Anais da IX Conferência Internacional de Proteínas e Coloides Alimentares

The processing conditions of thermoplastic extrusion and the source and/or the mix of vegetable proteins may result in different protein-protein interactions in the elaboration of meat analogue. This works aimed to evaluate the type of chemical bonds and interactions occurred during the thermoplastic extrusion at low moisture content of meat analogue using soy protein isolate and vital gluten. A Composite Central Rotational Design with three independent variables was elaborated, where: X1 = vital gluten (0–20 %); X2 = moisture content (16–30 %); and X3 = 3rd and 4th zones temperatures (80–140 °C) and the results were evaluated by the Surface Response Methodology. The trials were extruded in a co-rotational twin screw extruder with fixed parameters set at 1st zone temperature (60 °C), 2nd zone temperature (80 °C), feed rate (9 kg.h-1), screw speed (300 rpm) and a double opening circular die (2.6 mm of diameter for each orifice). The protein solubility of the raw materials and for the product of the trials was evaluated in seven solvents systems: S1 (phosphate buffer 40 mM and pH 7.5); S2 (sodium dodecil sulphate 2 %); S3 (Triton 100X 3 %); S4 (urea 8 M); S5 (β mercaptoethanol 2 %); S6 (sodium dodecil sulphate 2 % + urea 8 M); and S7 (β mercaptoethanol 2 % + urea 8 M). The results of the trials ranged between 10.42 and 14.45 % (S1), 24.06 and 33.38 % (S2), 15.32 and 23.34 % (S3), 28.34 and 49.37 % (S4), 16.50 and 19.74 % (S5), 39.84 and 48.96 % (S6) and 26.88 and 47,53 % (S7). The independent variables showed statistically influence (P≤0.10) on the systems S1, S2, S4, S6 and S7, being the value of R2 at minimal 0.8680, Fcalculated was greater than Ftabulated and the p value <0.001. The influence on the protein solubilization was promoted by the moisture content > vital gluten > 3rd and 4th zones temperatures. By the study of the protein solubility of the meat analogues it was possible to verify that the formation of disulfide bonds, hydrogen bonds and hydrophobic interactions was the main protein interactions forming the fiber structure of the meat analogue. The best results were obtained with the use of vital gluten 5 %, of moisture content 18 % and of 3rd and 4th zones temperatures 135 °C.