Production of protein hydrolysate from overripe tempeh catalyzed by bromelain

Solid-state fermentation is an important food processing technology, often utilized in the food industry because of its production of secondary metabolites, amino acids, organic acids, and enzymes. Prolonged solid-state fermentation of tempeh can increase the protein and free amino acid content in it. By using bromelain, the production of overripe tempeh protein hydrolysate (OTPH) as a food ingredient may be possible. Bromelain was extracted from pineapple core and its’ optimum temperature and pH for its activity were determined. OTPH is made from soybeans that were fermented for 2, 3, 4, and 5 days, added with crude bromelain enzyme of 0.10, 0.15, 0.20, 0.25% (v/w), and incubated at the optimum condition obtained from the preliminary stage. A longer fermentation time and higher concentration of enzyme added resulted in significant increases in the protein content (ranging from 45.96% to 50.87%), water-soluble amino acids content (ranging from 14.55% to 39.86%), and total amino acid content with 0.25% crude bromelain produced the highest total amino acid content amounting to 36682.002 mg/100 g. These results showed the potential for the application of bromelain to produce protein hydrolysate from overripe tempeh.