Purpose: The objective of this study was to estimate classes of native microflora of WPC34 and WPC80 using different agar media and then investigate how storage temperatures (5, 10, 15, 22 and 30°C) for 7 days would affect survival and growth of each class of the bacteria estimated.
Methods: Immediately after receiving WPC34 and WPC80 from the manufacturer, the initial populations of aerobic mesophilic bacteria, coliform, yeast and mold, lactic acid bacteria including lipolytic bacteria were enumerated, and bioluminescent adenosine triphosphate (ATP) assay was used to estimate ATP level corresponding to the overall microbial populations associated with WPC34 and WPC80 products.
Results: Total microbial populations in WPC34 and WPC80 determined immediately and after storage for 7 days averaged 6.8 log and 7.1 log CFU/g, respectively, and the corresponding ATP values associated with the total microbial populations averaged 62 and 73 RLU, respectively. Class of microorganism estimated from WPC80 averaged 2.8 log CFU/g for aerobic mesophilic bacteria, below detection (<2 cfu="" g="" for="" yeast="" and="" mold="" coliform="" bacteria="" as="" well264="" log="" lipolytic="" lactobacillus="" respectively="" wpc34="" aerobic="" mesophilic="" determined="" averaged="" 3015="" below="" detection="" storage="" temperatures="" did="" not="" cause="" significant="" P > 0.05) changes in total microbial populations of WPC34 and WPC80.
Significance: The results of this study suggest that storage temperature up to 30°C for 7 days would not change the native microbial population and that the bioluminescent ATP assay can effectively be used to estimate total microbial populations in WPC34 and WPC80 products.