title: Investigation of the protective effect of whey proteins on lactococcal phages during heat treatment at various pH.
abstract: The incorporation of whey protein concentrates (WPC) into cheese is a risky process due to the potential contamination with thermo-resistant phages of lactic acid bacteria (LAB). Furthermore, whey proteins can protect phages during heat treatment, thereby increasing the above risk. The main objective of this work was to understand this protective effect in order to better control LAB phages and maximize whey recycling in the cheese industry. First, the inactivation of a previously characterized thermo-resistant lactococcal virulent phage (P1532) was investigated at 95 °C in WPC, in individual whey components β-lactoglobulin, α-lactalbumin, and bovine serum albumin as well as under different heat and pH conditions. The structural changes of the tested proteins were also monitored by transmission FTIR spectroscopy. Phage inactivation results indicated that the protective effect of whey proteins was pH and time dependent at 95 °C and was not restricted to one component. FTIR spectra suggest that the protection is related to protein molecular structures and to the level of protein aggregates, which was more pronounced in acidic conditions. Moreover, the molecular structure of the three proteins tested was differently influenced by pH and the duration of the heat treatment. This work confirms the protective effect of WPC on phages during heat treatment and offers the first hint to explain such phenomenon. Finding the appropriate treatment of WPC to reduce the phage risk is one of the keys to improving the cheese manufacturing process.
authors.affiliation: The Nutrition and Functional Foods Institute (INAF), Université Laval, Quebec G1V 0A6, Canada; Department of Food Science and Nutrition, Université Laval, Quebec G1V 0A6, Canada; Department of Biochemistry, Microbiology and Bioinformatics, Université Laval, Quebec G1V 0A6, Canada.
authors.forename: Hany
authors.initials: H
authors.lastname: Geagea
authors.affiliation: The Nutrition and Functional Foods Institute (INAF), Université Laval, Quebec G1V 0A6, Canada; Department of Food Science and Nutrition, Université Laval, Quebec G1V 0A6, Canada; Department of Food Science and Nutrition, National Research Center, Egypt.
authors.forename: Ahmed I
authors.initials: AI
authors.lastname: Gomaa
authors.affiliation: Coopérative Agropur, St-Hubert, Qc J3Z 1G5, Canada.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Remondetto
authors.affiliation: Department of Biochemistry, Microbiology and Bioinformatics, Université Laval, Quebec G1V 0A6, Canada.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Moineau
authors.affiliation: The Nutrition and Functional Foods Institute (INAF), Université Laval, Quebec G1V 0A6, Canada; Department of Food Science and Nutrition, Université Laval, Quebec G1V 0A6, Canada. Electronic address: Muriel.Subirade@fsaa.ulaval.ca.
authors.forename: Muriel
authors.initials: M
authors.lastname: Subirade
mesh_terms: D001435:Bacteriophages / Q000187:drug effects* / Q000502:physiology; D002611:Cheese / Q000821:virology*; D005511:Food Handling / Q000592:standards*; D005516:Food Microbiology; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007768:Lactalbumin / Q000494:pharmacology; D007782:Lactoglobulins / Q000494:pharmacology; D012710:Serum Albumin, Bovine / Q000494:pharmacology; D000067816:Whey Proteins / Q000494:pharmacology*
chemical_list: D007782:Lactoglobulins; D000067816:Whey Proteins; D012710:Serum Albumin, Bovine; D007768:Lactalbumin
keywords: Aggregation; FTIR; Heat treatment; Lactococcal phages; Whey proteins