Characterisation of soy extract processed under different drying methods and extraction conditions


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Soybean extract (SE), enriched in soy soluble polysaccharide (SSPS), was evaluated in three different conditions varying in extraction temperature and drying process: SE-A −80 °C, freeze-dried, SE-B −80 °C, spray-dried, SE-C −95 °C, spray-dried. Spray-dried SE presented lower moisture content, smaller and more uniform particles. In addition, zeta potential showed the same negative surface charge for all extracts showing the prevailing behaviour of SSPS. Moreover, all biopolymers were composed of three main molecular weight (Mw) fractions, but the Mw distribution was different between the three ingredients, reflecting their rheological behaviour in aqueous solution. Higher mean Mw led to enhanced apparent viscosity observed in neutral and acid pH for SE-A, followed by -B and -C, respectively. The inverse behaviour was observed for intrinsic viscosity at neutral pH. However, SE-C showed lower intrinsic viscosity at acid pH, which was attributed to protein–polysaccharide interaction presents in the solution.