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Antioxidant capacity is a surrogate measure of the quality and stability of vegetable oils

Castelo‐Branco, Vanessa Naciuk, Santana, Isabelle, Di‐Sarli, Vanessa Oliveira, Freitas, Suely Pereira, Torres, Alexandre Guedes
European journal of lipid science and technology 2016 v.118 no.2 pp. 224-235
acid value, antioxidant activity, canola, chemical composition, corn, fatty acids, food industry, gamma-tocopherol, linear models, lipid peroxidation, multivariate analysis, nut oils, oxidative stability, peroxide value, phenolic compounds, prediction, principal component analysis, quality control, shelf life, soybeans, sunflower oil, vegetable oil
Total antioxidant capacity (TAC) may be a comprehensive oil quality index because of its potential association with chemical composition, oxidative stability, and fresh oil quality. We aimed to investigate the chemical determinants of the oxidative stability and TAC of oils using multivariate statistical analyses and the use of the TAC assay as a predictor of oil stability. Fatty acids, tocols, phenolic compounds, peroxide value, acid value, induction period (by the Rancimat test) and TAC (by the TEAC assay) were determined in refined canola, corn, soybean, and sunflower oils as well as cold‐pressed nut oils. Principal component analysis was used for data reduction and variable extraction. Generalized linear models successfully estimated the TAC (R² = 90.3%, p < 0.005) and oxidative stability (R² = 91.6%, p < 0.001) of the oils, and γ‐tocopherol was the most important predictor in both of the models. The peroxide value and induction period were linearly associated with antioxidant capacity (R² = 0.65, p < 0.01 and R² = 0.70, p < 0.01, respectively), allowing the prediction of the initial quality and oxidative stability of the oils by the TEAC assay. Additionally, the proposed minimum TAC value for good quality refined oils was 2.2 mmol TE/kg. Practical Applications: Lipid oxidation is one of the major causes of vegetable oil degradation, affecting its global quality and limiting its shelf life. Therefore, a quality index applicable for estimating oxidative stability and initial quality of refined and cold‐pressed vegetable oils might be an important tool for quality control of oils in the food industry. We show that the TEAC assay, a simple and rapid spectrophotometric assay of antioxidant capacity, may be a useful tool for the determination of the global quality of oils due to its significant associations with the induction period and peroxide value. A minimum TAC value is advisable for good quality refined plant oils, especially when the initial quality and the shelf life are of concern. Antioxidant capacity is a surrogate measure of the quality and stability of vegetable oils. 2.2 mmol trolox equivalents/kg was proposed as a minimum total antioxidant capacity value for good quality refined oils.