Solid state fermentation (SSF) represents a technological alternative for processing a great variety of legumes and/or cereals to improve their nutritional quality and to obtain edible products with palatable sensorial characteristics. The objectives of this work were (1) to determine the best combination of SSF process variables (fermentation temperature FT/fermentation time Ft) for producing chickpea tempeh flour and (2) to characterise the physicochemical and nutritional properties of the product. Response surface methodology was applied as optimisation technique over three response variables: in vitro protein digestibility (PD), true protein (TP) and water absorption index (WAI). A central composite experimental design with two factors and five levels was used. The process variables FT and Ft had variation levels of 31-36°C and 48-72 h respectively. Rhizopus oligosporus (1 x 109 spores 1-1 in distilled water) was used as starter. Prediction models for response variables were developed as a function of process variables. A conventional graphical method was applied to obtain maximum PD, TP and WAI. Contour plots of each of the response variables were superimposed to obtain a contour plot for observation and selection of the best combination of FT (34.9°C) and Ft (51.3 h) for producing of chickpea tempeh, which was dried (52°C, 24 h) and milled to pass through an 80-US mesh (0.180mm) screen to obtain optimised chickpea tempeh flour. This flour had higher (p ≤ 0.05) TP (25.7 vs 19.7% dry matter (DM)), total colour difference (30.3 vs 16.7), WAI (4.18 vs 2.15 kg gel kg-1 DM), available lysine (42.7 vs 30.4 g kg-1 protein) and PD (83.2 vs 72.2%) and lower lipid content (2.6 vs 6.1% DM), phytic acid (1.1 vs 10.85 g kg-1 DM), tannins (2.65 vs 21.95 g catechin kg-1 DM) and pH (5.9 vs 6.3) than raw chickpea flour. © 2004 Society of Chemical Industry.
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