*2.1. Materials*

"Hass" avocado fruits were obtained from the production area of Uruapan, Michoacán, Mexico (19 ◦ 25'16 "N 102 ◦ 03'47" W). The xoconostle fruit variety *Opuntia oligacantha* var. Ulapa were from the municipality of Tetepango, Hidalgo, Mexico. The fruits that were used were in a state of physiological maturity.

The following reagents were used in this study: orange essential oil (Reasol, Mexico City, Mexico), soy lecithin (Reasol, Mexico City, Mexico), food-grade mineral oil (UltraSource, Kansas City, USA), catechol (Sigma-Aldrich, St. Louis, Missouri, USA), trichloroacetic acid (TCA) (Sigma-Aldrich, St. Louis, Missouri, USA), formaldehyde (analytical grade reagent), glacial acetic acid (analytical grade reagent), ethanol (analytical grade reagent), methanol (analytical grade reagent), paraplast (Sigma-Aldrich, St. Louis, Missouri, USA), Folin-Ciocalteu reagen<sup>t</sup> (Sigma-Aldrich, St. Louis, Missouri, USA), nitrite sodium (analytical grade reagent), aluminium trichloride (Meyer, Mexico City, Mexico), sodium hydroxide (analytical grade reagent), 2,2-Azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) (Sigma-Aldrich, St. Louis, Missouri, USA), potassium persulfate (analytical grade reagent), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) (Sigma-Aldrich, St. Louis, Missouri, USA).

#### *2.2. Preparation of the Nanoemulsion*

The nanoemulsion (W/O) was prepared with 70% orange oil (according to Hashtjin and Abbasi [7] the composition of orange essential oil is limonene (94%), myrcene (2%), linalool (0.5%) and some others), 10% xoconostle extract (according to Cenobio-Galindo et al. [5]. The extract has various polyphenols, such as rutin, ferulic acid, quercetin, hydroxybenzoic acid, apigenin, caffeic acid, kaempferol) and 20% soy lecithin. This mixture was sonicated (Sonics Vibra-cell, Connecticut, USA) with a 6-mm-diameter probe for 20 intervals of 50 s of sonication with rest periods of 10 s using 80% amplitude with a frequency of 20 kHz. The obtained nanoemulsion was stored in a refrigerator at 6 ◦C and protected from light until analysis and use.

#### Determination of the Particle Size and Zeta Potential (ζ)

To verify that the dispersion made was a nanoemulsion, the droplet size was determined, in addition to the stability by means of the zeta potential. The droplet size and zeta potential (ζ) of the system were determined using the methodology developed by Zambrano-Zaragoza et al. [12]; the assessments were made in a Zetasizer Nano-ZS particle size analyzer (Malvern Instruments, Worcestershire, UK), equipped with laser light scattering at an angle of 90◦, and the tests were performed in triplicate.

#### *2.3. Application of the Nanoemulsion in Avocado "Hass"*

Mature fruits homogeneous in weight and size were used and transported under refrigeration conditions (6 ◦C) to the laboratory located in the city of Tulancingo, Hidalgo, Mexico. The fruits were washed and sanitized with sodium hypochlorite (200 ppm) and were dried at room temperature. the nanoemulsion was applied by spraying the whole fruit. The fruits were coated with concentrated nanoemulsion (CN), nanoemulsion diluted 50% (N50), nanoemulsion 25% (N25) and a control (C) without the addition of nanoemulsion. Dilutions were made with food-grade mineral oil. The fruits were stored at 6 ◦C and were analyzed every 10 days until day 60.
