P2-110 Microbial Quality of Blueberries for the Fresh Market

Tuesday, August 2, 2016
America's Center - St. Louis
Joycelyn Quansah, The University of Georgia, Griffin, GA
Himabindu Gazula, The University of Georgia, Griffin, GA
Renee Holland, The University of Georgia, Athens, GA
Yue Cui, The University of Georgia, Griffin, GA
Harold Scherm, The University of Georgia, Athens, GA
Changying Li, The University of Georgia , College of Engineering, Athens, GA
Fumi Takeda, Appalachian Fruit Research Station, Kearneysville, WV
Jinru Chen, The University of Georgia, Griffin, GA
Introduction: Harvested blueberries are routinely sorted in packing house to remove pre-mature fruits and plant debris, packaged in plastic clamshells, and cooled in refrigeration facilities before being shipped to the fresh markets. Fresh berry packing involves no kill steps and berry consumption has been linked to foodborne outbreaks of infections.

Purpose: This study determined the microbial quality of fresh blueberries collected from berry-packing houses.

Methods: Unpacked and packed blueberries (n=92) were collected in duplicate in the morning, lunchtime, and evening from five different packing house in Georgia from May to June of 2015. Berries were rinsed (n=92) or homogenized (n=92) in 0.1M PBS and appropriate dilutions were inoculated on tryptic soy agar, MacConkey agar, Enterococcus agar and potato dextrose agar and resulting microbial colonies were enumerated. The influence of packing, sample source, sampling time, and sample preparation method on berry-borne microbial counts was determined.

Results: Average aerobic bacteria, yeast and mold, and total coliform counts of collected berries ranged from 3.13 to 5.20, 3.76 to 4.85, and 0.62 to 2.21 log CFU/g, respectively. Six berry samples from two processing plants tested positive for fecal coliforms and one sample tested positive for enterococci. Sample source and sampling time have a significant influence (P≤0.05) on the aerobic bacteria counts, and yeast and mold counts. Berry samples collected in the evening had the lowest microbial counts. Packing of fresh berries had no significant influence (P>0.05) on microbial counts, however, non-packed berries had higher aerobic bacteria, yeasts and molds counts than packed berries. Homogenization of berries before enumeration resulted in higher yeast and mold counts than rinsing.

Significance: This study suggests that sorting of blueberries before packing for the fresh market does not lead to reduction in microbial counts. Packed blueberries are labelled as not ready to eat products therefore, thorough washing of retail blueberries before consumption should be encouraged.