Meat Preservation.ppt
- 1. Meat Preservation Prof. Dr. Fahim Shaltout Professor of Meat Hygiene Faculty of Veterinary Medicine Benha University fahimshaltout@hotmail.com
- 2. Chemical Changes in food during Preservation The primary purpose of food preservation is to prevent food spoilage.
- 3. The primary cause of food spoilage is the action of microorganisms; bacteria, moulds, or yeasts aided by enzymes.
- 4. Under unfavorable conditions the microorganisms die or fail to develop As physical means Chemical means Combination of physical and chemical means
- 5. The principle of all food preserving methods is the creation of conditions unfavorable to the growth or survival of spoilage microorganisms by for example extreme heat or cold, removal of water and some times oxygen , excess of saltiness or increased acidity .
- 6. 41°F 140°F Danger Zone Keep cold foods cold Keep hot foods hot “Food Safety Thermometer” Temperature range of rapid pathogen growth = Danger Zone Hot Cold
- 7. Methods of preservation drying, curing, cold, heat, chemicals and irradiation
- 8. Time Changing the Bacterial Growth Curve *Sub-optimal means lowered: pH, AW , Temperature, etc. Much longer Lag Phase Number of Bacteria (log10)
- 9. Time Lag Phase Resting Phase Death Phase Bacterial Growth Curve Number of Bacteria (log10)
- 10. Drying (Dehydration ) The meat should be cut into strips for easily removal of water. Dried meat contains 10 % water. Inactivation of bacteria till reach 12 % water in the product .
- 11. Drying methods 1-Sun drying: 2- Mechanical dryers 3- Sublimation (Freeze drying ) 4- Smoking then drying 5- Cure drying 6- Electronic drying
- 12. Affections 1-Mould growth : R.H. of air over 75 % 2-Hardening of surface 3- Public health dangers : a- Salmonella b- contamination due to handling , preparation and storage
- 13. Refrigeration or Cold Storage 1-Natural type : put in or on ice 2- Mechanical type : by using ammonia , Freon , or methyl chloride
- 14. Chilled meat At 0 to -1 C Chilling methods 1-Traditional 2- Quick chilling 3-Ultra – rapid chilling
- 15. Changes in chilled meat or affections 1-Conditioning ,ripening or maturation 2-Shrinkage 3-Soiling 4- Absorption of foreign odor 5- Sweating 6- Loss of bloom 7-Chemical changes 8-Spoilage a-Mould formation b-bacterial decomposition
- 16. Effect of CO2 CO2 in less than 20 % to prevent formation of metamyoglobin
- 17. Effect of exposure to air Myohemoglobin may be converted to Metahaemoglobin ( brown color ) due to exposure to air
- 18. Frozen meat Freezing rate 1-Slow Feezing -15 to -29 C 36-72 hours ice crystals 12mm x 3mm 2- Rapid freezing -18 to - 40 C 30 minutes ultra microscopic ice crystals 0.001 – 0.002mm
- 19. Freezing methods 1-Still air freezing 2-Blast freezing 3-Direct immersion freezing 4-Cryogenic freezing 5-Plate freezing
- 20. 1-Still air freezing At -10 to -30 C Placing packaged or loose foods in suitable freezing rooms till freezing
- 21. 2-Blast freezing As still air but using a compressor Push cold air to pass over, under and through the food Air temperature -10 to -40 C Air velocity 15 m /s
- 22. 3-Direct immersion freezing Direct immersion of food in a liquid refrigerant as Nacl ,glycerol , and sugar solutions Liquids must be: Safe , non toxic , cheap , with low viscosity , good heat conductors
- 23. 4-Cryogenic freezing The best method of quick freezing use condensed gases such as liquid nitrogen ( -195C) or liquid nitric oxide ( - 79 C) and Freon ( - 30 C) Advantage : 1- non toxic 2-minimize oxidative changes 3-less dehydration 4-less drip
- 24. 5-Plate freezing By indirect contact with refrigerants food is placed on cold plates or walls. Food may be packed in a can
- 25. Effect of freezing on m.o. and parasites Anthrax bacilli can resist -130 C Salmonella to -175 C for 3 days T.b. 2 days at -10 C FMD virus 76 days Swine fever virus 73 days Trichinella spiralis at -15 C for 20 days C. bovis at -10 C for 10 days C. cellulose at – 10 C for4 days
- 26. Changes in frozen meat • 1-Physical changes • A-muscle plasma b-Ice crystal formation • 2-Fungal formation • A-Stickiness : Wiping • B- black spots: Cladosporium herbarium • C-White spot: Sporotrichum carnis Wiping • D-Whiskers: thamnidium elegans: Wiping • E-Green bluish patches: Penicillum spp • F-Yeast : causing sliminess, lipolysis, off-odor and discoloration : Wiping
- 27. Changes in frozen meat • 3-Fat rancidity • 4-Freezer burn • 5-Brine staining : Cacl2: dull or pale greenish color , bitter taste: trimming • 6-bacterial slime • 7-bone taint • 8-Weeping or dripping
- 28. Canning Preservation of food in a permanent sealed containers by the effect of heat ,causing destruction of microorganisms. permanent sealing is to prevent recontamination
- 29. Types of containers • 1-Metal • High conductivity of heat • Opaque, to avoid bad effect of light • Can not be easily broken • 2-Glass
- 30. Canned food divided into • 1-Acid food pH below 4.5 as fruits and some vegetables. • 2-Low acid food pH above 4.5 as corned beef or corned pork or sheep, sea food.
