Abstract: There is a folk tradition of producing oil from Cucumis bisexualis seeds. In order to promote the development and utilization of this wild plant resource, in this study, the physicochemical and thermal characteristics of the oil pressed from Cucumis bisexualis seeds were investigated. The results showed that thousand-grain mass (TGM) of Cucumis bisexualis seeds was 6 g with an oil yield of 25%. The acid value (0.37 mg/g) and peroxide value (0.17 g/100 g) of the oil met the national standard for the quality of edible oils. The relative content of unsaturated fatty acids (UFAs) was 86.27% and linoleic acid was the most predominant fatty acid (67.1% of total fatty acids) along with a lesser amount of γ-linolenic acid. Notably, the oil contained high contents of γ-tocopherol (1 614.21 μg/g) and β-sitosterol (186.18 mg/100 g) and consequently had high oxidative stability. At an initial oxidation temperature of 221.6 ℃ (measured by differential scanning calorimetry (DSC)), the oxidative induction time (OIT) of the oil was 263.91, 133.64 and 26.50 min in an oxygen atmosphere under isothermal conditions at 110, 120 and 140 ℃, respectively. The oxidative stability was superior to that of rapeseed oil. Thermogravimetric (TG) analysis indicated that the smoking point of Cucumis bisexualis seed oil was 300–350 ℃, and mass loss began to occur at 300 ℃. It had excellent thermal stability and could be utilized as a potential cooking oil.

Key words: Cucumis bisexualis seed oil; linoleic acid; γ-tocopherol; differential scanning calorimetry; oxidative stability; thermal characteristics