Effects of nisin and lysozyme on the microbiological quality of cream

Cream is a valuable dairy product used both freshly and in preparation of foodstuffs, especially pastry. Although it is obtained from heat-processed milk, it may contain high number of microorganisms. This microflora affects average life of cream and cream-products that are extremely suitable for microbial growth. This study is conducted to research efficacy of nisin and lysozyme from natural antimicrobials to improve stability of cream used in the pastry industry. For this purpose, nisin (12.5mg/L) and lysozyme (500mg/L) were added as permitted by the regulatory requirements. Their effect on natural microflora and Staphylococcus aureus added experimentally were examined. Neither nisin nor lysozyme had negative effect on the sensory quality of the cream. Nisin have significantly slowed down development of Staphylococcus aureus and aerobic spore-forming bacteria including total mesophilic aerob bacteria and lactic acid bacteria during cream storage at different temperatures and it did not show any inhibitory effect on coliforms and mold-yeast development. The lysozyme addition had a similar effect even if it is not as good as nisin. From the results, it is concluded that nisin can be successfully used to increase shelf life by slowing down development of microbial growth of cream that has relatively short duration and protect against possible S.aureus intoxications associated with cream