*3.1. Bruise Analysis*

The results in Figures 4 and 5 show the total apple bruise area and volume for each tray material after completion of drop testing. As the drop height increased from 30 cm to 50 cm, the bruise sizes increased in both EPS and MF. As demonstrated by Lu et al. [25] and T. Fadiji et al. [1], the bruise area and volume increased due to drop height and number of drops. For a bruise to form, the apples absorb kinetic energy that is not dissipated by the packaging material [5,27–29]. At both test drop heights, the apples in the MF trays experienced more damage and bruising. Both tray systems prevent direct apple-to-apple contact, but the protective nature of the EPS material plays a crucial role in minimizing bruising. The lower bruise damage results from the EPS trays absorbing more kinetic energy than the MF trays from the same drop height. The amount of bruising observed on the apples is dependent on the amount of energy absorbed by the packaging in the apple supply chain. The amount of bruising directly affects the quality of the apple fruit and the consumers purchasing behavior [5,26,30,31].

There was an increase in bruise area and volume for both the MF and EPS when comparing the 30 cm to 50 cm drop height results. The differences in the bruise area were not significant for Trays 2–4 but were significantly different for Tray 1 for the MF trays. The bruise area for apples packaged with EPS trays was not significantly different for Trays 1 and 4, but was for Trays 2 and 3. Furthermore, when comparing these results, no significance was reported between the MF Trays 2 and 3 dropped from 30 cm and EPS Trays 2 and 3 dropped from 50 cm. This indicates the apples dropped from 50 cm with EPS trays had similar damage to apples dropped from 30 cm inside MF trays.

Evaluating the results from the 30 cm drop height, no statistical differences in tray location between apples packaged with EPS trays were observed. The 30 cm drop resulted in impact energies low enough to be within the cushion material's working length, resulting in a similar performance of the tray throughout all tests. For the 30 cm drop height, all of the bruise areas were below 240 mm2 for the EPS trays. Regarding the MF tray locations, there were significant differences in bruise area and volume for Trays 2 and 3. The bottom and top trays (Trays 1 and 4) were aided in protection by the corrugated container, likely reducing the impact energy on apples in those locations.

Statistical differences were noted for the package system dropped from a height of 50 cm for both the EPS and MF tray types. Tray 4 (top tray) had the smallest bruise area compared to apples located in other tray locations for both tray types. Apples packaged using MF saw significantly greater damage in Trays 1–3 as compared to Tray 4. For apples inside EPS trays, the two middle layers were significantly different than Trays 1 and 4. These results are consistent with Fadiji et al. [1], who noted apples packaged in the middle trays of an MK4 corrugated container had more bruising damage than those packaged in the bottom and top trays.

**Figure 4.** Bruise area of apples by tray location packaged using MF and EPS trays from 30 and 50 cm drop height (mean ± SD, *n* = 2). Different letters indicate statistically significant differences at *p* < 0.05. Bars with no common letters are significantly different (*p* < 0.05).

**Figure 5.** Bruise volume of apples by tray location packaged using MF and EPS trays from 30 and 50 cm drop height (mean ± SD, *n* = 2). Different letters indicate statistically significant differences at *p* < 0.05. Bars with no common letters are significantly different (*p* < 0.05).

Additionally, the frequency, or occurrence, of bruising was observed during the analysis. Figures 6 and 7 display bruise frequency based on the drop height and tray material. Results from the 30 cm and 50 cm drops show EPS trays reported a lower total count of bruises than the MF trays. The MF trays from 30 cm show an increasing trend in

the total number of bruising from the bottom to top trays, whereas the remaining treatments have the greatest number of bruises occurring to the middle trays.

**Figure 6.** Bruise frequency of apples by tray location packaged using MF and EPS trays from 30 cm drop height (mean ± SD, *n* = 2). Different letters indicate statistically significant differences at *p* < 0.05. Bars with no common letters are significantly different (*p* < 0.05).

**Figure 7.** Bruise frequency of apples by tray location packaged using MF and EPS trays from 50 cm drop height (mean ± SD, *n* = 2). Different letters indicate statistically significant differences at *p* < 0.05. Bars with no common letters are significantly different (*p* < 0.05).
