Spoilage of Meat and Meat products

Meat, Spoilage, Contamination, Aerobic Bacteria, Anaerobic Bacteria, microbial contamination

1. Presented By: GEETARANI LOUSHIGAM Of MSc Food Technology and Quality Assurance, 2020-22 COLLEGE OF INDIGENEOUS FOOD TECHNOLOGY, KONNI FOOD MICROBIOLOGY Spoilage of meat

2. CONTENTS Meat 1 Contamination 2 Spoilage 3 General types of spoilage in meat 4 Spoilage of different kinds of meat 5

3. MEAT Meat refers to the muscles of warm-blooded terrestrial four-legged animals , the chief ones being cattle, sheep and pigs. Meat also includes the glands and organs of these animals. Meat products include many of the byproducts from animal slaughter, such as animal gut used for sausage casings, the fat from the meat used in the manufacture of lard, gelatin and others.

4. CONTAMINATION Food contamination is when food is contaminated with microbes and any other substance and eating it could result in foodborne illness . The healthy inner flesh of meats have been reported to contain few or no organisms but they have been found in lymph nodes , bone marrow, & even flesh . Staphylococci, Streptococci , Clostridium, & Salmonella have been isolated from the lymph nodes of red meat animals. Hence, lymph nodes are removed from the edible parts during slaughtering practices Approved “humane” methods of slaughter- mechanical, chemical, electrical- have little effect of contamination. The important contamination comes from external sources during bleeding, handling & processing . During bleeding, skinning & cutting, the main source of micro-organisms are the exterior of the animal & intestinal tract

5. Frequently Isolated Microorganisms from Meats Candida, Torulopsis , Debaryomyces , and Rhodotorula . Yeasts Cladosporium , Geotrichum , Sporotrichum , Mucor , and Thamnidium . Molds Acinetobacter , Moraxella, Pseudomonas , Aeromonas , Alcaligenes , and Micrococcus Bacteria Debaryomyces , Torula , Torulopsis , Trichosporon , and Candida . Yeasts Aspergillus, Penicillium , Rhizopus , and Thamnidium Molds Lactobacillus and other lactic acid bacteria, Acinetobacter , Bacillus , Micrococcus, Serratia , and Staphylococcus Bacteria Fresh and Refrigerated Meat Processed and Cured Meats

6. SPOILAGE Food spoilage is any undesired change in the natural color, taste or texture of food items that makes it unfit for consumption as it has lost its quality and nutritional value. Raw meat is subjected to change by its own enzymes & by microbial action & its fat may be oxidized chemically. Factors that influence the microbial invasion include :- a. The load of gut of the animal - more the load, greater the invasion of tissues. b . The physiological condition of the animal immediately before slaughter- if the animal is excited, feverish bacteria is more likely to be enter the tissues. c . The method of killing & bleeding - the better sanitary the bleeding, better would be the keeping quality of meat. d . The rate of cooling- rapid cooling will reduce the rate of invasion of tissues

7. Factors that influence the growth of microorganisms to cause spoilage The kind and amount of contamination with microorganisms & the spread of these organisms in the meat. The physical properties of meat- The amount of exposed surface of the flesh influence on the rate of spoilage. 3. The chemical properties of meat- The moisture content of the meat determine organisms to grow. 4. Availability of oxygen- Aerobic conditions at the surface of meat are favorable to yeasts, molds & aerobic bacteria. 5. Temperature- Low-temperature organisms can grow on stored temperature of meat i.e. not far above freezing.

8. GENERAL TYPES OF SPOILAGE OF MEAT Aerobic Bacteria Surface slime Discolorations Gas production Change in odors Fat decomposition Anaerobic Bacteria Souring Putrefaction and foul odor Taints Mold Sticky and whiskery surface Discolorations Changes in odor Fat decomposition Yeast Surface slime Discolorations Changes in odor and taste Fat decomposition

9. Aerobic bacteria Surface slime- which may be caused by species Pseudomonas, Leuconostoc , Bacillus, Alkaligenes , Micrococcus etc. Temperature & availability of moisture, influence the kind of organisms causing surface slime . Changes in color of meat pigments- The production of oxidizing agents causes change in red color of meat to shades of green, brown & gray, by bacteria species of Lactobacillus . Red color of meat called as “ bloom”. Species of Lactobacillus and Leuconostoc causes greening of sausages. Changes in fats- The oxidation of unsaturated fats in meats takes place chemically in air & may be catalyzed by light & copper . Lipolytic bacteria may cause lipolysis off flavor due to aldehyde & acids. Lipolytic species viz., Pseudomonas & Achromobacter .

10. 4 . Phosphorescence- Uncommon defect caused by luminous bacteria. Ex . Photobacterium growing on the surface of meat. 5 . Various surface color due to pigmented bacteria- Red spot caused by Serratia marcescens . Blue colour caused by Pseudomonas syncyanea . Yellow pigments produced by the sps of Micrococcus or Flavobacterium . Greenish blue to brownish black spots on stored beef caused by Chromobacterium lividum . Purple “stamping ink” discoloration of surface fat caused by yellow pigmented cocci and rods. 6 . Off odors and off tastes- “ Taints” or undesirable tastes & odors, appear in meat due to growth of bacteria on the surface often are evident before other signs of spoilage. Souring is term applied to almost any defect, that gives a sour odor may be due to volatile acid. “ Cold storage flavor” or taint is an indefinite term for a stale flavour . Actinomycetes may cause musty or earthy flavour . Contd..

