Quality of recycled oil and used in deep frying potato chips and fresh fish by street processors in Kampala

Abstract

Cooking oil is widely used in the preparation of deep-fried foods such as fish and chips. To cut costs, most processors recycle their cooking oil with little or no concern for its quality and the resultant health effects. This study evaluated the knowledge, attitudes and practices (KAP) of processors of deep-fried fish (n = 88) and chips (n = 213) in Kampala with regard to cooking oil quality. Recycled cooking oil samples (n=70) collected from the street processors were analyzed for peroxide value (PV), acid value (AV), thiobarbituric acid value (TBA), iodine value (IV), moisture content (MC), density (DO) and colour intensity (COI). Additionally, the study determined maximum acceptable recycling frequency on the quality of cooking oil used for deep-frying fish and chips. Processors had sufficient knowledge (mean score = 65.6%) and attitudes (67.7%) regarding cooking oil quality. However, their practices were just above average (54.8%). There was no significant relationship between knowledge and attitudes of the processors. However, there was a significant relationship (p ˂ 0.05) between their knowledge and practices. Similarly, there was a significant relationship (p ˂ 0.05) between their attitudes and practices. The PV of all the recycled oils did not conform to quality specifications. The PV of all the recycled oils did not conform to quality specifications. The mean PV, of recycled oil used to deep fry potato chips (40.51±13.29 mEq O2/kg) and fish (40.47±23.62 mEq O2/kg) were about fourtimesthe maximum allowable limit(10 mEq O2/kg). The acid value of the oil used to deep-fry potato chips (0.77±0.33 mg KOH/g) was slightly above the maximum allowable limit of 0.6 mg KOH/g. However, that of deep-fried fish 2.57±1.96 mg KOH/g was about four times higher. The TBA values for potato chips (8.69±4.26 mg MDA/kg) and fish were five to ten times above the specified limit (2 mg MDA/kg) respectively. The moisture content for potato chip and fish (0.34±0.46 g/100 ml and 0.42±0.49 g/100 ml) and oil density (1720 ± 86 kg/m3, and 1699 ± 98 kg/m3) were almost twice the specified limits 0.2g/100ml and 900 kg/m3 respectively. Values of TBA (chips = 3.12± 0.39 MDA/kg and fish = 7.27 ±0.55 MDA/kg) were above the acceptable limit (2 mg MDA/kg) after the first frying cycle but the rest of the parameters were still within their acceptable limits. Therefore, this study showed that the KAP of street processors of deep-fried potato chips and fish in Kampala with regard to cooking oil quality was poor. Consequently, the quality of their recycled cooking oil was also poor. It is also not advisable to recycle cooking oil used to deep-fry potato chips and fish. Key words: Cooking oil, recycling, deep-fat frying, chips, fish, food