Abstract: In this study, NaOH and trypsin were used to hydrolyze cold pressed peanut cake as a byproduct of the cold pressed extraction of peanut oil to obtain peanut protein. Orthogonal array design was employed to optimize the hydrolysis conditions of cold pressed peanut cake for maximum extraction efficiency of protein. The optimal NaOH treatment conditions were pH 9.0, 1:8 material/liquid ratio (g/mL), 8 ℃ extraction temperature, and 2 h extraction time, resulting in an extraction efficiency of 80.68%. The optimal trypsin treatment conditions were 1:50 enzyme/substrate ratio (m/m), 5 g/100 mL substrate concentration, pH 9.0 and 50 ℃ hydrolysis temperature, and the resulting extraction efficiency of protein 96.26%. The optimal conditions for fermentation of hydrolyzed peanut protein obtained using trypsin and desalted whey powder by direct vat set (DVS) lactic-acid bacteria starter for peanut polypeptide beverage with the best taste were hydrolyzed peanut protein amount 2 g/100 mL, desalted whey powder 1 g/100 mL, innoculum amount 1:25 (g/kg), fermentation at 42 ℃ for 5 h, post-aging for at 4 ℃ for 15 h and amount of sucrose addition in fermentation products 9%.

Key words: cold pressed peanut cake, peanut protein, peanut polypeptides, lactic acid bacteria-fermented beverage