Effect of Ultrasonic-Assisted Enzymatic Hydrolysis on Functional Properties and Antioxidant Activity of Eri Silkworm Pupa Protein Isolate

Kanchana Thongrattanatrai; Rarisara Impaprasert; Worapot Suntornsuk; George Srzednicki

doi:10.1155/2023/9409710

Effect of Ultrasonic-Assisted Enzymatic Hydrolysis on Functional Properties and Antioxidant Activity of Eri Silkworm Pupa Protein Isolate

Int J Food Sci. 2023 Nov 29:2023:9409710. doi: 10.1155/2023/9409710. eCollection 2023.

Authors

Kanchana Thongrattanatrai¹, Rarisara Impaprasert², Worapot Suntornsuk¹, George Srzednicki³

Affiliations

¹ Department of Microbiology, King Mongkut's University of Technology Thonburi, Bangkok 10140, Thailand.
² Division of Food Technology, Kanchanaburi Campus, Mahidol University, Kanchanaburi 71150, Thailand.
³ Food Science & Technology, School of Chemical Engineering, The University of New South Wales, Sydney, NSW 2052, Australia.

Abstract

Philosamia ricini (Eri silkworm) pupa protein isolate (EPI) was utilized to prepare pupa protein hydrolysate (EPIH) through enzymatic hydrolysis. Additionally, the isolate underwent ultrasonic treatment at 20 kHz to become ultrasound pretreated EPI (EPIU), which was then enzymatically hydrolyzed to obtain ultrasound pretreated protein hydrolysate (EPIUH). The physicochemical properties of these samples were investigated, including molecular weight, solubility, foaming and emulsion properties, water- and oil-holding capacity, antioxidant activity, and color. When compared to EPI (used as the control), EPIU exhibited a high degree of hydrolysis at 20 minutes (DH = 29.24%). At a total process time of 20 minutes, the degree of hydrolysis for EPIH, EPIU, and EPIUH was found to be 13%, 29%, and 41%, respectively. SDS-PAGE analysis indicated no difference in molecular weight between EPI and EPIU (11-75 kDa). However, the molecular weight profiles of EPIH and EPIUH were reduced (8-45 kDa), resulting in changes in protein functionalities. The high DH value contributed to the enhancement of antioxidant activity, solubility, emulsion capacity, emulsion stability, and foam capacity of the protein isolate at pH 7. Furthermore, the ultrasonic pretreatment of the protein hydrolysate increased the lightness of the protein powder by reducing the enzyme activity of the polyphenol oxidase (PPO). These results suggest that ultrasonic pretreatment of the protein hydrolysate could be applied to improve the properties of Eri silkworm pupa protein for use in the food and beverage industry, such as protein-rich beverages or salad dressings.