PPT-food preser

1. FOOD FOOD PRES ERV AT ION PRES ERV AT ION

2. PRINCIPLES OF FOOD PRE S ERV AT ION PRINCIPLES OF FOOD PRE S ERV AT ION 1. 1. § § § § § § § § CONTROLLING MICROORGANISMS BY: CONTROLLING MICROORGANISMS BY: KEEPING MICROORGANISMS OUT OF FOOD KEEPING MICROORGANISMS OUT OF FOOD REMOVING MICROORGANISMS FROM FOODS REMOVING MICROORGANISMS FROM FOODS DELAYING MICROBIAL GROWTH DELAYING MICROBIAL GROWTH KILLING MICROORGANISMS OR SPORES KILLING MICROORGANISMS OR SPORES 2. 2. § § § § CONTROLLING ENZYMES BY: CONTROLLING ENZYMES BY: INACTIVATING ENDOGENOUS ENZYMES INACTIVATING ENDOGENOUS ENZYMES PREVENTING OR DELAYING CHEMICAL PREVENTING OR DELAYING CHEMICAL REACTIONS IN THE FOOD REACTIONS IN THE FOOD 3 3 CONTROLLING INSECTS, RODENTS, BIRDS AND CONTROLLING INSECTS, RODENTS, BIRDS AND OTHER OTHER PHYSICAL CAUSES OF FOOD PHYSICAL CAUSES OF FOOD DETERIORATION DETERIORATION

3. Classific ation of foods Classific ation of foods § § PERISHABLE FOODS: PERISHABLE FOODS: § § NOT PROCESSED (MINIMALLY) AND HAVE A NOT PROCESSED (MINIMALLY) AND HAVE A SHELF LIFE OF SHELF LIFE OF <60 DAYS <60 DAYS. Meat, vegetables, fruits, milk fruits, milk § § SEMI SEMI- -PERISHABLE FOODS: PERISHABLE FOODS: § § SHELF LIFE: SHELF LIFE: 2 TO 6 MONTHS 2 TO 6 MONTHS AS A RESULT OF A PRESERVATION METHOD. Ice cream, cheese PRESERVATION METHOD. Ice cream, cheese § § SHELF SHELF- -STABLE FOODS: STABLE FOODS: § § SHELF LIFE SHELF LIFE > 6 MONTHS > 6 MONTHS. Cereal grains, dehydrated pasta, frozen food, canned food, dehydrated pasta, frozen food, canned food, dehydrated vegetables dehydrated vegetables . Meat, vegetables, AS A RESULT OF A . Cereal grains,

4. ROLE OF FOOD ROLE OF FOOD P PRE S ERV AT ION RE S ERV AT ION ELIMINATE ANY POTENTIAL ELIMINATE ANY POTENTIAL MICROBIOLOGICAL HARM TO THE MICROBIOLOGICAL HARM TO THE CONSUMER CONSUMER MAINTAIN QUALITY OF FOOD (SENSORY MAINTAIN QUALITY OF FOOD (SENSORY PERCEPTIONS) PERCEPTIONS) MAINTAIN NUTRITIONAL VALUE WITHIN MAINTAIN NUTRITIONAL VALUE WITHIN LIMITS DICTATED BY THE PRODUCTION LIMITS DICTATED BY THE PRODUCTION OF A SAFE FOOD PRODUCT OF A SAFE FOOD PRODUCT § § § § § § NO PRESERVATION METHOD WILL NO PRESERVATION METHOD WILL COMPLETELY ELIMINATE SPOILAGE PHENOMENA ELIMINATE SPOILAGE PHENOMENA COMPLETELY

5. Classific ation of food preservation methods Classific ation of food preservation methods Antimicrobial Antimicrobial material material Method Method Procedure Procedure Internal Internal Mechanism Mechanism External External Mechanism Mechanism Typical Typical surviving surviving microbes microbes a aw w, pH , pH Temperature Temperature - - Thermophil Thermophil bacteria, spores bacteria, spores Physical Physical Pasteurization Pasteurization sterilization sterilization a aw w Temperature Temperature - - Psychrophils Psychrophils, , Psychrotrophs Psychrotrophs Cold Cold processing processing a aw w RH RH ( (relative relative humidity humidity - - Xerophiles Xerophiles Control of Control of water content water content a aw w (Temperature (Temperature- - microwave microwave) ) - - Spores Spores Irradiation Irradiation a aw w - - NaCl NaCl H Halophilic alophilic bacetria bacetria Chemical Chemical Salting Salting a aw w (Temperature) (Temperature) Nitrites Nitrites Gr Gr+ bacteria + bacteria Curing Curing a aw w (Temperature) (Temperature) Phenols, Phenols, acids acids Depending on Depending on further preservation further preservation method method Smoking Smoking pH pH Organic acids Organic acids Bacteria tolerate Bacteria tolerate acid acid Preservatives Preservatives a aw w, pH, E , pH, Eh h (Temperature) (Temperature) Organic acids Organic acids Depending on Depending on ecological factors ecological factors Fermentation Fermentation Biological Biological

