The Potential Source of B. licheniformisContamination During Whey Protein Concentrate 80 Manufacture

• Autores: Siti Norbaizura Md Zain, Rod Bennett, Steve H. Flint
• Localización: Journal of food science, ISSN 0022-1147, Vol. 82, Nº 3, 2017, págs. 751-756
• Idioma: inglés
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• Resumen

  • The objective of this study was to determine the possible source of predominant Bacillus licheniformiscontamination in a whey protein concentrate (WPC) 80 manufacturing plant. Traditionally, microbial contaminants of WPC were believed to grow on the membrane surfaces of the ultrafiltration plant as this represents the largest surface area in the plant. Changes from hot to cold ultrafiltration have reduced the growth potential for bacteria on the membrane surfaces. Our recent studies of WPCs have shown the predominant microflora B. licheniformiswould not grow in the membrane plant because of the low temperature (10 °C) and must be growing elsewhere. Contamination of dairy products is mostly due to bacteria being released from biofilm in the processing plant rather from the farm itself. Three different reconstituted WPC media at 1%, 5%, and 20% were used for biofilm growth and our results showed that B. licheniformisformed the best biofilm at 1% (low solids). Further investigations were done using 3 different media; tryptic soy broth, 1% reconstituted WPC80, and 1% reconstituted WPC80 enriched with lactose and minerals to examine biofilm growth of B. licheniformison stainless steel. Thirty-three B. licheniformisisolates varied in their ability to form biofilm on stainless steel with stronger biofilm in the presence of minerals. The source of biofilms of thermo-resistant bacteria such as B. licheniformisis believed to be before the ultrafiltration zone represented by the 1% WPC with lactose and minerals where the whey protein concentration is about 0.6%. Whey protein concentrate is a useful ingredient in many food formulations. Consistent microbiological quality of this product is important for customers. Spore-forming bacteria are the most likely contaminants as they are resistant to heat. Understanding the potential source of these contaminants through the manufacturing process will enable strategies to minimize contamination.