Herbal yield, nutritive composition, phenolic contents and antioxidant activity of purslane (Portulaca oleracea L.) grown in different soilless media in a closed system

Purslane (Portulaca oleracea L.) is a valuable plant and crop with potential industrial uses, yet little is known on how its cultivation could benefit from soilless substrates. This study aimed to assess the effects of different soilless growth media on herbal yields (fresh and dry), proximate chemical composition, total phenolic, flavonoid and anthocyanin content, and antioxidant activity of purslane cultivated in a closed system. The greatest yields over five harvest cycles were obtained with tuff-peatmoss (2:1 mixture) compared with other soilless substrates, although the edible leaves were not as rich in proteins, lipids, minerals, and phenolic compounds. The highest content of proteins (31.4% and 30.4%), lipids (0.68% and 0.75%), total phenolics (646.9 and 684.9 mg/100 g), flavonoids (597.8 and 563.8 mg/100 g), and moisture (92.5% and 93.5%) in the leaves were found in purslane grown in tuff-peatmoss-perlite (2:1:1) and in zeolitic tuff, respectively. Antioxidant activity of leaf extracts was also the highest in purslane grown in both substrates and was similar to the antioxidant activity of leaf extracts from soil-grown purslane obtained commercially and from the wild. The protein and lipid content obtained with tuff-peatmoss-perlite (2:1:1) and zeolitic tuff were superior to those of soil-grown purslane. The results show that the nutritive and antioxidant qualities of purslane can be enhanced through soilless cultivation and selection of suitable culture media.