Desidratação osmótica à vácuo do filé de mapará (Hypophthamus edentatus)

Abstract

The aim of this work was to evaluate the process of vacuum osmotic dehydration of mapará fillet (Hypophthamus edentatus). Mapará fillets with dimensions of 5 x 2 x 0.5 cm were subjected to vacuum osmotic dehydration in accordance with a rotational central composite design 24, in which were evaluated the effects of the independent variables temperature, time, vacuum pressure and NaCl concentration on the dependent variables water loss (WL), solids gain (GS) and water activity (aw), order to obtain optimal condition of process with greater PA, lower GS and lower aw. The kinetics of osmotic dehydration of mapará was performed under optimal conditions, where were monitored the parameters PA, GS and aw as a function of process time. The empirical model proposed by Azuara et al. was used to represent the kinetics of mass transfer during the process of osmotic dehydration. The mapará fillet presented 76.70% moisture, 15.57% protein, 5.38% fat and 0.93% ash. The NaCl concentration (linear) was the variable that presented the greatest effect on the dependent variables, being positive on WL and GS and negative about the aw. The models obtained for PA, GS and aw were significant at 95% confidence and showed no significant lack of fit, being useful to predictive purposes. Was determined as optimum condition for the process: NaCl concentration 25%, temperature of 25 ° C and time of 120 min. The model proposed by Azuara et al. showed fit good to the experimental data of PA and GS kinetics of osmotic dehydration of mapará fillet. The fillet mapará had a reduction moisture after osmotic dehydration in optimal conditions, however did not meet the humidity recommended by law for salted fish, since the chloride content increased and attended law for salted fish. In relation the instrumental color were observed, after osmotic dehydration, significant statistically differences in lightness (L *) that decreased, indicating that the mapará darkened and the hue angle (h °) that increased, but still showed a tendency to yellow.