High‐intensity ultrasound treatment: An effective way of modifying thermal and rheological properties of sunnhemp (Crotalaria juncea) protein isolate (SHPI) by varying ultrasound amplitude and time

Abstract In this study, sunnhemp protein isolate was prepared to investigate the effect of ultrasound amplitude (40% and 50%) and time (10, 20, and 30 min) on the physicochemical, thermal, and rheological properties of sunnhemp protein isolates (SHPIs) at fixed power and frequency. Ultrasound treatment decreased the water activity of SHPIs. Improvement in the in vitro protein‐digestibility was observed during ultrasound treatment. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) results indicated changes in the denaturation temperature and weight loss in all ultrasonicated sunnhemp protein samples. Thermal stability of ultrasound‐treated SHPIs was improved indicating modification in the secondary structures of SHPI caused by ultrasound treatment. From the rheology results, dramatically higher storage and loss modulus values as a function of frequency and temperature were observed in modified SHPIs samples over native sample. Ultrasonication is an efficient approach for modifying the physico‐chemical, thermal and rheological characteristics of sunnhemp proteins for food applications where thermal stability is required. Practical Applications Today's consumer is not only concerned with the relationship between food intake and wellness, but also with the sustainability of the environment as well. So, the consumption of plant‐based proteins over animal‐based proteins is on the rise. There is a need to explore underutilized plant‐based protein sources, which should be incorporated in our nutritional diet. Sunnhemp seeds are loaded with high protein content and are therefore, a novel and sustainable plant‐based protein source. Sunnhemp seeds also have well balanced amino acid composition and have other medicinal properties. However, plant‐based protein shows poor functionalities when compared to animal‐based protein. Therefore, there is a need to modify plant‐based proteins before incorporating into the final food products. In the present research, sunnhemp protein isolate has been modified to increase its functionality, which could be taken by food processing industries.