1. Food Safety and Hygiene Meat and Meat Products MRS J.M MUYENGA

2. Introduction Meat and its product are highly nutritious food that is widely consumed by people all over the world. Meat can be obtained from various birds (chicken, turkey, ducks, etc.) or mammals (pork, mutton, buffalo, sheep), and after slaughtering, carcasses and primary cuts are processed to raw or processed food products. It is a nutritious, protein-rich food that is highly perishable and has a short shelf life. MRS J.M MUYENGA

3. The biological and chemical nature of meat leads to its deterioration from the time of slaughter until consumption. Meat and its products such as ham, sausages, cooked meat, dry meats, smoked meats, vacuum-packed meat, minced meat, etc. are all susceptible to microbial spoilage MRS J.M MUYENGA

5. Contamination Source and Causes Meat spoilage can be caused by natural processes, such as lipid oxidation or autolytic enzymatic action that occurs in the muscle after slaughtering. Several factors are responsible for microbial contamination of meat such as: Bacterial flora of animal. Knives, utensils, hands, and clothing of the workers. Pre-slaughter handling of livestock and post-slaughter handling of meat. handling during slaughtering, evisceration, and processing MRS J.M MUYENGA

6. temperature controls during slaughtering, processing and distribution type of packaging used Handling and storage A series of the events takes place during rigor mortis after the slaughter of the animal such as: Respiration ceases, which stops ATP synthesis. The lack of ATP causes stiffening of muscle MRS J.M MUYENGA

7. Reduction of oxidation-reduction potential due to lack of oxygen The loss of vitamins and antioxidants causes the development of rancidity. Glycolysis begins in which most glycogen is converted to lactic acid that reduces pH The ending of a reticuloendothelial system leads to the susceptibility of meat to microorganisms. Nervous and hormonal regulations cease, thereby causing the temperature of the animal to fall and fat to solidify. Various metabolites accumulate that also aid protein denaturation MRS J.M MUYENGA

8. Spoilage of fresh Meat Fresh meat is subjected to spoilage by its enzymes and microbial action. The autolysis changes cause proteolytic action on muscle and connective tissue and hydrolysis of fats. The survival and growth of microorganisms are influenced by the composition of the atmosphere surrounding the meat. Fresh meat contains nutrients such as sugars, amino acids, vitamins, cofactors, etc and it has pH (5.5-5.9) and Aw (0.85) values that influence the growth of microorganisms. MRS J.M MUYENGA

9. The most common bacteria isolated from fresh meat are bacteria of the genera Acinetobacter, Pseudomonas, Brochothrix thermosphacta, Flavobacterium, Psychrobacter, Moraxella, Staphylococci, Micrococci, lactic acid bacteria (LAB), and various genera of the Enterobacteriaceae. The microbial pathogens found in fresh meat are Salmonella, Campylobacter, E.coli, Listeria monocytogenes. There are two types of spoilage of meat: Spoilage under aerobic condition Spoilage under anaerobic condition MRS J.M MUYENGA

10. ConditionKind of defectsMicroorganisms Aerobic condition Surface slime Pseudomonas, Moraxella, Streptococcus, Bacillus, micrococcus The red color of meat called “bloom” caused by the production of an oxidizing compound Lactobacillus, Leuconostoc Oxidative rancidity Pseudomanas spp, Archromob acter Red spotSerratia marcescens, Blue colorPseudomonas syncyanea Greenish blue or brownish black spot Chromobacterium lividum Stickiness, whiskers, Green patchesMold MRS J.M MUYENGA

11. Anaerobic condition Putrefaction Clostridium spp, Alcaligennes, Proteus SouringLactic acid bacteria MRS J.M MUYENGA

12. Spoilage of Meat Microbial growth, oxidation, and enzymatic autolysis are the three basic mechanisms responsible for the spoilage of meat. The nutrient composition, high water content, and moderate pH of meat make it an excellent medium for microbial growth. The normal flora of an animal’s lymph nodes contaminating meat is Staphylococcus, Streptococcus, Clostridium, and Salmonella. Meat may contain different bacteria that include species of Acinetobacter, Aeromonas, Alcaligenes, Alteromonas, Brochothrix, Carnobacterium, Escherichia, Enterobacter, Enterococcus, Flavobacterium, Lactobacillus, Leuconostoc, Micrococcus, Proteus, Pseudomonas, Sarcina, Serratia, and Streptococcus. MRS J.M MUYENGA

13. Pathogenic microbial species contaminating meat are Salmonella enteric strains, Yersinia enterocolitica, Campylobacter jejuni, Aeromonas hydrophila, Listeria monocytogenes, and Escherichia coli. Mold species found in meat include Cladosporium, Sporotrichum, Geotrichum, Penicillium, and Mucor while yeasts species include Candida spp., Cryptococcus spp., and Rhodotorula spp. The main defects observed in meat are off-odor, off-flavor, discoloration, and gas production. MRS J.M MUYENGA

