PREDICTION OF WATER ACTIVITY OF AQUEOUS SOLUTIONS IN CONNECTION WITH INTERMEDIATE MOISTURE FOODS: EXPERIMENTAL INVESTIGATION OF THE a _w LOWERING BEHAVIOR OF SODIUM LACTATE AND SOME RELATED COMPOUNDS

Abstract

ABSTRACT The water activity lowering behavior of sodium lactate, lactic acid, and other related hydroxy acids as well as its sodium salts, has been experimentally determined. The results for the sodium salts were very well fitted to Bromley's (1973) model for a w in aqueous solutions of strong electrolytes, while the a w , data for the acids were very well described by Norrish's (1966) equation. It was found that sodium lactate does not present any exceptional negative deviation from Raoult's law as it has been reported in the literature. The B number for sodium lactate (0.050 kg/mol −1 ) was found to be somewhat lower than that corresponding to sodium chloride. Moreover, lactic acid was found to have a small positive deviation from Raoult's law.