CONICET | Buscador de Institutos y Recursos Humanos

The ability of exopolysaccharides (EPSs) produced by the fungus Sclerotium rolfsii ATCC 201126 to minimize the liquid separation (syneresis) experienced by cooked starch pastes through cold storage was investigated. Different techniques were compared and finally the extent of syneresis was estimated by daily measuring of the liquid phase length (Äh) separated above the sedimented phase throughout storage at 5°C. The degree of syneresis was represented by Äh/h0, where h0 stands for the initial height of the sample dispersion. Evaluation involved 2% w/v corn starch/EPS aqueous blends in proportions varying between 9.90/0.10 and 9.00/1.00 (w/w), and 2% w/v corn starch (CS) as control. Up to day 20 of refrigeration and for the highest tested proportion (9.00/1.00), the EPS II was able to inhibit syneresis completely, while EPS I prevented syneresis in a 91% compared to the CS control. EPS II was selected as the optimal syneresis preventive and its rheological behaviour in distilled water, skimmed and whole milk was further analysed. It was able to increase viscosity exhibiting a non-Newtonian, pseudoplastic behaviour in the three solvents tested. When rheology of CS/EPS II blends was evaluated for the three same solvents, a desirable synergistic effect was found as witnessed by the increase on viscosity, high consistency coefficients and low flow behaviour indexes, in comparison to the independent polysaccharides. Additionally, EPS II was able to prevent syneresis without affecting pH, gelling properties, hardness or gel colour. These results revealed the scleroglucan potential for becoming a food-approvable hydrocolloid with prospective use as food stabilizer and water loss preventive. Keywords: scleroglucan, Sclerotium rolfsii, syneresis, starch, rheology, milk

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