Extração assistida por banho ultrassônico de óleo de café verde (Coffea arabica) utilizando etanol e hexano como solventes e caracterização dos extratos por cromatografia gasosa e ressonância magnética nuclear de hidrogênio

Abstract

The solid-liquid extraction, or solvent extraction, is the method most used by the chemical industry, because it has a higher yield in obtaining oils, especially from the low moisture feedstocks, such as seeds. The universal solvent used in this process is the hexane, which due to its polarity, has high affinity with lipid fraction of the grains, managing to remove large amounts of oil from the seeds, besides obtaining products of greater purity and using less process time, however, this solvent has high toxicity and flammability. Among the most sustainable options for oil extraction, ethanol stands out, because it represents a solvent of plant origin, originated from raw materials that are abundant in Brazilian territory, such as sugar cane, reducing process costs and dependence on oil-based solvents. However, due to its polarity, ethanol presents molecular interaction with water, decreasing the solubility in triglycerides and, consequently, the extraction yield. A proposal to remedy the difficulties presented by ethanol and at the same time to reduce the environmental impact of hexane, is the usage of a mixture of solvents in the extraction. Therefore, in this work, the variables of the green coffee oil extraction process was stuided, that has not yet gone through the roasting process, observing the crude oil yield, with extraction using an ultrasonic bath, varying the solvents in hexane, ethanol and a mixture of ethanol and hexane in a 1/1 (vol/vol) proportion. For this, extractions were carried out with different solvents at different times, determining the extraction saturation time, to later perform the extractions with different solvent / sample proportions (mL.g-1) and grains particles diameters (mm), finding the best conditions of extraction with particles diameters of 0.7 mm and solvent/sample proportions of 7: 1. After the analysisof the oil content yield, qualitative analyzes were carried out via gas chromatography, identifying the fatty acids present in each one, and via nuclear magnetic resonance, showing the presence of the diterpenes from the kaurans family. At the end of this work, it was possible to conclude that the substitution with solvents was feasible, yet, with some adaptations throughthe process.