Quiz 4

What affects the delay phase of rigor mortis

ATP is partially regenerated by CP and Glycolysis.

Define pH and temperature relationship:

Activity of enzymes are temperature dependent and can affect the pH decline through lactic acid production; changes in ATP-ase activity at low temperatures is partially due to the loss of ability to sequester calcium at low temperatures; rate of pH decline is faster at 37C than at 0C.

Describe the challenges related with intact male pork production.

Aggression - Aggression can make the animals harder to handle as well as resulting in blemishes and bruises. These would result in losses to the carcass weight. Intact males are more likely to have problems with being dark cutters. Partly because of the aggression, but also because intact males seem to not have any moderation in the activation of glycogen for energy. They tend to reduce glycogen stores quickly which contributes to more dark cutters, and higher ultimate pH that can affect tenderness. Less flavor - Intact males will use more energy for growth and because of this there is less external fat but also less marbling. Since the flavor associated with each species is associated with fat, the meat from intact males will have less species flavor and more flavors associated with lean tissue, metallic, serum-y etc. Boar Taint - Boar taint is off flavors and odors associated with intact male pigs. The older the animal the more likely the off-flavors are likely to occur. Andostenone is a pheromone that breakdown products concentrate in the fat and contribute to the off-flavor and odors. Countries that rear intact male pigs for meat will test back fat for skatole, a breakdown compound that is concentrated in the fat of carcasses that will have the off flavors and odor.

Lairage is designed to

Allow animals to recover from transport

Identify the characteristics that affect color intensity and stability.

Animal factors and production (meat quality and pH)- species and age affect the amount of myoglobin in the muscle and thus the color intensity of meat, ultimate pH and rate of pH will both affect the color perceived Part of this is due to oxygenation rate or the ability of the oxygen to dissolve in surface water and carry it to the myoglobin. The penetration of oxygen will determine how deep the oxymyoglobin layer will be in the meat. As long as the diet supplies enough energy to have glycogen stores, there is little effect of diet on color. However there are changes in color when the pH is higher. Incorporating vitamin E in the diet can result in longer color stability. Temperature - Both storage time and temperature have a great effect on color stability. Color acceptability decreases as storage time increases, however the length of time the color is acceptable is greatly affected by storage temperature. Fresh meat products should be stored at temperatures of -1.5C (30F) to give maximum color shelf-life of products Muscle differences Different muscle function, fiber types and location will affect the intensity of color by altering the amount of myoglobin in the muscle. Postmortem age of the meat - The length of time the meat source has been stored postmortem affects the color stability. Increased time from slaughter results in reduced color stability because co-factors necessary for the reduction of metmyoglobin are depleted as postmortem time increases. Many companies that manufacture fresh sausages utilize pre- rigor meat. The pre-rigor meat has a higher pH and a more active reducing enzyme system which allows for increased color stability Ground vs. Whole muscle- Grinding or other particle size reduction incorporates air. The more air that is incorporated, the more stress is put upon the metmyoglobin reducing system. Smaller meat particles result in shorter color shelf-life of raw meat products. Packaging, Oxygen & other atmospheres - Packaging will impact the color of fresh meat. If the product is vacuum packaged (exclusion of oxygen) then the color pigment will be very stable, but it will be darker as the pigment is in the myoglobin state. Overwrapping (oxygen permeable film) has been used for years to package fresh meat in the retail counter. However, this product will have a shorter color shelf-life as there is a constant conversion of pigments until there is no more reducing enzymes functioning to return the pigment to myoglobin. This is especially challenging with fresh sausage. The system is stressed by particle size reduction and increased microbial contamination because of increased surface area. The answer to this was to develop modified atmosphere packaging (MAP). This type of packaging alters the atmosphere to reduce the oxygen amount but to also include nitrogen as an inert gas and carbon dioxide as an antimicrobial. This will result in extended color shelf-life compared to overwrap but not as good as vacuum packaging. Oxygen pressure between 40 and 60 mm of mercury are needed for oxymyoglobin to be the predominant state. Modified atmosphere packaging utilizes this information. This packaging will be flushed with a mixture of gases, oxygen, nitrogen and carbon dioxide. Oxygen is for color and nitrogen and carbon dioxide is for their antimicrobial properties. This is also why vacuum packaged fresh meat usually has the dark, purplish red color we associate with a freshly cut meat surface. Once the meat is taken out of the vacuum package and oxygen is allowed to dissolve in surface moisture, the meat will recover its bright red color and bloom. Processing ingredients and Heating- During the cooking process, myoglobin is denatured. All of the pigment is not affected at the same time or to the same extent and this is why you get reddish color at different end point temperatures when cooking. The cooked pigment is denatured metmyoglobin. It is brown and is easily recognized in cooked meat products. Certain meat conditions can result in protection of the myoglobin. The ultimate pH of the muscle is one of these conditions. The ultimate pH of meat or meat products will affect how the meat color changes during cooking. Higher ultimate pH will protect the globin portion of the myoglobin and slow down denaturation. This means that if the meat has a high pH, it will have to be cooked to higher end-point temperatures to get the same visual degree of doneness as one with normal pH. Frequently, complaints of this hard to cook defect are associated with a high pH of the meat or meat product. This meat appears raw in color, dark red to purple, long after appropriate cooking temperatures have been reached.

