## 3 Results
### Color Parameters  
In this study, color parameters were changed after infrared drying of avocado pulp with different formulations. Primarily, it was observed that L\({}^{\star}\) and b\({}^{\star}\) values decreased; however, there was an increase in a* value after drying (see Figure 2). Furthermore, changes in color characteristics had strong correlations with total polyphenols and total chlorophylls (Table 2). Color is a widely used criterion for evaluating the efficiency of operation, and it has a considerable influence on the purchasing intention. Figure 2 shows that the color of the dried product became darker (decrease in L* value), less green (increase in a* value), and more yellow (increase in b* value), indicating an increase in browning pigments and a loss of natural pigments in products (see Figure 3). For hot air drying of sliced avocados [52] and infrared-vacuum drying of grapefruit slices [53], the same trend was observed, with an increase in a* value and a decrease in L* and b* values. This study found each investigated factor showed a significant impact on the change of color parameters. Plus, their interaction also had significant effects on a* and b* values, but an insignificant effect on L* values (\(p=0.333\)). \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & **TPC** & **TCC** & **AA** & **L\({}^{\star}\)** & **a\({}^{\star}\)** & **b\({}^{\star}\)** \\ \hline
**TPC** & 1 & & & & & \\ \(p\)-value & - & & & & & \\ \hline
**TCC** & **0.83** & 1 & & & & \\ \(p\)-value & \(7.1\times 10^{-7}\) & & & & & \\ \hline
**AA** & **0.77** & **0.90** & 1 & & & \\ \(p\)-value & \(9.6\times 10^{-6}\) & \(2.4\times 10^{-9}\) & - & & & \\ \hline
**L\({}^{\star}\)** & **0.93** & **0.72** & **0.71** & 1 & & \\ \(p\)-value & \(6.7\times 10^{-11}\) & \(7.0\times 10^{-5}\) & \(1.1\times 10^{-4}\) & - & & \\ \hline
**a\({}^{\star}\)** & \(\mathbf{-0.79}\) & \(\mathbf{-0.82}\) & \(\mathbf{-0.73}\) & \(\mathbf{-0.78}\) & 1 & \\ \(p\)-value & \(5.2\times 10^{-6}\) & \(7.8\times 10^{-7}\) & \(6.0\times 10^{-5}\) & \(5.7\times 10^{-6}\) & - & \\ \hline
**b\({}^{\star}\)** & **0.93** & **0.91** & **0.79** & **0.87** & \(\mathbf{-0.91}\) & 1 \\ \(p\)-value & \(2.5\times 10^{-11}\) & \(8.1\times 10^{-10}\) & \(3.9\times 10^{-6}\) & \(4.5\times 10^{-8}\) & \(6.1\times 10^{-10}\) & - \\ \hline \hline \end{tabular} Correlations in bold are significant at the 1% level (2-tailed).  
\end{table} 
Table 2: Pearson correlation coefficients between the total phenolic content (TPC), total chlorophyll content (TCC), antioxidant activity (AA), and color parameters (L\({}^{\star}\), a\({}^{\star}\), b\({}^{\star}\)) of avocado pulp powder obtained by infrared drying. Figure 2: The changes in values of L\({}^{\star}\) (**a**), a\({}^{\star}\) (**b**), and b\({}^{\star}\) (**c**) of avocado pulp powder obtained by infrared drying at different drying temperatures and formulations. During processing, the discoloration of the product was directly related to the changes, such as pigment destruction and oxidation, enzymatic and non-enzymatic browning, and phenol polymerization [54]. Whereas the color shift in green-pigmented foods is mostly due to the biotransformation of chlorophylls to pheophyltins, which replaces magnesium with hydrogen [55], the browning of fruit containing polyphenols is linked to the enzymatic breakdown of polyphenols. Some previous studies presented that the change in avocado pulp color had a strong correlation with an increase in PPO activity [40,56]. Table 2 also shows a strong relationship between total polyphenols, total chlorophylls, and color parameters with a positive correlation for L* and b* values and a negative correlation for a* value. It could be concluded that both polyphenol and chlorophyll degradation occurred in infrared drying of avocado pulp with different formulations, causing color damage. Figure 2 further reveals that APM had greater L*, 1a*1, and b* values than AP. When hydrocolloids were added to the avocado pulp, it suggested that the sample brightness would enhance.