Browsing by Subject "N2"

The literature review dealed with stunning of poultry. The effects of the stress induced by handling on the physiological and biochemical changes, and how they further affect the meat quality, were discussed. Suitability of different stunning methods for poultry was also reviewed. Methods for measuring the welfare of poultry before slaughtering and the meat quality were described, at the end of the literature review. The aim of the experimental work was to find out the influence of two different types of stunning gases, CO2 and N2, on turkey meat quality. An additional aim of the study was to examine how the chilling rate affects meat quality and also if there are any differences between the stunning methods concerning this. Furthermore, the most suitable gas stunning method for small-scale slaughterhouses, from a meat quality perspective, was hoped to be revealed by the results. Two-phase CO2-stunning was used as a control treatment. The turkeys were stunned using a gas stunning mask designed for the conditions of small-scale slaughterhouse. The post mortem metabolism was controlled with the rate of the pH fall as well as with the glycogen and lactate contents. Drip loss, cooking loss and tenderness were measured to predict the meat quality. The post mortem pH fall was significantly faster in the breast muscles of the nitrogen stunned turkeys than in the breast muscles of the turkeys stunned with other gases. Stunning with N2 could enable the fast chilling of the carcasses without the risk of cold shortening because the meat of the N2 stunned birds was not as tough as the meat of the CO2 stunned birds, when chilled at 0 °C. The pH fall of the CO2 stunned turkeys was similar to the birds stunned with the two-phase method. As a result, CO2 could be a good alternative for gas stunning. On the other hand, CO2 has been stated noxious for poultry to breath in high concentrations. In addition, there is a risk of cold induced toughening when using carbon dioxide if chilled rapidly.