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 center dot 0 and 7 center dot 5% fat to final concentrations of 40, 80, 120 and 240IUml(-1). Spores from Bacillus thuringiensis, Bacillus cereus and Paenibacillus jamilae were inoculated into samples at 10sporesml(-1) prior to pasteurization at 130 degrees C for 2s. Milk pudding without inoculation was pasteurized using less heat condition (100, 110 and 120 degrees C for 2s) to measure the effect of adjusting the ingredients to prevent naturally occurring bacteria. The viable cells during storage at 15, 20 and 30 degrees 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 80IUg(-1) nisin A in 5 center dot 0% fat and at 120IUg(-1) in 7 center dot 5% fat milk pudding. An aroma compound analysis and organoleptic assessment showed processing at 110 and 120 degrees C decreased the temperature-dependent unpleasant odours, for example, reduced dimethyl sulfide and dimethyl disulfide by 1 center dot 2-1 center dot 5times and increased rankings in taste tests compared with 130 degrees 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.