Hamburger

Beef minced or flaked and formed.

How does aging affect meat tenderness?

Calpains break down cytoskeletal proteins to increase fragmentation; collagen changes; calcium leaks from the SR to activate calpains

What is the implication of choosing for higher calpain and lower calpastatin activity to improve tenderness?

Calpastatin inhibits calpain activity. Calpains are responsible for the initiation of protein turnover. if you choose for less calpastatin activity, you could be selecting for muscle mass.

Rapid temperature decline postmortem

Can cause cold shortening in lightweight carcasses; results in calcium release from the SR to increase shortening of sarcomeres; affect can be ameliorated by using electrical stimulation

Describe carcass bruising or blemishes

Caused by mounting and butting behaviors, understocking and overstocking can lead to damage, speed moved can influence bruising

How does carcass suspension affect tenderness?

Change from tendon to aitch bone suspension stretches the loin muscle increasing sarcomere length; Improves loin tenderness but reduces tenderness in round muscle

Technological characteristics

Color and drip

DFD results from?

Depletion of glycogen stores

When should dry aging be used?

Dry aging will cause changes in flavor and tenderness. The tenderness improvement is mostly due to endogenous enzymes breaking up the myofibrils with some breakdown of collagen, especially if the aging period is beyond 14 days. The flavor changes are a mixture of protein degradation to amino acids and oxidation of fatty acids. Resulting flavors are linked to the microorganisms on the surface of the cuts. Traditionally dry aging was applied to higher quality cuts that were destined for the high end restaurant trade. More recently, research has included using it on meat from grass-finished animals. When deciding when to use dry aging you need to consider the end user. The dry aging results in a distinct flavor and aroma. Tenderization on aging can occur in a vacuum bag as well as it can in air. The flavor changes will be different under the different aging conditions. Moisture and trim loss are much greater in dry aging. This means the sell price will need to reflect the losses. The "buttery" notes normally associated with dry aging seem to be associated with changes in the lean. The flavors show in both the beef from grain finished and grass-finished animals. Some of the main considerations to decide whether or not to dry age is going to be non meat related, flavor and aroma. Tenderness will occur in either situation. However, there is some indication that the flavors associated with grass finished meat seem to be reduced with dry aging. Beef from grass finished animals tends to be less tender. However, the fact that the carcass from grass-finished animals are less fat, they will result in more moisture loss and result in higher trim that be edible if not dry aged.

Describe the effects and benefits of electrical stimulation.

