The prediction of water activity in aqueous solutions in connection with intermediate moisture foods IV. a_W Prediction in aqueous non electrolyte solutions

Abstract

Sum ma ryA systematic survey was made of water activity reduction in single non electrolyte aqueous solutions together with an examination of the theoretical aspects of a, predictions. The prediction of a, in multicomponent aqueous solutions of non electrolytes as well as of mixed strong electrolyte-non electrolyte solutions was also studied.

Prediction of Water Activity in Aqueous Polyol Solutions

“…On the contrary, the Norrish equation was successfully used also for higher molecular weight compounds. This equation is more accurate in predicting a w values over a wider range of solute concentrations [29]. In this study, it is shown that the combination of the Raoult's law with the Norrish equation accurately predicts the water activity development as a function of the polyol concentration in the water activity range of 0.6 to 0.8, and also at higher water activities.…”

“…The Norrish equation with modified k i values resulted in a good approximation of experimental a w values in aqueous sorbitol and glycerol solutions [12,29]. It has been proven to be a successful model for predicting a w values of multi-solute aqueous polyol solutions [16,31,32].…”

“…2. In addition, the prediction was also performed using k i values from literature (data from [29], see Tab Predicted and experimentally determined a w values for monomeric sorbitol and glycerol solutions. Symbols: -a w predicted using constant k i from [19], -a w predicted using constant k i calculated from experimental data,~ex-perimental data sorbitol, .…”

“…(4) and (5) 66.7 [25] 73.0 [20] Sorbitol/glycerol 17.5 no literature data from Chirife et al [29] were taken which are commonly used with the Norrish equation. Experimentally determined data and the corresponding a w value predictions are shown in Fig.…”

Efecto De Solutos Sobre El Crecimiento De Hongos Deteriorativos De Alimentos Effect of Solutes on Growth Parameters of Food Spoilage Moulds

“…Donde a w es la actividad de agua del medio de cultivo, x w es la fracción molar del agua, x s es la fracción molar del soluto y k es la constante para el soluto, que en esta ecuación tomó los valores de 6,47 y 1,16 para sacarosa y glicerol respectivamente (Chirife et al, 1980). Ecuación de Favetto y Chirife:…”