6. Physic al methods Physic al methods – – HEAT T REAT MENT HEAT T REAT MENT § most effective method to kill the microorganisms + to inactivate the tissue enzymes § Thermisation § Pasteurization § Sterilization § influencing factors § heat resistance of microbes § water activity, pH and protective materials (sugar, protein, fat) of foods

7. Physic al methods Physic al methods – – HEAT T REAT MENT HEAT T REAT MENT Heat resistance of microbes § D value: decimal reduction time (time required to destroy 90% of the organisms = the duration of heat treatment required to reduce the number of micro-organisms to one-tenth of the initial value) § the temperature (constant) is shown as a subscript, (e.g. D121is time at 121°C) § Can be determined from the survival curve

8. Classific ation of mic robes Classific ation of mic robes according to their heat resistance according to their heat resistance Group of microbes Group of microbes Typical D Typical D- -value value 40≈ ≈ 1 minute 1 minute Psychrophilic Psychrophilic bacteria bacteria D D40 50≈ ≈ 1 1- -5 minutes 5 minutes Psychrotophic Psychrotophic bacteria bacteria D D50 60≈ ≈ 1 minute 1 minute Most of Most of mesophil mesophil bacteria bacteria D D60 60≈ ≈ 5 5- -20 Extreme heat resistant Extreme heat resistant mesophil mesophil bacteria bacteria (Enterococcus, (Enterococcus, Microbacterium Thermophil Thermophil bacteria bacteria D D60 20 minutes minutes Microbacterium) ) 60≈ ≈ 100 minutes 100 minutes D D60 60≈ ≈ 0.1 Yeast and moulds Yeast and moulds D D60 0.1- -0.5 minutes 0.5 minutes 120≈ ≈ 0.1 Bacterial Bacterial endospores endospores D D120 0.1- -5 5

9. Physic al methods Physic al methods – – HEAT T REAT MENT HEAT T REAT MENT Heat resistance of microbes § 12-D concept: refers to process lethality requirement § Requirement for pathogens (Cl. botulinum) § N/N0= 10-12. TDT = 12D § Sterilization § Appertization § Pasteurization § § (non-pathogenic and incapable of developing within the product under normal condition of storage) 12 D 8-10 D § TDT value (thermal death time): this is the time necessary to kill a given kind and amount of microorganisms at a definite temperature

10. Heat resistanc e of pathogens and Heat resistanc e of pathogens and spoilers spoilers Vegetative forms (z≈5oC) Campylobacter sp. Salmonella sp. E. coli Staph. aureus, L. monocytogenes Yeasts and moulds Enterococcus sp. Lactobacillus sp. Endospores (z≈10oC) Cl. botulinum B. stearothermophilus Cl. thermosaccharolyticum D65 (min) 0,02 0,07 0,5 1,0 0,5-3,0 3,0-6,0 20-30 D121 (min) 0,1-0,2 5 3-4

11. Physic al methods Physic al methods – – HEAT T REAT MENT HEAT T REAT MENT Heat resistance of microbes § F value: § F0value (Time equivalent of the sterilization process) § The effectiveness of the heat treatment process is given by an isotherm heat treatment at 121.1°C for F0minutes. § The heat treatment is equal to an F0minutes heat treatment at 121.1°C, referring to the thermal destruction of Cl. botulinum

12. Physical methods Physical methods – – HEAT T REAT MENT T REAT MENT HEAT § § Viruses can be killed by heat treatment Viruses can be killed by heat treatment commonly used in the food industry commonly used in the food industry § § Parasites also Parasites also § § Most of Most of mycotoxins mycotoxins can not be inactivated in autoclave inactivated in autoclave § § Enterotoxins produced by staphylococci Enterotoxins produced by staphylococci are heat resistant (botulinum toxins can are heat resistant (botulinum toxins can be inactivated by cooking) be inactivated by cooking) can not be

