Effect of Heating/Frying on Trans Fatty Acid Content and Oxidative Stability of Groundnut Oil

• Published in: Annals of nutrition and metabolism 2019-01, Vol.75, p.147
• Main Authors: Jain, Akanksha, Passi, Santosh Jain, Selvamurthy, William, Singh, Archna
• Format: Article
• Language: English
• Subjects: Abuse; Anisidine; Chemical reactions; Fatty acids; Food law; Food safety; Frying; Gas chromatography; Groundnuts; Heating; High temperature; Nutrition; Oxidation; Peroxide; Safety regulations; Stability; Temperature; Trans fatty acids
• ISSN: 0250-6807; 1421-9697
• DOI: 10.1159/000501751

Background/Aims: Heating/frying at elevated temperatures cause numerous physico-chemical reactions including oxidative deterioration and trans fatty acids (TFA) formation. The study aimed at assessing the effect of constant heating/frying on formation of TFA and oxidative stability in groundnut oil. Methods: Freshly-cut potato strips were fried constantly at varying temperatures for one hour at certain temperatures (160, 180, 200, 220, and 230 .C). Analysis of TFA was performed using gas chromatography, while other chemical parameters were assessed following the official methods of AOCS. Results: Oil samples subjected to heating/ frying at various temperatures demonstrated a significant increase in TFA (p < 0.05) and saturated fatty acids (p < 0.05), while there was a corresponding decrease in cis-unsaturated fatty acids (p < 0.05). Frying process at 160 and 230 .C demonstrated greater formation of TFA with 0.11 ± 0.01 and 2.33 ± 0.05 g/100 g, respectively, as compared to heating alone at similar temperatures (0.07 g ± 0.01 and 0.47 ± 0.02 g/100 g), indicating that a significant difference in the generation of TFA during the two thermal treatments (p = 0.05). With increasing temperatures, acid value, p-anisidine value and total oxidation value also showed a significant increase (p < 0.01); however, peroxide value was found to be inconsistent. Conclusions: For groundnut oil, TFA formation and oxidative indices (except for peroxide value) are directly influenced by the temperature of heating/frying. Since formation of TFA and poor oxidative stability can pose serious health concerns, food safety agencies need to formulate appropriate policies and food laws and impose necessary safety regulations to avoid oil abuse during the process of heating and frying of foodproduct.