Optimization of tomato pomace separation using air aspirator system by response surface methodology

Tomato pomace contains seeds and peel, which are rich in protein and fat, and in dietary fiber and lycopene, respectively. Developing a suitable method to separate the seeds and peel in tomato pomace is important for achieving value-added utilization of tomato pomace. The objectives of this research were to study the feasibility of air separation of tomato pomace using a laboratory-scale fluidized-bed dryer; to evaluate the effect of moisture content, air velocity, and feeding rate on the separation of tomato pomace using an air aspirator; and to optimize the separation conditions using response surface methodology (RSM). Separation in the fluidized-bed dryer at 3.3 m s^-1 air velocity resulted in 80.49% separation efficiency with more than 85% purity of peel and seeds. Single-factor experiments with the aspirator showed that moisture content (5.7% to 23.0% on dry basis) of tomato pomace, air velocity (5.3 to 7.1 m s^-1), and feeding rate (15 to 90 kg h^-1) significantly affected the purity of both the peel and seed fractions and the separation efficiency. The optimal separation conditions using the aspirator were tomato pomace moisture content of 8.0%, air velocity of 6.4 m s^-1, and feeding rate of 40 kg h^-1, which achieved purities of 82.20% ±3.26% and 86.11% ±3.65% for the peel and seed fractions, respectively, with a separation efficiency of 68.56% ±6.52%. The predicted separation results were highly fitted with the experimental data, which indicated the high accuracy of the quadratic models. The results of this study showed that an air aspirator could be used for industrial separation of tomato pomace.