13. Physic al methods Physic al methods – – HEAT T REAT MENT HEAT T REAT MENT Other influencing factors of heat treatment § Water activity: the heat resistance of microbes increases with decreasing humidity or moisture (efficiency of dry hot ↔hot steam) § „Protective materials” (sugar, glycerine, protein, fat): generally increase the heat resistance of microorganisms ( ↓ aw; in fat drop → dry heat – not so effective) § pH: microorganisms are most resistant to heat treatment at their optimum pH (7.0) As pH is lowered or raised from this optimum value → consequent increase in heat sensitivity § Lower pH → lower temperature is enough for heat treatment: § pH>4.5 → above 100oC (meat, vegetable, fish) § pH<4.5 → under 100oC (fruits) § C. botulinum pH<4.5 → no growth no toxin production

14. Heat treatment procedures Heat treatment procedures sections of heat treatment process § heating → temperature keeping /holding → cooling § temperature → time profile § time equivalent of heat treatment (F0) → min., = 121,1oC Cl. botulinum

15. T hermal profile of the T hermal profile of the heat treatment proc ess heat treatment proc ess § § Temperature Temperature (T) (T) Time Heating Keeping/holding Cooling

16. Heat treatment Heat treatment proc ess proc ess § § 1. 1. T Thermisation hermisation § § 57 57- -65 65o oC for at least 15 seconds C for at least 15 seconds § § raw milk raw milk → → killing of killing of mesophil (no pasteurization!) (no pasteurization!) Hard, semi semi- -firm firm cheeses mesophil microbes microbes cheeses § § Hard,

17. Heat treatment Heat treatment proc ess proc ess § § 2. pasteurization 2. pasteurization § § heating to temperature high enough (< 100 heating to temperature high enough (< 100o oC) to § § destroy most of pathogens ( destroy most of pathogens (mycobacteria pathogen pathogen strepto strepto- - and staphylococcus and staphylococcus spp Yersinia and Yersinia and Vibrio Vibrio spp spp., etc.) ., etc.) § § destroy destroy most of the spoilage organisms ( most of the spoilage organisms (≥ ≥99%) § § inactivate of enzymes inactivate of enzymes § § thermoduric thermoduric bacteria may survive bacteria may survive → Micrococcus, Micrococcus, Microbacterium Microbacterium, , Brevibacterium § § spores also survive spores also survive → → Cl § § Combination with other preservation methods to prevent Combination with other preservation methods to prevent spoilage + growth of toxin spoilage + growth of toxin- -producing bacteria producing bacteria → ( (<10 <10° °C C – – usually <6 usually <6° °C C), a ), aw w↓ ↓, pH C) to , salmonella, ., Campylobacter, mycobacteria, , brucella spp., Campylobacter, brucella, salmonella, 99%) → Enterococcus, Enterococcus, Brevibacterium Cl. botulinum, Bacillus . botulinum, Bacillus spp spp. . → cooling cooling , pH↓ ↓ (package) (package)

18. Heat treatment Heat treatment process process § § 2. pasteurization 2. pasteurization § § pasteurization of milk: pasteurization of milk: § § LTLT (low temperature; long time) or holder method: 62 LTLT (low temperature; long time) or holder method: 62- - 65 65o oC, 30 min C, 30 min § § HTST method (high temperature; short time): 72 HTST method (high temperature; short time): 72- -75 sec sec § § flash pasteurization: 85 flash pasteurization: 85o oC, 1 75o oC, 15 C, 15- -40 40 C, 1- -2 sec 2 sec § § UHT (ultra high temperature): 135 UHT (ultra high temperature): 135- -140 § § pasteurization of egg products: 60 pasteurization of egg products: 60- -64 § § pasteurization of canned ham pasteurization of canned ham ( (semi 0 0. .3 min 3 min 140o oC, 1 64o oC, 2 semi- -cans cans) ) 70 C, 1- -2 sec 2 sec C, 2. .5 5- -3 min 70- -85 3 min 85o oC, 0 C, 0. .1 1- - → always chill always chill- -stored! § § pasteurized products pasteurized products → stored!

