High-Definition Screening for Boar Taint in Fatback Samples Using GC–MS

Jul 01, 2011

This article discusses the application of high-definition screening for the detection and identification of boar taint in fatback samples by gas chromatography–mass spectrometry (GC–MS). The application of data mining software is described and the relative merits of high-definition screening for target and nontarget compounds by GC–MS are discussed.

Boar taint is the offensive odor that can be evident during the cooking of pork or pork products derived from noncastrated pigs after they reach puberty, equivalent to a carcass weight of about 80 kg. Studies demonstrate that approximately 75% of consumers are sensitive to boar taint, with women being more sensitive than men and some ethnic groups also being more sensitive than others (1). People who are particularly sensitive to the presence of boar taint claim that the smell is very offensive, resembling urine, feces, musk, or onions. As a result, it is necessary that pork producers control boar taint.

Boar taint is caused by the accumulation of androstenone and skatole in the fatback of pigs. Androstenone is a male pheromone that is produced in the testes, and its levels increase dramatically as male pigs reach puberty. Skatole is a by-product of intestinal bacteria or a bacterial metabolite of the amino acid tryptophan and is produced in both male and female pigs. Skatole levels are much higher in intact adult male boars because testicular steroids inhibit the compound's breakdown by the liver.

Traditionally, pork producers have used castration of male piglets as the primary method of controlling boar taint. However, castration is associated with a number of limitations, including production losses due to infection, injury and herniation, reduced feed conversion compared to intact boars, and pain and stress for the animal. In some countries, such as the United Kingdom, male pigs are not castrated but are slaughtered early before reaching puberty. Nevertheless, as pig growth rates are rapid in the late finishing stage of breeding, slaughtering young animals can negatively impact the quality of pork and pork products. Another method to control boar taint is to raise only female pigs; however, this approach results in 50% less production.

Legislative Framework

European Union (EU) Regulation 854/2004 (2) mandates that meat will be declared unfit for human consumption if it exhibits organoleptic anomalies; specifically, a pronounced sexual odor. This regulation requires that the meat should be examined to identify characteristics indicating whether it presents a health risk, including odor of muscle tissue or organs. In addition, Directive 64/433/EEC (3) specifies that male carcasses weighing more than 80 kg may be allowed for human consumption provided that they bear a special mark and undergo treatment before entering the food chain. The directive further requires that carcasses must be inspected post mortem to identify any anomalies in smell.

At the same time, Directive 2008/120/EC (4) lays down minimum standards for the protection of pigs. More specifically, the directive mandates that castration of male pigs should be performed by means other than tearing of tissues. Additionally, if castration is practiced after the seventh day of life, it shall only be performed under anesthetic and additional prolonged analgesia by a veterinarian. However, as castration of piglets has raised animal welfare concerns, being viewed as a painful intervention, the EU has recently taken steps to abolish it. An agreement has been reached to stop castrating piglets without anesthesia by January 1, 2012, and a total ban has been scheduled to be implemented by 2018 at the latest (5). In Norway, piglet castration has been banned since January 1, 2009 (6).

In light of the total ban of piglet castration, an alternative method to control boar taint is necessary. Chemical analysis of meat on the slaughter line can serve as an efficient method to identify and remove tainted carcasses.

Boar Taint Detection

Presently in the EU, there is no harmonized method for detecting boar taint, but some member states are using their own testing techniques. In the United Kingdom, a hot wire test is occasionally used or a soldering iron is applied to the exposed fatback of the carcass. In Bonn, Germany, an institute has developed a reference method in which fatback is microwaved to separate the tissue from the fat; the fat is then melted and prepared for quantitative analysis. The sample is placed in a methanol extract, and incubated in an ultrasound bath at 50 °C. After this gentle heating, the solution is frozen to eliminate the fat and retain the more volatile substances for subsequent analysis. Overall, this method is particularly time-consuming as it involves extensive sample preparation.

As a result, there is a need for a more rapid technique, capable of facilitating timely detection of boar taint in the fatback of carcasses. The method must be sensitive enough to be able to identify even low levels of the compounds responsible for boar taint. Androstenone levels in fatback must lie between 500 ng/g and 1000 ng/g, whereas the maximum amount of skatole allowed is 250 ng/g.

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