Coffee pulp as a source for polyphenols extraction using ultrasound, microwave, and green solvents

Abstract

Coffee pulp is rich in bioactive compounds. Currently, the use of “green methodologies” is being sought that promote cleaner, safer extraction protocols with lower energy consumption. The present study proposes the extraction of polyphenolic compounds from the coffee pulp through the use of methodologies such as ultrasound and microwave. Different extraction conditions were evaluated, varying the mass:volume ratio and the water:ethanol ratio. The mineral content, the amount of total and condensed polyphenols was determined as well as the characterization of the coffee pulp polyphenolic extracts by FT-IR, and HPLC-MS. The main mineral in the coffee pulp was potassium. The total content of polyphenols using ultrasound-microwave extraction was 165.2-328.9 mg GAE/g, where the best ratio was 1:16 m/v and the water/ethanol ratio showed no difference in the levels of polyphenol extraction. Likewise, for condensed polyphenols, values between 10.06-20.52 mg CE/g were obtained. The main polyphenols were 3-p-coumaroylquinic acid, 3-feruloylquinic acid, quercetin 3',7-dimethyl ether, (+)-gallocatechin, 2,3-dihydroxybenzoic acid, (–)-epicatechin-(2a-7)(4a-8)-epicatechin 3-O-galactoside, and 1,3-dicaffeoylquinic acid. Therefore, the coffee pulp can be used to obtain bioactive compounds through green methodologies such as ultrasound and microwave.