Frying performance and storage stability of potato chips fried in genetically modified canola oils
A study was undertaken to compare the frying performance of low linolenic (LLCO) and high oleic (HOCO) canola oils with regular (RCO) and hydrogenated (HYCO) canola oils, and the storage stability of potato chips fried in these oils. Potato chips were fried over a five day period and oil samples were collected each day for analyses. The results from chemical and instrumental analyses performed on the oils showed that there was no single olr that had consistently lower initial amounts or rates of accumulation of the degradation products. All oils demonstrated some degree of deterioration during the 5 day frying period. The frying stability of HOCO and LLCO showed a slight improvement over RCO based on the levels of free fatty acids, conjugated dienes and polars that formed in the oil. There are several explanations as to why the differences between the genetically modified oils and RCO were not as pronounced as expected. The initial quality of HOCO was impaired by the use of a high deodorization temperature during processing; high initial levels of tocopherols were found in RCO compared to HOCO and LLCO and, therefore, may have delayed the degradation of the RCO; the practice of replenishing the used oil with fresh oil each morning prior to frying may have slowed down the decomposition particularly for the RCO by introducing the additional levels of tocopherol. The storage stability of potato chips fried in each oil from frying day 1 and 5 was determined by storing the chips over 16 days at 6O oC. The results of sensory and chemical/instrumental analyses revealed that all chips had higher sensory scores for oxidation odours and accumulated primary and secondary oxidation products as storage increased. RCO potato chips had higher rates of accumulation of peroxides, free fatty acids, conjugated dienes and polars, and higher amounts of total volatiles compared to HYCO, LLCO and HOCO chips, indicating lower storage stability of RCO chips. HYCO potato chips had lower rates of accumulation of peroxides and conjugated dienes than LLCO and HOCO chips, and lower rates of free fatty acids accumulation than LLCO chips, demonstrating better stability. The changes in sensory quality appear to be supported by the chemical and instrumental results. Potato chips from frying day 5 usually had a slower accumulation of degradation products during storage compared to chips from frying day 1. Thus, the prooxidative effect of frying oil degradation products on the storage stability of potato chips was not demonstrated in this study in contrast to results from other researchers. Only HYCO chips showed an increased rate of stale/musty odour accumulation for frying day 5 compared to frying day 1...