8/24/2016 Learning Objectives Food Understand how the canning industry overcomes the challenge of spore heat resistance Define the traits of low-acid canned foods and how they must be processed Chapter 3 AN INTRODUCTION with the Spores and Their vation Significance Compare a spore to a vegetative cell Explain the physical chemical bases for spore heat resistance haRh空造Ka R.Mathe Compare the cycles of sporulation and germination with the gain and loss of spore resistance characteristics What are spores? The Life Cycle of an Endospore-Forming Bacterium vival in times of adw rse conditions and/or for reproduction. Enable a cell to survive environmental stress .Heat ·Freezing ·High salt conditions Drying -High acid conditions Spore-forming bacteria are found in foods grown in the soil and in animal products
8/24/2016 1 Chapter 3 Spores and Their Significance 1 Learning Objectives • Understand how the canning industry overcomes the challenge of spore heat resistance • Define the traits of low-acid canned foods and how they must be processed • Understand the fundamental difference between a bacterial spore and a vegetative cell • Correlate the unique properties of spores with the challenge they present for food preservation • Compare a spore to a vegetative cell • Explain the physical chemical bases for spore heat resistance • Compare the cycles of sporulation and germination with the gain and loss of spore resistance characteristics 2 What are spores? • Bacterial endospore – small, dormant, resistant derivative of a bacterial cell that germinates under favorable growth conditions into a vegetative cell • Spore – specialized cell form that can be used for dissemination, for survival in times of adverse conditions and / or for reproduction. • Enable a cell to survive environmental stress - Heat - Freezing - High salt conditions - Drying - High acid conditions • Spore-forming bacteria are found in foods grown in the soil and in animal products 3 4
8/24/2016 Spore-forming bacteria and heat resistant fungi cause big problems in the food industry Toxin-producing spore-forming bacteria -Clostridium botulinum Spores in the Food Industry -Clostridium perfringens -Bacillus cereus ·Spoilage species Alicyclobacillus -Geobacillus Sporolactobacillus Sporeformers,Disease,and Food Canning Industry Spoilage Early 1900s,US,appertization(heating foods 120C)developed into canning industry as Low-acid foods (>4.6 pH)packaged in scientific principles were developed cans,bottles,pouches or vaccum sealed Prescott,Underwood,and Russell-spore-forming containers are particularly vulnerable bacilli cause spoilage of thermally processed food Diseases and spoilage caused by Esty and Meyer-values for heat resistance of sporeformers are usually associated spores with thermally processed foods Ball-mathmatical foundation for commercial Heat kills vegetative cells but NOT canning spore-forming microbes rescued the US canning industry from near death in the 1940s due to botulism outbreaks 2
8/24/2016 2 Spores in the Food Industry 5 • Spore-forming bacteria and heat resistant fungi cause big problems in the food industry • Toxin-producing spore-forming bacteria - Clostridium botulinum - Clostridium perfringens - Bacillus cereus • Spoilage species - Alicyclobacillus - Geobacillus - Sporolactobacillus 6 Sporeformers, Disease, and Food Spoilage • Low-acid foods (>4.6 pH) packaged in cans, bottles, pouches or vaccum sealed containers are particularly vulnerable • Diseases and spoilage caused by sporeformers are usually associated with thermally processed foods • Heat kills vegetative cells but NOT spore-forming microbes 7 Canning Industry • Early 1900s, US, appertization (heating foods 120°C) developed into canning industry as scientific principles were developed • Prescott, Underwood, and Russell - spore-forming bacilli cause spoilage of thermally processed food • Esty and Meyer – values for heat resistance of spores • Ball – mathmatical foundation for commercial canning rescued the US canning industry from near death in the 1940s due to botulism outbreaks 8
8/24/2016 Canning Industry Low-Acid Canned Foods Canned-food industry gave rise to ·FDA and USDA Quantitative thermal process a food with a final pH of >4.6 and a -Understanding of spore heat water activity of >0.85 resistance Thermal process,facility,equipment,and Aseptic processing formulations must be filed with the FDA and USDA before a canned product can be Implementation of HACCP concept made Requlations are described in US Code of Federal Regulations(21 CFR,parts 108 to 114) Commercial Sterility Inactivation of Clostridium botulinum spores Uses heat to inactivate foodborne pathogens and spoilage microoganisms that Primary processing goal for low-acid food can grow in the food canning Hermetically sealed-air tight containers Most heat resistant pathogen Shelf-stable product with negligiblemicrobial Severity of treatment depends on survival -Class of food (uncured meat vs cured meat) Also produced by acidification or reduction -Spore content in the water activity of the food pH and water activity -Storage conditions Combine techniques to reduce heat and improve product quality Foods with high spore loads(mushrooms spices)require monitoring