Electrical stimulation is used with lighter weight carcasses or ones with less fat that will chill more quickly. These carcasses may cold shorten. For cold shortening to occur, the muscle temperature will be less than 40 - 50 F before onset of rigor. Cold shortening occurs because calcium leaks from the sarcoplasmic reticulum before the ATP is depleted. Electrical stimulation works to prevent cold shortening by rapidly reducing ATP levels. Application of the electrical current causes massive muscle contraction which in turn uses up ATP so the myosin can release actin. The reduction in ATP will mean there is not enough for the muscle to shorten much after the stimulation. The stimulation also will result in activation of calpain and some tearing of the muscle which will both result in some tenderization

Describe the challenges associated with animal transport.

Facilities - Facilities with broken boards or siding can result in bruises, cuts or other blemishes. Extreme cases can result in broken bones. Distances - Transportation will result in stress. Previous exposure can make the response less. The distance for the transport results in increased time off feed and water. Initial stress will result in increased epinephrine and cortisol release thus increased energy demand. Increased time off feed coupled with increase in stress hormones will result in reduction in muscle glycogen. If this is extreme then there can be an increase in dark cutters. Time off feed - It is normal for animals to be held off feed prior to harvest. This results in less fill in the gut and thus will result in less problems with evisceration and less bacterial contamination. However, if the time off feed is extreme and is associated with more stress, there is more likelihood that the glycogen stores in the muscle will be reduced. This will result in less pH decline postmortem and therefore a darkening of color. Vibration and motion - Vibration and motion requires the animal to engage muscles to maintain standing and position. This process requires energy which again can reduce glycogen stores. Crowding - There is a fine line between too much space and not enough space. Too much space can cause problems if there is not another animal to use for balance and results in falls. If it is too crowded there can be challenges to cooling animals, especially if the temperatures are warm. Also if an animal falls when the truck is too crowded, the animal may not be able to get up and can be trampled. Fighting - Fighting of animals is not uncommon if unknown animals are mixed. This is especially true with pigs. Fighting will lead to bruises and blemishes but also decreases in glycogen stores and can result in more dark cutters. Ambient temperatures - Animals need to maintain a constant body temperature. Increases in temperatures stress the system as the animal sweats (not pigs, they don't have the ability to sweat) and increases respiration to help cool the animal. Decreases in temperatures result in shivering which can result in lowered muscle glycogen, but long term it could result in reduced marbling

Canned pineapple will have the same affect on tenderness as fresh

False

What are some factors that are important to consistency and tenderness?

Growth promotants- growth implants and ractopamine have been implicated in reduced tenderness. Sex - heifers have been reported to be less tender than steers but also bulls can have an effect as well. Carcass weight - this is related to growth rate and diet. Heavier carcasses are also related to specific breeds and other management practices that have been related to more tender product. Carcass Conformation - can be used to recognize tropical breeds and dairy breeds. The tropical breeds have more variation in calpastatin and thus tenderness is more variable. Ossification - associated with physiological age Increased physiological age related to more cross-linkages in collagen and less tender Hanging method - There are two main ways to hang a carcass, Achilles tendon or the aitch bone. Hanging the carcass differently stretches different muscles. Hanging from the Achilles tendon stretches the leg muscles more than the loin. Hanging from the aitch bone stretches the loin more than the leg muscles. The stretching alters the tenderness of these muscles. Marbling - A minimum amount of marbling is important for tenderness. However, most of the marbling effect is lubrication which improves the perception of tenderness. Marbling explains only about 10% of the variation in tenderness. Extreme marbling like what is seen in the Japanese grading system would contribute to tenderness by replacing myofibrils with fat. Meat Color/pH Meat color is influenced by ultimate pH and the pH will influence tenderness. Sorting carcasses on color have been suggested as a method to guarantee tenderness with various success. Rib fat measurement - Increased rib fat or back fat implies increased nutrient consumption which would also imply a more rapid growth rate. Both of these would also improve tenderness. Also, external fat will slow temperature decline which can also improve tenderness. This will be variable. Fat Color - suggests whether it has been grain or grass finished Animals that have been finished on grass will have more yellow fat then those grain finished. Yellow fat color has also been linked to age of animal. Via Saleyard - this is associated with stress Animals through the saleyards will have more variation in handling and could result in more bruising and stress which can affect the carcasses Cut ageing - Postmortem aging results in more fragmentation of the sarcomere which will result in a more tender cut. Cooking method/Individual Cut - Individual cut will indicate how much collagen is in a cut. This will also determine what cooking methods should be used to improve tenderness and eating satisfaction

What is related to PSE?