19. Heat treatment Heat treatment proc ess proc ess § § 3. S 3. Sterilization terilization § § inactivation of all forms of microorganisms inactivation of all forms of microorganisms (also spores) (also spores) → → sterile sterile § § would require up to 150 would require up to 150o oC pressure) pressure) § § Aim of food industry: (not full sterilization) Aim of food industry: (not full sterilization) appertisation appertisation → → food may contain some food may contain some surviving spores or vegetative forms surviving spores or vegetative forms → longer capable of growing under normal longer capable of growing under normal storage storage → → aim: long aim: long- -term storage without chilling chilling C → → 1 1- -2 sec (under 2 sec (under → no no term storage without

20. Heat treatment Heat treatment process process § § 3. S 3. Sterilization terilization § § heat treatment requirement: heat treatment requirement: „ „12 12 log unit reduction in 12 log unit reduction in Cl § § influence of pH on spores influence of pH on spores § § pH > 4.5 pH > 4.5 → → Cl § § pH < 4.5 pH < 4.5 → → Cl § § → min. min. 12- -D principle D principle” ” → Cl. botulinum . botulinum spores spores → 121 121o oC C → <100 <100o oC C → → rapid cooling <30 rapid cooling <30o oC ( (thermophilic thermophilic micro micro- -organisms may organisms may rapidly multiply!) rapidly multiply!) Cl. botulinum . botulinum → Cl. botulinum . botulinum → C § § sterilized products: milk, fruit juices, canned foods sterilized products: milk, fruit juices, canned foods

21. Heat treatment Heat treatment process process § § 4. Blanching 4. Blanching § § It is a cooking term that describes a It is a cooking term that describes a process of food preparation wherein process of food preparation wherein § § the food (vegetable or fruit) is plunged into the food (vegetable or fruit) is plunged into boiling water boiling water § § removed after a brief, time removed after a brief, time- -interval and § § finally plunged into iced water or placed finally plunged into iced water or placed under cold running water to halt the under cold running water to halt the cooking process. cooking process. § § It destroys enzymes to help retain the It destroys enzymes to help retain the flavour, colour and texture of vegetables flavour, colour and texture of vegetables and fruits and fruits interval and

22. C C old processing old processing - - temperature reduc tion reduc tion temperature § § temperature temperature ↓ ↓ → → → inhibition of microbial and chemical spoilage inhibition of microbial and chemical spoilage § § multiplication fully inhibited: multiplication fully inhibited: § § psychrophil psychrophil bacteria bacteria - -5 5 → → - -10 § § yeasts yeasts - -10 10 → → - -12 12o oC C § § moulds moulds - -15 15 → → - -18 18o oC C § § biochemical activity fully inhibited: freezing of biochemical activity fully inhibited: freezing of protoplasma protoplasma, no transport process , no transport process → influenced by composition of food influenced by composition of food → a aw w↓ ↓ § § methods: chilling, freezing methods: chilling, freezing → → bacterial growth + biochemical activity bacterial growth + biochemical activity ↓ ↓ 10o oC C → markedly markedly → freezing point freezing point → → → never never can → → parasites parasites can (e.g., (e.g., Trichinella spiralis Trichinella spiralis, , cysticercus cysticercus) ) can produce sterility produce sterility can be killed be killed

23. Mic robial resistanc e against Mic robial resistanc e against temperature reduc tion temperature reduc tion Effects of temperature reduction on microorganisms: Effects of temperature reduction on microorganisms: § § Slower metabolism Slower metabolism → → stop stop § § Slower reproduction Slower reproduction → → stop stop § § Psychrophilic Psychrophilic bacteria § § Usually Usually Gr Moraxella Moraxella and § § Gr Gr- - from from soil § § Psychrotrophic Psychrotrophic bacteria § § Intestinal bacteria ( Intestinal bacteria (Enterobacter § § Facultative Facultative anaerobe ( anaerobe (Vibrio § § Pathogen bacteria ( Pathogen bacteria (L. monocytogenes, Yersinia enterocolitica, L. monocytogenes, Yersinia enterocolitica, Cl Cl. botulinum E . botulinum E) ) bacteria , aerob (Pseudomonas, Pseudomonas, Acinetobacter and Flavobacterium Flavobacterium spp soil ( (Arthrobacter Arthrobacter spp spp, , sporoform bacteria Enterobacter, , Serratia Vibrio, , Aeromonas Gr- -, aerob ( Acinetobacter, , Alcaligenes spp. .) ) sporoform bacteria) bacteria) Alcaligenes, , Serratia spp Aeromonas spp spp); spp); ); );

