Meat quality
Collected by: Sayed Mohammd Naim KHALID
Date: 14 Aug 2012
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 (1).
Visual Identification
what factors affect meat quality?
There are many factors that can affect meat quality. It is important that producers and packers are aware of these factors in order for maximum lamb quality to be obtained.
Stress as a result of change of environment, rough handling, temperature, humidity, light, sound, and even confinement can decrease meat quality at the time of slaughter. Stress can result in meat that is pale, soft, firm, and dry.
A summary of the factors determining the meat quality is shown in the figure below (6):
Genetic factors also affect meat quality. It has been determined that color, firmness, and even marbling is inheritable. Furthermore, the sex of the animal affects meat quality due to varying amounts of sex hormones in the blood. Young rams tend to have meat that is darker and tougher than that of whethers or ewes of the same age.
The manner in which the lamb is slaughtered can also have an effect on meat quality. Slaughtering the lamb with stunning renders it unconscious but does not stop the heart. The beating heart helps remove blood from the lamb more quickly. This is important because extra blood in meat is unappealing to consumers. Furthermore, this method reduces the risk of hemorrhages, which cause blood spots in the meat and is also unacceptable to consumers. In addition, the removal of excess blood removes media for microorganisms responsible for meat spoilage.
The diet fed to the lamb is also a factor in meat quality. Consumption of wild onions or garlic may leave an undesirable meat flavor and grazing can result in the accumulation of yellow fat that is badly perceived by consumers.
what are the basic meat quality problems?
Pale, Soft, Exudative (PSE) condition is a quality problem most commonly affecting beef, lamb, and poultry.PSE condition results from an abnormally rapid drop in the pH of the carcass after slaughter.
Red, Soft, Exudative (RSE) condition which has characteristics similar to PSE except that the meat has a darker color. RSE also appears to be related to abnormally low pH levels and can result from preslaughter animal stress.
Dark, Firm, Dry (DFD) condition is a quality problem affecting beef and lamb. DFD meat (also referred to as dark cutting meat is characterized by its dark color and dry or sticky texture. It is less appealing to consumers due to its unappealing dark color and less pronounced taste. An additional problem with this type of meat is that it is more susceptible to spoiling since it has a higher than normal pH which is favorable for the growth of microorganisms. This condition occurs in animals which have survived stress before slaughter but have not had a chance to replenish their glycogen reserves (7).
Collected by: Sayed Mohammd Naim KHALID
Date: 14 Aug 2012
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 (1).
The visual identification of quality meat is based on colour, marbling and waterholding capacity. Marbling is small streaks of fat that are found within the muscle and can be seen in the meat cut. Marbling has a beneficial effect on juiciness and flavour of meat. Meat should have a normal colour that is uniform throughout the entire cut. Beef, lamb, and pork should also have marbling throughout the meat (1 &2).
Smell
Another quality factor is smell. The product should have a normal smell. This will be different for each of the species (i.e. beef, pork, chicken), but should vary only slightly within the species. Any rancid or strange smelling meat should be avoided .
Firmness
Meat should appear firm rather than soft. When handling the retail package, it should be firm, but not tough. It should give under pressure, but not actually be soft.
Juiciness
Juiciness depends on the amount of water retained in a cooked meat product. Juiciness increases flavour, helps soften meat - making it easier to chew, and stimulates saliva production in the mouth. Water retention and lipid content determine juiciness. Marbling and fat around edges helps hold in water. Water losses are from evaporation and drip losses. Meat aging can increase water retention and therefore increases juiciness.
Water retention and lipid content determine juiciness. Marbling and fat around edges helps hold in water. Water losses are from evaporation and drip losses. Meat aging can increase water retention and therefore increases juiciness. Using proper cooking methods, such as cooking slowly and/or with moist heat, can increase juiciness. Cooking past medium can also dry out meat. The best way to increase the juiciness of the meat being prepared is to learn the best cooking method.
Tenderness
Has been linked to several factors, such as the animal's age, sex or the muscle location. One important way to tenderize meat is by aging. Carcasses are aged by holding them at refrigeration temperatures for extended periods of time after slaughter and initial chilling.
Tenderness can be attributed to a person's perception of meat, such as:
Softness to tongue and cheek
Resistance to tooth pressure
Ease of fragmentation
Mealiness (if it breaks up too much in the mouth)
Adhesion (if it clumps together in the mouth)
Residue after chewing
Softness to tongue and cheek Resistance to tooth pressure Ease of fragmentation Mealiness (if it breaks up too much in the mouth) Adhesion (if it clumps together in the mouth) Residue after chewing
One important way to tenderize meat is by aging. Meat is aged by holding it at refrigeration temperatures for 2 to 4 weeks which allows enzymes within the meat to break down the muscle and connective tissue which makes the meat more tender.
