Effect of residual oxygen on colour stability during chill storage of sliced, pasteurised ham packaged in modified atmosphere

The critical level of residual oxygen to avoid light induced oxidative disc oloration during chill storage of sliced, pasteurised ham packaged in modif ied atmosphere (20% carbon dioxide balanced with nitrogen in a 1:3 product to headspace volume ratio) was found to lie between 0.1 and 0.5% oxygen. In 0.5% oxygen light induced discoloration was significant, as detected by th e tristimulus colorimetry redness parameter, when compared to the same prod uct stored in the dark, while at 0.1 and 0.02% oxygen the colour was stable both in the dark and when exposed to light for up to 27 days in chill stor age. Lipid oxidation, determined as 2-thiobarbituric acid-reactive substanc es, and total plate counts showed no difference between discoloured and col our stable products, although a trained panel in a triangle test could diff erentiate between the taste of ham from packages with 0.02 and 0.5% oxygen after 27 days of chill storage. (C) 2000 Elsevier Science Ltd. All rights r eserved.