Evaluation of antioxidants on oxidative stability and fatty acid profile of poultry offal oil used in the pet food industry

The aim of this study was to examine the use of antioxidants on the oxidative stability of poultry offal oil used in the pet food industry. Five commercial synthetic and two natural antioxidants were used in the following treatments: Control (CON); CON + (BHT + BHA + ETH95); CON + (BHT + BHA); CON + (BHA + PG + CA); CON + (BHT + BHA + ETH70); CON + BHA; CON + (ASC + rosemary); and CON + (ASC + tocopherols). Inclusion levels were 0.5% for the synthetic and 0.625% for the natural antioxidants. Oxidative stability was determined at three temperatures (90, 110 and 130 ºC). To determine the fatty acid profile, the original sample of the offal oil was considered a negative control. The fatty acids were determined based on the preparation of methyl esters by a transesterification reaction with methanol in alkaline medium, followed by gas chromatography analysis. The different fatty acid types were identified by comparing the retention times of the fatty acid methyl ester standards with the retention times of the observed peaks. Compositional data analysis was carried out. Without the use of antioxidant, induction time is shorter, resulting in lower oxidative stability of the offal oil and consequent loss of its quality due to less time taken to oxidize. The antioxidants used in CON + (BHT + BHA + ETH95), CON + (BHA + PG + CA) and CON + BHA better preserved the essential fatty acids (linolenic and linoleic). Natural antioxidants exhibited higher oxidation, with higher proportions of saturated fatty acids and the worst ω6:ω3 ratios. In conclusion, the synthetic antioxidants used in CON + (BHT + BHA + ETH95), CON + (BHA + PG + CA) and CON + BHA provided greater protection against oxidation and better preserved the essential fatty acids. The natural antioxidants tested in the present study did not provide satisfactory protection.