Reduction of backfat skatole through dietary means
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Research partners: BPEX Pork Chain Unit (University of Bristol)
Sponsors: Premier Nutrition, Bowes of Norfolk
Project duration: 2007 – 2009
Boar taint is an odour of cooking pork or bacon fat which has high levels of two compounds, skatole and androstenone. Odour is part of flavour so flavour is affected too. Some people object to levels of skatole above 0.2 µg/g and androstenone above 1.0µg/g of fat. This project is examining the possibility that including dried chicory root in the pig’s diet just before slaughter might change the conditions in the hind gut so that less skatole is produced. A special finishing diet including chicory, whose active component is inulin, could guarantee freedom from boar taint. Chicory will not affect the androstenone level in fat tissue but evidence suggests that skatole is the compound most responsible for boar taint.
If backfat skatole can be reduced by simple inclusion of chicory in the diet for a short period before slaughter and reduction can be shown to improve odour/flavour, then producers will have a tool which guarantees superior tasting pork. This will be attractive to butchers, consumers and exporters to the rest of Europe and the high welfare status of entire males will be enhanced by high taste. The cost of chicory inclusion at present (January 09) is estimated to be £2.60 per pig.
The project has been conducted in three stages. In the first, the concentrations of both boar taint compounds were measured in 50 male pigs from 30 farms supplying a major processor. These data provide a benchmark for the rest of the trial. Strips of backfat were removed on the slaughter line and transported to Bristol for analysis. In the second part of the study, a level of dried chicory based on published work and contacts with overseas researchers was fed on six farms with another six acting as ‘controls’. The pigs were slaughtered after two weeks on the diets; this trial produced promising results (ie skatole was significantly reduced).
Stage three involved feeding four levels of dried chicory on one farm where there were four sheds for separation of the diet groups. The first pigs to finish from each shed received no chicory. Chicory was then introduced and further pigs were slaughtered after one and two weeks on the diets.
Backfat samples were removed from 50 pigs in each chicory level and time on diet group in the abattoir. These were returned to Bristol where skatole and androstenone concentrations were measured and ‘sniff’ tests conducted using the taste panel to determine if reducing skatole has also reduced boar taint. In stage three of the project, faecal samples were removed in the abattoir to determine if the gut microflora were changed by feeding chicory.
There is evidence that inulin, which is a complex fibre, causes increased concentrations of ‘good’ bacteria in the gut and reduces concentrations of ‘bad’ bacteria such as Salmonella. Any benefits of chicory here will add to the benefits of a finishing diet targeted mainly at reducing boar taint.