effect of elevated concentrations of co2 in modified atmosphere packaging on the quality of sayer dates

the purpose of this research was to determine the effect of modified atmosphere packaging (map) containing high carbon dioxide gas concentrations on the quality of sayer dates, to be used as a safe alternative to methyl bromide fumigation. different percentages of gases (85% co2 + 3% o2 + 12% n2; 75% co2 + 12% o2 + 13% n2; 34% co2 + 37% o2 + 29% n2) were injected into the cellophane packages. the control samples were cellophane packages with normal atmosphere content and simple heat seals. the packages were stored at 4ºc and 30ºc and sampled after 30, 60, 90 and 150 days of storage. the dates were tested for sugar spotting, blemish formation, ph value, water activity (aw), survival of oryzaephilus surinemensis insects, and mold and yeast counts. the samples were analyzed in three replications using a randomized complete factorial design. the percentage of insects and the mold and yeast counts were highest in the control samples stored at 30ºc and the lowest values were in packages containing 85% co2 + 3% o2 + 12% n2. the lowest ph value was found in samples in map with 34% co2 + 37% o2 stored at 30ºc. samples stored at 30ºc had a significantly lower ph values than did those at 4ºc (p<0.05). gas concentration did not have a significant effect on blemishing but the interaction effect of gas concentration and period of storage was significant (p<0.05). increasing co2 concentrationhad a significant effect on the reduction of sugar spotting with the least sugar spotting percentages reported in map containing 85% co2 + 3% o2 + 12% n2 (p<0.05). overall, the map treatment of samples containing 85% co2 + 3% o2 + 12% n2 and stored at 4º c was considered the most suitable for sayer date fruit preservation and disinfestation.