Physiological and physico-chemical changes in 1-methylcyclopropene-treatedguava (Psidium guajava L. cv. Queso de Bola) fruit stored at ambient condition

The marketability of guava fruit is influenced by its quality attributes desired by consumers such as crispiness and crunchiness, green peel color, absence of defects, and better taste. ‘Queso de Bola’ guava fruits were treated with 600 nL L-1 of 1- methylcyclopropane (1-MCP) for 12 hrs then stored at ambient condition (29±2°C, 60- 80% RH). Reduced respiration rate with 1-MCP treatment was observed only starting on the 5th day of storage. Ethylene production, however, was not suppressed. The continuous decline in polygalacturonase activity with 1-MCP treatment coincided with firmness retention of the fruit until the 15th day. Higher firmness of 1-MCP-treated fruits than control fruits was further supported by higher sensory scores for crispiness and crunchiness particularly towards the later part of storage. 1-MCP treatment did not prevent peel browning as shown by similar polyphenol oxidase activity and pattern of change in total phenolic content. Total soluble solids, titratable acidity, and pH were not affected by 1-MCP treatment and did not markedly change during storage. Ascorbic acid content decreased in both treatments until day 6 followed by a slight increase with 1-MCP treatment exhibiting higher levels than the control. In general, 1-MCP treatment prolonged the marketability of guava by 3-4 days which was attributed to the maintenance of firmness, retention of green peel color, and reduced disease incidence.