*2.4. Bruise Analysis*

To allow for the full development of bruising sustained during the mechanical shock testing, the apples were kept at ambient laboratory conditions after drop testing for a period of 24 h, prior to inspection and analysis. The total number of bruises per apple was recorded for each tray to determine the frequency of occurrence and distribution of bruising inside the container. The bruise area (BA) and bruise volume (BV) were measured for each apple after testing. The bruise dimensions were measured using digital calipers (±0.01 mm). The BA was measured using the major and minor bruise width, and the BV was calculated by measuring the depth of the bruise by cutting the fruit perpendicularly along the major bruise width (Figure 3). BA and BV were quantified using an assumed elliptical bruise shape [24–26] using Equations (1) and (2).

$$BA = \frac{\pi}{4} w\_1 w\_2\tag{1}$$

$$BV = \pi \frac{d\_b}{24} (3w\_1 w\_2 + 4d\_b^2) \tag{2}$$

where *w*<sup>1</sup> is the bruise width along the major axis (mm), *w*<sup>2</sup> is the bruise width along the minor axis (mm), and *db* is the depth of the bruise (mm)

**Figure 3.** Elliptical bruise thickness method used for BA and BV.

The bruise susceptibility (BS) was computed as the ratio of the *BV* to the impact energy (*IE*), as shown in Equation (3) [2,26]. Table 1 and Equation (4) display how *IE* was calculated for each tray type.

$$BS = \frac{BV}{IE} \tag{3}$$

where *BV* is the bruise volume (mm3) and *IE* is the impact energy (J).

$$IE = m\_i \mathfrak{g} h\_d \tag{4}$$

where *mi* is the mass of the falling object (kg), *g* is the acceleration due to gravity (m/s2), and *hd* is the drop height (m).

**Table 1.** Equivalent impact energy (J) of the package types.

