Why Does Beef Have to Lowest Bacterial Count
Full general hygiene principles for meat treatment
Current recommendations for handling all meat products are to keep them clean, cold and covered in social club to maintain quality and protect against food poisoning and affliction. Mostly contamination occurs when the product comes into contact with muddied easily, habiliment, equipment or facilities. If the product is kept clean in that location volition be little or no contamination by microorganisms whether bacteria, yeasts, moulds, viruses or protozoa or past helminths and poisonous chemicals.
Effect OF BACTERIAL GROWTH ON THE SHELF-LIFE OF MEAT AND MEAT PRODUCTS
The total viable count of bacteria (TVC) expressed every bit organisms/cm2 or equally organisms/g on fresh meat or a meat product sets a limit to its shelf-life. Meat will "spoil" with TVC at 106/cm2 considering of off-odours. Slime and discoloration appear at 108/cm2. The main factors determining the time taken for the TVC to reach these levels are the initial count due to contagion during slaughtering and processing, further contagion during storage, temperature, pH and relative humidity. An example of how the level of contamination affects shelf-life is shown in Tabular array 1.
After cleanliness, keeping meat products common cold is the second most important requirement in social club to achieve a desirable shelf-life. Microorganisms rapidly proliferate at elevated temperatures and slime development is a definite visual sign of microbial growth. The importance of temperature in the control of microbial growth is shown in Tabular array 2.
Bacteria relevant to meat, meat products and other food are divided into iii groups according to the temperature range within which they tin can abound: mesophiles 10–45°C, psychrophiles 0–28°C and psychrotrophs 10– 45°C, or slow growth at 0–x°C. Mesophiles will not abound beneath 10°C but psychrotrophs, of which Pseudomonas are the more of import, volition grow down to 0°C. The nearer to 0°C the storage temperature the slower the growth of the spoilage bacteria and the longer the shelf-life (Fig. 9).
TABLE 1
Consequence of initial contamination on the storage life of lean beef
| Initial bacterial count (org./cmii) | Days at 0°C before slime evolution |
| 100 000 | 8 |
| x 000 | 10 |
| ane 000 | 13 |
| 100 | fifteen |
| x | 18 |
TABLE 2
Relationship between storage temperature and slime evolution
| Storage temperature (°C) | Days earlier slime develops |
| 0 | ten |
| 1 | vii |
| 3 | 4 |
| 5 | iii |
| 10 | 2 |
| 16 | 1 |
Under ideal conditions leaner double in number every twenty minutes. A single bacterium multiplies to over i one thousand thousand in less than seven hours:
| Time | Number of bacteria |
|---|---|
| 12.00 | 1 |
| 12.20 | 2 |
| 12.40 | 4 |
| 13.00 | 8 |
| 14.00 | 64 |
| xv.00 | 512 |
| 16.00 | 4 096 |
| 17.00 | 32 768 |
| 18.00 | 262 144 |
| 18.40 | 1 048 576 |
Some leaner cause product spoilage, others crusade nutrient poisoning. The one-time limit product shelf-life but the latter cause affliction. Almost all foodpoisoning bacteria are mesophiles so refrigeration beneath 10°C offers practiced protection. Many mesophiles cause spoilage, but since meat is refrigerated nearly spoilage is due to psychrophiles. Storing meat at temperatures close to 0°C volition inhibit the growth of pyschrotrophs. Shelf-life will exist extended past fugitive contagion through good hygiene practices.
Aerobic bacteria have an absolute requirement for oxygen which limits their growth to the meat surface. Anaerobic bacteria grow within the meat as they demand the absence of oxygen. Facultative anaerobes can grow slowly within oxygen but grow better in its presence. Food-poisoning bacteria are anaerobes and facultative anaerobes. The most important spoilage bacteria (Pseudomonas spp.) are aerobic.
| 9. Dissimilar types of leaner can grow within different temperature ranges |  |
Water is required past micro-organisms so reducing the h2o bachelor below the optimum level will prolong shelf-life. If meat is stored at a relative humidity (RH) below 95 percent, moisture will be lost from the surface. Since near spoilage bacteria, existence aerobic, can grow only on the surface, this surface drying will extend the shelf-life. Moulds (fungi) are able to abound in drier conditions than leaner so that desiccation has a selective upshot on microbial growth.
