Sesame ash and charcoal-grass evaporative storage: effects on postharvest quality and marketability of tomato ( Solanum lycopersicum L.)

Tomatoes (Solanum lycopersicum L.) are highly perishable in sub-Saharan Africa, where limited access to cold storage results in substantial postharvest losses among smallholder farmers. This study evaluated the independent and combined effects of sesame (Sesamum indicum L.) ash and a locally constructed charcoal – grass evaporative storage structure on the physiological, chemical, and sensory quality of three tomato cultivars ('Cherry,' 'Galisota,' and 'Tengeru') in Malawi. A total of 648 physiologically mature fruits were assessed in a 3 × 2 × 2 Completely Randomized Design with three replicates per treatment over a 28-day storage period. The combined ash and evaporative storage treatment significantly reduced physiological deterioration compared with untreated ambient controls. Weight loss declined from 44–55% in controls to 8–20% under combined treatment, while decay incidence decreased from 40–52% to 3–7%. Titratable acidity and ascorbic acid (vitamin C) were influenced by ash and storage environment (p < .05), with differences partly attributable to variations in moisture loss. Potassium content remained relatively stable. Sensory evaluation showed improved firmness, appearance, and overall acceptability under the combined treatment. These findings demonstrate that integrating sesame ash with low-cost evaporative storage can effectively reduce postharvest losses and maintain marketable quality using locally available materials.