A new study, published in Meat Science, has determined that up to 33 percent tainted boar meat can be used in the production of emulsion-type sausages (Frankfurters) which would provide a sustainable use for boar tainted pork that has been deemed inferior or not acceptable for the fresh pork market.

The study

Conducted by Johanna Mörlein, Lisa Meier-Dinkel, Jan Gertheiss, Wolfram Schnäckel and Daniel Mörlein, the study tested 16 variants of Frankfurters in two independent studies using evaluations provided by 211 consumers in total. The sausage variants differed through four separate factors: content of tainted BOAR MEAT (0, 33, 67, 100 percent); duration of SMOKE (15 min vs 19 min); and the concentrations of each of the spices, MACIS and CORIANDER (normal (1.13g/3kg) vs 3.5 times increased (3.94g/3kg)).

The production and other ingredients included in the sausages were standardised so that the only influencing factors were the four mentioned above. The consumer tests were conducted within ten days after production.

To avoid individual animal effects, mixtures of five boars were used. For each test, carcasses were selected in a commercial slaughter house. Therefore back fat samples of 25 boars were collected and later evaluated by sensory assessors trained on the detection of boar taint in fat according to a 6 point schema described here as well as by SPE-GC–MS (solid phase extraction and gas chromatography/mass spectrometry) for the analysis of androstenone and skatole. Five boars that were considered heavily tainted were selected. The boars selected had the highest fat score according to the panelists' evaluation (≥2.5; scale from 0 = no deviation to 5 = strong deviation from standard fat) and accordingly high levels of androstenone and skatole. Standard raw material was collected from five castrates/female pigs at the same day.

Each consumer evaluated all 16 sausages on the two testing days. Sample amount per consumer was approximately 25 g. Frankfurters of the same variant were heated in plastic bags in water to avoid dilution effects of water. Directly after heating, samples had a mean core temperature of 80 °C; samples reached consumers with a mean of 59 °C core temperature. Instructions were to eat at least half of the sample. Sensory data were collected on individual screens using EyeQuestion software (Logic8 BV, Elst, The Netherlands) in the following order: odour liking, flavor liking, check-all-that-applies (CATA) for flavour attributes, just-about-right-scale (JAR) for texture, and aftertaste liking. All liking scores were recorded on nine-point hedonic scales (1 = dislike extremely to 9 = like extremely). After the flavour liking, a CATA ballot with 16 terms describing sensory attributes was presented for 45 seconds (balanced according to bad and good associations): sour, meaty, smoky, savory, liver, salty, musty, rancid, sweat, stable, pig, strong, pepper, mild, herbs, fatty (not shown).

On the second day of each study, after the sensory evaluation, the olfactory sensitivity to androstenone and skatole was determined by a smell test. The smell test comprised three consecutive triangle tests for each substance using cardboard smell strips. 20 μl of androstenone (approximately 4.3 μg/ml) and skatole (1 μg/ml skatole) diluted in propylene glycol (PG) was transferred onto paper smell strips; absolute amount on strips were 0.09 μg androstenone and 0.02 μg skatole. Blank samples contained the solvent (PG) only. A consumer was considered sensitive to the respective odorant when they discriminated the odd strip from the identical strips in two out of three triangles, thus reducing the probability of being considered as sensitive just by chance to 11 percent.

The results

The results of the study indicated that neither traditional smoking methods nor the two spices used reliably mask boar taint in these high-fat, emulsion-type sausages, and also cannot be successfully used to compensate for high levels of boar taint. The researchers believe that the key to reducing the volume of wasted carcasses due to boar taint, is to determine a percentage of tainted raw materials that can be incorporated into products without impacting consumer satisfaction.

Conclusions

Based on the findings of this study, the researchers determined that up to 33 percent of meat and fat of carcasses with skatole concentrations of up to 0.3 μg/g and androstenone concentrations of up to 3.8 μg/g in melted backfat may be used for the production of Frankfurter-type sausages. This would be a sustainable use of meat that would normally be deemed un-usable for human consumption.