Influence of Ultimate pH on Meat Quality and Consumer Purchasing Decisions21 November 2005
By Ronald Klont, PIC’s Northern European Pork Chain Manager - Ronald Klont defines the relationships between ultimate pH and four of the five meat quality attributes that impact consumer purchasing decisions - taste, appearance and juiciness.
What is Meat Quality?
Factors such as juiciness, tenderness,
taste, appearance, price, package
appearance, colour, size, brand name and
food safety all influence consumer
decisions to purchase meat in the retail
store. Consumers’ behaviour is
influenced by several questions: When I
cook this product, is it going to taste good?
What about the tenderness and juiciness?
Is the product free from contamination?
Does the product look good?
Research shows that the top five attributes that influence consumer decisions are taste, tenderness, food safety, appearance, and juiciness. Taste, tenderness, and juiciness are attributes that are influenced by past experiences. Was this product tender the last time I purchased it? Was it juicy? Another important attribute is appearance. It includes packaging, cut size, meat-case lighting and amount of juice released, but mostly colour of the meat. It is considered one of the most important properties that consumers use to judge meat quality.
According to meat scientists, factors such as ultimate pH, colour, water-holding capacity, and intramuscular fat, are the main technical attributes that drive consumer purchasing decisions.
What is Ultimate pH and how does it influence Meat Quality?
The pH of muscle/meat is a
measurement of acidity. In a normal
living muscle the pH is approximately 7.2.
Glycogen is broken down to lactic acid
when muscle turns into meat. The pH of
meat can range from 5.2 to 7.0. The
highest quality products tend to fall in the
pH range of 5.7 to 6.0. Both the rate and
extent of post-mortem pH fall will
influence pork quality characteristics.
Pale, Soft, and Exudative (PSE) pork
commonly results from a rapid
breakdown of glycogen into lactic acid
after slaughter. This rapid pH fall can be
seen in pigs carrying the halothane gene
The ultimate pH is determined by the extent of the pH decline at 24 hours after slaughter. The variation in ultimate pH influences factors such as colour and the ability of the meat to retain water. A low ultimate pH results in meat proteins having decreased water-holding capacity and a lighter colour. Conversely, a higher ultimate pH will give a darker colour and less drip loss. Figure 1 (opposite) shows the relationship between ultimate pH and the amount of drip loss in a halothane-gene-free pig population.
For slaughterhouses and further processors, a lower ultimate pH will lead to less saleable product, due to increased drip losses during the production processes of fresh meat and/or cooked pork products. Drip loss in a consumer package will negatively affect the appearance and thereby the purchase intent. Ultimate pH also impacts eating quality characteristics such as juiciness, tenderness, and taste. Pork with a higher ultimate pH, which retains more water during storage, will also keep more juice after preparation of the meat. More juice in the prepared meat will give a juicier, more succulent and tender eating experience (see Table 1 above).
How can Genetics and Gene Markers influence ultimate pH and Pork Quality?
Environment, genetics and the
interactions between both factors will
influence the extent of pH fall. Longer
times of feed withdrawal, before
transport for instance, will decrease the
amount of glycogen present in the
muscle at slaughter; thereby resulting in a
higher ultimate pH. There are differences
in ultimate pH between and within
different pig breeds. An extreme breed,
like the Berkshire, is known to have a
higher ultimate pH than other more
commercial breeds. It is possible,
however, to genetically increase the
ultimate pH of modern pig breeds by
using this trait in the selection procedure
for commercial parent boars and gilts e.g.
in PIC’s terminal 280 sire, a pure red
Duroc line - lean and efficient with high
The use of gene marker technology is a powerful tool to increase ultimate pH (and other meat quality traits) in a pig population. The RN gene is an example of a major gene which influences ultimate pH. Two copies of the negative allele (22) cause an extreme low ultimate pH ("acid meat") and most of the breeding companies have erased the negative allele from the breeding herds.
Researchers are constantly searching for DNA variation that is associated with variation in meat quality traits. Once these associations are identified, young animals can be tested for their potential to deliver better quality meat, before they are tested for traditional traits such as growth rate. Sygen has developed a series of DNA markers that can be used to improve meat quality attributes, such as pH, colour and tenderness, to increase the accuracy and speed of genetic improvement. Selection of the right genotypes, based on multiple DNA markers, can shift a pig population from a low to high ultimate pH and thereby decrease drip losses.
Selection for greater meat quality characteristics does not necessarily result in a higher cost of production. Extremes do exist within the rare breeds, such as Gloucester Old Spot, Tamworth or Berkshire, that provide exceptional meat quality, but at a cost of poor efficiency and low overall lean. But by using a tailored selection index, DNA marker technology and good on-farm nutrition, meat quality can be greatly enhanced within efficient, fast-growing and lean commercial lines. Ultimate pH is an important meat quality characteristic and the aim is to optimize pork quality whilst continuing to improve the cost of production for different market requirements.
Source: PIC UK - June 2005