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Food Technologies for Safe & Quality Foods

Learn how food technologies can preserve, improve quality, and ensure safety of food products while controlling microbiological hazards.

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Food Technologies for Safe & Quality Foods

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  1. FoodTechnologies torenderandkeepfoodssafe FS05021 2000

  2. Introduction (1) Historically, objectives of food technologies have been - preservation of food - rendering food more palatable and digestible FS05022 2000

  3. Introduction (2) In modern times, food technologies are applied with the additional objectives - developing new food products - giving food desired functional properties - improving nutritional and organoleptic q-ality - ensuring safety FS05023 2000

  4. Foodtechnologies and foodsafety Basic knowledge of food technology can help to - identify appropriate control measures (may involve application of several technologies) - select parameters which assure their effectiveness - decide how these parameters need to be monitored FS05024 2000

  5. Objective To understand - how different food technologies can be used to prevent and/or control hazards in foods - the factors (parameters) which influence the process and thus the safety of the final products, - how to monitor these factors FS05025 2000

  6. Classesof foodtechnologies Food technologies can be classified into those that - render food safe - control contaminants i.e. prevent growth of microorganisms or production of toxin(s) - prevent (re-) contamination FS05026 2000

  7. Foodtechnologies thatmaykillcertainmicrobes - Heat treatments - Irradiation - Disinfection - Freezing (parasites only) - High pressure technology FS05027 2000

  8. Heattreatments Method of heating Heating medium water cooking air baking / roasting water boiling oil frying air grilling electromagnetic radiation microwave heat exchanger / water pasteurisation steam under pressure sterilisation FS05028 2000

  9. D-value Heat resistance is measured by the decimal reduction time D No: Initial number of microorganisms N: Number of microorganism at time t log N/No 0 T (°C) -1 t = D. log No/N -2 D -3 t FS05029 2000

  10. Heatresistance(1) D-values (min) Vegetative organism 55°C 60°C 65°C Escherichia coli Salmonella spp 4 0.1 0.02-0.25 0.056 Salmonella typhimurium Salmonella senftenberg Staphylococcus aureus Listeria monocytogenes Campylobacter jejuni 0.8-1.0 0.2-2.0 5.0-8.3 1.1 FS050210 2000

  11. Heatresistance(2) D-values (min) Bacterial endospores 100°C 110°C 121°C C.botulinum type A and B C.botulinum type E 50 0.1-0.2 < 1 sec C.perfringens C.sporogenes Bacillus cereus 0.3-20 0.1-1.5 5 FS050211 2000

  12. Heatresistance(3) Heat resistance ( D-value ) is influenced by many factors, e.g. u type or strain of microorganism uphysico - chemical parameters of the medium e.g. water activity, pH, composition u age of the cells or state of growth FS050212 2000

  13. Pasteurisation schemes Low temperature 63° C for 30 min High temperature 72° C for 15 sec Ultra-high temperature 135° C for 1 sec FS050213 2000

  14. Temperaturegradient in hamburger Temperature (o C ) 200 surface Crust 150 3 mm 3.5 mm Cooked 4 mm centre zone 100 Crumb Raw meat 50 Time (s) 900 1800 2700 3600 FS050214 2000

  15. Microwavetreatment Heat is generated by friction of water molecules under the influence of electromagnetic waves (500 MHz to 10 GHz) Rapid but non - uniform heating (cold and hot spots) FS050215 2000

  16. Freezing Effective against parasites Critical limit: - 18° C for minimum 24 to 48 h No or minimal effect on u survival of bacteria and viruses u enzymatic activity (polyphenol oxidase, lipase) FS050216 2000

  17. Foodirradiation - Food irradiation at any dose has been assessed by IAEA, FAO and WHO as safe - Macronutrients and essential minerals are not affected by food irradiation - Certain vitamins e.g. thiamine and tocopherols are sensitive, but the loss is small (10 - 20 % or less) and comparable to thermal processing or drying FS050217 2000

  18. Sensitivityofmicroorganisms Parasites G - Bacteria Necessary dose Parasites 1.0 kGy Bacteria 1-7 kGy (Viruses > 30 kGy) G + Bacteria, moulds Spores, yeasts Viruses + FS050218 2000

  19. Chemicaldisinfection Example of application Example of disinfectant agent Water chlorine Fruits and vegetables Surfaces and hypochlorite chlorine dioxide iodine equipment chloramines ozone FS050219 2000

  20. Chlorinationofwater(3) The normal conditions for chlorination free resid. chlorine > = 0.5 mg / l contact time minimum 30 minutes pH < 8 water turbidity < 1 NTU FS050220 2000

  21. Chlorinationofwater(4) To eliminate parasites and decrease turbidity, chlorination is combined with u coagulation and flocculation u filtration FS050221 2000

  22. Disinfectionof fruitsandvegetables Depending on type of fruits and vegetables some decrease may be obtained Not fully effective FS050222 2000

  23. Foodtechnologies to controlthedevelopmentof microbiologicalhazards FS050223 2000

  24. Technologies Technologies based on - temperature control - control of water activity - control of pH - control of redox potential - antimicrobial agents FS050224 2000

  25. How temperature affects growth rate of a bacterial population B (Optimum) C (Minimum) A (Maximum) Cold Hot Temperature FS050225 2000

  26. GrowthofS.typhimurium atdifferenttemperatures 9 8 7 25° 20° 6 15° 5 10° 4 3 2 1 0 0 1 2 3 4 5 Time (Days) FS050226 2000

