# Investigation of Salt and Water Diffusion During Dry Salting, Wet Curing, and Ultrasonic Wet Curing
## 3 Results and Discussion
### Diffusion Constants  
#### 3.4.1 Diffusion Constant for Salt  
The values of the diffusion coefficients estimated by the diffusion models for salt are given in Table 3. It is clear that, of the three models examined, the model of [PERSON] et al. (2011) [16] best approximated the measured salt content values, regardless of the curing method. According to this model, the diffusion coefficient of a cylindrical long ion meat sample treated with dry salting at 20 \({}^{\circ}\)C, with a length of 80 mm and a diameter of \(\mathcal{O}\)15 mm was 4.22 \(\times\) 10\({}^{-10}\) m\({}^{2}\)/s, which can be improved by 36.3% (5.75 \(\times\) 10\({}^{-10}\) m\({}^{2}\)/s) using wet curing and by 102.6% (8.55 \(\times\) 10\({}^{-10}\) m\({}^{2}\)/s) using wet curing assisted by active ultrasound (14.1474 W/cm\({}^{2}\) and a frequency of 19 kHz). We can also state that, despite the fact that the other two modeling methods gave different numerical results, they determined the relationship between the individual curing methods in the same way (see Figure 5). Based on the smallest RMSE values, [PERSON]'s model is recommended for determining the diffusion of salt in meat.  
[PERSON] et al. (2003) [21] performed similar studies on caiman meat. With a 25% (nearly saturated) brine concentration, at 20 \({}^{\circ}\)C, and a meat/brine ratio of 0.2, the salt diffusion coefficient was 8.42 \(\times\) 10\({}^{-10}\) m\({}^{2}\)/s. The approximately 46% faster diffusion is likely due to the different animal species.  
Figure 4: Average water content differences between dry salting and wet curing methods (wet curing + wet curing with ultrasound) and the regression curve (4.579 \(\times\) (1 \(-\) e\({}^{(-0.021\times\)Time)}\)), R\({}^{2}\) = 0.796).  
\begin{table}
\begin{tabular}{c c c c c c c} \hline  & \multicolumn{2}{c}{**Diffusion Constant—D \(\times\) 10\({}^{-10}\) [m\({}^{2}\)/s]**} & \multicolumn{3}{c}{**RMSE**} \\ \hline  & **M** & **A** & **T** & **M** & **A** & **T** \\ \hline
**DS** & 4.42 & 4.22 & 3.36 & 0.0225 & 0.0048 & 0.0102 \\ \hline
**WP** & 5.84 & 5.75 & 4.45 & 0.0244 & 0.0098 & 0.0152 \\ \hline
**US** & 8.53 & 8.55 & 6.3 & 0.0304 & 0.0105 & 0.0265 \\ \hline \end{tabular}
\end{table}
Table 3: Estimation of the diffusion constant of the salt content based on the fitted literature models.  
The effect of ultrasound intensity on the diffusion coefficient of salt was demonstrated by [PERSON] et al. (2009) [22]. However, it is important that the energy investment required for higher intensity is consistent with the degree of diffusion acceleration. Compared to the experiments of [PERSON] et al. [13], which were conducted under similar conditions to those in this study, our results showed that the application of ultrasound improved the diffusion of salt to a greater extent ([PERSON] et al.: \(\times\)1.25, own data: \(\times\)1.48). However, since the applied acoustic intensity was increased from 5.09 W/cm\({}^{2}\) to 14.15 W/cm\({}^{2}\) (i.e., approximately 2.8 times), it can be stated that the improvement in the diffusion coefficient of salt is not proportional to the additional energy investment required.