The effect of different drying methods on nutritional composition and antioxidant activity of purslane (Portulaca oleracea)


Abstract: The aim of this study was to determine the effect of different drying methods on the nutritional content and antioxidant activity of purslane. Two different purslane samples have been dried using four different methods (sun, vacuum, hot air, and freeze drying). Dried and fresh samples were analyzed for their dry matter, β-carotene content, chlorophyll a and chlorophyll b contents, total flavonoid content, total flavonol content, total phenolic content, %DPPH radical scavenge activity, metal chelating activity, and color. The dry matter content of fresh purslane was 3.86%-5.28%. The β-carotene, chlorophyll a and b amounts varied from 61.31 to 67.08 mg/100 g, 103.11 to 138.11 mg/100 g and 56.14 to 62.06 mg/100 g, respectively on dry weight basis. The total flavonoid, total flavonol, and total phenolic contents were 9.61-28.20 mg RE (rutin equivalent)/g DW (dry weight), 3.48-17.27 mg RE/g, and 14.86-17.95 mg GAE (gallic acid equivalent)/g DW, respectively. DPPH scavenging activity ranged from 158.19 to 168.22 μg/mL, and metal chelating activity varied between 5.75% and 22.44%. Fresh purslane color values L*, a*, and b* ranged from 33.41 to 35.25, -6.70 to -7.28, and 13.51 to 14.60, respectively. Dry matter content, total phenolic content, antioxidant activity, β-carotene, flavonoid, flavonol, and color (L*, a*, and b*) values were significantly affected by drying method. Drying methods caused a significant decrease in β-carotene, total flavonoid, total flavonol, and total phenolic contents of purslane. On the other hand, an increase in dry matter, metal chelating, chlorophyll a and chlorophyll b have been observed as a result of drying. Considering the variations in the effects of drying methods on the examined parameters and the disadvantages of some drying methods; in addition to the reasonable results obtained by hot air drying. Hot-air drying process could be suggested as a recommendable drying process for purslane.

Keywords: Purslane, drying methods, phenolic content, and antioxidant activity

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