11. Aerobic growth of yeast Surface slime Discolorations Change in odor and taste Fat decomposition

12. Aerobic growth of molds  Stickiness : Incipient growth of molds makes the surface of the meat sticky to the touch. Whiskers : White fuzzy growth can be caused by a number of molds including sps . Thamnidium , Mucor , Rhizopus and others. Black spot : Cladosporium herbarum . White spot : Sporotrichum carnis , Geotrichum . Green patches : Penicillium expansum , Penicillium asperulum , Penicillium oxalicum . Decomposition of Fats : Many molds have lipases and hence cause hydrolysis of fats. Off odour and off tastes : Molds give a musty flavour to meat in the vicinity of their growth . Sometimes this defect is given a name called “ thamnidium taint”.

13. Whisker meat Green patches in meat Black spot in meat

14. ANAEROBIC bacteria Facultative and anaerobic bacteria are able to grow within the meat under anaerobic conditions to cause spoilage . The terminology used in connection with this spoilage is:- Souring :- The term implies a sour odor. This could be caused by formic, acetic, butyric , propionic and higher fatty acids or other organic acid like lactic. Vacuum packed meats, especially those in gastight wrappers, commonly support the growth of lactic acid bacteria. Acid and gas formation accompany the action of the “butyric” Clostridium spps and the coliform bacteria on carbohydrates. Souring can result from- Action of meat own enzymes during ripening Anaerobic production of fatty acids or lactic acid during ripening. Proteolysis without putrefaction, caused by anaerobes & called as “Stinking sour fermentation”.

15. 2. Putrefaction:- True putrefaction is the anaerobic decomposition of protein with the production of foul smelling compounds . It usually is caused by species of Clostridium . But facultative bacteria may cause putrefaction in its production, by species of Pseudomonas like P. putrefaciens , P. putrificum etc , chiefly in the genera Pseudomonas and Alcaligenes . Gas formation accompanies putrefaction by clostridia, the gases being hydrogen & CO2. Trimethyl amine in fish and isovalenic acid in butter are described as putrid odors. 3 . Taint:- This word is implied to any off-taste, off-odor. The term ‘bone taint’ is implied to souring or putrefaction. True putrefiers require temperature above those of refrigerator. Contd..

16. SPOILAGE IN DIFFERENT KINDS OF MEATS Extended refrigeration may have the growth of Pseudomonas, Acinetobacter , Moraxella and causes spoilage of fresh meat Lactic acid bacteria chiefly of the genera Lactobacillus, Leuconostoc , Streptococcus, Brevibacterium and Pediococcus are present in most meats, fresh or cured and can grow even at refrigerator temperatures . 1. Spoilage of Fresh meats : Putrefaction, Souring, Phosphorescence, discolorations. ( Pseudomonas & Micrococci ) . 2 . Fresh beef: Bacillus, Clostridium, Escherichia coli, Enterobacter , Proteus, Pseudomonas, Alcaligenes , Lactobacillus , Leuconostoc , Streptococcus, Micrococcus and Sarcina . 3. Hamburger: Lactobacilli, Leuconostocs , Microbacterium , Micrococcus, Alternaria . 4. Fresh pork sausage:

17. SPOILAGE OF DIFFERENT KINDS OF MEATS Sodium nitrite lactic acid bacteria in sausages like thuringer & leads to lactic acid fermentation 5. Spoilage of cured meats: Sour – by variety of bacteria Red – due to Halobacterium salinarum or red Bacillus sps . Blue – Pseudomonas syncyanea , Penicillum Spinulosum (purplish ), Rhodotonela sps . 6. Dried Beef or Beef Hams: Aspergillus, Alternaria , Monilia , Oidium , Fusarium , Mucor , Rhizopus , Botrytis and Penicillium . 7 . Bacon: Greening of sausage is due to the production of peroxides (Ex: H 2 O 2 ) by hetero-fermentative sps of Lactobacillus and Leuconostoc or other catalase negative bacteria. Acid forming Micrococci (Micrococcus candidus ) and Bacillus may grow in liver sausage and bologna. 8. Sausages:

18. SPOILAGE OF DIFFERENT KINDS OF MEATS Souring caused by Alcaligenes , Bacillus, Pseudomonas, Lactobacillus, Proteus, Serratia , Bacterium, Micrococcus, Clostridum . 9. Ham: Pseudomonas, Acinetobacter and Moraxella 10. Refrigerated packaged meats: Multiuse brines generally spoiled by putrefactive bacteria. Ex: Vibrio, Alcaligenes or Spirillum. Souring can be caused by Lactobacillus and Micrococcus and slime by Leuconostoc or Micrococcus lipolytics . 11. Curing solutions (or) pickles:

19. SPOILAGE IS ALSO INFLUENCED BY TEMPERATURE Not only air but temperature has an important influence on the type of spoilage to be expected in meat . When meat is held at temp. near 0°C, microbial growth is limited to molds, yeasts, & bacteria able to grow at low temperatures. This include:- sliminess, discoloration and spots of growth on the surface. Many bacteria can cause souring. Such as Pseudomonas, Lactobacillus, Leuconostoc , Streptococcus .. etc.

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