**2. Materials and Methods**

### *2.1. Plant Material*

In two successive experiments during 2020, fruits of strawberry (*Fragaria* × *ananassa* Duch.) cv. Winterstar, a short-day genotype adapted to an annual plastic culture growing system, were harvested at commercial maturity (red color on 80% of the fruit surface) at 30◦35 34.5 N, 30◦42 58.4 E, Behira Governorate, Egypt. The plant is compact, upright, and with long pedicels, making the fruit easy to harvest. This variety produces conical and firm fruit that is uniform in shape throughout the season and has low sourness. The mature fruit has red color on about 90% of its surface [44]. Those fruits were chosen that had red color on over 80% of their surface and were free from mechanical damage, blemishes, and disease [27]. On the same day of harvesting, the fruits were delivered to the laboratory of Alex Postharvest Center (APHC), Faculty of Agriculture, Alexandria University. Then, they were washed with fresh water, air dried, and used in the post-harvest treatments.

### *2.2. A. vera Gel Extraction and HPLC Analysis of Phenolic Compounds*

*A. vera* mature leaves were obtained from the Nursery of Floriculture, Ornamental Horticulture and Garden Design Department, Faculty of Agriculture, Alexandria University (Alexandria, Egypt). The leaves were washed in tap water and then the gel was separated and blended to obtain a homogeneous mixture. The mixture was filtered using a muslin cloth and then centrifuged at 10000× *g* for 25 min to remove the fibers [45]. Then, concentrations were prepared for HPLC analysis as follows: 0.5 g of powdered *A. vera* gel was extracted by ultrasound for 30 min at 25 ◦C using methanol/water (80%, *v*/*v*) and filtered.

Phenolic compounds were identified by high-performance liquid chromatography equipment (Agilent 1100, pump PU-1580; UV detector UV-1570; injector equipped with a 20 μL loop) (Agilent Technologies, Santa Clara, CA, USA). The samples were separated using a 250 mm × 4.6 mm stainless-steel column Discovery-C18 4 μm (Agilent Technologies, Santa Clara, CA, USA). The flow rate of the mobile phase was kept at 1 mL/min. Solvent A was water containing 0.05% formic acid, and solvent B was acetonitrile/methanol (80%:20%, *v*/*v*). The gradient conditions were as follows: 0–5 min, 10% B; 5–15 min, 10%–18% B; 15–25 min, 18% B; 25–30 min, 18%–25% B; 30–35 min, 25% B; 35–40 min, 25%–35% B; 40–45 min, 35%–60% B; 45–50 min, 60%–10% B; and 50–55 min, 10% B. The temperature of the column was controlled at 25 ◦C.

### *2.3. Extraction and Chemical Analysis of Lemongrass EO*

Lemongrass leaves were obtained from the Nursery of Floriculture, Ornamental Horticulture and Garden Design Department, Faculty of Agriculture, Alexandria University. About 100 g of fresh leaves were chopped and put ina2L flask and the essential oil (EO) was hydrodistillated using a Clevenger-type apparatus for 3 h. The collected EO was kept in brown bottles at 4 ◦C until use [46].

The EO chemical composition was determined using a Trace GC Ultra-ISQ mass spectrometer (Thermo Scientific, Austin, TX, USA) with a direct capillary column TG–5MS (30 m × 0.25 mm × 0.25 μm film thickness). To prepare the EO for GC–MS, 5 μL from the pure lemongrass EO was dissolved in 1.5 mL of hexane. Then, 1 μL was injected into GC–MS. The temperatures of column oven, chemical separation and identification conditions can be found in a previous study [47]. The match factor (MF) between the mass spectrum obtained for each compound and the library mass spectra for each compound was measured and reported, where it was accepted if its value ≥ 650 [35].

### *2.4. Preparation of A. vera–Lemongrass EO Coating*

*A. vera* gel solution (20%–40%) + lemongrass EO 1% was mixed by dissolving lemongrass EO in distilled water with a few drops of Tween-80 (0.01% *w*/*v*) for 2 min, then the gel was added under vigorous shaking for approximately 2 min [12].

### *2.5. Treatment Application and Analysis*

The fruits were separated into five groups (150 fruits per group and 3 replicates/treat -ment). Each group was treated by immersing fruits with the treatments mentioned in Table 1, for 1 min. Then, the fruits were left to air-dry at room temperature for 1 h so that their surfaces were dry [27,48]. The treated fruits were drained, packed in perforated polystyrene bags (1 L), and stored at 5 ± 1 ◦C under 90%–95% relative humidity for 16 days. The parameters were recorded every 4 days for each treatment.



### *2.6. Physical Parameters of Strawberry*

### 2.6.1. Weight Loss (%)

The fresh weight of fruit of each replicate was measured on the treatment day and at 4, 8, 12, and 16 days of sampling time. The cumulative weight loss was expressed as a percentage loss of the original fresh weight: weight loss (%) = (F0 − F1)/F0 × 100, where F0 is the initial fresh weight and F1 is the measured weight on each sampling day.

### 2.6.2. Fruit Firmness

The strawberry fruit firmness was determined using a texture analyzer for each treatment and storage period using FT011 Fruit Firmness Tester (Wagner Instruments, Greenwich, CT, USA). This instrument consists of penetrating cylinder (1 mm in diameter) to penetrate inside the pulp of fruits up to a constant distance of 5 mm at a speed 2 mm/s. The firmness per Newton (N) was measured.
