Comparative evaluation of the effect of methyl bromide fumigation and phytosanitary irradiation on the quality of fresh strawberries

Abstract

Fresh strawberries are highly perishable and have a short shelf-life especially when the cold chain is not maintained. Strawberries exported to Asia are currently fumigated with methyl bromide for phytosanitary purposes, which exposes strawberries to warm temperatures for several hours and air freight without temperature control, resulting in a shelf life of just a few days in the destination country. Irradiation offers an efficacious alternative to fumigation and can be performed on cold fruit. This study was conducted to compare the quality of strawberries subject to methyl bromide fumigation or irradiation followed by simulated commercial air freight shipment of strawberries to Asian markets and ambient temperature retail display. ‘Amado’ and ‘Marquee’ strawberries were treated with methyl bromide fumigation or gamma irradiation at 400Gy. The strawberries were wrapped with insulated foil and ice packs for 24h to mimic commercial air freight conditions then maintained at ambient temperature for two days to simulate retail display. The strawberries lasted only 2 days at ambient temperature, however berries treated with methyl bromide had the highest severity of decay. Irradiated berries were an average of 20% softer than fumigated strawberries and 23% softer than control fruit, however, consumer sensory panels showed no difference in liking for irradiated, fumigated, or control strawberries. Titratable acidity, soluble solids content, color values, and ascorbic acid content were unchanged due to treatments. The marketability of irradiated strawberries was similar to the control and better than the fumigated berries, thus, irradiation at 400Gy could serve as a viable alternative to methyl bromide fumigation for export of air freighted strawberries.