Effects of gamma radiation and packaging on conservation of toyonoka strawberries stored under refrigeration

Strawberries have short post harvest life due to the rapid spoilage caused by fungal infections, even when stored under refrigeration. The effects of gamma radiation (0.0, 1.5, 2.0 and 2.5 kGy) and two kinds of packages (plastic boxes with or without PVC film wrapping) were evaluated using Toyonoka strawberries kept under refrigeration (3 to 6 deg C and relative humidity of 55%) for 1, 8, 15 and 22 days after irradiation, applied 1 day after harvesting. Deterioration progression and loss of weight occurred in the course of storage and although the content of ascorbic acid had also increased, total titratable acidity, p H and ratio remained constant during all the experimental period, independent of the samples treatments. The use of PVC film packing inhibited dehydration of the strawberries along the storage and also caused reduction in soluble solid content of the fruits stored for more than 8 days. The treatments with 2.0 and 2.5 kGy had caused significant losses of ascorbic acid the higher dose also significantly reduced the texture of the fruits. Sensorial analysis has been performed with 30 untrained judges to evaluate the acceptability of strawberries packed without the PVC wrapping and irradiated with doses of 0.0, 1.5 or 2.0 kGy. No irradiation effects were observed and the samples were acceptable with no significant difference between samples stored for 1 or 8 days after irradiation. PVC film packaging and irradiation were not efficient in delaying post harvest decay of Toyonoka strawberries in the conditions used in these experiments. (author)