Paper No.: 08
Paper Title: TECHNOLOGY OF MEAT, POULTRY, FISH AND SEAFOOD
Module – 08: Quality attributes of meat
Technology of meat, poultry,
fish and Seafood products
Conten t
• Introduction
• Perception of meat quality by Consumer
• Factors affecting meat quality
• Age Muscle Location Feeding
• Post-Mortem pH Decline Temperature Humidity
• Water activity (aw) Thaw Rigor Cold Shortening
• Carcass Electrical Stimulation Heat
• Meat Quality Attributes
• Visual Identification Tenderness &Texture Smell & taste
• Juiciness Colour Flavour
Introductio n
• Meat is an animal flesh mammalian species (pigs, cattle, lambs, etc)
• Usage varies worldwide, depending on cultural or religious preferences
• Meat quality is normally defined by the compositional quality (lean to fat ratio) and the palatability factors such as visual appearance, smell, firmness, juiciness, tenderness, and flavour
Perception of meat qualit y by Consumer
Ø INTRINSIC
• At point of sale:
• Colour - purple and red colures are natural for fresh meats
• Fatness - Fresh meat has white and a bit of yellow fat (except old beef meet –its fat looks yellow
• Drip loss – Meat with high drip loss has an unattractive appearance & leads to:
• Poor colour
• Low consumer acceptance
• Loss of sales
• Nutritional - concentrated source of protein
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Cont …
Ø On cooking:
• Aroma
• Shrinkage
• Exudates
Ø On eating:
• Tenderness
• Juiciness
• Flavour
Factors affecting meat quality
• Age
• MuscleLocation
• Feeding
• Post-MortempHDecline
• Temperature
• Humidity
• Wateractivity(aw)
• ThawRigorandColdShortening
• CarcassElectricalStimulation
• HeatRigor
Effect of Age on meat quality
• Animal aging causes darkening of meat
• Tenderness is also greatly affected by age
• Less tender as the animal ages
• Meat flavour also intensifies with age
• The flavour meat of older animals, especially sheep, may be so intense that some find it to be objectionable.
Effect of Feeding on meat quality
• Starchy foods and sugars fed before slaughter can help restore depleted muscle glycogen levels to allow development of a
normal post-mortem pH
• Grass contains high levels of beta-carotene, which can be stored in fat giving the fat a yellow colour.
• An undesirable "grassy" flavour may result from compounds found in forage.
• Consumption of wild onions and garlic can also give an undesirable meat flavour.
• Animals should not be allowed to forage for several weeks before slaughter instead, they should be fed a grain diet.
Effect of pH Decline on meat quality
pH decline - rate at which the carcase pH level falls from 7.10 (live animal pH) to the level at which it will not fall any further (this is known as the ultimate pH).
If the pH decline is too fast and the ultimate level is reached while the temperature is still high, heat-shortening will result. This does not make the meat as tough as cold shortening but has undesirable effects including:
• an increase in toughness
• meat which is very pale and sometimes watery (known in industry as Pale Soft Exudative – PSE – meat)
• ‘two-toning’ in some cuts leading to unattractive retail appearance
• the prevention of ageing
• reduced water-holding capacity
Effect of Thaw Rigor and Cold Shorteningon meat quality
• When meat is frozen before the onset of rigor mortis a more severe form of rigor mortis will set in upon thawing the meat.
This is called thaw rigor.
• Due to thaw rigor meat is very tough and lacks juiciness
• Cold shortening develops when meat is not frozen but is stored between 32 and 59 degrees Fahrenheit. It is less severe than thaw rigor.
Effect of carcass electrical stimulat io n on meat quality
• Widely used method of improving the tenderness of beef and lamb
• Protects against cold shortening and may improve meat tenderness, colour, and appearance
• It also hastens the development of quality characteristics such as bright red muscle colour, muscle firmness, and marbling
• It reduces aging time.
Effect of humidity on meat quality
• In cutting rooms the humidity of the air should be below the level which would cause vapour condensation on the surfaces of the meat being deboned and cut
• A balanced air humidity(70%) that does not cause wet surfaces on the meat with resulting accelerated bacterial growth, but on the other hand keeps evaporation losses low.
• Maturation of raw hams or dry sausages of the salami type require 90–95 percent and after a certain period finalizing the process at 70–75 percent relative humidity
• Hygrometers - Suitable instruments (hygrometers) for the exact measurement of relative humidity
Effect of water activity on meat quality
• Free water available for microbial growth in a food product
• “water activity” - the ratio of the water vapour pressure measured in the product and the pressure of a saturated water vapour atmosphere at the same temperature
• The minimum moisture content necessary for microbial growth varies with the single species of micro-organisms and can be expressed in terms of minimum water activity required.
• The keeping quality of dried meats and meat products without refrigeration depends on their water activity.
• Dried meat such as biltong, charque, etc. reaches a sufficiently low water activity to be shelf-stable
Meat Quality Attributes
• Visual Identification
• Tenderness &Texture
• Smell and taste (aroma and flavour)
• Juiciness
• Colour
• Flavour
Meat quality attributes -Visual Identification
• The visual identification of quality meat is based on colour, marbling and water holding capacity.
