Comparative evaluation of milk proteins and oil‐seed‐cake‐derived proteins extracted by chemical and biological methods for obesity management

Abstract BACKGROUND In light of the exponential rise in global population, there is a critical requirement to reduce food waste on a global scale. According to studies, agricultural wastes such as oil‐seed cakes offer great nutritional value. Acid precipitation (A) and alkaline extraction methods (traditional methods) were used to extract protein from oil‐seed cakes; however, both procedures are linked to decreased protein quality and quantity, which prompted the development of a novel strategy known as the biological/microbial/probiotic (B) method. Therefore, the present study aimed to highlight the optimal way of protein extraction from oil‐seed cakes and the effect of extraction methods on protein efficacy against obesity. The outcomes were also compared with milk proteins. RESULTS In vitro study provided evidence that proteins from both sources (plant and milk) suppressed adipogenesis and stimulated adipolysis in 3T3L‐1 cells. For the in vivo study, mice were fed with different protein extracts: soya protein preparation (SPP), ground protein preparation (GPP), whey protein (WP) and casein protein (CP) containing 40% of their calories as fat. Body weight decreased significantly in all the rats except CP‐fed rats. Body mass index, atherogenic index, plasma triglyceride and very‐low‐density lipoprotein cholesterol level decreased significantly in all the groups in comparison to the model group (high‐fat‐diet group), but the decrease was more pronounced in plant proteins than milk proteins. In hepatocytes, the expression of fasting‐induced adipose factor, carnitine palmitoyltransferase I and peroxisome proliferator‐activated receptor α genes was increased significantly in SPP‐fed groups. Adiponectin gene expression was upregulated significantly in visceral fat tissue in groups fed SPP‐B, GPP‐A and CP, whereas leptin gene was downregulated significantly in all groups except SPP‐A. CONCLUSION This study demonstrates that SPP‐B showed the most effective anti‐obesity property, followed by WP. Additionally, we found that the biological precipitation approach produced better outcomes for plant proteins isolated from oil‐seed cakes than the acid precipitation method. © 2023 Society of Chemical Industry.