Halothane gene, mutation in ryanodine receptor

Chilling rate postmortem is important to

Improve WHC, reduce growth of E. Coli, reduce PSE incidence

What is related to DFD?

Increased WHC, high ultimate pH

How can cold shortening be prevented?

Increased fat on carcass, Increased cooler temperatures, electrical stimulation

What is related to low ultimate pH?

Increased glycogen stored in muscles, rendement napole

What causes cold shortening and thaw rigor?

Leakage of calcium from the SR while ATP is still available

Why is beef from grass-fed animals less tender than beef from grain finished animals?

Many differences; slightly older age especially when taking the same weight, less marbling affects perception of tenderness, lower pH because of lower glycogen stores.

Fresh sausage

Minced meat, mixed with seasonings, stuffed into casings sold refrigerated, must be cooked before eating

Describe the development of rigor mortis

Muscles will differ in the rate of rigor development because of temperature and fiber type differences; struggle prior to slaughter can deplete glycogen reserves and reduce the length of the delay-phase of rigor mortis.

Why does the meat get darker with age?

Myoglobin concentration gets greater in the muscle as the animals age increases.

Are older turkeys more susceptible to carcass damage at harvest than younger birds

No

Is organic food nutritionally better than conventional?

No

Is panting effective to regulate temperatures at high humidity?

No

Is the definition of quality always the same?

No

When harvested at same fat level, does the eating quality differ in dairy vs. beef breeds?

No

Does ambient temperature have a little effect on transport requirements of poultry and livestock?

No, large effect

PSE:

Pale, soft, exudative

Conformance quality

Product is consistent, tastes good, and meet the consumer expectations

Describe heat ring

Rapid chilling of external portion; slowed pH fall rate toward outside in response to rapid chilling causes dark color; darker band of muscle forming around outer portion of ribeye.

How does electrical stimulation prevent cold shortening?

Rapid reduction of ATP

Describe color triangle

Reactions involving myoglobin determine what the color of the meat will be. Myoglobin has three main parts that are important to color. The state of the protein moiety is important to color. Part of the alterations in color seen with altered pH declines are due to denaturation of the protein that is part of the myoglobin. The heme ring which has iron at its center is extremely important to the color reaction. The oxidation state of iron will determine the perception of the color. The last portion is the chemical compound that occupies the 6th orbital. Color perceived is always a mixture of all three pigments. The predominant pigment is going to determine what color is perceived. The fresh cut surface of meat are going to be purplish in color. This is because myoglobin will have water in the 6th orbital and the iron is in the reduced (Fe2+) state. When the meat is exposed to oxygen, it will dissolve in the water at the surface and interact with myoglobin. The pigment is oxymyoglobin with oxygen in the 6th orbital and the iron is in the reduced state (Fe2+). Oxidation of iron from either myoglobin or oxymyoglobin will result in a brown color. The key reactions for color are oxygenation and oxidation. Low oxygen levels, levels not enough to push the pigment to oxymyoglobin, the pigment will be brown, metmyoglobin.

Hwo can DFD be prevented?

Reduced stress during handling and shipping, reduced time in lairage, re-alimentation with simple sugars.

Hot processing

Reduces energy needed for chilling, has higher WHC and consistent color, pieces are different from cold boned carcasses.

What affects does temperament have on growth and carcass characteristics?

