Pages: (37-67 )
Abstract
Street fried foods are common food that people enjoy eating which is prepared by deep frying at very high temperature and repeated use of oil for frying lead to the formation of undesirable substances in food materials. The aim of the study was to determine the effect of repetitive use of oil on food degradation and nutrient quality. Proximate and free fatty acid analysis were used to monitor the level of degradation of nutrient quality in akara, fried yam and fish while sensory evaluation was used to test the general acceptability of these food samples. Samples were collected at different stages of frying (1st frying, 5th frying, and 7th frying) as it was noticed that vendors use frying oil for 7-10 times without discarding. The proximate result showed that the protein (7.71±0.09%) and carbohydrate (21.31±0.05%) content was highest in akara first frying while the lowest was the 5th frying. The fat content increased with number of frying times (9.18±1.23% to 16.47±1.10%). The protein and fat content for yam decreased with number of frying times but for the carbohydrate, the highest was the second stage of sampling (39.06±0.04%) while the lowest was the first stage of sampling (35.22±0.58%). For fish sample, the protein and carbohydrate decreased with number of frying times (23.73±0.26 to 21.87±0.05% and 11.11±1.76 to 3.44±2.69%), the fat content increased with number of frying times. The free fatty acid value for both fish and yam increases with number of frying times which ranges from (2.67±0.98 to 3.92±0.83% and 1.31±0.11 to 1.94±0.03%) respectively. All samples analysed exceeded the maximum level set by the Codex Alimentarius Commission. The study concludes that repeated use of oil decreases the nutrient quality of food samples even though the sensory evaluation result revealed that majority of the panellist preferred food samples fried with reused oil.
Keywords: Street fried foods, deep frying, repetitive use of oil, degradation, proximate analysis, nutrient quality, free fatty acid value.,