Optimization of Extraction Parameters of Protein Isolate from Tomato Seed Using Response Surface Methodology

Response surface methodology (RSM) and a central composite rotatable design (CCRD) were used to optimize the extraction conditions of protein isolate from the defatted tomato seed meal, which is a by-product of tomato processing. Water to raw material ratio, extraction time, and mixing time were the most significant (p < 0.01) factors affecting the protein yield. Optimum extraction was obtained with 82.81/1 (v/w) water to raw material ratio, 49.76 h extraction time, and 24.56 min mixing time. Confirmatory studies revealed that the protein yield under these conditions was 80.37 %, which is well in close agreement with the value predicted by the model (81.22 %). The results of optimized defatted tomato seed protein isolate (DTSPI) molecular weight distribution showed that two protein fractions and three major groups of polypeptides were identified by gel electrophoresis. DTSPI had also most of the essential amino acids and hence could be considered as bioactive peptides. DTSPI showed also a higher antioxidant capacity with an IC50 value of about 40.89 and 18.45 mu g/mL, respectively, with DPPH free radical scavenging activity and ABTS(aEuro cent+) radical scavenger methods. The results obtained suggest that DTSPI with good functional properties could be useful in the health food/nutraceutical/pharmaceutical industry for various applications.