However, high O2 levels in packs can result in undesirable flavour developing due to oxidation reactions (Estevez & Cava, 2004; Rhee & Ziprin, 1987). While convention has led to the use of high levels of O2 in packs to promote oxymyoglobin development, more recently, attempts have been made to investigate the use of lower O2 levels in MA packs of red meat so as to counteract some of the negative aspects of packing meat using high O2 contents (higher oxidation levels, increased toughness, increased drip loss etc.)