Mempelajari Proses Steam Blasting Kacang Kedelai, Karakterisasi Warna dan Tekstur Kacang Kedelai serta Sifat Fungsional Protein dari Tepung Kedelai yang Dihasilkan

Abstract

Soybean (Glycine max L.) is one kind of legume containing high protein, isoflavones, polyunsaturated fatty acid, amino acids, and no cholesterol. Soybean can be used as a raw material of various products, including soy flour. Beside those advantages, soybean contains various anti nutritional compounds such as trypsin inhibitor, phytic acid, and haemaglutinin. These compounds can be removed by heat, but the process can decrease the quality of sensory properties and nutritional value of products. The alternative soybean processing method is using heat and pressure treatment. An equipment that works based on heat and pressure treatment is steam blasting. The principle of this equipment is by splitting soybeans through a short heating process and the pressure drops suddenly. This study aimed to obtain an optimum pressure and time of steam blasting in soybean flour processing. The pressure used were 1,2,3,4, and 5 bar with heating time 5, 10, 15, 20, and 25 minutes. Tests conducted were SDS-PAGE assay (Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis) and soybean quality index assay like KOH Protein Solubility (KOH PS) assay, Protein Dispersibility Index (PDI) assay, and Urease Index assay. The result showed that at 1 bar pressure treatment with a 5 minute heating time could increase the solubility of soy proteins in neutral solution, eliminate most of antinutrition in soy, prevent overheat or underheat, and produce good quality soybean flour. Test statistics of various parameters (KOH PS, PDI, urease index) also showed that the treatment pressure of 1 bar 5 minutes is the most efficient treatment and meets the recommended soybean quality based on value of KOH PS, PDI, and urease index. Treatment pressure of 1 bar 5 minutes was not significantly different from the higher pressure treatment on KOH PS test and PDI, but significantly different in urease index test. Thus, treatment pressure of 1 bar with a 5 minute meet the adequacy standard of soybean heat processing. Meanwhile, SDS-PAGE assay showed that at 3 bar pressure treatment with a 25 minute heating time, all the dominant antinutrition substances in soybean was inactivated because denatured by heat and pressure. Those antinutrition substance were lipoxygenase, Bowman-Birk inhibitor, and lectin. Physical observations were conducted on soybean yield blasting process showed a change in color and texture with increasing in pressure and heating time. Soybean colour become increasingly brown color, due to the Maillard reaction and the oxidation of carotenoids found in soy. Soybean texture become increasingly soft, caused by high temperature and saturated steam which can damage and destroy the structure of soybean cotyledon compact.