Protein Isolation from Tomato Seed Meal, Extraction Optimization

Water extraction of tomato seed meal proteins was studied to find optimal conditions for protein extraction and isolation. A central composite design including temperature, pH, time and water/solids was used and second order models were employed. Optimum conditions were: 50°C, pH 11.5, 20 min and water/solids = 30/1 (v/w). Experimental values were: extraction yield (extracted protein to that in raw material) 66.1%, protein content of product 72.0%, and total protein yield (protein in isolated product to that in raw material) 43.6%. Estimated values were in good agreement with experimental values. Optimum conditions were confirmed by a larger scale experiment.     

Isolation of Tomato Seed Meal Proteins with Salt Solutions

Salt solutions were used in isolating tomato seed meal proteins. Na₂SO₃ and NaCl solutions at different concentrations, and pH were included in a central composite design to find optimum conditions of protein isolation. The highest total protein yield was achieved with water extraction (no salt present). Salt extraction at pH 7.5 produced isolates with protein content of 93.4% (NaCl 5% w/v) and 77.1% (Na₂SO₃ 0.5% w/v). Observed values were in good agreement with predicted values. Isolates extracted with different salt solutions ranged from less soluble but very resistant to heat and Ca²⁺, to very surface active with functional properties comparable to commercial soy isolates.