Effect of watering before slaughter and the evisceration method on the quality characteristics of fattened goose liver

Abstract

The aim of this study was to investigate the effect of watering before slaughter and different evisceration methods on the quality characteristics of fattened goose liver. A total of randomly selected 60 male Greylag Landaise geese (Anser anser) were used to execute the experiment which had been force-fed during their growing period. In the slaughterhouse, randomized block design was followed and the birds were randomly divided into four experimental groups and half of the them (30 birds) were given 200 ml tap water. During the slaughter bleeding kinetics was measured and after the traditional processing steps (scalding, defeathering, waxing, water cooling, clearing of wax residues, rinsing, feet removal) 50 % of the birds (30 birds) were immediately eviscerated. The other half of the carcasses were eviscerated after 8 hours of cooling. Then pH and hemoglobin content were determined and the livers were vacuum packed and stored at -18 °C for 35 days (5 weeks). During this time color measurement and microbial analysis were taken. Results showed that pH was not influenced by neither the watering nor the evisceration methods. Hemoglobin content was significantly reduced by watering (P<0.001). Cold evisceration was proved to have siginificant effect on the color parameters (P<0.001), however the impact was not immediate, the difference was first detected on day 21. According to microbiological analysis four species were identified but none of them are known to produce hydrogen sulfide (H2S) which is required to the formation of sulfhemoglobin which compound is most likely responsible for the greenish discoloration occured during the storage. In summary, it can be stated that the evisceration method had a great impact on the color of fattened goose livers and undesirable changes - e.g. surface greening - which commonly occur in case of vacuum packed and frozen stored livers could be prevented by the application of warm evisceration.