The objective of this study was to determine whether irradiation could serve as a suitable phytosanitary treatment alternative to methyl bromide (MB) fumigation for blueberries and sweet cherry and also to determine the effect of phytosanitary irradiation treatment on survival of Salmonella spp. and Listeria monocytogenes on these fruit. ‘Bluecrop’ blueberries (Vaccinium corymbosum) and ‘Sweetheart’ cherries (Prunus avium) were irradiated at 0.4 kGy or fumigated with methyl bromide and evaluated for quality attributes during storage.
Irradiation caused an immediate decrease in firmness of both fruit without further significant change during storage. Fumigated fruit, in contrast, softened by 11-14% during storage. Irradiation did not adversely affect blueberry and cherry shelf-life and irradiated fruit. MB fumigation did not impact blueberry and cherry quality attributes initially, however, fumigated fruit exhibited greater damage and mold growth than the control and irradiated samples. Irradiation at 400 Gy resulted in a ~1 log CFU/g reduction in Salmonella spp. and Listeria monocytogenes counts, indicating that this treatment cannot significantly enhance safety.
This study indicates that irradiation at a target dose of 0.4 kGy for phytosanitary treatment does not negatively impact blueberry and cherry quality and can serve as an alternative to methyl bromide fumigation.
Thang, K., Au, K., Rakovski, C. and Prakash, A. (2016), Effect of phytosanitary irradiation and methyl bromide fumigation on the physical, sensory, and microbiological quality of blueberries and sweet cherries. J. Sci. Food Agric., 96: 4382–4389. doi:10.1002/jsfa.7648