Tempe is chosen as the main ingredient of tempe drink powder (TDP) due to its protein digestibility, phytochemical compounds, as well as vitamins and minerals. Previous studies had been conducted to develop TDP formula. The commercial TDP formula showed that improvement of quality aspects needs to be done so the product has better physical and chemical characteristics. In order to optimize the TDP formula, the viscosity, water solubility index (WSI), water absorption index (WAI), sedimentation index (SI), proximate, antioxidant activity, isoflavone content, GABA content, and physicochemical properties were analyzed. The optimized formula was done using the mixture experiment optimization method with optimization d-optimal to obtain the best formula. The optimization result showed that the best formula proportion consisted of 70% (w/w) Tempe flour, 18.23% (w/w) maltodextrin and 1.77% (w/w) guar gum. The best formula was chosen due to having better chemical characteristics compared with the commercial TDP and commercial soy drink powder (SDP), with protein content of 42.61%, antioxidant activity of 58.36 mgAEAC/100g, daidzein and genistein isoflavones of each 48.18 and 140.06 mg/100g and GABA of 21.24 mg/g. Based on the physical characteristics, the optimum formula had a lower viscosity value (18.67 cP) and WAI (2.58g/g) as well as a higher SI value (10.18%) and WSI (9.70%) compared with the commercial TDP. The optimum TDP formula has fulfilled the quality requirements based on the Indonesian National Standard (SNI 7612:2011) regarding soy drink powder.

Tempe is a fermented soybean product that is rich in antioxidants and has high protein bioavailability, so it is good for consumption for public health. However, tempe has a short shelf life of only two days at room temperature. One of the ways to extend the shelf-life of tempe is to process it into defatted tempe flour (DTF). DTF production began with milling process and continued with fat extraction using n-hexane as solvent. The resulting DTF contains a protein of 75.68±0.13%, thus meeting the Codex requirements regarding soy protein concentrates. Furthermore, DTF was formulated with maltodextrin, xanthan gum, and stevia sweetener using Mixture Design (MD) to produce tempe beverage powder (TBP). The composition of the TBP formula recommended by the MD consisted of DTF 64.65%, maltodextrin 21.16%, sweetener 13.50%, and xanthan gum 0.19%. TBP sensory test with the addition of various concentrations (0.4, 0.5, 0.6% w/w) of vanilla milk flavor showed that the panelists highly preferred the dose of 0.6%. The selected TBP optimum formula had good physical, chemical, microbiological, and sensory characteristics and met all of the Indonesian National Standard (SNI 7612, 2011) requirements, except for fat content.