Nutrition Content, Protein Quality, and Antioxidant Activity of Various <i>Tempeh Gembus</i> Preparations

Abstract

Tempeh gembus is a fermented product of tofu processing that offers fairly good nutritional content at an affordable price. However, different food preparation techniques can change the nutrient content of this food product. This study aimed to determine a tempeh gembus preparation method that produces optimal nutrient content, protein quality, and antioxidant activity. Fresh, fried, steamed, and bromelain-added tempeh gembus samples were analyzed for moisture, ash, fat, protein and amino acids, protein digestibility, dietary fiber, isoflavone content, and antioxidant activity and then compared. Fresh tempeh gembus contained 1.87% fat, 11.09% dietary fiber, 4.90% protein, 89.67% protein digestibility, 14.03% amino acids, 48.07% antioxidant activity, 0.05% genistein, and 0.07% daidzein. Steamed samples contained less total fat (1.22%), dietary fiber (8.95%), protein (3.90%), protein digestibility (48.68%), amino acids (13.52%), and antioxidant activity (39.72%) but greater genistein (0.07%) and daidzein (0.09%) content versus fresh. Fried samples contained more total fat (18.23%), dietary fiber (22.24%), antioxidant activity (61.00%), and genistein (0.08%) versus fresh but lower total protein (3.92%), protein digestibility (47.68%), amino acids (4.10%), and daidzein (0.10%). Tempeh gembus with added bromelain contained 1.66% fat, 9.80% dietary fiber, 5.12% protein, 67.16% protein digestibility, 13.99% amino acids, 62.04% antioxidant activity, 0.06% genistein, and 0.07% daidzein. Addition of bromelain to tempeh gembus produced optimal nutrient content, protein quality, and antioxidant activity profiles relative to fresh samples, steaming, and frying.