OPTIMISING PROTEIN AND TOTAL DISSOLVED SOLID TO SYNTHESIZE SOY SAUCE FROM SOYBEAN RESIDUE USING BOX-BEHNKEN DESIGN

Soybean residues are the residue of milk processing with high protein content. It is often benefited as cattle meal; however, it is processed to produce soy sauce in this research. It aims to optimise the protein and totally dissolve solid content in the soy sauce synthesis with optimum water/soybean mass ratio, sodium chloride and time. Soybean is immersed for 10 hours in distilled water, blended at water/soybean mass ratio 4:1, 5:1, and 6:1, and filtered to get the residue. The maximum protein in the residue is 12.48% at water/soybean mass ratio 5:1; therefore, the synthesis uses the ratio to benefit the protein. The residue is fermented for four days until the mould grows in its surface. It is fermented in sodium chloride of 20, 25 and 30%. The synthesis is optimum at water/soybean mass ratio 5:1, fermentation time of four weeks and the sodium chloride concentration 25%. Optimising the soy sauce protein follows the second order polynomial with protein 1.01% and total dissolved solid 40.13%. These results are compared to SNI 3543.2:2013. The solid meets the quality requirements, but protein is still below the standard. In brief, the condition can be implemented to synthesize soy sauce from the soybean residue.