Meat-Preservation-1 Flashcards
The main aim of the meat preservation…
to check meat spoilage, which causes some changes in texture, flavour and odour of meat and finally loss of its wholesomeness.
Prevention or delay of microbial spoilage: This can be achieved by four following approaches:
(K.R.H.D)
- keeping out the microbes
- Removal of microbes
- Hindering the growth activity of microorganisms
- Destruction of microorganisms
Prevention or delay of self-autolysis/ decomposition of the food: This can be done by :
- Destruction of meat enzymes
- Prevention of chemical reaction
- the first and simplest method that has been adopted for the preservation of meat since antiquity
- refers to the removal of moisture (reduction in a*) from the food
drying
the food material by retarding the microbial growth, enzymatic and the chemical reactions that deteriorate the meat and cause spoilage
low temperature preserves
- refers to preservation by lowering the temperature of the meat to a point above the freezing temperature
- is also widely used for short-term preservation of meat as it has no adverse affect on appearance, flavour or nutritional value
chilling
- is cooled to O°C. Meat starts freezing at 1.5°C
- this method of preservation has its own importance because properly processed meat retain most of fresh properties for extended length of time
freezing
- aims at preventing the multiplication of harmful bacteria, molds and yeast as water is converted to ice and therefore, remains no longer available for microbes
- occurs at different rates in different parts ofthe material being frozen
freezing
Freezing of meat is achieved by two ways namely:
quick and slow freezing
is lowered to -20°C within 30 minutes by directly or indirectly passing refrigerated air onto the meat
fast freezing
required temperature is attained within 3-72 hours
slow freezing
The maximum formation of ice crystals occurs in the range of
-1°C to -4°C, which is called as ‘zone of maximum ice formation’
appears bleached due to patchy evaporation
freezer burn
To keep meat frozen during transportation’ the freezing of meat temperature as below as
-25°C
Freezing methods can also be classified into four broad categories namely;
(i) Contact with cold solids
(ii) Contact with cooled liquids
(iii) Contact with cooled air
(iv) Two phase freezing systems
- The process of thawing is reverse of freezing
- requires more time than the time required for freezing the same material
- is mainly because the thermal conductivity of water is much lower than that of ice
thawing
- exerts inhibitory effect on bacterial growth by bringing down the water activity (aw)
- imparts taste
Sodium chloride (salt)
- plays an important role in retarding/slow the growth of several bacteria, particularly Clostridium botulinum
Nitrite
- constituents in smoke also have bactericidal action
phenolic
- improve the texture by enhancing the water holding capacity (WHC)of muscle proteins
Phosphates
Methods of curing the meats include following two approaches:
- dry curing
- Pickle curing
In this method, salt mixture is applied on the surface of meat and kept in chill room (2-4°C) for 7-10 days.
dry curing
In this method of curing, the meat is immersed in pickle solution (salt mixture dissolved in water)
pickle curing
Salts and chemicals used in curing are as follows:
i) Salt (sodium chloride)
ii) Nitrate
iii) Smoke
iv) Sorbates
V) Lactate
vi) Organic acids as acidulants
vii) Antioxidants
viii) Other Chemicals
- It is the most important ingredient used in curing of meats - the finished product containing about 2.5 per cent
- The halophilic (salt-loving) bacteria like Staphylococcus spp. grow well in high salt concentration unlike the non-halophilic bacteria, which exhibit slow growth under these conditions
Salt (sodium chloride)
- is a vital ingredient for meat curing
- It reacts with myoglobin to produce pink colour in cured meat
- specific protection against outgrowth of spores of Clostridium botulinum
ii) Nitrate
- is an integral part of curing process of meat
- provides specific colour (brownish or mahogany) and preservative and antioxidant effects
- contains more than 200 identified compounds include acids, phenols, carbonyls, alcohols and polycyclic hydrocarbons
- oldest method used for the preservation, smoking maintains flavour and colour of meat
smoke
- Sorbic acid and its salts are effective inhibitors of mold and yeast growth
- also act as effective antimicrobial agents in meat
sorbates
antimicrobal activity of sodium lactate has been demonstrated against a broad range of microorganisms in both fresh and cured meats
lactate
- Acidulation (addition of acids) is a method of preservation of meat that is being used since ancient times
- Pickled products are good examples in this regard
- Vinegar (about four per cent acetic acid) is a common preservative used in meat pickles
- Other organic acids such as citric acid and lactic acid can also be used
Organic acids as acidulants
- substance used to prevent the auto-oxidation of lipids, which results rancidity or unwanted flavours in meat
- such butylated hydroxyanesole (BHA), butylated hydroxytoluene (BHT) and butylated hydroxyquinoline (BHQ)are phenolic compoundspossessing anti-microbialproperties against large number of micro-organisms including bacteria, yeast and molds, some viruses, mycoplasmas and protozoa, when used in a concentration range of 10 to 1000 ppm.
antioxidants
have potential for preservation of meat as some of them are non-toxic and can be used safely
Antibiotics and bacteriocins
is used as fungistat
natamycin
a bacteriocin produced by Lactococcus lactis is effective against most of the Gram-positive
nicin
- It is a simple, low-tech and inexpensive method of preservation of foods that can be practiced at ambient temperatures
- is a process in which chemical changes in an organic substrate are brought about through the action of enzymes liberated by microorganisms
fermentation
There are eight genera of lactic acid bacteria:
Lactobacillus
Leuconostoc
Pediococcus
Streptococcus
Corynebacterium
Enterococcus
Lactococcus
Vagococcus
The purpose of packaging is to
to protect the meat products from microbial contamination, light, physical damage or chemical changes
This method is helpful in preserving meat as it slows down oxidation of meat components especially when packaging material of low oxygen permeability is used which prevents air from entering the package
vacuum packaging
- Some-times, modified or controlled atmosphere is created inside the package by using 10 per cent CO, alone or incombination with oxygen and nitrogen for storage of meat, poultry and fish because, CO, has inhibitory effect on certain microbes
Modified atmosphere packaging
- A retortable pouch is made of a laminate of three layers held together by adhesive and used for replacing cans for cooked and ready-to-eat foods
- Retortable flexible pouches
gives a skin-tight (contour) fitting by employing a low oxygen permeability film, stabilizes the product and increases the shelf life
cryovac packaging
concept of food preservation is the modern concept and based on installing the ‘hurdles or blocks’ in the microbial growth pathways through ‘additive or synergistic effect’ of two or more methods of food preservation discussed above
hurdle