Temperament influences the amplitude of response from the hypothalamic-pituitary-adrenal axis (HPA) to a stressor. The concomitant response of cortisol, epinephrine, and associated increase in heart rate, body temperature, and metabolic can affect the energy storage in the animal. All animals will respond to a stressor, but temperament is a "measure" of the amplitude of the response. High systemic cortisol concentrations may have damaging effects on the growth and development, especially if the temperament of an animal becomes more flighty, and/or the presence of a conditioned fear response exists, there is a costly metabolic shift to supply energy. Cattle with excitable or poor temperaments have a lower ADG than cattle with an adequate or calm temperament. The differences observed in ADG can be attributed to a number of things including, excitable animals exhibit an increase in movement and expense of energy, and animals with excitable temperaments have decreased feed conversion efficiency which results in decreased ADG and growth of the animal. Carcass characteristics such as marbling and REA can be influenced. Transferring nutrients towards responding to stress would reduce the energy available to be stored as fat but also protein can be used for energy instead of contributing to the growth of muscle.

Describe marketing

Temperature changes during transport do cause stress, vibrations can cause physical stress, mixing unfamiliar animals is stressful, stress is caused by removing animals from their home environment.

Describe how different environmental conditions affect animals.

Temperature- higher or lower than body temperature requires the body to respond to maintain temperature. Decreases in temperature result in shivering which in turn can reduce glycogen stores. High temperature requires the body to cool itself. This is done through sweating and increased respiration rate. Higher temperatures result in higher metabolic rates. If harvested there will be an increase body temperature to start with which will alter the rate of pH decline. If the temperature of the carcass is high when the pH of the meat is low you will have the conditions similar to PSE and this will result in poor water holding capacity and bind. If the lactic acid in the body is too high and it cannot be dissipated in the live animal, death may occur. High humidity effects the perception of temperature. High humidity when it is warm results in lower sweat evaporation which will reduce evaporative cooling. High humidity either when hot or cold increases the discomfort of the animal and thus activates a stress response.

Describe the two main genetic factors on pork quality

The two main genetic anomalies for pigs are porcine stress syndrome (PSS) halothane positive and Rendement Napole (RN). PSS or halothane positive condition emerged during a time when selection was for increased muscle mass. The mutation is associated with the ryanodine receptor which helps to control calcium release in the muscle. The animals that have the mutation cannot control the calcium release in response to stress. Calcium will rush from the muscle activating phosphorylase to breakdown glycogen and feeds glycolysis so there is a rapid increase in lactic acid. If not treated appropriately, the animals that are homozygous for the mutation can result in death due to acidosis. The inheritance of the mutation simple Mendelian, dominant and recessive. This results in a carrier that will not always react in the same way. These can sometimes result in true PSE but often has color and protein solubility that is between the stress positive and the stress negative. The carcass will have a rapid pH decline postmortem. This will mean the pH in the muscle will be low when temperatures are still elevated. This results in the PSE condition with light color, loss of water binding and reduced protein solubility. The Rendement Napole (RN) mutation is related to a specific breed, Hampshire, and also emerged in the population when selection for more muscle and less fat were a major selection criteria. The animals carrying the mutation result in increased glycogen stores and the enzymes within glycolysis function to a lower pH than is normal. This results in a reduced ultimate pH. The reduction in ultimate pH results in lighter color and a reduction in water holding capacity. The loss in WHC is less in RN than in PSE. The solubility of the muscle proteins are reduced more than normal due to lower ultimate pH. this is not as detrimental as PSE, but more common.

How does pH react with endogenous enzymes and what affect does this have?

The ultimate pH and the rate of pH decline both have been implicated in tenderness. There is a proposed window where the pH and temperature combination will give a more tender product. All enzymes will have an optimum pH for activity. Calpains are neutral proteases which means the maximum activity occurs at pH 7. Research mimicking postmortem conditions have shown that calpains are still active at pH 5.0. Cathepsins are acid proteases. One of the reasons the Cathepsins are encased in the lysosomes is to give them an environment that will have the optimum pH without affecting the muscle. However, the degradation pattern that is seen in postmortem muscle suggest that calpains are the main protease responsible for the postmortem aging and tenderization. The proteins that seem to be affected postmortem are the Z-line proteins, C-protein, titin, nebulin, troponin T and desmin. All of these proteins are the targets of calpain. Alterations in pH will affect the speed at which the enzymes will work.