14. Some defects caused by microorganism in different kinds of meat are: ProductsDefectsMicroorganisms Vacuum packed meat Sulfide odorClostridium spp., Hafnia spp. H2S greeningShewanella spp. Blown PackClostridium spp., lactic acid bacteria Fresh meat Putrefaction Alcaligenes, Clostridium, Chromobacterium, Proteus vulgaris, Pseudomonas fluorescens SouringChromobacterium, Pseudomonas Cured meat Moldy odorAspergillus, Penicillium, Rhizopus GreeningPediococcus, Streptococcus SouringMicrococcus, Pseudomonas Slimy Leuconostoc Modified atmosphere packaging meats Souring, off-odor Leuconostoc, Lactobacillus SouringB. thermosphacta Refrigerated packaged meat Off-flavors, slime, putrefaction Pseudomonas, Acinetobacter, Moraxella sour, slime, and flavor changeLactic acid bacteria MRS J.M MUYENGA

15. Spoilage of Refrigerated Meat When fresh meat is refrigerated at 4 ± 1°C, they remain in good condition for 5-7 days Refrigerated temperature favours the growth of psychrophilic organisms in due course of time. The contaminations occur during slicing and serving operations, from hands, slicing machines, and other equipment. Inadequate hygiene can lead to meat contamination by spoilage and pathogenic microorganisms The important bacterial genera associated with spoilage of refrigerated meat are Acinetobacter, Moraxella, Pseudomonas, Aeromonas, Alcaligenes, and Micrococcus. MRS J.M MUYENGA

16. The mold genera associated with spoilage of refrigerated meat are Alternaria, Cladosporium, Geotrichum, Mucor, Monilia, Penicillium, Sporotrichum, and Thamnidium; and yeast genera associated with spoilage of refrigerated meat are Candida, Torulopsis, Debaryomyces, and Rhodotorula. Generally, Brochothrix thermosphacta and lactic acid bacteria are the bacteria that cause spoilage of refrigerated meat. Pathogenic microorganisms found in refrigerated meats include C. botulinum type E, Yersinia enterocolitica, enteropathogenic Escherichia coli, Listeria monocytogenes, and Aeromonas hydrophila as they are capable of growing at temperatures below 5°C. MRS J.M MUYENGA

17. Spoilage of cured meat Cured meat is the meats in which are preserved by aging, drying, canning, brining, or smoking for enhancement of flavor and to extends its shelf life. Some examples of cured meats are sausage, bacon, salami, ham, canned meat, dry spicy meat, meat pickles, kebab, meatballs, meat patty, etc. The cured meat has a long shelf-life compared to fresh and raw meat however they are not immune to spoilage. MRS J.M MUYENGA

18. Other spoilage causing microorganism found in cured meats includes Clostridium spp, Hafnia spp, Weisella spp, Shewanella spp, Pseudomonas spp, Enterococcus spp, etc. The pathogenic microorganisms found in cured meat include Escherichia coli, Salmonella, Staphylococcus aureus, Listeria monocytogenes, Clostridium botulinum, and Toxoplasma gondii. Microbial growth in cured meat can result in slime formation, structural components degradation, decrease in water holding capacity, off odors, and texture and changes in appearances. MRS J.M MUYENGA

19. Some defect in different cured meat products caused by microorganism are: Cured meat productsDefects Microorganisms Dried-fermented sausage small dark spot B.thermosphacta, Lactobacillus, Leuconostoc, Microbacterium, Micrococcus, Alternaria CO2 productionheterofermentative LAB Nitric oxide gas productionnitrate-reducing bacteria Greening with H2O2 heterofermentative Lactobacillus fructivorans, L. jensenii, L. viridescens, Leuconostoc, Enterococcus faecium, Enterococcus faecalis, Pediococcus Slime layer on the surfaceMicrococcus and yeasts fuzziness and discoloration Penicillum verrucosum Aspergillus glaucus MRS J.M MUYENGA

20. Cured meats H2S productionVibrio, Enterobacteriaceae Bacon Cabbage odorProvidencia white and gray or grayish-green spot Aspergillus, Alteraria, Fusarium, Mucor, Rizopus Ham PutrefactionEnterobacteriacae, Proteus Souring Lactic acid bacteria, Enterococcus, Micrococcus, Bacillus, Clostridium Bone taint Serratia spp, Clostridium spp, Proteus spp Red spotHalobacterium salinarum Blue spot Pseudomonas syncyanea, Penicillum Soinulosum, Rhodotonela spp Dark spotAlternaria MRS J.M MUYENGA

21. Sausages Souring, off-odorLactic acid bacteria Surface slime Bacillus, Lactobacillus, Leuconostoc Greening Enterococcus, Lactobacillus, Leuconostoc, Pediococcus Dried meats Surface slimeMicrococcus souringHalobacterium salinarum Off-odorFlavobacterium Blue colorP. syncyanea, P. Spinulosum red colorBacillus spp Smoked products Off-odorMicrococcus, yeasts, molds Souring Lactobacillus Plantarum, L. Mesenteroides, Clostridium spp Pickled meat PutrefactionVibrio, Alcaligenes, Spirillum souringLactobacillus, Micrococcus Slime formationLeuconostoc. MRS J.M MUYENGA

