Effect of Postharvest Polyamine Treatments on Physicochemical Quality and Shelf Life of Papaya (Carica papaya L.) cv. Red Lady during Refrigerated Storage

Abstract

Papaya (Carica papaya L.) cv. Red Lady is a highly perishable climacteric fruit that undergoes rapid ripening and quality deterioration after harvest. This study evaluated the effectiveness of postharvest polyamine treatments for maintaining physicochemical quality and extending shelf life during refrigerated storage. Uniform fruits were subjected to ten treatments comprising an untreated control, spermine at 0.5–1.5 mM, spermidine at 0.5–1.5 mM, and putrescine at 2.0–4.0 mM. Treated fruits were stored at 13 ± 1°C and 90–95% relative humidity for 21 days, and observations were recorded at 3-day intervals. Polyamine treatments delayed deterioration compared with the control, with putrescine at 4.0 mM consistently showing the most favourable response. At 21 days, this treatment recorded 17.93% physiological loss in weight, a respiration rate of 20.96 mL CO₂ kg⁻¹ h⁻¹, firmness of 4.34 N, and a fruit disease index of 18.26%, compared with 24.52%, 28.64 mL CO₂ kg⁻¹ h⁻¹, 1.14 N, and 59.29%, respectively, in the control. Putrescine at 4.0 mM also produced the longest shelf life of 21.00 days, compared with 15.33 days in untreated fruits. Overall, postharvest polyamine application, particularly putrescine at 4.0 mM, delayed ripening-associated changes, maintained fruit quality, reduced disease development, and extended the marketable storage life of papaya under refrigerated conditions.