Effects of modified atmosphere and vacuum packaging on inhibition of Listeria monocytogenes and quality in hot-smoked rainbow trout fillets

Abstract

Hot-smoked rainbow trout were inoculated with Listeria (L.) monocytogenes, then packaged under vacuum or under 100% CO2 (MAP 1) or 50% CO2 and 50% N-2 (MAP 2). Afterwards, the samples were stored at +2 degrees C. Non-inoculated samples packaged under the same conditions served as controls. Listeria growth and quality parameters were observed in all samples stored at +2 degrees C over a period of seven weeks. L. monocytogenes counts in samples stored under vacuum, MAP 1 and MAP 2 packaging decreased significantly over time, The results obtained from this study showed that the inoculation of L. monocytogenes in hot-smoked rainbow trout is best inhibited at 100% CO2 (MAP 1). The sensory acceptability scores for odour, taste and texture of hot-smoked vacuum and modified atmosphere packaged trout decreased with storage time. The results of this study indicated that the shelf-life of non-inoculated vacuum packaged and MAP 1 as well as MAP 2 packaged smoked trout stored at +2 degrees C as determined by sensorial data is four and five weeks, respectively. Total volatile basic nitrogen and thiolbarbituric acid values gave acceptable results for up to six weeks for the hot-smoked rainbow trout stored in vacuum and MAP1 or MAP 2 storage.