Purpose: Determine the efficacy of postharvest room cooling on microbial quality control during peach storage.
Methods: Peaches, harvested from different orchards in Florida, were collected from pallets (fresh), pre-pack (room-cooled), and post-pack line. Three trials with triplicate samples were analyzed (n=9). Each sample was a composite of five peaches (diameter ~ 6.5 cm) and was collected in sterile plastic bags, which were transported in ice-box to the lab and immediately analyzed. Hundred ml 0.1% sterilized peptone water was added to each bag, then aerobic plate counts (APC) and yeast and mold counts (YM) were determined. Peaches from the post-pack line were incubated at 1.1°C for 21 days. Representative samples were withdrawn on days 1, 7, 14, 21.
Results: The average APC from fresh samples, pre-pack and post-pack lines were all 5.2 log CFU/peach. At the end of the 21-day incubation period, the APC on peaches from the postpack line was 4.9 log CFU/peach. The average YM counts from fresh peach and room-cooled samples were 6.2 and 6.1 log CFU/peach, respectively. After packing, the YM counts on the postpack samples were 6.0 log CFU/peach and increased slightly to 6.2 log CFU/peach at the end of the 21-day incubation. The changes in microbial counts on peaches from different stages of the postharvest process were not statistically significant (P>0.05). The APC was significantly higher (P<0.005) in trial three as compared to the other two trials, possibly due to heavy rainfall prior to harvest.
Significance: Information obtained will be used to recommend the best temperature management for maintaining the postharvest quality of peaches.