The effect of temperature during retail display on the colour stability of CO pretreated vacuum packaged beef steaks

Abstract

The effect of CO pretreatments applied to beef striploin steaks (Longissimus thoracis et lumborum, LTL) prior to vacuum packaging and display temperature on colour stability, shelf life and tenderness was determined. Steaks were exposed to 5% CO, 60% CO and 35% N for 3 (CO3), 5 (CO5) or 7 (CO7) h, followed by 28 days display at 2 °C (good industry practice) or 6 °C (mild abuse). CO5 was the optimum exposure time as it induced the desirable colour while not retaining the bright colour, irrespective of display temperature. K/S ratios confirmed that CO pretreatment did not mask spoilage and could be more sensitive than colour parameters at monitoring discoloration as colour was not retained. Exposure to CO did not have any negative effect on meat quality attributes, while mild temperature abuse (6 °C) increased purge loss and decreased pH.

The effects of varying gas concentrations and exposure times on colour stability and shelf-life of vacuum packaged beef steaks subjected to carbon monoxide pretreatment

“…At the end of storage (28 days) all treatments except for the controls had C* values above 14, which is considered brown or discoloured (MacDougall et al, 1986). The 5% CO/5 h pretreatment had a C* value of (16.04) which is just above the limit of acceptability (C* = 16) (MacDougall et al, 1986) in line with previous work (Van Rooyen, Allen, Crawley et al, 2017, 2018. For 1% CO/5 h C* was 15.2 on day 28, just below the limit of acceptability, but were above C* = 14 which is considered as 40% metmyoglobin and causes consumer purchase rejection (Greene, Hsin, & Zipser, 1971).…”

“…Meat is considered to have a robust buffering system which may have contributed to this result (Ramanathan, Mancini, Naveena, & Konda, 2010). Similar findings were also evident in previous studies by this group and others where CO pretreatments before vacuum packaging beef steaks did not have a significant effect on the pH (Aspé et al, 2008;Sakowska, Guzek, Glabska et al, 2016;Van Rooyen et al, 2018).…”

“…Colour stability was analysed at 0, 2, 10, 21 and 28 days. A previous study carried out by this group (Van Rooyen et al, 2018) showed the benefits of using K/S ratios to estimate myoglobin redox forms and provide a greater understanding of surface colour stability.…”

“…K/S ratios for MMb are a useful method for monitoring meat discolouration (Van Rooyen et al, 2018). The results for K/S ratios for MMb are presented in Fig.…”

“…Vacuum packaging permits prolonged storage in an anoxic environment favouring tenderness but has a negative effect on meat colour. Carbon monoxide (CO) applied as a pretreatment prior to vacuum packaging would enhance the colour and tenderness (Van Rooyen, Allen, Gallagher, & O'Connor, 2018). CO binds to myoglobin to form carboxymyoglobin and produces a much more stable cherry red colour compared to oxygen (oxymyoglobin) (El-Badawi, Cain, Samuels, & Anglemeier, 1964).…”