Effect of Ultrasonic Homogenization on the Functional Properties of Cowpea Protein Isolate

Lim, Shi Qi (2023) Effect of Ultrasonic Homogenization on the Functional Properties of Cowpea Protein Isolate. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

Cowpea, Vigna unguiculata is an inexpensive source of protein that can be converted into protein rich food ingredients such as protein isolate to serve as a supplement in several other food products. However, the efficacy of utilizing protein isolates in food applications depends on their functional properties, as they directly affect the overall quality and sensory characteristics of food products. Ultrasound technology emerges as an alternative method for modifying the functional properties of cowpea protein. This study aims to investigate the effect of the amplitude of UH on the functional properties of cowpea protein isolate (CPI). 10% of CPI dispersions were prepared and subjected to ultrasonic homogenization (UH) at different amplitudes (50%, 70% and 90%) for 5 minutes and non-UH treated CPI was used as a control sample. The particle size distribution, zeta potential, protein solubility, protein surface hydrophobicity, flow behavior and gelling properties of CPI were evaluated. The result showed that UH amplitude significantly (p<0.05) affected zeta potential, protein solubility, protein surface hydrophobicity, particle size distribution, flow behavior and gelling properties. The findings revealed that the solubility and surface hydrophobicity in all UH treated CPI were significantly higher (p<0.05) compared to the control CPI. In addition, UH treatment decreased the particle size and zeta potential of CPI. Rheological analysis indicated that all samples exhibited shear thinning behavior, characterized by a significant increase in the flow behavior index, along with a significant decrease in both consistency and viscosity. UH treatments increased both the storage modulus and loss modulus while decreasing the tan ζ of CPI dispersions and hence formed more elastic solution. The findings of this study demonstrated that the application of UH has the potential to substantially enhance the functional properties of CPI. Keywords: Cowpea protein isolate, ultrasonic homogenization, functional properties