Caracterização de atividade de água, textura e cor de filés de tilápia em diferentes tempos de liofilização

Abstract

Fish is a perishable product and requires great care throughout its production stage, therefore, it is important to develop processing techniques that allow a longer storage period without causing damage to the physical-chemical characteristics of the final product, and the technique of lyophilization which is based on dehydration by sublimation can generate a product with high nutritional values and a longer shelf life. Thus, the objective of this study was to characterize the physicochemical aspects of freeze-dried fillets of Nile tilapia Oreochromis niloticus submitted to different processing times. The lyophilization procedures were carried out in four stages and three processes with initial mass for each time, using fresh fillet as a control treatment. Water activity, texture and color data for large and small fillets were analyzed. The 36-hour processing with an initial mass of 2,500 kg was the one that obtained the best results for water activity (small fillet - 0.741 and large fillet - 0.765) and presented the highest shear force (small fillet - 53.40 kgf and fillet grande – 27.56 kgf) indicating greater stiffness in the freeze-dried fillet. As for chromaticity, the freeze-dried fillets and the control treatment were in the grayish tone, showing positive and negative a* values and b* only positive values. The results obtained did not respond positively to the dehydration of freeze-dried fillets, as they did not reach the limiting values of Aw to prevent the development of microorganisms, suggesting that further studies are carried out to obtain the appropriate time and initial mass to have a product quality dehydrated.