**2. Materials and Methods**

*A. vera* was grown in Madiun District, East Java, and purchased through a national *A. vera* supplier in Sidoarjo District, East Java Province, Indonesia. Meanwhile, the tomatoes were obtained from local farmers in Malang District, East Java Province. The tomatoes (cv. Ratna) were harvested 90 days after sowing in July 2021. A total of 150 tomatoes were selected, 5 tomatoes for each coating and non-coating treatment and for 3 replications. The tomatoes were chosen within the turning level of maturity, which means that more than 10% but not more than 30% of the surface in the aggregate shows a definite change in color from green to tannish-yellow, pink, red, or a combination thereof. The average diameter of the tomatoes was 2.5 ± 0.25 cm, weight 20 ± 2 g for each tomato, and they had

a slightly acidic taste with the absence of injury. Meanwhile, the *A. vera* was harvested at six months (July 2021), possessed a clean green skin color, was approximately 45 ± 4.5 cm long, weighed around 350 ± 35 g for each rind, and had the absence of injury on the surface of the rind. Moreover, the chemicals used for analysis (NaOH, phenolphthalein indicator, H2SO4, FeCl3, Folin Ciocalteau, Na2CO3, gallic acid, NaNO2, AlCl3, hexane, acetone, ethanol, DPPH, BHT, FeSO4.7H2O) were purchased from Merck, Darmstadt, Germany, and Sigma Aldrich, Singapore, unless otherwise stated.

### *2.1. Preparation of A. vera Coating Gel and Coating Process*

The *A. vera* rind was washed to remove the impurities. Then, it was trimmed, and the thick outer skin was peeled. Next, the gel fraction was washed with warm water to remove the yellow sap. The gel was then crushed using a blender and filtered through 80 mesh sieves to separate the gel from the solid fraction. The gel was then heated in an iron cast pot using a stove at 80 ◦C for 5 min. After heating, the *A. vera* gel was allowed to cool to room temperature. Meanwhile, the tomato was washed to remove the impurities, soaked in the *A. vera* gel for 5 min, and placed in an open tray at room temperature to let the *A. vera* gel dry. The coated tomato was then kept in the open space at room temperature for 12 days. The observation was conducted at the interval of 3 days.
