate the physicochemical and functional properties of grass pea (Lathyrus sativus L.) protein isolate was extracted, as a promising source of plant‐based protein, using conventional (CP), pre‐ultrasonic (PUP) and ultrasound‐assisted (UAP) treatments. Findings Extraction yield, protein content, and protein yield of ultrasound treatments were increased. Ultrasound treatments improved the functional properties of pea protein. Thermal and surface properties were also altered due to the conformational changes in protein molecules during sonication. According to sodium dodecyl sulfate‐polyacrylamide gel electrophoresis, there were no differences in protein fractions of different samples in terms of molecular weight, and protein fractions between 23 and 100 kDa were observed. However, Fourier transform infrared spectroscopy results revealed changes in different treatments suggesting that sonication changed protein secondary structures. Correspondingly, optical and fluorescence microscopy images of protein solutions and foams revealed changes in the structure of proteins and CP presented larger protein aggregates and larger foam bubble sizes than PUP and UAP. Conclusions Ultrasound treatment could increase extraction and improve the functionality of proteins which was attributed to changes in the secondary structure of proteins. Significance and Novelty Grass pea protein isolate can be considered a novel source of valuable protein and ultrasound treatment could enhance the functionality of the protein increasing potential applications of this ingredient in the food industry.

Persian everlasting pea (Lathyrus rotundifolius L.) protein isolate as a potential protein source for food application: Effect of ultrasound‐assisted extraction method on the properties of the protein isolates

“…Mir et al (2019b) expressed that the infrared spectrum of ultrasound‐treated quinoa protein isolates compared with the native one, showed a reduction in ultrasound treated sample in the wave number in the region of 3000–3500 cm −1 which ascribed to the O–H and N–H bonding. These results are consistent with the report of Mir et al (2019b), Xiong et al (2016), and Youshanlouei et al (2022) which expressed that the ultrasound treatment altered protein secondary structures in quinoa, ovalbumin, and grass pea protein isolates, respectively.…”

“…Calorimetric measurement was investigated using DSC instrument (DSC‐400, Sanaf, Tehran, Iran) based on the method suggested by Youshanlouei et al (2022). From each of samples, 15–40 mg was accurately weighed into aluminum pans.…”

“…In order to study the structure of foam proteins, a sample was taken immediately after foaming and placed on a slide for the device. Samples were imaged at least 10 times and images were examined with Image J software (Youshanlouei et al, 2022).…”