- 31. Canning operation • 1-Preparation and blanching of the food • 2-Filling of the can • 3-Exhosting • 4-Processing • 5-Cooling
- 32. Spoilage of canned food • A- According to the cause • 1-Microbial • 2-Chemical • 3-Physical • 4-Rust or damage
- 33. Microbial spoilage • A-Bacterial spoilage • Factors influencing bacterial spoilage: • a-the types of microorganisms: • b-number of M.O. • c-Efficiency of processing • d-Access of air to the cans • a-the types of microorganisms: • 1-Non spore forming bacteria i-Proteolytic bacteria as pseudomonas, Achromobacter Flavobacterium ii- Fermenting bacteria as Strept. thermophilus
- 34. 2-Spore formers • i-Aerobic bacteria • Flat sour bacteria as Bacillus subtilis, Bacillus mesentricus • Ii-Anaerobic spore forming bacteria • Putrefactive type produce gas as • Cl. botulinum, Cl. Sporogens
- 36. 2-Chemical Spoilage • A- Hydrogen swells • B-Sulphiding • 3-physical Spoilage • 4-Rust & damage
- 37. B-According to the condition and content of the can ( Appearance) • 1-Flipper • 2-Springer • 3-Swelling • 4-Leaker : Leaker test • A-physical test • B-hepp apparatus • C-water bath • D-Mohramann test E.coli broth • E- silver nitrate grey blue clouds • 5-Over filled cans 6-Flat souring
- 38. Electromagnetic radiation • 1- Ionizing radiation (short wave radiation ) • (Cold sterilization ) • (X ray & Gamma rays) • II-Non- ionizing radiation • (Long wave radiation ) • (Heat sterilization ) • as Radio wave ,Infra red & UV rays
- 39. Preservation by Ionizing radiation • Used for sterilization of canned , and refrigerated food even in combination with antibiotics • Side effect: • Change in colour, flavor , odour and texture of the treated food . these reduced by irradiation at temperature below 20 C
- 40. Preservation by non- ionizing radiation • Used to control surface spoilage of sausage, and meat kept at warm temperature or to sterilize air in cold stores • Advantage of radiation: • 1-Extend the shelf life of food. • 2-Minimize high cost of refrigeration and canning • 3-used in defrosting frozen food and blanching of vegetables
- 41. Disadvantage • 1-Induced radio activity. • 2- Carcinogenic production.
- 42. Chemical means of preservation • A- By antibiotics: • 1-Taken as a part of normal feeding in small doses for long period. • 2-in food in large doses for short period. • 3-injection of antibiotic into living animal shortly before slaughtering. • 4-injection into quarter by artery pump • 5-applying either to surface or within the finished product. • 6-aid in other processing of food treatment as canning, heat treatment or smoking.
- 43. B- By other chemicals • To mask putrefaction • Takes place by addition of • 1- 2% sulfur dioxide • 2- Borax dust • 3-Burning sulfur and salt petre
- 44. Smoking • Purpose of smoking • 1-creation of new product • 2- As a method of preservation • 3- colour development • 4- Flavor development • 5- Antioxidant
- 45. Kind of smoking • 1- Hot smoking at 35-60 C for 24-36 hours • 2-Cold smoking at 22 C for 24 hours
- 46. Smoke mixture • Phenol , cresol , formaldehyde , acetaldehyde, acids as propionic , lactic butyric, alcohols as methanol
- 47. The preservative action • 1- Bactericidal • 2- Surface dehydration • 3- formation of crusts on surface by protein coagulation resist bacterial invasion • 4- help in production of desirable flavor • 5- help in production of desirable colour
- 48. Preservation by salting and pickling • Salting use of dry salt • Pickling use of salt solution
- 49. The value of curing agents • A- common salt: sodium chloride • 1- cause plasmolysis sharp cytoplasmic destruction Gram negative plasmolysis easily Gram positive very resistence 2- dehydration of food 3-ionized producing cl ions harmful to bacteria 4- reduce solubility of oxygen 5-interfere with action of proteolytic enzymes
- 50. B- salt petre ( Na nitrate or Na nitrite) • 1- Act as colour stabilizer • 2- reduced by air and light • 3-in excess lead to hard meat • 4-inhibit growth of Clostridium botulinum • 5-retard development of rancidity. • It is prohibited to use in canned baby food. • Carcinogenic effect due to nitrosamine formation
- 51. nitrosamine • Nitrite ntrous acid dimethylamine • as seconary amino acid ntrosamin • Formed during cookin • This problem reduced by adding • 550 ppm sod. Ascorbate + 120ppm sod nitrite or use K sorbate
- 52. C-sugar • 1-counter act saltiness of salt and hardness of salt petre • 2- sugar fermentation counteract putrefactive microorganisms growth • 3-help in growth of certain bacteria help in flavor development • 4-prevent nitrite oxidation
- 53. Storage stability of dressed poultry • Type temperature storage life • Chicken -9 C 2m • 4 m -12 C • 10 m -18 • 18 m -22 3 m -12 C Turkey • 6 m -18 C • 12 m -23 • 5-7 m -18 C Duck and geese