Determining the oxidative stability and quality of tiger nut (Cyperus esculentus) oil and its antioxidant activity during microwave heating

Abstract

Introduction: The emphasis on high-oleic vegetable oils is prominent in human communities all over the world. That being said, the high level of monounsaturated fatty acid (oleic acid) in tiger nut (Cyperus esculentus) oil shows that it is resistant to oxidative stability. The purpose of this study, therefore, was to see if tiger nut oil can be exploited for use as an alternative or supplementary source of high-quality and nutritious cooking oil. Materials and methods: In this study, Color, RI, viscosity, PV, p-AV, FFA, TPC, at 233 and 269 nm, thermal behavior, TAG and FAC were used to evaluate the oil after microwave heating. Results: The PV, p-AV, FFA, TPC and specific extinction were increased during the microwave heating. Significant differences (p < 0.05) were detected for peroxide, anisidine, acid value, polar compounds and specific extinction. During microwave heating, the amounts of peroxide, anisidine and TOTOX values increased from initial value 3.06, 0.72 and 6.84 for unheated oil to 4.11, 10.02 and 18.25 after 15 min heating respectively. Free fatty acid changed from 0.10 to 0.12% during microwave heating. Amount of unsaturated fatty acids decreased during the heating significantly. During microwave heating the antioxidant activity was significantly decreased (p<0.05) from 68.60 to 19.66 (for unheated tiger nut oil and after 15 min heating in high concentrations by DPPH test, respectively). Conclusions: This may indicate that it can bear thermal treatments in such culinary methods as frying, and it can thus be concluded that tiger nut oil is stable in heating processes, especially frying.

Keywords

• Cyperus
• Oxidation-Reduction
• Microwaves
• Antioxidants