Fate of on Fresh Apples under Different Storage Temperatures.

Fresh apples are typically stored for up to 1 year commercially; different apple varieties require different storage temperatures to maintain their quality characteristics. There is sparse information available about survival on fresh apples under various storage temperatures. The objective of this study was to comprehensively evaluate the effect of storage temperature on apple fruit decay and survival. Unwaxed apple fruits of selected varieties (Fuji and Granny Smith) were dip inoculated in a three-strain cocktail to establish ∼3.5 and 6.0 Log CFU/apple. Twenty-four hours post-inoculation, apples were subjected to 1, 4, 10, or 22°C storage for up to 3 months. Apples under the different storage treatments were sampled at 1-, 4-, 7- and 14-day for short-term storage under all four tested temperatures, and 2-, 4-, 8-, and 12-week for long-term storage at 1, 4, and 10°C. A set of uninoculated and unwaxed apples were simultaneously subjected to the previously mentioned storage temperatures and sampled biweekly for their total bacterial count (TPC) and yeasts/molds (Y/M) count. During the 2-week short-term storage, population on organic Granny Smith apples stored at 1, 4, or 10°C was reduced by 0.2-0.3 Log. When apples were stored at 22°C, there was a 0.5-1.2 Log CFU/apple reduction 14-day post storage dependent on the initial inoculation level. During the 12-week cold storage under 1, 4, and 10°C, count on organic Granny Smith apples decreased by 0.5-1.5 Log CFU/apple for both inoculation levels. had similar survival pattern on conventional Granny Smith and Fuji apples with 0.8-2.0 Log CFU/apple reduction over a 3-month cold storage period. Interestingly, both TPC and Y/M count were stable regardless of apple variety or cultivation practice during the 12-week storage at all tested temperatures. In summary, while did not proliferate on apple surfaces during 12 weeks of refrigerated storage, only a limited reduction of was observed in this study. Therefore, the apple industry cannot rely on cold storage alone to control this pathogen. Additional interventions are needed to eradicate on fresh apples during long-term cold storage.