title: 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%.
authors.affiliation: Massey Inst. of Food Science and Technology, Massey Univ., Private Bag 11 222, Palmerston North, New Zealand.|Applied Science Faculty, UiTM Negeri Sembilan, Kuala Pilah campus, 72000, Kuala pilah, Negeri Sembilan, Malaysia.
authors.forename: Siti Norbaizura
authors.initials: SN
authors.lastname: Md Zain
authors.affiliation: Massey Inst. of Food Science and Technology, Massey Univ., Private Bag 11 222, Palmerston North, New Zealand.
authors.forename: Rod
authors.initials: R
authors.lastname: Bennett
authors.affiliation: Massey Inst. of Food Science and Technology, Massey Univ., Private Bag 11 222, Palmerston North, New Zealand.
authors.forename: Steve
authors.initials: S
authors.lastname: Flint
mesh_terms: D000069976:Bacillus licheniformis / Q000254:growth & development*; D018441:Biofilms / Q000254:growth & development*; D002364:Caseins; D003470:Culture Media; D003611:Dairy Products / Q000382:microbiology*; D004866:Equipment Contamination; D005511:Food Handling / Q000379:methods*; D007785:Lactose; D008903:Minerals; D011492:Protein Hydrolysates; D013193:Stainless Steel; D014462:Ultrafiltration; D000067816:Whey Proteins
chemical_list: D002364:Caseins; D003470:Culture Media; D008903:Minerals; D011492:Protein Hydrolysates; D000067816:Whey Proteins; C026375:trypticase-soy broth; D013193:Stainless Steel; D007785:Lactose
keywords: biofilm; dairy; whey protein