# Construction of Color Prediction Model for Damaged Korla Pears during Storage Period
## 3 Variation Laws of Colors of the Damaged Korla Fragrant Pears during the Storage Period  
### Variation Laws of \(L^{*}\) Value  
The size, shape, and weight were within a small range and considered similar, and the damaged area of pears falling from the same height was considered similar. Therefore, it was only necessary to use the average value of the damaged area of a batch of pears falling at the same height to represent the damage degree of the pears falling at this height.  
\begin{table}
\begin{tabular}{l l l l l} \hline \hline
**Training** & **Membership** & **Number of** & **Number of** & **Output** \\
**Optimization** & **Function Types** & **Membership Functions** & **Epochs** & **Function Type** \\ \hline Hybrid & ANFIS-Tri-mf & 3, 3 & 100 & Linear \\ Hybrid & ANFIS-Trap-mf & 3, 3 & 100 & Linear \\ Hybrid & ANFIS-Gbell-mf & 3, 3 & 100 & Linear \\ Hybrid & ANFIS-Gauss-mf & 3, 3 & 100 & Linear \\ Hybrid & ANFIS-Gauss2-mf & 3, 3 & 100 & Linear \\ Hybrid & ANFIS-Pi-mf & 3, 3 & 100 & Linear \\ Hybrid & ANFIS-Dsig-mf & 3, 3 & 100 & Linear \\ Hybrid & ANFIS-Psig-mf & 3, 3 & 100 & Linear \\ \hline \hline \end{tabular}
\end{table}
Table 1: Initial values of the ANFIS parameters.  
The mean damaged areas of fragrant pears under six impacting heights were 77.71 mm\({}^{2}\), 296.91 mm\({}^{2}\), 604.05 mm\({}^{2}\), 900.77 mm\({}^{2}\), 952.30 mm\({}^{2}\), and 993.42 mm\({}^{2}\), respectively.  
The brightness (L*) expresses the color intensity. The higher L* value indicates a brighter color, and the lower L* value implies a darker color. The variation laws of the L* values of fragrant pears at different damage degrees with storage time are shown in Figure 4. As can be observed, the L* value decreased with the increase in storage time. The difference in the L* value between the control group and the fragrant pears with the maximum degree of damage increased from 0.3573 at 0 d to 1.4584 at 40 d. In other words, the pericarp brightness of fragrant pears gradually declined with the increase in storage time. The L* value of fragrant pears with the minimum degree of damage slowly decreased, while the L* value of fragrant pears with the maximum degree of damage quickly decreased. The degree of damage of fragrant pears was also positively related to the darkening rate of the pericarp. The variation curve of the L* value during the storage period was basically consistent with that of the undamaged fragrant pears when the damaged area was 77.71 mm\({}^{2}\). No visible damage on the pericarp except for mild pulp damage after eliminating the pericarp was also detected (Figure 5).  
This reveals that the physiological activity of fragrant pears slightly changed under mild damage and no pericarp damage. When the damaged area exceeded 77.71 mm\({}^{2}\), the physiological activity of fragrant pears greatly changed with the intensifying damages. This is because fragrant pears are a type of climacteric fruits that can increase respiratory rate and ethylene production after harvest [23]. As a result, the damaged fragrant pears can strengthen their respiration, accelerate their metabolism, and self-repair [24; 25]. The pericarp color of fragrant pears also became darker due to respiratory oxidation. Moreover,  
Figure 4: Variation laws of the L* value of fragrant pears at different damage degrees with storage time (the mean values \(\pm\) standard deviations).  
Figure 5: Fragrant pear falling at 30 cm height with 77.71 mm\({}^{2}\) damaged: (a) No epidermal damage. (b) Minor pulp damage.  
after the fragment pears were damaged, the cytomembrane was broken, which destroyed the regional distribution of phenolic substances and polyphenol oxidase (PPO). The contact between the phenolic substances and PPO triggered enzymatic browning, thus deepening the pericarp colors [26; 27; 28]. Hence, the L* value of fragment pears with a higher degree of damage declined more quickly.