Flavour
Flavour and aroma are intertwined to create the sensation the consumer has during eating. These perceptions rely on the smell through the nose and on the sensations of salty, sweet, sour and bitter on the tongue. Meat flavour is affected by type of species, diet, cooking method and method of preservation (e.g. smoked or cured).
Meat flavor is affected by many different things. A major portion of flavor is believed to be due to the breakdown products of ATP or energy. This phenomenon leads to a stronger flavor in energy storing muscles than in other muscles. This is also part of the changes in flavor attributed to aging, where certain molecules in the product are being destroyed over time.
Flavor is also attributed to many of the water soluble components of the muscle. These components are held in by water retention during cooking. Also sulfur and nitrogen compounds in the product will lead to a slightly different flavor.
Each species will have a slightly different flavor which can be traced to the fat within the muscle. Animals with different uses and different diets will deposit fat that contains different products. The fat melts during cooking and gives each species it's own distinctive flavor.
Changing cooking methods can also affect the flavor of the meat. Dry heat cooking will change the flavor on the outer portions of the product, while wet cooking will change more of the inner tissue taste. Reheated products also have a distinctive flavor that is usually unappealing. This distasteful flavor is caused by changes to the meat components during refrigeration. Smoked and cured products will also have a distinctive flavor.
How we can determine quality indicators?
This said that there is a positive relationship between pH and eating quality. An increase in the pH level is positively associated with a more desirable value for each of the eating quality variables: flavor, juiciness, tenderness, and texture.
This study found further that although pH is a good predictor of quality, measuring two other key variables of Instron (Star probe) and marbling can improve the prediction of eating quality characteristics.
This said that there is a positive relationship between pH and eating quality. An increase in the pH level is positively associated with a more desirable value for each of the eating quality variables: flavor, juiciness, tenderness, and texture.
This study found further that although pH is a good predictor of quality, measuring two other key variables of Instron (Star probe) and marbling can improve the prediction of eating quality characteristics.
There are many factors that can affect meat quality. It is important that producers and packers are aware of these factors in order for maximum lamb quality to be obtained.
Stress as a result of change of environment, rough handling, temperature, humidity, light, sound, and even confinement can decrease meat quality at the time of slaughter. Stress can result in meat that is pale, soft, firm, and dry.
A summary of the factors determining the meat quality is shown in the figure below (6):
Genetic factors also affect meat quality. It has been determined that color, firmness, and even marbling is inheritable. Furthermore, the sex of the animal affects meat quality due to varying amounts of sex hormones in the blood. Young rams tend to have meat that is darker and tougher than that of whethers or ewes of the same age.
The manner in which the lamb is slaughtered can also have an effect on meat quality. Slaughtering the lamb with stunning renders it unconscious but does not stop the heart. The beating heart helps remove blood from the lamb more quickly. This is important because extra blood in meat is unappealing to consumers. Furthermore, this method reduces the risk of hemorrhages, which cause blood spots in the meat and is also unacceptable to consumers. In addition, the removal of excess blood removes media for microorganisms responsible for meat spoilage.
The diet fed to the lamb is also a factor in meat quality. Consumption of wild onions or garlic may leave an undesirable meat flavor and grazing can result in the accumulation of yellow fat that is badly perceived by consumers.
what are the basic meat quality problems?
Pale, Soft, Exudative (PSE) condition is a quality problem most commonly affecting beef, lamb, and poultry.PSE condition results from an abnormally rapid drop in the pH of the carcass after slaughter.
Red, Soft, Exudative (RSE) condition which has characteristics similar to PSE except that the meat has a darker color. RSE also appears to be related to abnormally low pH levels and can result from preslaughter animal stress.
Dark, Firm, Dry (DFD) condition is a quality problem affecting beef and lamb. DFD meat (also referred to as dark cutting meat is characterized by its dark color and dry or sticky texture. It is less appealing to consumers due to its unappealing dark color and less pronounced taste. An additional problem with this type of meat is that it is more susceptible to spoiling since it has a higher than normal pH which is favorable for the growth of microorganisms. This condition occurs in animals which have survived stress before slaughter but have not had a chance to replenish their glycogen reserves (7).
Sources:
- http://www.fao.org/AG/AGAINFO/themes/en/meat/quality_meat.html
- http://ag.ansc.purdue.edu/meat_quality/qualities_of_meat.html
- http://ag.ansc.purdue.edu/sheep/ansc442/Semprojs/2004/process/MeatQuality.htm
- http://www.ans.iastate.edu/report/air/2007pdf/R2181.pdf
- http://www.extension.umn.edu/distribution/nutrition/DJ0856.html
- http://www.thepigsite.com/stockstds/54/factors-affecting-meat-quality
- http://ag.ansc.purdue.edu/meat_quality/meat_quality_problems.html
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