24. Minimal reproduc tion temperature Minimal reproduc tion temperature Genus / species Genus / species Minimal temperature for Minimal temperature for reproduction ( reproduction (o oC) C) Pathogens / facultative pathogens Pathogens / facultative pathogens C. C. Jejuni Jejuni 32 32 Salmonella Salmonella enterica enterica 6 6 E. coli E. coli 7 7 Staph Staph. aureus . aureus 6 (10*) 6 (10*) Vibrio Vibrio parahaemolyticus parahaemolyticus 5 5 Cl Cl. perfringens . perfringens 12 12 Cl Cl. botulinum A, B . botulinum A, B 10 10 Cl Cl. botulinum E . botulinum E 3 3 L. monocytogenes L. monocytogenes 0 0 Yersinia Yersinia enterocolytica enterocolytica - -1 1 Fusarium Fusarium, , Penicillium Penicillium - -10 10 * * toxin production toxin production § §

25. Minimal reproduc tion temperature Minimal reproduc tion temperature Genus / species Genus / species Minimal temperature for Minimal temperature for reproduction ( reproduction (o oC) C) Microorganisms cause spoilage Microorganisms cause spoilage Enterococcus Enterococcus faecium faecium 0 0 Ps. Ps. fluorescens fluorescens - -3 3 Achromobacter Achromobacter - -4 4 Bacillus Bacillus psychrophilus psychrophilus - -5 5 Yeasts Yeasts - -10 10 Moulds Moulds - -18 18

26. C C old processing old processing - - temperature reduc tion reduc tion temperature § § 1. Chilling 1. Chilling § § aim: to maintain quality and lengthen the aim: to maintain quality and lengthen the shelf shelf- -life (during the whole cold chain) life (during the whole cold chain) § § fresh, highly perishable foods (e.g., meat, fresh, highly perishable foods (e.g., meat, fish, milk) fish, milk) → → rapid temperature rapid temperature ↓ ↓ → prevention of spoilage and growth of prevention of spoilage and growth of pathogens pathogens § § swine, cattle swine, cattle → → carcass carcass < < 7 7o oC, offal § § poultry poultry → → poultry poultry meat meat ≤ ≤ 3 3- -4 4o oC C § § milk milk → → ≤ ≤ 4 4- -5 5o oC in 2 hours C in 2 hours § § In cold storage establishments In cold storage establishments → → C, offal ≤ ≤ 3 3- -4 4o oC; C; → - -1+2 1+2o oC C

27. C C old processing old processing - - temperature reduc tion reduc tion § § 2. Freezing 2. Freezing § Freezing „point” <0oC temperature reduction § Freezing „range” normally start: -1 → -3oC → depends on composition of food § antimicrobial effect: low temperature + ↓aw § <0oC: psychrophilic bacteria (pseudomonas) osmophilic yeasts moulds (→ -18oC) temperature

28. Changes in w ater ac tivity of foods Changes in w ater ac tivity of foods below below 0 0o oC temperature C temperature Temperature ( Temperature (o oC) C) a aw w - -1 1 0 0. .99 99 - -5 5 0 0. .95 95 - -10 10 0 0. .91 91 - -18 18 0 0. .84 84 - -24 24 0 0. .79 79 - -30 30 0 0. .75 75

29. C C old processing old processing - - temperature reduc tion reduc tion temperature continued 2. Freezing 2. Freezing continued osmotic effect (antimicrobial effect) internal ice crystal formation → mechanical damage + denaturation of cell constituents (below the freezing point) § § § § some microorganisms are killed, but about 50% survive § spores unaffected § Gram+ bacteria and cocci more resistant than Gram- bacteria when microbial growth inhibited → still, microbial or endogenous enzymes may cause spoilage § vegetables → blanching § (limits the duration of cold storage) freezing rates (slow, quick → shocking) § Slow: extracellular ice crystal formation → osmotic effect → microbial death ↑, Quality ↓ § Quick: internal ice crystal formation → microbial death ↓ thawing § Quick: short osmotic effect → microbial death ↓ § Slow: microbial death ↑, microbial growth ↑ § After thawing a product freezing again is prohibited § during and after thawing – above 8-10°C –pathogens can grow § poor quality § § § §

30. Control Control / / reduc tion of water reduc tion of water c ontent (drying) c ontent (drying) § § the oldest process among the (dehydrating) preservation the oldest process among the (dehydrating) preservation method methods s § § aim: a aim: aw w↓ ↓ without markedly modifying of the original without markedly modifying of the original characteristics characteristics § § Types of dehydration: Types of dehydration: I. Physical removal of water from food I. Physical removal of water from food § § 1. Drying with hot air (sun drying 1. Drying with hot air (sun drying - - fruits, vegetables) § § 2. Spray drying/ mechanical drying (vegetables, milk, egg 2. Spray drying/ mechanical drying (vegetables, milk, egg products) products) § § 3. Freeze drying (meat, fish) 3. Freeze drying (meat, fish) § § 4. Evaporation / concentration 4. Evaporation / concentration II. Addition of substances that bind water in food (making it II. Addition of substances that bind water in food (making it unavailable unavailable) ) § § Preservation with sugar (jam, syrup) Preservation with sugar (jam, syrup) § § Salting (fish, meat, vegetables) Salting (fish, meat, vegetables) fruits, vegetables)

