Effect of packaging materials and dissolved oxygen on the survival of probiotic bacteria in yoghurt

The effects of packaging materials on the dissolved oxygen and the survival of the probiotic bacteria in yoghurt were studied. Oxygen adapted and non-oxygen adapted strains of Lactobacillus acidophilus and B fidobacterium spp. were incorporated in yoghurts, which were packaged in oxygen permeable high-impact polystyrene (HIPS), oxygen-barrier material (Nupak(TM)) and Nupak(TM) with an oxygen scavenging film (Zero(2)(TM)). During storaae the dissolved oxygen increased steadily in HIPS packaged yoghurt whereas it remained low in yoghurts packaged in Nupak m and Zero(2)(TM). In all yoghurts, no significant decreases were observed in the viability of either oxygen adapted or non-oxygen adapted cells of L. acidophilus and Bifidobacterium spp. Thus, although the dissolved oxygen in yoghurt can be influenced by the type of packaging material, it may not affect the survival of probiotic bacteria in yoghurts.