Carbon monoxide concentration and exposure time effects on the depth of CO penetration and surface color of raw and cooked beef longissimus lumborum steaks

This study investigated the influence of carbon monoxide (CO) exposure time (0, 7, 14, and 21 days) and concentration in gas mixture on depth of penetration and the surface color of raw and cooked striploin steaks. Seven packaging treatments were evaluated: vacuum, vacuum after 48 h of exposure to 0.1%, 0.3% or 0.5% CO (mixed with 30% CO2 and 69.5-69.9% N2), and modified atmosphere packaging (MAP) containing the same gas mixtures. CO penetration depth increased as exposure times and CO concentration in gas mixtures increased (p < 0.05). However, the carboxymyoglobin that formed did not always turn brown during thermal treatment. In cooked samples treated with 0.3% and 0.5% CO-MAP, a red carboxymyoglobin border was visible at the cross section, whereas other CO packaging treatments had its partial or total browning. To create a red color in raw and avoid a red boarder in cooked beef, up to 0.5% CO in vacuum packages and only 0.1% for MAP can be recommended.