Detection of off-flavor Boar Taint using Parasitic Wasp Bio Sensor

Summary

The off-flavor boar taint associated with the substances skatole, androstenone, and possibly indole represents a significant problem in the European pig husbandry industry. Boar taint may occur in meat from un-castrated sexually mature male pigs and consumers commonly show a strong aversion to tainted meat. Consequently, there is a need for real-time methods to sort out and remove tainted carcasses at the slaughter-line. The wasp hound, a detection device developed to detect volatile compounds, was proven to detect these chemicals and to detect the boar taint in pig carcass meat.

Situation

Across Europe, the majority of male piglets intended for pork production are surgically castrated to avoid potential consumer dissatisfaction due to boar taint. However, animal welfare concerns have resulted in legal consequences being imposed on the practice of surgical castration in European countries. It is likely that surgical castration might be banned in some countries or even across the European Union (EU) as a whole in the near future. Given that there are currently no alternatives available to entirely exclude boar tainted meat and to prevent the exposure of consumers to tainted pork, there is a great need for rapid (10-20 s measurement time), perceptive and reliable detection methods to sort out tainted carcasses on the slaughterline. In particular, such methods should detect and report the presence of these compounds at low concentrations (ppm) on a fat basis, in entire male pig carcasses.

Response

We tested the ability of the parasitic wasp, Microplitis croceipes, to perceive and learn the three boar taint compounds both individually and in combination using classical conditioning paradigms. We also established the effectiveness and reliability of boar taint odor detection when wasps were used as biosensors in a contained system called the 'wasp hound' using a cohort of trained wasps. We found that the wasps are able to successfully learn indole and skatole and to also detect them when presented a 1:1:1 mixture of all three compounds. This was shown for both a single hand-manipulated wasp bioassay and when using the wasp hound detector device. In contrast, the wasps showed a weak conditioned response to androstenone at the concentration tested. The estimated gas phase concentrations that the wasps perceived during training were in the range of 10±0.4 pg/s for skatole and indole, and 2±0.5 pg/s for androstenone. We conclude that use of these wasps as biosensors presents a promising method for boar taint detection and discuss future training paradigms that may improve their responses to compounds such as androstenone.

Impact

Application of the 'wasp hound' for the commercial detection of the chemicals studied appears to have great potential. The wasp hound could be adapted to use in slaughter houses for on-site sorting of entire male pig carcasses. By using one wasp hound detection unit for each of the boar substances and connected in parallel, they could be targeted for direct taint detection ahead of the deboning of the carcass. A standardized automated gas-phase sampling still would need to be optimized for this purpose and integrated with the wasp hound device. In addition, subsequent studies will address the potential influence of temperature in the slaughterhouse on the rate of volatile release and wasp response, in order to standardize a specific temperature interval applicable to slaughter line conditions. For simple industrial operations, such a fully integrated measurement system could be automated with easily readable computer displays and alarms, both auditory and visual, could be used to indicate the change in wasp behavior when meat with boar taint is sampled.

State Issue

Food Safety

Details

• Year: 2011
• Geographic Scope: International
• County: Tift
• Program Areas:
  • Agriculture & Natural Resources