Stunning pigs with inert gases at low residual oxygen does not compromise meat quality

In the project for "Testing Inert Gases in order to Establish Replacements for high concentration carbon dioxide (CO₂) stunning for pigs at the time of slaughter" (TIGER), we were investigating the effect of different inert gas atmospheres on meat quality. In two subsequent experiments a total of 1138 pigs were either stunned with argon or nitrogen (N₂) as well as mixtures of those with 10-30 % CO₂ or two high concentration CO₂ atmospheres. With a newly developed and patented gas supply technology, we were able to create stunning atmospheres with a residual oxygen concentration < 1 %. In both experiments various meat quality traits (pH, temperature, and electrical conductivity) were assessed in M. longissimus thoracis et lumborum (LTL) and M. semimembranosus (SM) 45 min and > 24 h post mortem, respectively. Drip loss, cooking loss, razor shear force and color (CIE L*a*b) were examined for the LTL (experiment 1) and for the SM (experiment 2). Additionally, sensory analyses were carried out in the second experiment. Statistically significant differences between meat quality traits were found in both experiments. For instance, a reduction of pH₄₅ in LTL was observed when animals were stunned with high concentrations of N₂, yet without causing the formation of pale, soft & exudative meat. Overall, the significant differences observed are considered of minor importance for consumers and meat processors. Therefore, we conclude from these experiments that the alternative gas mixtures investigated herein are not inferior to conventional CO₂ stunning concerning meat quality of LTL and SM.