29E-1 |
Kinetic prediction of mass transfer during the vacuum impregnation of sardine (Sardinella aurita) filets |
M. NUNEZ REYES, V, Depto. de Tecnologia de Alimentos, IUT Jacinto Navarro Vallenilla, Carretera via el Pilar Valle de Canchunchu, Carupanos, 6124, Venezuela and A. Vegas, Sr., Depto. de Almacen, Industrias Conservas del Mar, Zona Industrial, Carupano, 6124, Venezuela. The traditional way of impregnation process is by placing food in a hypertonic solution under atmospheric pressure. A new alternative technology using vacuum impregnation (VI) has been designed. VI consists in the application of vacuum pressure to a solid-liquid system for a short period of time (approx. 5-15 min.), followed by restoration of atmospheric pressure. The objective of this research was to establish a predictive model of the kinetic of mass transfer during VI of sardine (Sardinella aurita) filets. For atmospheric osmotic dehydration (AOD), sardine filets were placed in identical dessicators. Samples for VI were placed in similar dessicators but modified for use with a vacuum pump. The experiment was conducted at 32, 35 and 38°C using three concentrations of NaCl solutions, 21.6, 24.1 and 26.6% (w/w). In the VI process, 70, 230 and 286 mbar were applied to each dessicator containing the sardine filets. Evaluations were performed to determine effective porosity (εe), moisture loss (Mw), salt uptake (Ms), internal solution concentration (Zs) and salt difussion coeficient (De). The effective porosity (εe) values ranged from 0.635 to 3.668% (w/w) and were lower at 38ºC compared to the lower temperatures. The best model for adjustment of driving force (Y) for AOD was the proposed by Crank (1975) for short period of time. De values ranged from 1.860x10-9 to 4.332x10-9 m2/sec and were significantly affected (p < 0.05) by NaCl concentration. Square root adjusted models were found for Mw and Ms variables. Significant reduction (p < 0.05) in moisture and increase in the percent salt uptake were observed in VI when compared to AOD. The driving force values reported by Fito and Chiralt (1996) were overestimated in the model. Results indicate that the fitted models could be used to predict the mass transfer during VI of sardine (Sardinella aurita) filets under the conditions of this study.
Session 29E, Food Engineering: Transport processes and kinetics
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