Evaluating the Hygiene Status of Harvest Containers and Flats in a Food Safety Study

By Wei Yang
Professor and Blueberry Extension Agent

The surging global demand for blueberries has driven a remarkable expansion in blueberry production across the world. Leading the way in highbush blueberry production are states such as Washington, Oregon, Michigan and Georgia. This growth in production, though, raises awareness regarding food safety, given that fresh produce can serve as potential carriers of foodborne pathogens. The contamination of fresh berries is a risk that may appear at various stages of the production process, particularly during harvesting and packing. Harvest containers, including lugs, flats and handpicking buckets, are potential procreating grounds for microbial contaminants if they are not subjected to proper cleaning and sanitization practices. Recognizing the paramount importance of food safety, the Oregon Blueberry Commission has placed a strong emphasis on research and education in this domain.

The study we're researching into since the 2021 harvest season involved four commercial blueberry operations, with two located in Oregon and two in Georgia. The primary aim of the study was to examine the hygiene status of blueberry harvest containers, taking into account various cleaning methods employed by these operations.

Swab samples were gathered from both used and cleaned/sanitized berry lugs, flats and handpicking buckets in the selected blueberry farms and packing facilities. These samples were subjected to an initial lab prep and transported under controlled conditions to ensure the sample integrity. Upon reaching the UGA laboratory, a series of microbiological analyses were conducted on these samples, including the enumeration of various microbial populations.

The findings from this comprehensive study were then statically analyzed. Among the harvest containers, berry lugs emerged as some of the most heavily contaminated during the harvesting process. Samples collected from facilities in both Oregon and Georgia exhibited notably higher mean counts of total aerobes and total yeasts and molds. Interestingly, as the harvest season progressed, there was a discernible improvement in container cleanliness, with mean counts generally decreasing during the second visit.

In Georgia, the study revealed that used berry lugs and handpicking buckets displayed significantly higher mean total aerobe and total yeast and mold counts compared to their cleaned/sanitized counterparts. A similar trend was observed in Oregon, where used handpicking buckets exhibited significantly higher mean total aerobe and total coliform counts than their cleaned/sanitized counterparts.

These findings underscore the pivotal role of effective cleaning and sanitization practices in maintaining the hygiene of blueberry harvest containers. Notably, containers that underwent a soaking process in chlorinated water, followed by manual washing and scrubbing, demonstrated superior results in reducing microbial counts compared to those cleaned using washing machines with unchlorinated water. Furthermore, the study revealed that chlorination of water in the washing machine after each use was a more effective method compared to manual washing.

In conclusion, this research serves as a compelling reminder of the critical importance of thorough cleaning and sanitization procedures for blueberry harvest containers. By implementing these practices, the blueberry industry can enhance the microbial safety of its berries, thus ensuring the well-being of the public and fostering consumer confidence in the consumption of fresh blueberries.