pH in conventional meat

This is a quick paper that I wrote for my Meat Processing class.  It is based upon conventional animal (beef) meat.  These meats are typically grain fed.  Conventional beef animals are castrated, finished (fattened) on corn, and harvested (pc term for slaughtered) young in order to retain a flavorful, juicy, and tender product.  Castration, corn finishing, and slaughter young (1-2 years old typically) all lead to the above qualities.

The consumer often believes that grass fed and finished, beef is not as tender, flavorful or juicy.  I have eaten primarily grass fed/finished beef for the last several years and would strongly disagree.  Just as the agriculture industry has responded to the above traits, they will respond to the consumer demand of  healthier food.  If the consumer were to choose the product based upon health traits then we would all have grass fed/finished beef.  Then the product would decrease in price and become widely available.  Anyway, it’s an interesting, short topic that I hope you enjoy.  I guess I’ll go to class now so I can turn in my paper.

Introduction

The color of beef is an important factor for the consumer. Two proteins determine the color of fresh meat. These proteins are hemoglobin and myoglobin. Blood contains hemoglobin while meat contains myoglobin. The fresh beef at the grocery store should consist of 80%-90% myoglobin and 20%-10% hemoglobin. Vascular blood is largely drained from the carcass prior to the product becoming meat. The remaining hemoglobin is found in the blood that is stored in the meat itself. This percentage range gives beef the pleasing color that the consumer is accustomed to. The pH of the meat prior to harvest, as well as the changes afterwards, have an effect on the color of meat. A high pH (more alkaline) will cause the meat to be darker. The meat appears darker because there is less light reflected as well as the ability to see the darker red color located deeper in meat.
The informed customer knows that meats tend to be to tougher when the color is darker. As pH lowers (becomes more alkaline) meat becomes darker and therefore tougher. Typical meat is dark cutting at a pH of 6.0 after 30 or more hours post harvest. Some consumers may see meat as dark cutting meat while having a pH lower than 6.0. In the event that the customer does not understand important steps in choosing meats, the customer may ask the individual selling the meat. The person selling the meat should be well versed and able to explain the important attributes to the consumer. If the purveyor is unable to give a concise but detailed report on the choosing of meats, the consumer should consider shopping elsewhere in order to retain the highest quality meats as possible.
pH in Meat
The scale that is used in order to determine if something is alkaline or acidic is pH. Anything less than 7 is acidic and anything greater than 7 is basic. 7 is neutral. The further from 7 you get the stronger the acid or base is. The pH in meat is an important factor. The final pH, after rigor mortis, affects many aspects of the quality of the meat for the consumer. These factors include tenderness, color, flavor, and shelf-life. The typical meat pH is 5.4 – 5.8. As pH increases, the following occurs; tenderness decreases, meat becomes darker, quality of flavor decreases for individuals, and the meat becomes more likely to be infested with bacteria therefore leading to spoilage quicker.
How does beef becomes dark?
Upon harvest, lactic acid is produced causing an increase in acidity due to the bodies’ inability to remove these products. Lactic acid production continues due to stored energy reserves of the animal, thus lowering the pH into the 5.4 to 5.8 ranges. The reader may relate to lactic acid through personal experience. Lactic acid is the cause of the muscular pain after a strenuous workout. The live body decreases this lactic acid allowing the body to maintain an appropriate pH, however the carcass is unable to purge this lactic acid therefore decreasing the pH of the meat. Stress to the animal prior to harvest decreases energy stores necessary to produce the lactic acid; therefore, the meat is unable to lower the pH sufficiently. Electrical stimulation of the carcass increases the rapidity of rigor mortis and therefore allows the product to reach the final pH quicker. Sufficient glycogen stores are required for the meat to reach the appropriate pH level.
A few causes of dark beef are as follows; pH above 6.0, bull meat, length of time since harvest, rapid cooling of the carcass.
Minimization of factors contributing to dark meat
In order to decrease the incidence of dark meat we must ensure the animal does not use up glycogen prior to harvest. Glycogen stores allows the muscle to continue functioning, creating lactic acid, after the harvest of the animal. Therefore, we must focus on ensuring the animal is not stressed (physically or psychologically) through cold weather, disease, or increased activity/stress. Handling of the animal through transport, holding, and harvest should be as calming as possible. Prior to harvest the animal should have two to three days of rest in order to restore appropriate glycogen stores. Some animals have increased excitability; this trait should be culled from the herd.
Conclusion
The pH of meat is highly dependent upon the glycogen stores in the animals’ muscle prior to harvest. The greater the glycogen stores available the lower the
pH of the meat will be. A higher pH, due to decreased glycogen stores, leads to meats that are darker, tougher, and off-putting in taste. These meats may taste gamey to the individual. This is because game meat is often tougher than production meat. Low stress handling of the animal and a 2-3 day rest period prior to harvest helps the animal recuperate glycogen stores. The glycogen stores leads to increased lactic acid production after harvest that leads to tender, flavorful, well colored meat for the consumer. Meat is a major portion of the US agriculture system, and producing a product that pleases the consumer is of paramount concern. At this time a large percentage of American’s choose their meat products based upon flavor, tenderness, and cost. The agriculture industry has responded accordingly and the manipulation of the pH of the meat is an important factor in the production of those meat traits.

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