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ABSTRACT
Effective strategies for extending fluid milk product shelf-life by controlling bacterial growth are of economic interest to the dairy industry. To that end, the effects of addition of L-arginine, Nα-lauroyl ethylester monohydrochloride (LAE) on bacterial numbers in fluid milk products were measured. Specifically, LAE was added (125, 170, or 200 mg/L) to conventionally homogenized and pasteurized 3.25% fat chocolate or unflavored milk products. The treated milks and corresponding untreated controls were held at 6°C and plated on standard plate count agar within 24 h of processing and again at 7, 14, 17, and 21 d of storage. Bacterial counts in all unflavored milk samples treated with LAE remained below the Pasteurized Milk Ordinance limit for grade A pasteurized fluid milk of 4.3 log cfu/ mL for the entire 21 d. Bacterial counts in unflavored samples containing 170 and 200 mg/L of LAE were significantly lower than those in the untreated unflavored milk at d 17 and 21 postprocessing. Specifically, bacterial counts in the milk treated with 200 mg/L of LAE were 5.77 log cfu/mL lower than in untreated milk at 21 d postprocessing. Bacterial counts in chocolate milk treated with 200 mg/L of LAE were significantly lower than those in the untreated chocolate milk at d 14, 17, and 21. In chocolate milk treated with 200 mg/L of LAE, bacterial counts were 0.9 log cfu/mL lower than in the untreated milk at 21 d postprocessing. Our results show that addition of LAE to milk can reduce bacterial growth. Addition of LAE is more effective at controlling bacterial growth in unflavored milk than in chocolate milk.
Key words: milk, lauric arginate, shelf life
In recent years, the dairy industry has made strides in improving the quality of commercial fluid milk prod- ucts (Carey et al., 2005). However, the highly competi- tive nature of the overall US beverage industry (IDFA, 2007) underscores the need for the dairy industry to employ innovative methods to ensure retention and possible growth of the fluid milk market share. Specifically, to compete with the rapidly expanding market share enjoyed by such products as shelf-stable bottled water and fruit juice-based beverages (US Census Bureau, 2008), fluid milk processors are striving to further improve product quality and extend shelf life. The...