Evaluation of fatty acid‐related nutritional quality indices in fried and raw nile tilapia, (Oreochromis Niloticus), fish muscles

Abstract

During frying, fat degrade and many reactions occur resulting in numerous altered fatty acid products. This would lead to the formation of Tran's fatty acids and changes in nutritional qualities. Hence, this study was aimed to determine the changes during frying on fatty acid composition of Nile tilapia (Oreochromis Niloticus) fish muscle from local fish market of Hawassa, Ethiopia. Fish fryers reported that they usually use palm oil for frying. They also indicated that the oil is kept for days and reused for frying at different cycle. In fried fish, 35 types of fatty acids were identified and 27 in raw fish muscle. Palmitic, stearic, heptadecanoic, and tetradecenoic acids were the abundant saturated fatty acids in both fried and raw fish muscle. Oleic, Docosahexaenoic, Eicosapentaenoic, and Linoleic acid were the major unsaturated fatty acids. The percentages of total saturated fatty acids (SFA) of raw fish muscle (47.4%) were found to be lower compared with fried fish muscle (51.8%). The n‐6/n‐3 ratio (7.83), index of atherogenicity (0.85), and thrombogenicity (1.71) in the fried fish muscle were in the undesirable values. The hypocholesterolemic/hypercholesterolemic ratio was relatively similar in the fried (1.09) and raw (1.02) fish muscles. The total unsaturated fatty acids (UFA) level of raw fish muscle (52.2%) was higher than the fried fish muscle (47.2%). Higher percentage of Tran's fatty acid was identified in the fried fish muscle compared with raw. Frying considerably altered fatty acid composition of fish muscle. It increased saturated fatty acid concentration and decreased unsaturated. Hence, frying noticeably decreases the nutritional quality of fish muscle. Therefore, it is suggested that further analysis on fatty acid composition of oil usually used for frying and the nutritional quality index across frying cycles.

Application of Deep, Vacuum, and Air Frying Methods to Fry Chub Mackerel (Scomber japonicus)

“…The results show that frying decreased both the saturated and unsaturated fatty acids. This is consistent with the work of Mekonnen et al [47], who reported a decrease in fatty acid content in fish muscle after frying. The decrease in fatty acids might be due to the oxidation of fat during frying.…”

Effects of Repeated Heating on Fatty Acid Composition of Plant-Based Cooking Oils

“…Therefore, the n–3/n–6 PUFA ratio can be used for the potential cardiovascular (and health) effect of foods. In the present study, the n–3/n–6 PUFA ratios were declining in each oil during heating sequences, in concert with previous findings on the effect of frying on the n–3/n–6 PUFA ratios in different foods and oils [ 51 , 55 , 56 , 68 , 69 , 70 , 74 , 78 , 79 , 80 ].…”

“…Heating decreased the HH ratio in each plant-based oil investigated in the present study. In contrast, a previous study didn’t find lower HH ratio in tilapia after frying [ 70 ], while in mussels the HH ratio was even increased compared to fresh samples [ 80 ]. To the best of our knowledge, no previous studies have investigated the effect of heating on the HH ratio of oils, only in fried foods.…”

“…As heating and frying result in a decrease in the MUFA and PUFA values as well as in an increase in SFA and TFA values, these indices will also change into a more atherogenic and thrombogenic direction. Among different food preparation methods, frying can increase IA and IT values to the greatest extent [ 68 , 69 , 70 , 71 ]; however, the nature of the oils used during the processes can also greatly influence these values [ 51 , 55 , 56 , 68 , 72 , 73 , 74 ]. An experimental study showed that frying at lower temperature, in small amounts of oil and for a short time resulted in the highest IA and PUFA/SFA values [ 75 ], so the nutritional quality of fried food could be optimized with careful preparation.…”

Characterization of the Key Aroma Constituents in Fried Tilapia through the Sensorics Concept

“…The crispiness of the fried product, the aroma of baking and frying, and the pleasant golden to brown color make fried tilapia a popular food worldwide [ 3 ]. The smell of food is an important index in food evaluation, so the study of fried food is very important [ 4 ].…”