Changes in the microflora of commercial soft goat milk cheese during refrigerated and frozen-storage

Abstract

Three batches of commercial soft goat cheese were divided into fresh-unfrozen, 3 and 6 months frozen-storage treatment groups. All groups were stored refrigerated at 4 °C for 0, 14 and 28 days. Microbiological contents of the cheeses, including total aerobes, Escherichia coli, coliforms, Staphylococcus aureus, yeast and mold levels were determined using Petrifilm plate counts techniques. Mean total plate count (TPC), yeast and mold counts of the initial unfrozen cheese for 0 day storage at 4 °C were 5.58, 5.16 and 4.47 log cfu/g, respectively. The TPC, yeast and mold counts after 6 months frozen-storage and 0 day storage at 4 °C were 5.86, 3.70 and 3.00 log cfu/g, indicating that significant reductions of yeast and mold counts occurred during frozen-storage. These microbial populations gradually decreased during subsequent aging in refrigerated storage at 4 °C for 14 and 28 days. No detectable levels of E. coli, coliform, and S. aureus counts were found in the fresh, or frozen samples. It was concluded that commercially marketed soft goat milk cheeses were free of pathogenic bacteria, and the present study confirmed that consumers may purchase fresh and frozen-stored goat cheese products without food safety concerns.