22. The bacterial spoilage causing organisms in processed and cured meats are lactic acid bacteria (such as Lactobacillus sake, Lactobacillus curvatus, Leuconostoc gelidium, Leuconostoc carnosum, Leuconostoc mesenteroides), Acinetobacter, Bacillus, Micrococcus, Serratia, and Staphylococcus. The spoilage causing mold found in cured meat includes Aspergillus, Penicillium, Rhizopus, and Thamnidium The spoilage causing yeast found in cured meat includes Candida, Debaryomyces, Torula, Torulopsis, and Trichosporon. MRS J.M MUYENGA

23. Spoilage of fish and shellfish Owing to their high nutritive value the spoilage of fish and fishery products proceeds at a faster rate. Spoilage of fish and shellfish is the result activities of autolytic enzymes, oxidation and associated microorganisms. MRS J.M MUYENGA

24. Enzymatic spoilage Enzymatic spoilage is caused by the autolytic fish enzymes. Fishes are highly perishable than meat because of more rapid autolysis by fish enzymes, and favorable conditions for microbial growth due to less acid reactions. The autolytic spoilage can be prevented by reducing the activity of enzymes by lowering the temperature. Oxidation or non-enzymatic spoilage Oxidation or non-enzymatic spoilage is caused by the oxidation of fish fat. The oxidative deterioration of many unsaturated fish oils leads to spoilage of fish. Thus, the fatty fishes spoil much faster than lean fishes. MRS J.M MUYENGA

25. Bacterial spoilage Bacterial spoilage is caused by the activities of microorganism associated with the fish. Bacterial spoilage of fish begins only after the completion of rigor mortis, which results in the release of products of protein denaturation due to decrease in pH, which is utilizable by bacteria. Thus, prolonging rigor mortis helps to delay spoilage and thereby keeps fish fresh. MRS J.M MUYENGA

26. Rigor mortis is hastened by struggling of the fish, lack of oxygen and warm temperature. However, rigor mortis can be delayed by reducing enzyme activities by lowering pH and adequate cooling of fish. The pH of the fish has important influence on perishability because of its influence on growth of bacteria. Lower the pH of fish, slower will be bacterial decomposition of fish. Lowering of pH occurs during rigor mortis when muscle glycogen is converted to lactic acid. MRS J.M MUYENGA

27. Spoilage of both marine and fresh water fish occurs in the same manner. Fish contain high levels of protein and non- protein nitrogenous constituents (16~20 %), lack carbohydrate, and have varying amounts of fat depending on the species of fish. The non-protein nitrogenous compounds in fish include free aminoacids, volatile nitrogen bases- ammonia and trimethyl amine (TMA), creatine, taurine, betaines, uric acid, anserine, carnosine and histamine. Spoilage of fish begins from the surface, gill and intestine because of high bacterial load. From gills, intestine and surface microorganisms ¬gradually migrate to adjacent tissue and cause spoilage. Spoilage organism first utilizes simpler compounds and later fish protein releasing various off-odour compounds converted to lactic acid. MRS J.M MUYENGA

28. Factors affecting spoilage The kind and rate of spoilage of fish is affected by several factors. 1. Kind of fish Fishes differ considerably in perishability. Some flat fishes spoil more readily than round fish because they pass through rigor mortis more rapidly. Certain fatty fishes (oil sardine) deteriorate rapidly because of oxidation of unsaturated fat/oil. Fishes high in trimethyl amine oxide (TMAO) spoil quickly and produce stale fishy smell by producing TMA- TRYMETHYL AMINES i.e A volatile gas 2. Conditions of the fish when caught Fishes that are exhausted due to struggle while capture (Ex: gill netting, long lining), lack of oxygen and excessive handling spoil rapidly. This is because of exhaustion of glycogen during struggling and causing smaller drop in pH. Feedy fish (fishes with full of food in stomach) are more easily perishable than those with empty intestine.

29. MRS J.M MUYENGA 3. Kind and extent of contamination of fish Contamination of fish with bacteria from various sources (mud, water, handlers, contact surfaces, slime etc.) increase bacterial load. Bacterial from slime, gill and intestine invade the flesh and cause spoilage. In general, greater the load of bacteria of fish the more rapid the spoilage. In ungutted fish (whole fish) decay of food in the gut may release odorous substances enabling diffusion of decomposition products into the flesh. Gutting the fish on boat spreads intestinal and surface slime bacteria to flesh. But, thorough cleaning will remove most bacteria, and adequate chilling will inhibit bacterial growth. Any damage to fish skin or mucous membrane will reduce the keeping quality of the product. 4. Temperature Warmer the temperature faster will be the bacterial growth and quicker will be the spoilage. Reducing the temperature of fish by chilling will delay bacterial growth, hence, spoilage slows. Cooling temperature around zero degree celcius (0oC), helps to delay spoilage. 5. Use of preservatives Use of preservatives including antibiotics will prevent bacterial build up thus extend shelf life of fish.

30. MRS J.M MUYENGA THANK YOU