An investigation of the physicochemical properties and bioactive components of oil extracted from gamma-irradiated tiger nuts (Cyperus esculentus L.)

To explore the impact of gamma irradiation on the physicochemical properties and micronutrient contents of tiger nut oil (TNO), tiger nuts were irradiated at 0, 2, 4, 6 and 8 kGy and stored for 0 and 90 days. The physicochemical indexes, fatty acids, and the contents of tocopherols, sterols and phospholipids in TNO were identified and the structure was analyzed by FTIR. The results revealed that irradiation had no significant influence on the fatty acids of TNO, but increased its physicochemical indexes. Also, bioactive constituents, for instance, tocopherols and carotenoids, decreased with increasing irradiation dose. The phospholipid content increased with irradiation dose, but total sterols increased only at an irradiation dose of 2 kGy. FTIR confirmed that irradiation disrupted the structure of triacylglyceride, exhibiting a minor change in peaks at 3007, 2925, 2855, 1158, 1094 and 1032 cm^− 1. After 90 days of storage, both irradiated and unirradiated samples showed similar deterioration in oil quality indices compared to the initial storage period. It is recommended that gamma irradiation of tiger nuts should be limited to less than 2 kGy.