EFFECTS OF pH, LACTATE CATION (K, Na, Ca), AND LACTATE ION CONCENTRATION ON IN VITRO METMYOGLOBIN-REDUCING ACTIVITY

Lactic acid salts with three different cations (K, Na, Ca) were investigated at three lactate (L) concentrations (0.1, 0.3 and 0.6 M) to evaluate in vitro metmyoglobin-reducing activity (MRA) at three pH levels (5.7, 6.4 and 7.4). All lactates generated MRA at normal meat pH (5.7), with greater MRA at pH 7.4 than at both pH 6.4 and 5.7 ( P <  0.05). No consistent differences were noted among lactates for generating MRA, except at pH 7.4 where CaL was greatest ( P <  0.05). At pH 6.4 and 7.4, MRA increased ( P <  0.05) as lactate concentration increased. This study provides evidence that lactate oxidation at postmortem muscle pH generates reducing equivalents and that addition of CaL, NaL or KL should increase MRA and color stability.

PRACTICAL APPLICATIONS

Lactate products are commonly used by the meat industry for microbial control, specifically of Listeria monocytogenes . Previous research has shown lactates to increase meat color stability as well. This research examines whether lactate products, with three different cations, can generate metmyoglobin-reducing activity (MRA) to a similar extent. Results of this study indicate that the three lactates increase MRA in vitro , even at postmortem meat pH (5.7). These data should lead to further testing of lactate products in both fresh and processed meat systems in different packaging formats, which would add additional information to meat processors' decision-making process.