The Effect of Roasting on Oil Content, Fatty Acids, Bioactive Compounds and Mineral Contents of Purslane (Portulaca oleracea L.) Seeds

In this study, the effect of oven and microwave roasting at different times on oil content, total phenol, flavonoid, fatty acids, phenolic components and mineral contents of purslane seeds was investigated. The total phenolic quantities of the purslane seeds roasted in the oven and microwave were characterized to be between 252.0 ± 1.80 (180 °C/5 min in the oven) and 256.6 ± 3.51 (10 min in the oven), and between 216.3 ± 0.28 (720 W/15 min in the microwave) and 203.7 ± 1.93 GAE/100 g (30 min in the microwave), respectively. The highest total flavonoid (613.8 ± 4.36 mg QE/100 g) was detected in the application of roasting in the oven for 10 min. Roasting in the oven for 5 min caused a decrease in the total flavonoid content (584.3 ± 4.95 mg QE/100 g), while roasting for 10 min caused an increase in the flavonoid content (613.8 ± 4.36 mg QE/100 g). The oil yields of purslane seed samples roasted in the oven for 5 min and 10 min were defined as 40.40 ± 0.99% and 45.00 ± 0.71%, respectively. Statistical differences were observed between the oil, total phenol and flavonoid contents of the samples depending on the roasting times in the oven and microwave (p ≤ 0.01). The protein contents of the purslane seeds were established to be between 27.89 ± 0.279% (control) and 37.24 ± 0.407% (10 min in the oven). The calcium (Ca) contents of the purslane seeds changed between 8314.99 ± 327.53 ppm (5 min in the oven) and 4340.62 ± 498.45 ppm (15 min in the microwave), while the phosphorus contents varied between 4905.13 ± 43.02 ppm (15 min in the microwave) and 4051.23 ± 6.39 ppm (unroasted). In addition, the potassium content was found to be between 4565.89 ± 153.47 (5 min in the oven) and 3904.02 ± 7.17 ppm (unroasted). It was also observed that the purslane seeds roasted in the oven for 10 min maintained a linolenic fatty acid content of up to 65.57%. Considering the bioactive properties and phytochemical components of purslane seeds roasted in both roasting systems, they are important in terms of the nutritional enrichment of foods as a food supplement.