Oil Composition and Phenolic Compounds of Plum Seeds Obtained from Fruit Processing By-products Treated by Heat

In this study, the effect of microwave drying on oil content, bioactive compounds, antioxidant activity, polyphenols and fatty acid profiles of fresh (control) and dried plum kernels was investigated. The oil quantities of plum seeds dried were found between 27.40% (control) and 42.42% (900 W). Total phenolic and flavonoid values of fresh (control) and dried-plum seeds were assessed to be between 9.77 (control) and 41.66 mgGAE/100 g (900 w) to 6.90 (control) and 23.67 mg/100 g (900 W), respectively. Total phenol and flavonoid quantities of the plum seeds dried at 900 W were slightly higher than those of the plum seeds dried at 720 W. L* (brightness) values of plum seeds changed between 55.97 and 59.62. Roasting in the microwave oven at 720 W was decreased the L* values of samples, while L* value of sample roasted at 900 W was closed to control. Gallic and 3,4-dihydroxybenzoic acid values of plum kernel samples were assigned to be between 1.19 (720 W) and 2.01 mg/100 g (900 W) to 0.22 (control) and 7.09 mg/100 g (900 W), respectively. Also, catechin and rutin quantities of plum seeds were established between 0.20 (control) and 7.55 mg/100 g (900 W) to 1.42 (control) and 3.59 mg/100 g (900 W), respectively. In general, the amount of phenolic compounds of plum seeds dried at every two watts showed an increase (except quercetin) compared to the control. Only the amount of quercetin decreased partially in the dried samples. While oleic acid quantities of raw (control) and dried plum kernel oils are reported between 68.28% (720 W) and 71.60% (900 W), linoleic acid amounts of plum kernel oils were found between 20.77% (900 W) and 23.49% (720 W). The quantities of saturated fatty acids in plum kernel oils were found to be quite low compared to the content of unsaturated fatty acids.