A balance needs to be reached when concerning needs of little fat for flavor but too much fat gives too much waste.

True

What is measured in MLA and Quality Mark System of New Zealand?

Ultimate pH

Describe the physiological response an animal has to stress.

When cattle are confronted with stress, the brain triggers sympathetic and parasympathetic neurons that subsequently alter vital organs to extensively alter metabolic, physiologic, and psychologic function. To initiate " Flight or Fight" response, sympathetic post paravertebral ganglia terminate at the adrenal gland, systemically releasing epinephrine as the animal is exposed to a stressor. There was a concomitant increase in vasoconstriction and heart rate, which would result in a subsequent increase in glycolytic activity. Epinephrine increases lipolysis and hepatic glycogenolysis, increasing systemic free fatty acids and glucose concentrations, respectively. In addition, epinephrine increases skeletal and cardiac muscle contractility while uniquely relaxing bronchial smooth muscle to allow for higher respiration rates. Corticotropin-releasing hormone (CRH) is released in response to epinephrine arriving at the hypothalamus, and initiates the start of the neuroendocrine-endocrine cascade involved in the physiological response to stress that ultimately restores the homeostatic condition of the animal via down-stream secretion of glucocorticoids. CRH is secreted into this hypophseal portal and causes the release of ACTH from the anterior pituitary. ACTH subsequently enters the peripheral blood system. ACTH stimulates the adrenal glands to secrete cortisol in response to a stress stimulus. Cortisol acts on metabolism to maintain glucose in the blood, maintains ion balance and cell response.

Major components of meat quality

Wholesomeness, appearance, palatability

Can transport be up to two weeks in some countries?

Yes

Do concepts of quality change over time?

Yes

Does wholesomeness include food safety and nutrients that contribute to health?

Yes

Is PSE caused by the acidification of muscle early post-mortem when carcass temperature is still high?

Yes

Rapid postmortem pH decline

affects postmortem aging, can cause protein denaturation, affects tenderness.

Why is PSE a problem in the industry?

carcasses can lose significant weight due to drip in cooler; PSE has poor functionality and results in poor processing yields; fresh product has poor color stability and acceptability in the retail store.

Levels of quality

convenience, wholesomeness, and minimum shrinkage

Describe DFD meat

effects flavor of cooked meat, will have detrimental effects when processed, has an ultimate pH of 6 or higher, has high spoilage potential and a poor shelf life

Which are easiest to control?

fat/carcass yield, wholesomeness, and palatability

PSS results from?

genetic predisposition that causes inappropriate calcium control in SR

What factors are related to pig deaths during transport

genotype, temperature

What affect does stress hormone have on conversion of muscle to meat?

increase metabolism & reduce glycogen stores, increase blood pressure and can result in increased bloodsplash, effects ion balance and acid-base balance.

Why does collagen get stronger with age?

increased cross-links within the collagen molecule and increased cross-links between collagen molecules. These are mostly disulfide bonds that are hard to break. Increases the shrinkage and solublization temperature of the collagen making the cooked meat tougher.

Lack of succulence is due to low water binding or...

low intramuscular fat

Dry sausage

minced meat mixed with seasonings formed and cooked

Cooked sausage

minced, seasoning and starter culture added, fermented and held at temperatures to facilitate water loss.

MSA window

pH above 6 when temperatures are above 35C; pH below 6 before temperatures fall below 12C

Thaw rigor

severe shortening on thawing after meat is frozen and before the onset of rigor

What are some concerns about animal production?

welfare, land use, animal waste, greenhouse emissions, conservation, etc.

Considering a wholesaler, farmer, processor, and consumer; who is worried over what?

wholesaler & farmer: meat yield processor: tech characteristics (WHC) consumer: palatability

Describe fat color

yellow fat is associated with older animals, the yellow color comes from green pigmented plants, yellow pigmented fat is also associated with certain cattle breeds.