9/18/2016 Biofilms:Special Challenges for Intrinsic Factors that Influence the Food Industry Microbial Growth Foodborne pathogens form biofilms on Characterisitics inherent to the food itself food surfaces and food contact equipment are called intrinsic factors .Only proper cleaning ensures that cells in the biofilm are reached by sanitizers such ·pH as trisodium phosphate ·Water activity(a,) Other methods of control: .Oxidation-reduction potential -Ultrasound Natural compounds that inhibit Superhigh magnetic fields bacterial growth Proteolytic and glycolytic enzymes Equipment with highly polished surfaces ·preservatives impede biofilm formation Acid-Base Balance: The amount of H'in a solution the Concept of pH pH of Common 11 .o is expressed as pH(potential Foods 10 of hydrogen) Increasing [H'],increases acidity ·1 unit change in pH is a L 9.0 change factor of 10 in 8.0 the concentration of Too high or too low pH. proton ions enzymes change in shape 6.0 ·pH is defined by pH=-log:o[H-] 5.0 Chemical reactions in a cell are ·Food with a pH of6is 4.0 sensitive to oH 10 times more acidic 3.0 Most biochem cal processes in a cell involve OH-and H ions than one with a pH of 7 2.0 12 9/18/2016 12 Biofilms: Special Challenges for the Food Industry • Foodborne pathogens form biofilms on food surfaces and food contact equipment • Only proper cleaning ensures that cells in the biofilm are reached by sanitizers such as trisodium phosphate • Other methods of control: - Ultrasound - Superhigh magnetic fields - Proteolytic and glycolytic enzymes - Equipment with highly polished surfaces impede biofilm formation 45 Intrinsic Factors that Influence Microbial Growth Characterisitics inherent to the food itself are called intrinsic factors • pH • Water activity (aw) • Oxidation-reduction potential • Natural compounds that inhibit bacterial growth • preservatives 46 Acid-Base Balance: • The amount of H the Concept of pH + in a solution is expressed as pH (potential of hydrogen) • Increasing [H+], increases acidity • Increasing [OH] increases alkalinity • Too high or too low pH, enzymes change in shape cannot promote chemical reactions in a cell • Chemical reactions in a cell are sensitive to pH • Most biochemical processes in a cell involve OH and H+ ions 47 • 1 unit change in pH is a pH of Common Foods g p change factor of 10 in the concentration of proton ions • pH is defined by pH = log10[H+ pH = log ] 10[H • Food with a pH of 6 is 10 times more acidic than one with a pH of 7 48