31. Control of water c ontent (drying) Control of water c ontent (drying) § effect of drying on microorganisms § temperature - water activity § spore formers and Gram+ cocci are more resistant (higher osmotic pressure in the cells, structure of their cell wall) § typical residual flora of mechanically dried products: § spore formers (Bacillus) § enterococci § moulds (Aspergillus, Penicillium, Alternaria) § milk powder - Salmonella may survive → pasteurized milk § frozen dried products - 30% of the original flora may survive

32. Control of water c ontent (drying) Control of water c ontent (drying) § Rehydration § water used markedly influences the microflora of dried foods → spoilage § hot water → Bacillus § lower temperature → more heat-unstable organisms § storage of rehydrated foods: - room temperature - few hours - refrigerator - 1-2 days

33. Irradiation (treatment with ionizing energy / radiation) § § Provide energy which destroys Provide energy which destroys cell structures structures including including DNA in bacteria, parasites, insects, parasites, insects, moulds cell DNA in bacteria, moulds

34. Irradiation (treatment w ith ionizing energy / radiation) Ultraviolet and ionizing radiation Ultraviolet and ionizing radiation § § UV radiation UV radiation § § 200 200- -280 nm wavelength 280 nm wavelength § § energy and penetration low energy and penetration low → reduction of microbial reduction of microbial contamination in air (e.g., contamination in air (e.g., packaging of fluids) packaging of fluids) § § Germicide effect (DNA) Germicide effect (DNA) § § ionizing radiation ionizing radiation § § α α- -radiation radiation → → penetration poor → → no importance no importance § § β β- -radiation radiation → → max depth of penetration 4 penetration 4- -5 cm treatment treatment § § γ γ- -radiation radiation → → excellent penetration penetration → → 30 → penetration poor max depth of 5 cm → → surface surface excellent 30- -40 cm depth 40 cm depth

35. Ionizing Radiation Ionizing Radiation

36. Irradiation (treatment with ionizing energy / radiation) § § SOURCE SOURCE § § Gamma Gamma r rays § § Cobalt 60 Cobalt 60 § § Cesium 137 Cesium 137 § § Accelerated electron beams Accelerated electron beams § § X X- -Rays Rays ays from radioactive material from radioactive material

37. Ionizing Radiation Ionizing Radiation § When radiation strikes other material, § it transfers energy and this can cause heating, as with microwave cooking or, § if there is enough energy, it can knock electrons out of the material bombarded, breaking the molecular structure - thus forming ions (free radicals) hence the name (Ionizing Radiation)

38. Ionizing Radiation Ionizing Radiation § Causes disruption of internal metabolism of cells by destruction of chemical bonds § DNA cleavage results in loss of cells ability to reproduce § (“Free radicals” formed upon contact with water containing foods) § Free radicals react with cellular DNA causing radiation damage § (DNA considered “radiation sensitive” portion of cells)

39. History of ionizing radiation History of ionizing radiation 1905 1905 - - Scientists receive patents to use ionizing radiation to kill Scientists receive patents to use ionizing radiation to kill bacteria in foods. bacteria in foods. 1920s 1920s - - French scientists discover French scientists discover irradiation preserves foods. 1921 1921 - - U.S. patent is granted for a process to kill U.S. patent is granted for a process to kill Trichnella meat using X meat using X- -rays. rays. 1940s 1940s - - U.S. Army begins testing irradiation of common foods. U.S. Army begins testing irradiation of common foods. 1958 1958 - - The Food, Drug, and Cosmetic Act is amended and defines The Food, Drug, and Cosmetic Act is amended and defines sources of irradiation for using in processing food. sources of irradiation for using in processing food. 1963 1963 - - Irradiation is approved by the U.S. government to control Irradiation is approved by the U.S. government to control insects in wheat and wheat powder. Although irradiation was not insects in wheat and wheat powder. Although irradiation was not used in United States at this time, 400,000 tons of wheat per year we in United States at this time, 400,000 tons of wheat per year were irradiated in the Ukraine to kill insects. irradiated in the Ukraine to kill insects. 1964 1964 - - Government approves irradiation to extend shelf life of white Government approves irradiation to extend shelf life of white potatoes. potatoes. 1966 1966 - - The U.S. Army and USDA petition FDA to approve irradiation The U.S. Army and USDA petition FDA to approve irradiation of ham. of ham. 1970s 1970s - - NASA adopts irradiation to sterilize food for astronauts. NASA adopts irradiation to sterilize food for astronauts. § § irradiation preserves foods. § § § § Trichnella spiralis spiralis in in § § § § § § used re § § § § § §

