Microbiology:General Principles of Food Preservation
Download as PPTX, PDF23 likes10,327 views
The document discusses the general principles of food preservation, emphasizing the importance of preventing microbial and self-decomposition, as well as damage from insects and mechanical causes. Key preservation methods include asepsis, removal of microorganisms, temperature control, drying, and the use of chemical preservatives. The document also outlines specific techniques such as pasteurization, freezing, and irradiation to enhance food safety and longevity.
Microbiology:General Principles of Food Preservation
- 1. General Principles of Food Preservation Elizabeth P Thomas Assistant Professor Department of Microbiology St. Mary’s College,Thrissur
- 2. Introduction Food is any substance consumed to provide nutritional support for an organism Good nutrition – an adequate, well balanced diet combined with regular physical activity Poor nutrition - reduce immunity, increased susceptibility to disease, impaired physical and mental development, and reduced productivity. General Principles of Food Preservation, Elizabeth P Thomas, St.Mary’s College
- 3. General Principles of Food Preservation, Elizabeth P Thomas, St.Mary’s College Food from plants Food from animals • Cereal and cereal products • Sugar and sugar products • Vegetables and vegetable products • Fruit and fruit products • Meat and meat products • Poultry and eggs • Fish and other seafood • Milk and milk products
- 4. Principles of food preservation Prevention or delay of microbial decomposition Prevention or delay of self decomposition Prevention of damage because of insects,animals and mechanical causes General Principles of Food Preservation, Elizabeth P Thomas, St.Mary’s College
- 5. Prevention or delay of microbial decomposition By keeping out micro organisms(asepsis) By removal of microorganism(filteration) By hindering the growth and activity of microorganism(drying,chemicals) General Principles of Food Preservation, Elizabeth P Thomas, St.Mary’s College
- 6. Prevention or delay of self decomposition By prevention or delay of purely chemical reactions(antioxidants) By destruction or inactivation of food enzymes(blanching) General Principles of Food Preservation, Elizabeth P Thomas, St.Mary’s College
- 7. Prevention of damage because of insects , animals, mechanical causes General Principles of Food Preservation, Elizabeth P Thomas, St.Mary’s College
- 8. Growth curve of microbial culture and delay of microbial decomposition Many common methods of food preservation depend on delay in the initiation of growth and hinderace to growth once it begun. General Principles of Food Preservation, Elizabeth P Thomas, St.Mary’s College
- 9. Applications to food preservation Lengthening of Lag phase and phase of positive acceleration By introducing as few spoilage organisms -by reducing the amount of contamination By avoiding the addition of actively growing organisms Unfavourable environmental conditions Process methods-heating, irradiation General Principles of Food Preservation, Elizabeth P Thomas, St.Mary’s College
- 10. Methods of food preservation Asepis Removal of microorganisms Maintenance of anaerobic conditions Use of high temperature Use of low temperature Drying Use of Chemical preservatives Irradiation Mechanical destruction-grinding,High pressure Combinations of any above method General Principles of Food Preservation, Elizabeth P Thomas, St.Mary’s College
- 11. Asepsis - Keeping out of microorganism In nature-Shells of nuts,skin of fruits,husk Application-Packing Removal of microorganism Filteration-Liquid food Centrifugation-Milk Washing-Fruits,Vegetables Trimming-Fruits,Vegetables Maintenance of anaerobic conditions Sealed foods, Using CO2 and N2 General Principles of Food Preservation, Elizabeth P Thomas, St.Mary’s College
- 12. Use of high temperature Pasteurization Heating about1000C- Baking,Roasting,Cooking,Warming up Heating above1000C -Canning/Appertization General Principles of Food Preservation, Elizabeth P Thomas, St.Mary’s College
- 13. Use of low temperature Common/Cellar storage Chilling/Cold Storage Freezing/Frozen storage General Principles of Food Preservation, Elizabeth P Thomas, St.Mary’s College
- 14. Drying Solar drying Mechanical Dryers Freeze Drying Smoking Electronic drying General Principles of Food Preservation, Elizabeth P Thomas, St.Mary’s College
- 15. Chemical preservatives • Natural sources-Salt,Sugar • Organic acid and its salt-Propionates,Benzoates • Nitrites/Nitrates • Sulfer dioxide • Ethylene • Formaldehyde • Alcohol • Wood smoke General Principles of Food Preservation, Elizabeth P Thomas, St.Mary’s College
- 16. Irradiation(Cold Sterlization) Non Ionizing-ultraviolet radiation Ionizing- Gamma rays, Cathod rays Microwave processing General Principles of Food Preservation, Elizabeth P Thomas, St.Mary’s College
- 17. References William C Frazier and Dennis C Westhoff, Food microbiology,Tata McGraw -Hill Company General Principles of Food Preservation, Elizabeth P Thomas, St.Mary’s College