Extraction and Evaluation of Bioactive Compounds from Hass Avocado (Persea americana Mill.) Agro-Industrial Residues

Barranca (Lima, Peru) is a major avocado-producing region; the seeds and skins of Hass avocados (*Persea americana* Mill.) constitute agroindustrial byproducts that could serve as sources of bioactive compounds for the food industry. The objective of this study was to isolate and evaluate bioactive compounds from agro-industrial waste derived from Hass avocados for their potential application in functional foods, by determining the total phenolic content (TPC) and total flavonoid content (TFC) of the seed, while also investigating the determination of phenolic compounds in the peel. The fresh samples underwent ultrasound-assisted extraction (45 °C, 45 min) using 50%, 70%, and 80% methanol, with a sample-to-solvent ratio of 1:10 (w/v), followed by centrifugation (4800 rpm, 15 min). The supernatants were stored at ultra-low temperatures until analysis. TPC was determined using the Folin-Ciocalteu method (gallic acid standard; 725 nm), and TFC was determined using the NaNO₂-AlCl₃-NaOH method (quercetin standard; 415 nm), with absorbance measured using a spectrophotometer. The experiments were evaluated using a 3 × 2 factorial design with three replicates per treatment, and the data were analyzed using a general factorial ANOVA (Minitab, α = 0.05). For the total flavonoid content (TFC) of the seeds, the model was significant (F = 8.62; p = 0.001; R² = 78.2%), with significant effects observed for the solvent (p = 0.033), the aliquot (p = 0.009), and the interaction between the two (p = 0.001). The average total flavonoid content (TFC) ranged from 6.23 to 8.48 mg QE/g; the highest value (8.48 ± 0.23 mg QE/g) was obtained using 50% methanol. Regarding the total phenolic content (TPC) of the seeds, the model was also significant (F = 3.45; p = 0.037), showing significant effects for the solvent (p = 0.023) and the aliquot (p = 0.028), but not for their interaction (p = 0.783); the values remained virtually constant (0.61–0.62 mg GAE/g). Regarding the seed coat, reliable spectrophotometric readings could not be obtained; therefore, it is necessary to optimize the assay conditions, such as extract dilution and blank response. The significant interaction between the solvent and the aliquot with respect to TFC indicates that the effect of the aliquot depends on the methanol concentration; consequently, these factors cannot be optimized independently, and the aliquot volume must be standardized as an analytical variable. The minimal variation in TPC suggests that low methanol concentrations are sufficient to extract phenolic compounds. In conclusion, Hass avocado seeds extracted with 50% methanol exhibited the highest levels of flavonoids, supporting their potential as a source of bioactive compounds for functional foods.