40. History of ionizing radiation History of ionizing radiation § § 1980 1980 - - USDA inherits the U.S. Army's food irradiation USDA inherits the U.S. Army's food irradiation program. program. § § 1983 1983 - - Spices and dry vegetable seasonings approved for Spices and dry vegetable seasonings approved for irradiation to kill insects and bacteria. irradiation to kill insects and bacteria. § § 1985 1985 - - Irradiation in very low doses is approved to control Irradiation in very low doses is approved to control Trichinella in pork. Trichinella in pork. § § 1986 1986 - - Irradiation is approved to control insects and Irradiation is approved to control insects and maturation of fruit and vegetables, although it is not widely maturation of fruit and vegetables, although it is not widely used. used. § § 1990 1990 - - FDA approves irradiation for poultry to control FDA approves irradiation for poultry to control salmonella and other food borne bacteria. salmonella and other food borne bacteria. § § 1992 1992 - - USDA approves irradiation to kill bacteria in poultry, USDA approves irradiation to kill bacteria in poultry, although it is not widely adopted by industry. although it is not widely adopted by industry. § § 1997 1997 - - Irradiation is approved to kill bacteria in beef, veal Irradiation is approved to kill bacteria in beef, veal and other red meat. and other red meat.

41. History of ionizing radiation History of ionizing radiation § § 1999 1999 - - USDA's USDA's regulations are proposed to allow regulations are proposed to allow irradiation of refrigerated and frozen uncooked irradiation of refrigerated and frozen uncooked meat, meat by meat, meat by- -products, and certain other meat products, and certain other meat food products. food products. § § 2000 2000 - - Final rule on allowing irradiation of Final rule on allowing irradiation of refrigerated and frozen uncooked meat, meat by refrigerated and frozen uncooked meat, meat by- - products, and certain other meat food products products, and certain other meat food products issued. issued. § § 2000 2000 - - FDA amends regulations to permit FDA amends regulations to permit irradiation of fresh shell eggs to control irradiation of fresh shell eggs to control salmonella. salmonella.

42. § § "COLD PASTEURIZATION "COLD PASTEURIZATION„ „ § § As of December 2006, food irradiation As of December 2006, food irradiation has been approved by some 60 countries has been approved by some 60 countries either for specific or unlimited either for specific or unlimited applications, and it has been applied applications, and it has been applied successfully for several types of food in successfully for several types of food in more than 30 countries. more than 30 countries.

43. Countries that have approved Countries that have approved food irradiation food irradiation (2002) (2002) Bangladesh Bangladesh China China India India Indonesia Indonesia Iran Iran Japan Japan Korea Korea Thailand Thailand Algeria Algeria South Africa South Africa Argentina Argentina Brazil Brazil Chile Chile Peru Peru § § § § § § § § § § § § § § § § § § § § § § § § § § § § Belgium Belgium Croatia Croatia Czech Republic Czech Republic Denmark Denmark Finland Finland France France Germany Germany Hungary Hungary Israel Israel Netherlands Netherlands Norway Norway Poland Poland Ukraine Ukraine § § § § § § § § § § § § § § § § § § § § § § § § § § • • United Kingdom United Kingdom • • Serbia Serbia • • Canada Canada • • Cuba Cuba • • Mexico Mexico • • United States United States • • Philippines Philippines • • Russian Federation Russian Federation • • Syria Syria • • Italy Italy • • Spain Spain • • Costa Rica Costa Rica • • Uruguay Uruguay

44. Irradiation (treatment w ith ionizing energy) § § susceptibility of microorganisms susceptibility of microorganisms § § Gram Gram- - bacteria are more sensitive than Gram+ bacteria are more sensitive than Gram+ § § spores especially resistant spores especially resistant § § viruses also highly resistant viruses also highly resistant § § parasites (pl. parasites (pl. Taenia Taenia, Trichinella spiralis relatively sensitive relatively sensitive § § toxins can not be inactivated toxins can not be inactivated § § Measure/unit: Gray ( Measure/unit: Gray (Gy absorbed in 1 kg absorbed in 1 kg , Trichinella spiralis) ) Gy) ) = 1 joule E = 1 joule E

