Polyphosphates are important functional additives used in meats and other food products, and the phosphate movement in meats is assumed to occur by a diffusion process. The objective of this study was to investigate the effects of temperature on phosphate diffusion mechanism in meat samples (prepared ill 2 x 2 x 2 cm) dipped in different concentrations of sodium tripolyphosphate (STP) solutions. For this purpose, different combinations of STP solutions (0%, 2%, 4%, and 6%; w/v) at different temperatures (similar to 18-20, similar to 20-22, similar to 28-30 and similar to 34-36 degrees C) were applied. During experiments, meat samples were dipped in the STP solutions for 30 min, and both phosphate content changes of meat samples and STP solutions were determined using a modified spectrophotometric method. The experimental data was then used to determine the diffusion coefficients (D-values) of STPs. The D-values for STPs changed with dipping time, and therefore average D-values were determined using the least squares analysis. Naturally occurred orthophosphates in meats and STPs in the solutions resulted in a counter-current diffusion, and this was important in interpretation of the phosphate diffusion and evaluation of the D-values of both STPs and orthophosphates. The counter-current diffusion was found to be strongly temperature-dependent. Knowledge of D-values at different conditions may lead to predict the diffused amount of STPs into meat samples, and these findings may also be used for further optimization studies in different industrial applications. (c) 2005 Elsevier Ltd. All rights reserved.