Meat pH is the level of acerbity in meat. Stored sugars are broken downwardly to lactic acrid. In living muscle it is near seven.0 (above this is alkaline, below is acid). It falls to 5.four–5.6 within 24 hours. Loftier last-pH values upshot when animals are exhausted at slaughter, for instance because of fighting in lairage or transport. Spoilage bacteria multiply rapidly on high-pH meat and shorten the shelf-life. Exhausted animals should exist rested earlier slaughter.
A high TVC resulting from severe contamination during slaughter or processing will shorten the shelf-life even in ideal weather. It also indicates poor hygiene so that contamination with food-poisoning bacteria is probable.
EFFECT OF CONTAMINATION ON SENSORIC Properties OF MEAT AND MEAT PRODUCTS
Aerobic spoilage by leaner and yeasts usually results in slime formation, undesirable odours and flavours (taints). Colour changes, rancidity, tallowy or chalky flavours from the breakdown of lipids may also occur. Colour changes every bit a upshot of pigment oxidation may exist grayness, brownish or light-green discoloration. Aerobic spoilage past moulds results in a sticky surface, musty odours, booze flavours and flossy, black or green discoloration.
Anaerobic spoilage which occurs either within the meat or on the surface in sealed containers where oxygen is absent or very limited is marked by a souring due to the product of organic acids and gases.
FOOD POISONING
Food poisoning may be due to infection or intoxication. Infection is acquired by the consumption of alive bacteria which multiply in the body producing characteristic symptoms. Intoxication is due to toxins in nutrient produced by bacteria before the food was eaten. Toxins are chemic compounds which may linger in food with no microbes growing in it, and are therefore very dangerous.
Salmonellae are facultative anaerobes which cause infectious food poisoning. Ten or xx cells of Salmonella typhi are sufficient to cause typhoid merely x 000 to 100 000 cells of other species may exist necessary to cause an infection. Some are host-specific affecting the brute from which the meat was produced but failing to cause infection when consumed by man. Typical symptoms of salmonellosis include diarrhoea, fever and vomiting. The illness may final one to xiv days after a 12 to 24-60 minutes incubation menstruation. Victims may excrete the leaner for weeks after the symptoms subside. Poor personal hygiene will cause contagion of meat.
Staphylococcus aureus is a facultative aerobe that causes intoxication. Information technology lives in the olfactory organ, throat, hair and skin and on animal hides. Meat is contaminated past handling and by sneezing or coughing. Infinitesimal amounts of the toxin will cause illness, which starts inside one to eight hours of eating poisoned nutrient. Nausea, vomiting and stupor may concluding for 1 to two days. On rare occasions it is fatal. This bacterium does not produce off-odours or spoilage so it cannot be easily checked. Refrigeration volition command its growth. Cooking may destroy the bacteria but not the toxin as information technology is heat stable. Information technology is particularly troublesome in cooked cured meats, normally as a result of recontamination later on the curing procedure in subsequent handling, for instance during slicing.
Clostridium botulinum, an anaerobe, produces the toxin botulin, one of the most poisonous substances known. This attacks the key nervous organization causing death by respiratory paralysis. Dormant cells occur everywhere in the soil, fish, animals and plants. High-moisture, low-acrid, depression-salt weather at above iii°C favour growth and toxin production. Control measures must destroy spores or forestall growth and toxin formation. Botulism is usually due to undercooking processed meats. Pressure-cooking volition give commercial sterility. Pasteurization (heating to 70°C) and adding table salt (NaCl) and sodium nitrite (NaNOii) is used for canned ham. Refrigeration (0–10°C) is essential for vaccum-packed meats. Frozen storage prevents growth.
Clostridium perfringens, an anaerobic bacterium, is a common cause of food poisoning simply is rarely fatal. It grows well in warm meats so is normally plant in left-over meats that have non been kept chilled and not been reheated to 70°C to impale the bacteria nowadays. The main symptoms are diarrhoea and weakness which terminal for 12 to 24 hours after an incubation flow of eight to xx hours.
Source: https://www.fao.org/3/T0279E/T0279E03.htm
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