Extraction of Avocado Seed Oil with Ethanol and N-hexane Using CaCO<sub>3</sub> as Coadjuvant: Optimization and Characterization

Abstract

This study aimed to assess the impacts of addition of CaCO<sub>3</sub> as a coadjuvant in oil yield from Avocado Pear seed in a soxhlet extraction apparatus with ethanol and n-hexane as solvents. Response surface methodology (RSM) was employed to optimize parameters influencing oil yield during solvent extraction. A Box Behnken design with three factors: concentration of CaCO<sub>3</sub> (1, 1.5, 2%), extraction time (90, 145, 180 min), and extraction temperature (25, 35, 45°C) was utilized for the optimization process. The linear model provided the most accurate fit to the experimental data with determination coefficient (R<sup>2</sup>) value of 0.8273. The optimized yield of avocado oil was 4.2343% for n-hexane and 6.8156% for ethanol. The fatty acids present in the oil were determined using gas chromatography, and oleic acid was the dominant fatty acid. The values of main physiochemical properties evaluated were: Light Honey brown, Honey brown – colour; Fruity odour, Fruity odour – odour; 150.0114mgKOH/g, 67.32mgKOH/g – saponification value; 1.1809506%, 1.864302% – free fatty acid; 44.892mgI/g, 65.736mgI/g – iodine value; 1.95%, 1.17% – Moisture content; 5.07, 5.04 – pH and 0.291 meq/kg, 0.558 meq/kg – peroxide value for n-hexane and ethanol solvents, respectively. The oil high saponification value and low iodine value makes it applicable in soap making industries, as lubricant in industrial machine and as a stabilizer in other industrial process.