Carlos Prentice-Hernández

Development of oxidised and heat-moisture treated potato starch film.

This study investigated the effects of sodium hypochlorite oxidation and a heat-moisture treatment of potato starch on the physicochemical, pasting and textural properties of potato starches in addition to the water vapour permeability (WVP) and mechanical properties of potato starch films produced from these starches. The carbonyl contents, carboxyl contents, swelling power, solubility, pasting properties and gel texture of the native, oxidised and heat-moisture treated (HMT) starches were evaluated. The films made of native, oxidised and HMT starches were characterised by thickness, water solubility, colour, opacity, mechanical properties and WVP. The oxidised and HMT starches had lower viscosity and swelling power compared to the native starch. The films produced from oxidised potato starch had decreased solubility, elongation and WVP values in addition to increased tensile strength compared to the native starch films. The HMT starch increased the tensile strength and WVP of the starch films compared to the native starch.

Avaliação reológica e físico-química da gelificação térmica do surimi de jundiá

The objective of this work was to evaluate the rheological and physicochemical properties of thermal gelling of surimi from silver catfish (Rhamdia quelen). Four heating treatments were used: one-step heating at 90oC, for 15 min, was compared with three two-step treatments with pre-heating at 60oC for 30, 45 and 60 min, followed by heating at 90oC for 15 min. Each heat treatment was used on three formulations: two with protease inhibitors (bovine serum albumin + alpha2-macroglobulin and egg white) and a formulation without inhibitors. Samples with inhibitors and one-step heating reached better gelling, by an increase in the storage modulus and a decrease in phase angle. Pre-heated gels had large variation in viscoelastic parameters which interfered with the establishment of the protein network during thermal gelling of surimi. The soluble peptides concentrations did not change significantly, even when two-step heating was carried out, which indicates absence of proteolysis, besides showing protein network protection by inhibitors.