3.3.2. Fruit Firmness

The firmness of strawberry fruits significantly reduced after all treatments during storage of 4, 8, 12, and 16 days in the two experiments, as shown in Figure 3. The coating treatments showed a higher firmness value than the control strawberry fruits. The firmness of strawberries treated with *A. vera* gel at 20% and 40% was found to be lower than that of other coated samples with *A. vera* gel combined with EO during different days of storage, showing that the treated and control strawberry fruit become less firm due to reaping (Figure 3). Compared to that of the control, the highest firmness value was that of strawberry fruits treated with *A. vera* gel 40%, followed by the fruits treated with *A. vera* gel 20% and those treated with *A. vera* gel with EO 1%. *A. vera* gel coatings retarded the postharvest ripening process and reduced the firmness of table grape and sour cherry [67,68]. Lower water vapor from fruits subjected to *A. vera* gel coating results in maintained turgor pressure of the cell wall [69,70]. The treated fruits with *A. vera* with EO showed slightly higher firmness, that could be due to the higher hydrophobic properties in this treatment. In agreement with this work, the coated strawberry fruits with *A. vera* gel alone and combined with basil EO had a lower softening rate compared to the control treatment [71].

**Figure 3.** Firmness (N) (mean ± S.E.) of strawberry fruits stored at 5 ◦C as affected by coating treatments when stored for different lengths of time in both experiments. The mean ± S.E. of treatments in the figures with the same letters shows a nonsignificant difference according to Duncan multiple range test for *p* ≤ 0.05. AV: *A. vera* gel. (**a**) First experiment; (**b**) second experiment.

### *3.4. Color Value*

The data in Tables 4 and 5 show that the color value of strawberry fruits was influenced by the different coating treatments. The L\* of the strawberry fruits increased in lightness in both coating treatments during the shelf-life study. In other words, a coating of *A. vera* gel or *A. vera* gel with lemongrass EO helped to maintain the lightness of the fruit compared to the control samples (Tables 4 and 5). The chromaticity coordinate a\* value, representing the red-green color, was slightly affected by the coatings and remained stable in all treatments during the shelf life. The chromaticity coordinate b\* value of strawberry fruits slightly reduced over storage time and coating treatment by *A. vera* gel only. However, *A. vera* gel with lemongrass EO increased this parameter by day 16 in the two experiments. Coated and control fruits showed a significant decrease in hue during the first 8 days of storage and the hue increased as the storage period was increased to 16 days (Tables 4 and 5).

**Table 4.** Color values of strawberry fruits as affected by coating treatments after 0, 8, and 16 days of storage at 5 ◦C in Experiment 1.


The mean values with the same superscript letter/s in the same column show a nonsignificant difference according to Duncan multiple range test for *p* ≤ 0.05.

**Table 5.** Color values of strawberry fruits as affected by coating treatments after 0, 8, and 16 days of storage at 5 ◦C in Experiment 2.


The mean values with the same superscript letter/s in the same column show a nonsignificant difference according to Duncan multiple range test for *p* ≤ 0.05.

The color of strawberry fruits is an important property for product reception by the consumer; although the coating did not change the fruit initially color [72], and with the increased storage time, the fruit became redder and darker. This increase was probably due to a reduction in both the respiration rate and some enzymatic processes, maintaining the quality of the fruit and preventing its browning [73]. At the end of storage time, control fruits and those treated with gluten plus CaCl2 had a low L\* value (darker color) [74].