45. Approximate radiation doses for adequate Approximate radiation doses for adequate reduc tion of different mic roorganisms reduc tion of different mic roorganisms Microorganisms Microorganisms Dose ( Dose (kGy kGy) ) Gram Gram- -negative bacteria negative bacteria E. coli E. coli 2 2 Salmonella enteritidis Salmonella enteritidis 4 4 Ps. Ps. fluorescens fluorescens <1 <1 Gram Gram- -positive bacteria positive bacteria Staph Staph. aureus . aureus 5 5- -10 10 Str Str. . faecalis faecalis 5 5 Bacillus Bacillus spp spp. . 3 3 Bacillus cereus Bacillus cereus (spores) (spores) 25 25 Cl Cl. perfringens . perfringens 25 25 Cl Cl. botulinum A . botulinum A 25 25 Moulds and yeasts Moulds and yeasts Aspergillus Aspergillus flavus flavus 3 3 Saccharomyces Saccharomyces cerevisiae cerevisiae 10 10 Viruses Viruses >30 >30

46. Irradiation (treatment w ith ionizing Irradiation (treatment w ith ionizing energy) energy) T he T he Radura Radura logo required sinc e 1986 ( sinc e 1986 (labeling labeling sinc e 1966) radiation dose: up to 10 up to 10 kGy kGy toxicologically safe toxicologically safe § § approximate radiation doses for approximate radiation doses for adequate reduction of different adequate reduction of different microorganisms microorganisms § § aims of administration aims of administration § § spoilage spoilage ↓ ↓, shelf , shelf- -life life ↑ ↑ → → radurization radurization § § killing of pathogens killing of pathogens → → radicitation radicitation § § ( (Radappertization Radappertization – – 20 20- -60 60 kGY kGY) ) § § practical application practical application § § spices, dried vegetables, sprouting losses spices, dried vegetables, sprouting losses in stored potatoes in stored potatoes, , onion can be onion can be prevented prevented) )→ → registration registration § § foods of animal origin foods of animal origin → → based on special based on special permission (USA: routinely) permission (USA: routinely) logo required sinc e 1966) § § radiation dose:

47. Chemic al preservation § general principle: preservation by physical methods if possible, but …. § chemical preservation → approved § Frequently has also other effects (e.g., flavour) § Mode of action: § ↓ aw(salt, sugar) § Influence of ion balance and pH (organic acids, salt) § Specific antimicrobial effect (salt, nitrites) § Effect can be influenced by temperature, pH, aw, organic components

48. Chemic al preservation Method Method Chemical Chemical compounds compounds Aim of use Aim of use Application Application NaCl NaCl Flavouring, Flavouring, preservation preservation Meat, fish, meat Meat, fish, meat products, cheese products, cheese Salting Salting NaCl, nitrites NaCl, nitrites Colouration, Colouration, flavouring, flavouring, preservation preservation ( (Cl Cl. botulinum . botulinum) ) Meat, fish, meat Meat, fish, meat products products Curing Curing Phenols, acids Phenols, acids Flavouring, Flavouring, preservation preservation Meat, fish, meat Meat, fish, meat products, cheese products, cheese Smoking Smoking Sorbic Sorbic acid, benzoic acid, benzoic acid, propionic propionic acid acid, Preservation Preservation Cheese, bread, Cheese, bread, jam jam Preservatives Preservatives acid

49. Chemic al preservation § 1. Salting § NaCl: flavouring effect § antimicrobial effect: aw↓ + specific inhibitory effect § Cl. botulinum B → < 10% NaCl → aw<0.94 § L. monocytogenes → also grow in 12% brine § Staph. aureus → aw< 0.90 (18%) § mesophilic Gram- rods, psychrophilic bacteria → more sensitive § max tolerance: 4-10% § spore formers → sensitivity variable (4-16%)

50. Chemic al preservation § 1. Salting § Dry / humid varieties § amounts of NaCl used in food products is limited (meat products: 2-7%) § Red meat/ comminuted products: 2-2.5% → moderate preservative effect § dry sausages, salami: 4-5% → adequate microbial stability of the end product § NaCl → preservation of fish (frequently in combination with other substances) § normal Gram- microflora of fish (Pseudomonas/ Acineto- bacter) sensitive → micrococci+ halophilic bacteria (Halobacterium, Halococcus) → red discoloration (“pink fish”) § frequently in combination with Na-nitrites → curing