Journal of Food Processing & Technology

Abstract

Behavior of Native Microbial Populations of WPC-34 and WPC-80 Whey Protein Stored at Different Temperatures

Dike O Ukuku, Charles Onwulata, Audrey Thomas, Sudarsan Mukhopadhyay and Michael Tunick

Whey protein (WPC34 and 80) has been used as food ingredients and as a base for making biodegradable product. However, there is limited information on the behavior of native microflora associated with these products. 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. 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. 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 and coliform bacteria, as well as 2.6 and 2.4 log CFU/g for lipolytic and lactobacillus bacteria, respectively. For WPC34, aerobic mesophilic bacteria, yeast andmold, coliform bacteria, lipolytic and lactobacillus bacteria determined averaged 3.0, 1.5, below detection, 2.0 and 3.0 log CFU/g, respectively. Storage temperatures did not cause significant (p>0.05) changes in total microbial populations of WPC34 and WPC80 and bioluminescent ATP assay can effectively be used to estimate total microbial populations in WPC34 and WPC80 products.