ARS | Publication request: Sanitization Treatment of Blueberries for the Frozen/Processing Market

Submitted to: HortScience
Publication Type: Abstract Only
Publication Acceptance Date: December 15, 2009
Publication Date: April 15, 2010
Citation: Corbitt, M., Taejo, K., Silva, J.L., Marshall, D.A. 2010. Sanitization Treatment of Blueberries for the Frozen/Processing Market. HortScience. 45:498.

Technical Abstract: Fresh blueberries are packed without washing, however, those for the frozen and other processing markets are usually washed prior to packing. Washing is usually done by dipping the berries in a water bath or by spraying water on them. This step can result in an increase in microbial load and contamination if not properly done. However, it can also be used to reduce the microbial load of blueberries, especially mold and yeasts. The purpose of this study was to compare the effectiveness of selected postharvest sanitation treatments on microbial load of blueberries prepared for the processing market. Fresh rabbiteye (Vaccinium ashei) blueberries were dipped in water along with an oxidizing agent (Boxyl®) at different temperatures and, concentration and contact times. The response surface method (RSM) was used to evaluate the effect of temperature (60 - 90°C), contact time (10 – 30s), and Boxyl® concentration (0 – 0.1%) on aerobic (APC) and yeast and mold (YMC) reduction, wax/bloom removal, and color removal on the surface of blueberries. Addition of Boxyl® to water had the least effect on microbial reduction, while affecting quality. Contact time had a minimal effect on microbial reduction. However, solution (water) temperature was the only effective (p<0.05) factor affecting microbial reduction and product quality. The ridge analysis of the response surface indicated that maximum APC and YMC microbial reduction increases with an increase in temperature; whereas wax/bloom and color removal decreased as temperature decreased. Water temperatures above 80°C resulted in adverse effects on berry quality. It was found that holding berries in water at 75°C for 20s resulted in a reduction of 3.56 to 1.78 log10 CFU/g APC; and 4.58 to 1.60 log10 CFU/g YMC. Furthermore, this treatment showed no detrimental effect on the berries as determined by sensory results. Thus, using hot water at 75°C is an alternative to adding chemicals for reduction of microbial load in blueberries.