Author(s): Oshima S, Hirano A, Kamikado H, Nishimura J, Kawai Y,
Abstract Share this page
Abstract AIMS: The aims of this study were to evaluate the effectiveness of nisin A to control the growth of spore-forming bacteria, Bacillus and Paenibacillus, in chilled high-fat, milk pudding and to reduce heat treatment to improve aroma and flavour. METHODS AND RESULTS: Nisin A was added to milk pudding containing 5·0 and 7·5\% fat to final concentrations of 40, 80, 120 and 240 IU ml(-1). Spores from Bacillus thuringiensis, Bacillus cereus and Paenibacillus jamilae were inoculated into samples at 10 spores ml(-1) prior to pasteurization at 130°C for 2 s. Milk pudding without inoculation was pasteurized using less heat condition (100, 110 and 120°C for 2 s) to measure the effect of adjusting the ingredients to prevent naturally occurring bacteria. The viable cells during storage at 15, 20 and 30°C showed nisin A inhibited spiked bacteria to varying degrees depending on species, sensitivities to nisin A concentration and fat content, and inhibited natural populations at 80 IU g(-1) nisin A in 5·0\% fat and at 120 IU g(-1) in 7·5\% fat milk pudding. An aroma compound analysis and organoleptic assessment showed processing at 110 and 120°C decreased the temperature-dependent unpleasant odours, for example, reduced dimethyl sulfide and dimethyl disulfide by 1·2-1·5 times and increased rankings in taste tests compared with 130°C treated pudding. CONCLUSIONS: Nisin A was found to be effective as a natural preservative to control spoilage bacteria in high-fat milk pudding and extend its shelf life, when using reduced heat treatments to improve the flavour and aroma without compromising food safety. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report showing nisin A is effective in reducing spoilage bacteria in high-fat, chilled dessert, milk pudding. Therefore, nisin A can be used to improve milk puddings to satisfy both industry and consumer demand for food quality and safety. © 2014 The Society for Applied Microbiology.
This article was published in J Appl Microbiol
and referenced in Journal of Bioprocessing & Biotechniques