Work

Impact of Passive Solar Drying and Storage on Secondary Plant Metabolites and Nitrate Contents of Abyssinian Mustard, Amaranth, and Pumpkin Leaves

Year: 2026

Type: article

Abstract: ABSTRACT The present study compared the effect of passive direct solar dryer (PDSD) and passive indirect solar dryer (PISD), each followed by a 30‐day storage period, on the secondary plant metabolite and nitrate contents of amaranth, Abyssinian mustard, and pumpkin leaves. Total carotenoid contents were retained in amaranth (0.70–0.85 mg g −1 dry weight [DW]) and pumpkin leaves (1.04–1.16 mg g −1 DW) following PDSD and PISD. However, for Abyssinian mustard, a significant decrease of the total carotenoid contents (45% PDSD, 33% PISD) was observed compared to the control (oven‐dried leaves) (0.98 mg g −1 DW). Total flavonoid contents were maintained across the vegetables (2.83–78.20 mg g −1 DW) irrespective of the drying treatment, except for amaranth leaves, where a significant decline (54% PISD) was observed compared to the control (5.83 mg g −1 DW). Although no significant difference was found in total phenolic acid contents between the control and the variants in amaranth, a significantly higher content was observed in pumpkin leaves (25.12 mg g −1 DW, PDSD) compared to the control (17.38 mg g −1 DW). Exceptionally for pumpkin leaves, a significant decline of the total chlorophyll contents (18%, PDSD; 16%, PISD) was observed after a 30‐day storage compared to the initial contents (8.37 mg g −1 DW, PDSD; 6.49 mg g −1 DW, PISD). The nitrate contents obtained in this study (80–460 mg kg −1 fresh weight [FW], PDSD; 364–915 mg kg −1 FW, PISD) were below the maximum allowable limits by the European Commission Regulation (2000–4500 mg kg −1 FW), implying the safety of the dried vegetables with respect to nitrate levels. Practical Applications This study suggests the utilization of passive solar dryers as a cost‐effective drying alternative for smallholder farmers and households in vegetable quality preservation and minimization of postharvest losses.

Source: Journal of Food Science

DOI: 10.1111/1750-3841.70800

Authors: James S. Chacha, Nadja Förster, Susanne Huyskens‐Keil, Christian Ulrichs, Constance Rybak

Institutions: Humboldt-Universität zu Berlin, Sokoine University of Agriculture

Language: English

Topic: Food Drying and Modeling

Subfield: Food Science

Field: Agricultural and Biological Sciences

Domain: Life Sciences

SDG: Zero hunger

Open Access status: hybrid

Estimated APC paid: $4,550