P3-130 Efficacy of Buffered Vinegar in Controlling Listeria monocytogenes and Extending Shelf Life of Frozen Vegetable Products

Tuesday, July 28, 2015
Hall B (Oregon Convention Center)
Jasdeep Saini , WTI, Inc. , Jefferson , GA
Miguel Barrios , WTI,Inc. , Jefferson , GA
Introduction: Listeria monocytogenes (LM) is known to be an environmental contaminant in food processing areas and its ability to grow at 40°F makes it a pathogen of concern in frozen and refrigerated products. Handling of vegetables during packaging may introduce LM into the product and it can proliferate under abuse or elevated temperatures during storage of these products.

Purpose: This study evaluated the effectiveness of buffered vinegar (V) in controlling growth of LM and extending shelf life of frozen vegetable products.

Methods: A cold-adapted, five-strain cocktail of LM was used to inoculate (2 log CFU/g) frozen corn, edamame, and broccoli. After cell attachment for 2 h at 40°F, vegetables were sprayed with three treatments V (0.4%), DI water, and control (no spray) using a prototype sprayer. Six sub-treatments in this test included: inoculated DI, V, and control; un-inoculated DI, V, and control. Bacterial counts (25 g, n = 2) were determined (LM on MOX, shelf life on TSA, MRS and YM) after overnight freezing (day 1) and then during storage (45°F, 10 days) on days 3, 5, 8, and 10.

Results: LM counts did not increase (showed slight decrease 0.3 - 0.8 log CFU/g) throughout the 10 day abuse storage; control samples (DI and no treatment) showed an increase of 1.3 - 1.5 log CFU/g. Treatment with V also allowed shelf life extension to 10 days at 45°F. Total aerobic counts increased by 2.2 - 2.3 as compared to significant increase of 3.3 - 4.3 log CFU/g in controls. V treatment allowed yeast and mold counts to stay below 4 log CFU/g throughout the 10 day storage, while in controls, the counts were reported too numerous at day 8.

Significance: If there is a potential for temperature abuse, V can be used as a control measure to inhibit growth of LM in frozen vegetables post-thawing and extend shelf life.