• Meat should have a normal colour that is consistent throughout the entire cut
• unfavourable influences such as unclean meat surfaces, surfaces too wet or too dry, or unattractive
• blood splashes on muscle tissue.
• The way meat looks, either as a carcass or as boneless meat cuts, has an important impact on its
• objective or subjective evaluation.
• Grading is an objective evaluation method
• The way the consumers or the processors check the appearance of meat is subjective.
Meat quality attributes - Tenderness &Textur e
Tenderness and texture depend on several factors, which include:
• Size of meat fibres
• Activity of the muscle
• Amount, kind and distribution of connective tissue
• Degree of natural aging
• Mechanical means , marinades and enzyme treatments
Meat quality attributes –
Smell and taste (aroma and flavour)
• The freshness of meat is generally indicated by its smell together with its appearance and colour.
• The smell of fresh meat should be slightly acidic, increasing in relation to the duration of the ripening period because of the formation of acids such as lactic acid
• Unpleasant odour owing to substances originating from the bacterial
• Degradation of the meat proteins, such as sulphur compounds, mercaptane, etc.
• Any rancid or strange smelling meat should be avoided.
Ø Flavour of meat is depend up on:
• Age of the animal
• Aging (holding of meat after slaughter)
Meat quality attribute -Colour
• The natural colour of fresh meat, except poultry meat, is dark red, caused by the muscle pigment, myoglobine.
• Remarkable changes in the meat colour occur when fresh meat has been boiled or cooked. It loses its red colour almost entirely
• colour indicates the type and stage of the treatment to which the meat has been subjected, as well as the stage of freshness.
• Vacuum-packaged fresh meat is dark purple, indicates that no oxygen is present within the package
Meat Storag e
• Stored at 28 to 30°F
• Frozen meats should be stored at 0°F
• Ice crystal development due to temperature fluctuations during freezer storage
• Frozen meat products should be packaged in material, which prevent the evaporation of moisture and entrance of air
Interesting facts
•Meat quality is normally defined by the compositional quality (lean to fat ratio) and the palatability factors such as visual appearance, smell, firmness, juiciness, tenderness, and flavour.
•The nutritional quality of meat is objective yet "eating" quality, as perceived by the consumer, is highly subjectiveThe nutritional quality of meat is objective yet "eating" quality, as perceived by the consumer, is highly subjective
•Texture is a degree of meat fineness or coarseness. Texture measurement can be visually, touched or chewed.
•Maturation of raw hams or dry sausages of the salami type require 90–95 percent and after a certain period finalizing the process at 70–
75 percent relative humidity
Points to ponder
•The interior of the muscle will remain purple because oxygen cannot penetrate to the center of the meat.
•The importance of meat in the diet is as a concentrated source of protein which is not only of high biological value but its amino acid composition complements that of cereal and other vegetable proteins.
•Drip loss occurs during the conversion of muscle to meat
•Muscles which are free to shorten during rigor mortis are generally less tender.
•Consumption of wild onions and garlic can also give an undesirable meat flavour.
•After slaughter and exsanguinations lactic acid builds up in the animal carcass causing a decline in pH
Summary
Meat quality is normally defined by the compositional quality(lean to fat ratio) and the palatability factors such as visual appearance, smell, firmness, juiciness, tenderness, and flavour.
The nutritional quality of meat is objective yet "eating" quality, as perceived by the consumer, is highly subjective. Several factors affect the meat quality like Age, muscle location, diet, post mortem pH decline, temperature, humidity, and water activity, Thaw Rigor and Cold Shortening, Carcass Electrical Stimulation and Heat Rigor.
Suggested readings:
Charley, H. 1982. Food Science. John Wiley and Sons. New York, NY.
Ingram, M., and Simonson, B. 1980. Meats and meat products. In Microbial Ecology of Foods, Vol. II. Food Commodities. Academic Press. New York, NY.
Labropoulous, A.E., and Kelly, R.F. 1978. Delayed chilling of beef--A review. J. Food Protect. 41:483-485.
Levie, A. 1979. The Meat Handbook, 4th ed. Avi Publishing Co. Westport, CT.
Price, J.F., and Schweigert, B.S. 1971. The Science of Meat and Meat Products. 2nd ed.
W.H. Freeman and Co. San Francisco, CA.
Terrell, M.E. 1979. Professional Food Preparation 2nd Ed. John Wiley & Sons. New York, NY.
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Haverstock, D. October, 1987. Fresh vs. Frozen: Is One Superior? Restaurant Management.
Cleveland, OH.
Hendrickson, R.L. 1978. Meat, Poultry and Seafood Technology. Prentice-Hall, Inc.
Englewood Cliffs, NJ.
Liston, J. 1980. Fish and shellfish and their products. In Microbial Ecology of Foods, Vol. II Food commodities. Academic Press. New York, NY.
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