Optimization of compressed soybean tablet production using response surface method

The tabletting process increases the density of the food. This process also facilitates transportation and reduces transmission and storage costs. In this research, soybean powder was used for tabletting experiments. The effect of the tabletting process on particle density, compressive strength and shrinkage of soybean tablet was studied. The experiments were carried out using soybean powder at feedstock moisture content of 30, 40 and 50% w.b., feedstock temperature 25, 45 and 60 °C, relaxation time of 5, 10 and 15 s, and die diameter of 6, 8 and 10 mm. The response surface method (RSM) with central composite design was also used to analyze the data and optimize the process. The result showed that the highest particle density was 3714.32 kg/mm3 under conditions of the feedstock moisture content of 50% w.b., feedstock temperature of 25 °C, relaxation time of 5 s, and the die diameter of 10 mm. During the tabletting prosses, the highest compressive strength (518.18 N) was obtained at the feedstock moisture content of 50% w.b., feedstock temperature of 65 °C, relaxation time of 5 s, and the die diameter of 6 mm. The highest shrinkage of soybean powder (57%) was obtained at the feedstock moisture content of 50% w.b., feedstock temperature of 65 °C, relaxation time of 15 s, and the die diameter of 6 mm. The best optimization results for tabletting conditions for soybean powder was under feedstock moisture content of 50% w.b., feedstock temperature of 42.03 °C, relaxation time of 5 s and die diameter of 10 mm. The predicted values of particle density, compressive strength and shrinkage at the optimized conditions were 4895.49 kg/mm3, 433.17 N and 9.03% with a desirability of 0.853, respectively.