High-Intensity Ultrasound (HIUS) Treatment of Sunnhemp Protein Isolate (Crotalaria juncea L.): Modification of Functional, Structural, and Microstructural Properties

The effect of ultrasonication treatment on the functional, structural, and microstructural properties of sunnhemp protein isolates (SHPIs) was investigated. The SHPI was extracted and modified ultrasonically (amplitude, 40 and 50%) at different time duration (10, 20, and 30 min). The results revealed improvement in functional attributes of all SHPIs samples after ultrasound treatment as compared to untreated sample. Among all the ultrasound-treated SHPIs, the maximum improvement in functional properties (solubility, emulsifying, foaming, water and oil binding) was observed in US5 (50% ultrasound amplitude for 20 min) sample. The findings of FTIR and fluorescence spectroscopy confirmed modification in the secondary and tertiary structures of SHPI. Circular dichroism results indicated alterations in the secondary structures of sunnhemp proteins. Particle size of all ultrasound treated samples were reduced and their disintegration was also observed by SEM analysis. Surface hydrophobicity was also improved in all ultrasound treated samples. Zeta potential values were found to be increased in all ultrasonically treated samples. SHPI showed enhancement in free and total sulfhydryl (SH) groups. Based on the findings of ultrasound-treatment, SHPI samples may serve as a substitute for animal proteins for a wide range of food applications.