  27. Temperaturerange forgrowthofpathogens Temperature°C Min. Opt. Max. Salmonella 5 35 - 37 47 Campylobacter 30 42 47 E. coli 10 37 48 S. aureus 6.5 37 - 40 48 C. botulinum (proteolytic) 10 50 C. botulinum (non - proteolytic) 3.3 25 - 37 B. cereus 4 30 - 35 48 - 50 FS050227 2000

  28. Temperaturerangeforgrowth oftoxigenicmoulds Temperature °C Min. Opt. Max. Penicillium verrucosum Aspergillus ochraceus Aspergillus flavus 0 20 31 8 28 37 10 32 42 3 25 37 Fusarium moniliforme FS050228 2000

  29. Temperaturezones Boiling point 100° SAFETY Pasteurising temperature 72° 60° Body temperature DANGER 36.5° Fridge 10° 0° SAFETY Freezer FS050229 2000

  30. Psychrotrophicpathogens - L . monocytogenes - Y . enterocolitica - C . botulinum type FS050230 2000

  31. Wateractivity - Water is required for the growth and metabolism of microorganisms - All the water in foods is not available for microorganisms - The degree of availability of water is measured by water activity (a w ) -Chemical and enzymatic reactions are also affected by availability of water FS050231 2000

  32. Minimumlevels of aW permitting growth ( at nearoptimumtemperatures) Moulds Aspergillus chevalieri 0.71 Aspergillus ochraceus 0.78 Aspergillus flavus 0.80 Penicillium verrucosum 0.79 Fusarium moniliforme 0.87 Yeasts Saccharomyces rouxii 0.62 Saccharomyces cerevisiae 0.90 Bacteria Bacillus cereus 0.92 Clostridium botulinum (proteolytic) 0.93 Clostridium botulinum (non-proteolytic) 0.97 Escherichia coli 0.93 Salmonella 0.95 Staphylococcus aureus 0.83 FS050232 2000

  33. Rangeof aWinfoods andtheir microbial flora aw range Foods Microbial flora Fresh meats Fresh fish Fresh fruits (C. perfringens, Fresh vegetables > 0.98 Salmonella) Canned vegetables in brine Canned fruit (Pseudomonas) in light syrup (<3.5 % salt, 26% sugar) Fermented sausages (B. cereus, 0.93 - 0.98 Processed cheese Bread C. botulinum, Salmonella) Evaporated milk Tomato paste lactobacilli, bacilli and micrococci (10% salt, 50% sugar) FS050233 2000

  34. Rangeof aWinfoods andtheir microbial flora aw range 0.85 - 0.93 Foods Microbial flora S. aureus Dry fermented sausages Mycotoxin Raw ham (17% salt, producing moulds Spoilage yeasts saturated sucrose) and moulds Dried fruit Flour Xerophilic fungi 0.6 - 0.85 Cereals Halophiles Salted fish Nuts Osmophilic yeasts Confectionery Honey No growth but may remain viable < 0.6 Noodles Dried egg, milk FS050234 2000

  35. Wateractivity(4) aw can be reduced by - Removing water (drying) - Decreasing availability of water by crystalization (freezing) - Decreasing availability by binding water with water binding agents e.g. salt, sugar FS050235 2000

  36. pHvalueslimiting the growth of pathogens pH Min Max. Escherichia coli 4.4 8.5 Salmonella typhi 4 - 4.5 8 - 9.6 Bacillus cereus 4.9 9.3 Clostridium botulinum 4.6 8.5 Staphylococcus aureus 4 9.8 Saccharomyces cerevisiae 2.3 8.6 Aspergillus flavus 2.0 11.2 Fusarium moniliforme 2.5 10.7 Penicillium verrucosum 2.0 10.0 FS050236 2000

  37. pHandotherfactors Microorganisms can grow in lab media at a wider range of pH than would occur in foods Here, other factors come into effect e.g. microbial competition - oxygen tension - storage temperature - reduced aw - heat damage to cells during processing FS050237 2000

  38. pH Acidification - addition of vinegar Fermentation - organic acid - competitive exclusion - antimicrobial agents FS050238 2000

  39. pHofdifferentfoods Approximate pH ranges of some common food commodities pH 14 13 12 Fermented shark Egg white 11 10 9 8 fish milk flour meat 7 vegetables 6 5 4 beer Soft drinks Citrus fruits 3 2 FS050239 2000

  40. ControlofE h - Vacuum packaging - Modified atmosphere packaging by gas flushing: CO2 , N2 FS050240 2000

  41. Antimicrobialagents - Curing salts e.g nitrites - Bacteriocins e.g. nisin - Gas: e.g CO2 - Organic acids / salts e.g benzoic, sorbic and propionic acid FS050241 2000

  42. Foodtechnologies thatpreventcontamination FS050242 2000

  43. Additionaloperationsand aspectsofimportance - Packaging - Hygienic design of factories, lines and equipment - Cleaning and disinfection FS050243 2000

  44. Packaging - Prevent re-contamination - Protect solid food against moisture uptake - Maintain low oxygen atmosphere - Protect food against light FS050244 2000

  45. Packaging-Keymessages -The purpose of packaging is to protect the food from change in quality, including microbiological and physico-chemical alterations. -The major cause of alterations are water vapour or moisture, oxygen, light and chemicals. -Hazards can be associated with packaging material or processes -Packaging material must be chosen as a function of the preservation process, stability and characteristics of the food FS050245 2000

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