The Effect of Carbon Monoxide pre-Treatments on the Colour Stability of Vacuum Packaged Beef Steaks

Carbon monoxide (CO) as a component of wood smoke has a long history of applications in meat, fish, vegetable and fruit processing. More recently it has been used in meat packaging to enhance colour stability. Concerns have been raised by regulatory authorities that CO may mask meat spoilage and meat might be sold beyond its sell-by-date due to the bright red colour being retained. This study investigated the use of 5% CO as a pre-treatment prior to vacuum packaging beef striploin steaks (Longissimus thoracis et lumborum, LTL) to induce the desirable cherry red colour, while determining the optimum pre-treatment time to allow discoloration by 28 days of storage (2°C). A range of pre-treatment exposure times (1, 3, 5, 7, 9, 15 and 24 h) were applied to steaks using a gas mixture of 5% CO, 60% CO2 and 35% N2. Colour analysis was measured over 28 days of storage and microbiological analysis was analysed at the end of storage. The CO5 treatment appears to be the most appropriate as the bright cherry red colour desirable to consumers was achieved, and discolouration reached unacceptable levels (a* = 12, C* = 16)by the use-date of 28 days, thus ensuring the consumer of a reliable visual indication of freshness and addressing concerns about consumer safety. The 5% CO pre-treatment had no negative effect on the microbiological safety of steaks (P\u3e0.05)