Exploring the production of antioxidants and biogas from avocado (Persea Americana var. Americana) residues as an alternative for developing rural bioeconomies

Abstract

Avocado seeds and peels do not have a specific use at the local or industrial level. Valorization pathways to obtain high-value-added products are required to close the loop and increase sustainability in the avocado value chain. Bioactive compound extraction and biogas production have been profiled as alternatives to add value to these residues. Therefore, comparisons between different extraction methods and chemical characterization of the extracts are required before proposing any application. The assessment of the biogas production potential is needed to add value to the remaining solids after extraction. In this way, this research focuses on analyzing the production of bioactive compounds and biogas as potential alternatives to upgrade avocado residues and develop rural bioeconomies. For this, solid-to-liquid extraction and ultrasound-assisted extraction techniques were studied. The chemical characterization of extracts was done to elucidate potential applications. Biogas production potential was assessed by comparing experimental results with theoretical values. The optimum operating conditions to extract bioactive compounds from avocado seeds and peels are 45 °C for 20 min with an ethanol concentration between 30% and a solid-to-liquid ratio of 1:20. Flavonoids and catechins are the most abundant compounds found in avocado seed and peel extracts. Then, medical, cosmetic, food, and pharmaceutical applications can be proposed. Avocado peels have a higher biogas production potential than seeds since peels have a biogas yield of 234 Nm3/kg SV. Upgrading these residues can contribute to propose small-scale processes for implementation in rural zones.