Effects of tomato stalk waste–based growing media on postharvest quality and antioxidant capacity of tomato fruit during cold storage

Abstract Plant-waste-derived growing media have the potential to support circular soilless production; however, how raw and composted tomato stalk wastes affect the postharvest quality of tomato fruit remains insufficiently understood. In this study, raw tomato stalk waste (TSW) and tomato stalk waste composted for two months (PTSW) were compared with cocopeat and peat + perlite in the soilless cultivation of tomato ( Solanum lycopersicum L. cv. ‘Bandita F1’). The 4 × 3 factorial experiment, comprising four growing media × three storage periods, was conducted in a completely randomized design with three independent crate replicates for each combination. The fruits were stored in modified-atmosphere packaging at 8 ± 0.5 °C and 90 ± 5% relative humidity for 14 days. The effects of the growing media varied depending on the trait examined. On day 14 of storage, TSW reduced weight loss by approximately 54% compared with cocopeat, maintained relatively high titratable acidity, and resulted in the highest vitamin C content (206.5 mg kg − 1 fresh weight) and FRAP antioxidant activity (35.82 mmol Trolox equivalents kg − 1 fresh weight). PTSW exhibited the highest DPPH antioxidant activity, whereas cocopeat maintained the greatest firmness and peat + perlite resulted in the lowest respiration rate. The highest soluble solids content was recorded in cocopeat and PTSW, whereas TSW and PTSW maintained higher a* values. Peat + perlite, TSW, and PTSW maintained higher total phenolic and total flavonoid contents than cocopeat. Principal component analysis and hierarchical clustering indicated treatment-associated patterns, linking the waste-based growing media with bioactive and antioxidant traits, while false discovery rate-adjusted correlations revealed coordinated relationships among quality-preservation attributes. As a result, raw TSW in particular showed potential as an alternative soilless growing media for limiting selected postharvest quality losses; however, its performance varied depending on the trait examined and should be validated across different cultivars and production conditions.