## 3 Results and Discussion  
### Correlations Between Damage Index and Impact Parameters  
The electronic impact recorder (IRD 400) was used in this study to determine the relationship between the impact parameters and the damage index in harvesting and processing potatoes by modifying the type of impact surface, the height of the tuber drop,  
Figure 2: Measurement of the damage depth. and the related impact velocities. The results of comparative studies on the impacts of tubers of two potato varieties (Saturna, Hermes) and the IRD 400 device with different surfaces (bulk potatoes, rod conveyor, concrete plate, steel plate) for the initial impact velocity in the range of 2.43-4.43 m\(\cdot\)s\({}^{-1}\) are presented in Tables 1-4. Based on the analysis of variance, it can be concluded that the variety, surface, and initial impact velocity had a highly statistically significant effect on the variations in the tuber damage index and the peak acceleration of the IRD 400 device (Table 1). The critical significance level was significantly lower  
Confirmation of these results can be found in the work of [PERSON] et al. [34], who, based on orthogonal tests, ranked the factors influencing the depth of tuber damage in the following order: drop height (initial velocity), impact surface, number of impacts, and potato mass. In other studies [11], [PERSON] et al. found that the factor contributing to the susceptibility to damage is the biochemical composition of the tubers, which differs between varieties. Therefore, damage during the harvest and post-harvest processing of potatoes can be minimized by reducing the drop height and the associated initial impact velocity, as well as by using shock-absorbing impact surfaces. Used simultaneously, these two methods can reduce the risk of impact damage [35]. The observed regularities inspired us to find a relationship linking the tuber damage index with the characteristic impact parameters recorded by the IRD 400 device (peak acceleration, change in velocity during impact) (Table 2). In the study, Saturna variety tubers were less damaged, with an average damage index lower by 7.4% than that of the Hermes variety. This difference may have been due to the slightly different physical and biochemical properties of the tubers of these varieties. The highest damage rate occurred when falling onto hard steel and concrete surfaces because these generated higher impact forces, leading to more severe damage than soft surfaces. The key factor is the energy that the tuber absorbs relative to the surface. In turn, the plastic coating on the rods deforms on impact, reducing the energy transferred to the tuber, resulting in a lower damage rate than rates observed with steel and concrete surfaces. In similar studies, the depth of the damage to Kexin potatoes after impact with plastic rubber-coated steel rods was shown to be less than that after impact with an uncoated rod [36]. The cushioned impact surface of the rod did not significantly reduce the tuber damage index because there was a high-stress concentration due to the smaller tuber-rod contact area during the impact. A study by [PERSON] et al. [3] showed that steel coating materials, such as PVC, provide a slight cushioning effect. A low damage rate was obtained when tubers collided with each other because the elastic surfaces of the tubers had a better ability to absorb and dissipate energy and were more easily deformed without damage during the impact. Using a damage index based on damage depth, [PERSON] and [PERSON] [37] assessed the damage of 22 potato varieties. This rate was 54.17% after the potatoes had passed through the line of harvesting, transport, separation, and loading of the pile. Peak acceleration (_a_) is expressed as a multiple of the acceleration of gravity for the maximum acceleration during the impact.