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

Abstract

The objective of this study was to determine the possible source of predominant Bacillus licheniformis contamination 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. licheniformis would 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. licheniformis formed 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. licheniformis on stainless steel. Thirty-three B. licheniformis isolates 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. licheniformis is 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%.

Microbiological aspects and challenges of dairy powders – II: Biofilm/biofouling

“…Conditions in the production process of whey powders such as temperature, water activity, whey protein content, salt composition and lactose content in these areas affect the formation of biofilms and determine the most likely region for biofilm growth. All these factors vary throughout the production process and are likely to have an impact on biofilm formation (Md Zain et al 2017).…”

Role of Bacillus species in biofilm persistence and emerging antibiofilm strategies in the dairy industry

“…Enormous physiological versatility and extraordinary adaptability to environmental conditions enable Bacillus species to survive throughout the production, processing, and manufacturing of dairy food . Bacillus are Gram‐positive, motile, rod‐shaped, spore‐forming bacteria.…”

“…As Bacillus species are ubiquitously present in nature, they spread easily through food production systems, and contamination with these species is almost inevitable. Together with Geobacillus and Anoxybacillus species, Bacillus are considered as the most common bacteria found in dairy farms and processing plants . Moreover, they are the predominant type of gram‐positive bacteria isolated from both raw and pasteurized milk, pre‐ and post‐pasteurization segments of dairy plants .…”

“…Enormous physiological versatility and extraordinary adaptability to environmental conditions enable Bacillus species to survive throughout the production, processing, and manufacturing of dairy food. 25,[40][41][42] Bacillus are Gram-positive, motile, rod-shaped, spore-forming bacteria. As Bacillus species are ubiquitously present in nature, they spread easily through food production Together with Geobacillus and Anoxybacillus species, Bacillus are considered as the most common bacteria found in dairy farms and processing plants.…”

“…As Bacillus species are ubiquitously present in nature, they spread easily through food production Together with Geobacillus and Anoxybacillus species, Bacillus are considered as the most common bacteria found in dairy farms and processing plants. 40,[42][43][44][45][46][47] Moreover, they are the predominant type of gram-positive bacteria isolated from both raw and pasteurized milk, pre-and post-pasteurization segments of dairy plants. 36,43,48 The most common Bacillus species found in dairy-associated environments are B. licheniformis, B. cereus, B. subtilis, B. thuringiensis, B. weihenstephanensis, B. mycoides, B. sporothermodurans, and B. megaterium.…”