Does Daucus carota L. leaf provide a high potential as a source of bioactive constituents: A case study about the influences of process/storage conditions

Abstract

The current study focused on the valorization of carrot leaves, Daucus carota L. because of their high amount of ascorbic acid (AA), phenolic compounds, and the related antioxidant activity. In this study, the changes in carrot leaves caused by different drying techniques (freeze, vacuum, microwave‐assisted infrared, oven) and different storage conditions (room temperature and refrigerator) were investigated. AA contents of fresh, dried, and stored carrot leaf samples were chromatographically determined. Additionally, analysis of TPA (total phenolic content), TAC (total antioxidant capacity), total chlorophyll, carotenoid, and color were carried out. Additionally, fresh leaves were analyzed to compare their results with the corresponding values of processed or stored samples. TPA, TAC, AA, total chlorophyll, and carotenoid values of the samples stored in the refrigerator were 889 ± 63 mg/100 g d.b., 504 mg/100 g d.b., 269 A.A./100 g d.b., 253 mg/100 g d.b., and 2497 mg/100 g d.b., respectively, while the values of the samples dried at room temperature 620 ± 35 mg/100 g d.b., 303 ± 15 mg/100 g d.b., 110 ± 21 mg A.A./100 g d.b., 44 ± 3 mg/100 g d.b., 641 ± 16 mg/100 g d.b., respectively. Consequently, fresh carrot leaves have a higher vitamin C content than many leafy vegetables and even its own family, parsley. Fresh samples stored at room temperature and in the refrigerator for 7 days provided high ascorbic acid retention. Dried leaves with the MW + IR combined system provided better protection than others in terms of bioactive components. However, OD treatment at 40°C provided better protection and was one step ahead in terms of AA content.