The frying of frozen sardine fillets in olive oil. Effects of different thawing methods on the fat content and fatty acid composition

Abstract

To study the effect of freezing and different thawing methods on the moisture, fat an fatty acid content of fried sardines, fresh sardine fillets were first frozen and then some were thawed either in a refrigerator at 4°C or in a microwave over prior to frying. These fillets were then analyzed both before and after being fried in olive oil. Frying increased the fat content of the fillets, mainly due to water losses, especially in those thawed in the refrigerator. Mono-unsaturated fatty acid (MUFA) content increased in fresh and frozen fillets after frying from 21% to 55% and 56%, respectively. However, thawing prior to frying had a different effect depending on the method because oleic acid absorption was facilitated by refrigerator-thawing, the MUFA content increased to 61,8%, whereas after microwave-thawing the MUFA content reached 47%. Saturated and polyunsaturated fatty acids decreased in fried fillets compared to uncooked ones as a consequence of the increase in MUFA. Frying decreased the C22:6/C16:0 ratio with respect to fresh fillets in frozen fillets and in those thawed in the refrigerator but not in those thawed in a microwave.