Food Preservation Principles PDF

### Introduction *3* ### What Are Foods? ### Food Preservation #### Why Preservation? - The desired level of quality - The preservation length - The group for whom the products are preserved #### How Long to Preserve? #### For Whom to Preserve? -- -- -- -- --...

### Introduction *3* ### What Are Foods? ### Food Preservation #### Why Preservation? - The desired level of quality - The preservation length - The group for whom the products are preserved #### How Long to Preserve? #### For Whom to Preserve? -- -- -- -- -- -- -- -- -- -- ### Causes of Deterioration 1. Microorganisms a. Fungi: mold and yeast b. Bacteria c. Phages d. Protozoa 2. Insects and mites e. Directly by eating (infestation) f. Indirectly by spreading diseases (fruitfly, housefly) 3. Rodents g. Directly by consuming food h. Indirectly by spreading diseases **Food** ------------------------ -- -- Meat, fish, and milk Fruits and vegetables Root crops Grains, pulses, seeds, ### Food Preservation Methods -- -- #### Inhibition #### Use of Chemicals - They are usually ineffective when initial levels of microorganisms are high. - Many microorganisms use organic acids as metabolizable carbon sources. - There is inherent variability in resistance of individual strains. - The degree of resistance may also depend on the conditions \[24\]. - Strong acids do not themselves penetrate the cell membrane. These acids may exert their influ- ence by the denaturing effect of low pH on enzymes present on the cell surface and by lowering of the cytoplasmic pH due to increased proton permeability when the pH gradient is very large. - Weak acids are lipophilic and penetrate the membrane. The primary effect of such acids is to lower cytoplasmic pH and undissociated acids may have specific effects on metabolism that amplify the effects of the weak acid. - Acid-potentiated ions, such as carbonate, sulfate, and nitrate, which are inhibitors at lower pH. #### Controls of Water and Structure #### Control of Atmosphere 8. #### Inactivation 1. ##### Use of Heat Energy - Heat is safe and chemical-free - It provides tender cooked flavors and taste - The majority of spoilage microorganisms are heat labile - Thermally processed foods, when packed in sterile containers, have a very long shelf life ##### Use of High Pressure and Ultrasound ##### Use of Electricity ##### Use of Radiation ##### Use of Magnetic Field #### Avoid Recontamination (Indirect Approach) ### Other Preservation Factors ### References 1. Bengtsson, G. 2003. Keeping quality of fresh foods. Workshop on Food Safety and Quality, 13--14 December, Sultan Qaboos University, Muscat. 2. Booth, I. R., Kroll, R. G. 1989. 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Marcel Dekker, New York. pp. 735--768. 18. Petersen, B., Tomerlin, J. R., Barraj, L. 1996. Pesticide degradation: exceptions to the rule. *Food Technol*. 50(5): 221--223. 19. Raemy, A., Lambelet, P. 1991. Thermal behaviour of foods. *Thermochim. Acta*. 93: 417. 20. Rahman, M. S. 1999. Purpose of food preservation and processing. In: *Handbook of Food Preservation*. Rahman, M. S., Ed. Marcel Dekker, New York. pp. 1--9. 21. Rahman, M. S. 2006. *Food Properties: Users' Handbook*. ORK, Dhaka. 22. Roller, S. 1995. The quest for natural anti-microbials as novel means of food preservation: status report on a European research project. *Int*. *Biodeter*. *Biodegrad*. 36(3/4): 333--345. 23. Sebranek, J. G. 1996. Poultry and poultry products. In: *Freezing Effects on Food Quality*. Jeremiah, 24. Silliker, J. H., Elliott, R. P., Baird-Parker, A. C., Bryan, F. L., Christian, J. H. B., Clark, D. S., Olson, 25. Singh, R. P. 1994. Scientific principles of shelf life evaluation. 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