Purpose: The objective of this study was to determine the best handling practices for temperature management for quality control of blueberries.
Methods: Blueberries were harvested and split into two groups. The first group was sampled from the field, pre- and post-packing lines. The second group was cooled for 24 h and then packed. Field, pre-packed and post-packed (non-cooled) samples were examined on day 0, whereas post-packed samples (both non-cooled and cooled) were examined subsequently on days 1, 7, 14 and 21. Determination of aerobic plate count (APC) on plate count agar, and yeast and molds (Y&M) on potato dextrose agar from composite samples were performed. One hundred ml of 0.1% (w/v) sterile peptone water was added to the sterile sample bags with ~10 g of blueberries and homogenized for 60 s. One hundred μl of each dilution was spread plated, incubated, and APC and Y&M were counted.
Results: The average initial counts of APC from field samples were 4.2 log CFU/g, 3.8 log CFU/g from the pre-packing line, 4.5 log CFU/g from the post-packing (non-cooled) line, and 4.3 log CFU/g from the post-packing (cooled) line. Those counts for the latter two lines of samples reached 4.6 log CFU/g and 4.8 log CFU/g, respectively after 21 days. The average initial counts of Y&M were 3.9 log CFU/g, 3.6 log CFU/g, 3.9 log CFU/g and 3.5 log CFU/g for field, pre-packing line, post-packing (non-cooled) line and post-packing (cooled) line, respectively. After 21 days those counts for the latter two lines of samples reached 4.1 log CFU/g and 4.2 log CFU/g, respectively.
Significance: Information obtained will be used to recommend the best temperature management to maintain postharvest quality of blueberries.