title: Estimation of water activity from pH and °Brix values of some food products.
abstract: In this study, a predictive model for the estimation of water activity (aw(25°C)) as a function of pH (1.00-8.00) and °Brix (0-82.00) values of simulated food solutions (SFS) was developed, through response surface methodology. Response fit analyses resulted in a highly significant (pH<0.0001) square root polynomial model that can predict aw(25°C) of SFS in terms of pH and °Brix values within the defined variable ranges. The linear, quadratic and interactive influences of pH and °Brix on aw(25°C) were all significant (pH<0.0001). Model validations in SFS and in a number of actual food systems showed that the model had acceptable predictive performance, as indicated by the calculated accuracy and bias indices.
authors.affiliation: Department of Food Science and Nutrition, College of Home Economics, University of the Philippines, Diliman, Quezon City, Philippines. Electronic address: alonzogabriel@hiroshima-u.ac.jp.
authors.forename: Alonzo A
authors.initials: AA
authors.lastname: Gabriel
keywords: Predictive modelling; Response surface methodology (RSM); Soluble solids; Water activity; pH; °Brix