8/24/2016 3 Canning Industry • Canned-food industry gave rise to - Quantitative thermal process - Understanding of spore heat resistance - Aseptic processing - Implementation of HACCP concept 9 Low-Acid Canned Foods • FDA and USDA a food with a final pH of >4.6 and a water activity of >0.85 • Thermal process, facility, equipment, and formulations must be filed with the FDA and USDA before a canned product can be made • Regulations are described in US Code of Federal Regulations (21 CFR, parts 108 to 114) 10 Commercial Sterility • Uses heat to inactivate foodborne pathogens and spoilage microoganisms that can grow in the food - Hermetically sealed – air tight containers - Shelf-stable product with negligible microbial survival • Also produced by acidification or reduction in the water activity of the food • Combine techniques to reduce heat and improve product quality 11 Inactivation of Clostridium botulinum spores • Primary processing goal for low-acid food canning • Most heat resistant pathogen • Severity of treatment depends on - Class of food (uncured meat vs cured meat) - Spore content - pH and water activity - Storage conditions • Foods with high spore loads (mushrooms, spices) require monitoring 12
8/24/2016 Values Used to Describe Thermal Values Used to Describe Thermal Inactivation of Spores Inactivation of Spores 10 D value-time required Typical survivor curve zvalue-temperature 103 for a 1-log reduction D121c=6 min change required to in viability at a given alter the Dvalue by a Z=13f temperature factor of 10 101 Represents the heat Expressed as degrees sensitivity of a 0 Represents how heat microbe at a specific sensitivity changes as temperature temperature changes 481216 emperature(F Heating Time(min] Canning Industry Process Design Canning Industry Process Design General requirements: Protects against: Low-acid canned foods 1.Public health hazard from C.botulinum 12D killing achieved with 3-6 min at 121C(250F) spores Inactivates C.botulinum spores with a Di2roc of 0.21 min and a z-value of 10C (18F) 2.Spoilage from mesophilic spore- ·Economic spoilage formers 5D killing 3.Spoilage from thermophilic microbes in Inactivates mesophilic spores with D:2tc of 1 min containers stored in warm environments Foods distributed in warm climates 12D killing achieved with 20 min at 121C (250F) Inactivates spores from numerous spore-formers with a of 3-4 min
8/24/2016 4 Values Used to Describe Thermal Inactivation of Spores D value – time required for a 1-log reduction in viability at a given temperature Represents the heat sensitivity of a microbe at a specific temperature Typical survivor curve D121oC = 6 min 13 Values Used to Describe Thermal Inactivation of Spores z value – temperature change required to alter the D value by a factor of 10 Expressed as degrees Represents how heat sensitivity changes as temperature changes Typical thermal resistance curve Z = 13oF 14 Canning Industry Process Design Protects against: 1. Public health hazard from C. botulinum spores 2. Spoilage from mesophilic sporeformers 3. Spoilage from thermophilic microbes in containers stored in warm environments 15 Canning Industry Process Design General requirements: • Low-acid canned foods 12D killing achieved with 3-6 min at 121oC (250oF) Inactivates C. botulinum spores with a D121oC of 0.21 min and a z-value of 10oC (18oF) • Economic spoilage 5D killing Inactivates mesophilic spores with D121oC of 1 min • Foods distributed in warm climates 12D killing – achieved with 20 min at 121oC (250oF) Inactivates spores from numerous spore-formers with a D121oC of 3-4 min 16
8/24/2016 Aseptic Processing Aseptic Processing Case example-Aseptie fiing system Improves the quality of low-acid canned foods sa Reduces energy.packaging material,and distribution costs Clean room ·Three steps 1.Product is commercially sterilized outside of the container and achieves uniform temperature-quick high temp treatment 2.Product is cooled and transferred to 一00000000000000001d presterilized containers 3.Container is hermetically sealed in a sterile Storage and refrigeration are not required for aseptic technique environment Preserve Longer shelf life than conventional retorting process Bacteriology of Sporeformers of Public Health Significance Clostridium botulinum Principle microbial hazard Three species cause foodborne illness heat-processed vacuum- Clostridium botulinum packed foods Clostridium perfringens minimally processed refrigerated foods Bacillus cereus Other sporeformers may be associated Genus Clostridium -Gram-positive with food and food spoilage anaerobic spore-forming bacilli energy by fermentation 5
8/24/2016 5 Aseptic Processing • Improves the quality of low-acid canned foods • Reduces energy, packaging material, and distribution costs • Three steps 1. Product is commercially sterilized outside of the container and achieves uniform temperature – quick high temp treatment 2. Product is cooled and transferred to presterilized containers 3. Container is hermetically sealed in a sterile environment 17 Aseptic Processing • Storage and refrigeration are not required for aseptic technique • Preserves food quality • Longer shelf life than conventional retorting process 18 Bacteriology of Sporeformers of Public Health Significance • Three species cause foodborne illness Clostridium botulinum Clostridium perfringens Bacillus cereus • Other sporeformers may be associated with food and food spoilage 19 Clostridium botulinum • Principle microbial hazard - heat-processed vacuumpacked foods - minimally processed refrigerated foods • Genus Clostridium - Gram-positive - anaerobic - spore-forming bacilli - energy by fermentation 20