Plants · 8 authors, 3 centres
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This study analyzed the nutritional composition and sensory properties of two wild edible Sonchus species, finding them rich in vitamin C, β-carotene, lutein, and phenolic compounds. Cultivation increased vitamin C and β-carotene in both species and sugars and organic acids in S. tenerrimus, but decreased phenolic compounds in S. oleraceus. These results support the potential of these plants as sustainable, nutritious leafy greens for human consumption.
**Background:** Wild edible plants are underutilized genetic resources with potential to diversify diets and improve nutrition. Species of the genus Sonchus (Asteraceae), particularly S. oleraceus and S. tenerrimus, have been traditionally consumed in Mediterranean regions and are reported to contain high levels of vitamins, minerals, and bioactive compounds with antioxidant, anti-inflammatory, and anticancer activities. However, information on their organoleptic properties and the effect of cultivation on their nutritional composition is scarce. This study aimed to characterize the profiles of soluble sugars, organic acids, carotenoids, chlorophylls, vitamin C, and total phenolic compounds in these two species, evaluate their sensory attributes, and compare the composition of wild-collected versus cultivated plants to assess the feasibility of large-scale production.
**Methods:** The two-year study was conducted in the Region of Murcia, Spain. In the first year, wild plants were collected from multiple locations (5 batches of S. oleraceus, 12 batches of S. tenerrimus). Seeds were obtained from these plants for germination and cultivation trials. Germination rates were assessed in Petri dishes (controlled chamber) and in the field. For the cultivation trial, seeds were germinated in Petri dishes, transferred to seedbeds, and then transplanted to experimental plots with a density of 400 plants/m² in a randomized block design with four replicates per species. Plants were harvested before flowering. Metabolite analyses were performed on frozen leaf material: soluble sugars (glucose, fructose, sucrose) and organic acids were quantified by HPLC with RI or MS/MS detection; carotenoids and chlorophylls by HPLC-DAD; vitamin C by HPLC-MS/MS; and total phenolic content by the Folin-Ciocalteu method. Sensory evaluation was conducted by a panel of 15 trained assessors using a 9-point hedonic scale for overall attributes and a 10-point scale for specific taste characteristics. Statistical comparisons between species and between wild and cultivated plants were performed using ANOVA or Kruskal-Wallis tests.
**Key Results:** Germination rates in Petri dishes were 75.8% for S. oleraceus and 82.1% for S. tenerrimus, but field germination was lower (49.9% and 17.8%, respectively). In cultivated plants, total sugar content was higher in S. tenerrimus (2743.2 µg/g FW sucrose) than in S. oleraceus (748.7 µg/g FW sucrose). Organic acid profiles differed: S. tenerrimus had higher malic acid (1343.8 vs. 774.5 µg/g FW), while S. oleraceus had higher tartaric (356.0 vs. 205.4 µg/g FW) and fumaric acids (71.6 vs. 42.7 µg/g FW). Chlorophyll a and b concentrations were similar between species (130.5 and 51.6 µg/g FW in S. oleraceus; 147.4 and 56.2 µg/g FW in S. tenerrimus). Total carotenoid content was 88 µg/g FW in S. oleraceus and 99 µg/g FW in S. tenerrimus, with all-trans-β-carotene as the major carotene (49% and 50% of total carotenoids, respectively). Lutein was the predominant xanthophyll (23% and 19% of total carotenoids). Vitamin C was significantly higher in S. oleraceus (527.7 µg/g FW) than in S. tenerrimus (436.1 µg/g FW). Total phenolic compounds were significantly higher in S. tenerrimus (328.6 µg/g FW) than in S. oleraceus (188.7 µg/g FW). Sensory evaluation showed good overall acceptance (median scores 6-7 out of 9) for both species, with no significant differences in bitterness, crunchiness, fibrosity, sweetness, pungency, or acidity. Compared to wild plants, cultivation increased vitamin C by 93% in S. oleraceus and 58% in S. tenerrimus, and β-carotene by 31% in S. tenerrimus. However, cultivation decreased phenolic compounds by 57% in S. oleraceus. In S. tenerrimus, cultivation increased total sugars by 98% and organic acids by 73%.
**Clinical Implications:** This study demonstrates that S. oleraceus and S. tenerrimus are rich sources of bioactive compounds, including vitamin C, β-carotene, lutein, and phenolic compounds, with concentrations comparable to or exceeding those of common leafy vegetables like lettuce. The vitamin C content (527.7 µg/g in S. oleraceus) could supply the recommended daily allowance for women (75 mg) with consumption of approximately 142 g. The presence of luteoxanthin, which has shown potential anti-Helicobacter pylori and anticancer activities, and β-carotene, important for eye health, further supports the nutritional value. Cultivation can enhance certain health-promoting compounds (vitamin C, β-carotene) while reducing phenolic compounds, but overall quality remains high. The good sensory acceptance suggests these species could be incorporated into the diet as leafy greens or functional foods. These findings support the potential for sustainable cultivation of these wild species to provide a continuous, uniform supply of nutritious vegetables, contributing to dietary diversification and public health.