Spoilage fo Meat and Meat Product

Meat

Contamination

The healthy inner flesh of the meat contains few or number microorganism although they have been found in lymph node and bone marrow Staphylococci, StreptococciClostridium ,and salmonella have been isolated from the lymph node of red meat animal . Normal slaughtering practices would remove the lymph node from the edible part. The important contamination, however, comes from external sources during bleeding ,handling, and processing . During bleeding , skinning and cutting the main source of microorganism are the exterior of the animal (hide ,hooves and hair) and the intestinal track and the exterior of the animals harbour larger number and many kinds os microorganism from soil , water , food, and manure, as well as its natural surface flora and the intestinal contents, contain the intestinal organism . Knives .clother, air hands of the workers can server intermediates source of contamination. During handling off the meat ,contamination can come from the cart,boxes, and other containers.

Preservation

Following methods are employed for the preservation of meat

Asepsis: Asepsis prevents external microorganism from entering into the meat . Water spraying before slaughter is recommended to remove dirt and microorganism from hair hiding and food bath may be used to remove dirt from hooves other methods of sepsis include sanitization of knives,used fro killing and personal hygiene of food handling

use of heat : Canning is the specialised technique of preservation for meat . Canned meat are divided into two group on the basis of heat treatment employed for canning

• Nonself-stable canned meat: The processing temperature is about 65c a the size of the container is up to22lb . They kill only part of spoilage organism and the spoilage .
• Self-stable canned meat : The processing temperature are 98°cthe size of container is usually less than 1lb

Use of low temperature

• Chilling : Chilling temperatures vary from -1.4c to 2.2c with the lower temperatures preferred . The time limit for chilling storage depends on meat example 30 day for beef , 1-2 weeks for mutton. during chilling certain . Psychrophiles may give a problem .So, freezing must be done.
• Freezing;Freezing is the most effective method of preservation of meat of longer period of time . Freezing of meat is done at a temperature of -12.2c to -28.9c . Meats are frozen quickly in the package . Freezing process kills about half of the bacteria and their number decrease slowly during storage .

Preservation by radiation: UV ray used in rapid ageing of meat . Ionizing radiation used to kill nematodes and microorganism meat.

Preservation by chemical preservatives :Chemical preservatives are added meat as a component of wood smoke and curing solution.

• Wood smoking:Smoking of food usually have main purposes i.e adding desired flavour and preservation . Other desirable effects include improvement in colour and tenderization (soft) of meat . commonly smoke is obtained by burning hardwood and temperature of the smoking period last from a few hours to several days.
• curing :It is a common preservation method for a meat . Both solid cuts and ground meat are subjected to curing agent permitted in meat and vinegar function of ingredients use in curing are sodium chloride and sugar; it is a lower Aw and gives flavour and sodium nitrate ; it is a colouring agent . In acidic environment nitrite decomposes into nitric acid which reacts with heme pigment of meat to from nitroso myoglobin that gives stable red colour to the meat and vinegar ; It is a preservative. They are four methods of the introducing curing agent in meat . the key use in which the day ingredient age rubbed into the meat . The pickles cure in which meat is immersed in the solution the of the curing agent. The injecting cure is injected into the meat by needle and finally ,the direct addition method in which curing agent are added directing to the finely ground meat. The curing temperature, especially with pickle cure, is usually about 2.2c to 3.3c and the time of curing vary with the meat to be cured and the method used.

Antibiotics :Antibiotic most commonly recommended meat are chloramphenicol , oxytetracycline ,chlortetracycline , onion etc. Antibiotic may apply in meat by various ways .It may be fed to the animal for a long period ,it may be in high dose for a short period before slaughter , it may be injected into flesh and it may be applied or mixed directly to the meat.

Spoilage

A common type of microbial spoilage of meat can be classified on the basis of whether they occur under aerobic or anaerobic conditions and whether they are caused by bacteria , yeast or mould.

Spoilage under aerobic condition

• Bacterial spoilage

1. Surface spoilage :It is caused by Pseudomonas. AcinobacterMoraxellaa. Alkaligenes, Streptococcus , Lecconostoc , Bacillus and Micrococcus, temperature and viable moisture influence type of microorganism causing slime.
2. The surface in the colour of meat : Read colour of meat may be changed into green brown or grey due to the production of oxidising agent hydrogen sulphate etc. by the microorganism . example Lactobacillus and Leuconostoc cause greening in colour.
3. Change in fat : Fat of meat may become rancid due to the ;oppose producing microorganism . Such as Pseudomonas . Achromobacter.
4. Surface colour due to pigmented bacteria : Serratia marcescens give red spots , Pseudomonas syncytia , gives a blue colour . Flavobacterium gives yellow colour
5. Phosphorescence ; It is caused by luminous bacteria eg. Photobacterium groups on the surface of the meat .
6. Off odours off test (taints ) : Undesirable odour and a test called taints are caused by many bacteria due to the production of volatile acids . Such as formic acid .acetic acid , butyric acid etc . Actinomycetes give earthy flavour.

• Mold spoilage

1. Stick ness :Many molds grow on the surface of the meat and make it stick touch
2. whiskers : When meat is kept at a temperature near freezing mold grow slowly without sporulation on surface production white cottony grow . It may be caused by Thamnidium , Mucor Macedo ,Mucor across etc.
3. Black spot :It is caused byCladosorium herbarium
4. White spot :It is caused by Sporotrichum crisis
5. Green spot :it is caused by Penicillium species .
6. Chang in fat : Many molds produce lipase and cause hydrolytic of fat
7. Off odour and off taste : Many molds give earthy flavour

• Yes spoilage :Under aerobic conditions , yeast grows on the surface of meat causing sliminess (viscous) rancidity of fat off odour and off taste and discolouration like white , pink and brown spots.

Spoilage under anaerobic condation : In aneriobic condation , anerobic oe facultative anaeriobic bacteria spoil the meat.

• Souring :It is caused by formic acid , acetic acid , butyric acid , propionic acid and . Souring may also be caused by foods won enzyme
• Putre faction :It refers to the anaerobic decomposition of the protein with the production of offensive smelling compounds such as hydrogensulfite , mercaptans, indole , skatole etc. It is usually caused by Clostridium species but species of Pseudomonas , Proteus ,and Alkalines may cause Putrefaction.
• Taint :It refers to any undesirable odour or taste.

Spoilage of fresh meat

Fresh beef :

• White , green , yellow, greenish , blue, black spots . Due to pigmented microorganism .
• Phosphorescence
• Sliminess on the surface due to slime forming an organism . Stickiness due to mold whiskers due to mold
• Souring and putrefaction

Fresh pork sausage : Souring is the most common type of spoilage of refrigerated sausage . It may be causing mainly by Lactobacillus and Lactobacillus caused park sausage undergoes slime formation by mold on long term storage due to pigment organism.

Spoilage of cured meat :

Curing salts make meat market more susceptible to gram-positive bacteria and mold than to gram-negative bacteria

• Sausage : It moisture is available , micrococcus and yeast from slime on the surface with less moisture , the mold may give colony growth and coloured spots . A microorganism that produces peroxide causes a greening of sausage. example Lactobacillus , Leuconostoc etc .
• Refrigerated : Bacteria like Pseudomonas , Acinetobacter, and Moraxella cause spoilage like off flavour ,smile and sometimes purification .

Reference

Frazier, WC and Westhoff DC.Food Microbiology.3rd. New Delhi: Tata McGraw-Hill Publishing Company Limited, 1986.

Jay, MJ.Moderen Food Microbiology.Ed. India. 3rd. Delhi: CBS Publications and Distributions, 1987