14F-34 |
Relationship between water mobility (D) glass transition temperature (Tg) and sodium lactate concentration in intermediate moisture meats |
A. P. P. YANG, U.S. Army Natick Soldier Center, U.S. Army Research, Development & Engineering Command, Combat Feeding Innovative Science Team, Kansas St., Bldg. 36, Rm. E-108, Natick, MA 01760-5020 (1) JUSTIFICATION: One of the most important aspects of food stability and safety to be monitored is the potential to support microbial growth and /or toxin production. Many researches have shown that water activity (Aw) cannot adequately account for the observed stability behavior of much food systems. We hypothesize that water mobility and glass transition temperature (Tg) of a food system may be useful tools for predicting and controlling its stability. (2) OBJECTIVE: The objective was to study water mobility and Tg of intermediate moisture turkey meat systems, and to evaluate the abilities of these parameters to serve as predictors of food stability by correlating them with the growth and death of Staphylococcus arueus. (3) METHODS: Turkey rolls of different concentrations of sodium lactate (1, 2, or 3%) and Aw (0.92, 0.90, 0.88, and 0.86) were prepared. Meat (5grams) were packed and irradiated to obtain sterilized samples, then were inoculated with Staphylococcus arueus (103-104 CFU/g). A time domain NMR analyzer was used to measure water mobility and Tg values of samples. (4) RESULTS: Water self-diffusion coefficient (D) was used as indicator of water mobility, and Tg was used as indicator of system mobility. The Tg values decreased with increasing Aw or moisture content but increased with increasing sodium lactate concentration. The D values increased with increasing Aw or water content, while showed abruptly change between Aw of 0.90 and 0.88. Results from microbial count were consistent with Tg and D values; that is microbial count decreased with increasing mobility and showed dramatic change between Aw of 0.90 and 0.88. (5) SIGNIFICANCE: The results suggested that it might be more accurate to predict or control food stability by using water mobility and Tg of the system than using Aw. These parameters could also provide the basis for developing new food new food developing new food systems or improving existing ones.
Session 14F, Product Development: General
|