A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in F ood Engineering and Bioprocess Technology, School of Environment, Resources and Development

Thesis (M. Sc.) - Asian Institute of Technology, 2015

Defatted peanut cake, the protein dense material, is the major byproduct of peanut ( Arachis hypog aea Linn seed) oil processing factory. Although the annual defatted peanut cake production is about 6 million metric tons, most of them are commonly used as cattle feed and fertilizer. Nowadays, the market of protein hydrolysate has emerged because of thei r superior functional and antioxidant properties than native protein. The objectives of this study were to investigate the effect of enzyme types and role of degree of hydrolysis (DH) on functionality, antioxidant activity and molecular weight distribution of obtained peptides. Defatted peanut cake contained 35% protein , 23 % carbohydrate , 10.2 % moisture, 7.4% fat and 5% ash.It was used to isolate the protein by isoelectric precipitaton method. The extraction yield and protein content of peanut protein isol ate (PPI) were 33% and 72%.The optimum enzyme to substrate ratio (E/S) for alcalase and pepsin were measured by hydrolyzing the PPI with 0.4 to 1.6 E/S (w/w) for 6 hrs. Then, the effect of hydrolysis time on DH was studied for selected E/S (0.4 (w/w) for a lcalase and 1.6 (w/w) for pepsin).The peanut protein hydrolysate (PPH) which had (8%, 10%, 12%, 14% and 17%) DH were prepared at their corresponding hydrolysis time. The PPH had the protein content and yield percentage of 70.5% and 52.5% for alcalase and 3 9% and 73.5% for pepsin...