Vacuum frying process of gilthead sea bream (Sparus aurata) fillets

Vacuum frying was tested as an alternative technique to develop low oil content fried gilthead sea bream fillets. Three oil temperatures for vacuum frying (90, 100, and 110 °C) were considered. For each temperature the times investigated were 1, 2, 3, 4, 5, 6, 8 and 10 min. To compare the effect of vacuum frying to atmospheric frying on the characteristics of gilthead sea bream fillets and frying rate, treatment at 165 °C was considered. The effect of oil temperature and pressure conditions on the drying process and oil absorption of sea bream fillets was investigated. Other product attributes such as shrinkage and colour were analyzed. Atmospheric frying (165 °C) produces a greater decrease in the mass of the fillets than vacuum frying treatment. Compared with atmospheric frying, oil content of vacuum-fried fish fillets was lower. After ten minutes of treatment the values obtained for vacuum frying were 0.14 ± 0.01 goil/gdry solid, 0.18 ± 0.02 goil/gdry solid and 0.12 ± 0.01 goil/gdry solid for 90 °C, 100 °C and 110 °C respectively and 0.27 ± 0.01 goil/gdry solid for traditional frying at 165 °C. Atmospheric frying was the treatment that produced the greatest shrinkage in the fillets reaching values of 36.8% with respect to the fresh sample after ten minutes of treatment. For vacuum treatments shrinkage values ranged between 23.7% and 33.0% at 100 °C and 110 °C respectively after 10 min of frying. According to the results, the vacuum treated samples became lighter, less greener and more yellow.Industrial relevanceHealthy products are a tendency in the international market. Vacuum frying offers some advantages that can include: the preservation of natural colour and flavours of the products due to low temperature and low oxygen content during the process (better than with conventional deep fat frying), and has less adverse effects on oil quality. The use of this technology on fish products can improve the problems of market saturation at the present time for some species like gilthead sea bream (Sparus aurata).