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Video

Lipid Oxidation and Quality

Session:: Identification of Novel Antioxidants and Their Efficacies

Coffee husk supercritical and ultrasound extracts: characterization and antioxidant properties

Tuesday, May 2, 2023
11:20 AM – 11:40 AM MDT
Room: 205
Abstract: Coffee is one of the most significant beverages consumed worldwide, however, due to this great production and consumption, large amounts of by-products like the coffee husk (CH) are generated.
The objective of this study was to optimize supercritical fluid extraction (SFE) and ultrasound assisted extraction (UAE) conditions from CH in order to obtain natural extracts as a source of polyphenols (caffeine) with high antioxidant activity.
Arabica cv CH was provided by Nestle (Uruguay) and characterized in terms of moisture, protein, lipids, ash, fiber, carbohydrates, phenolic content (Folin-Ciocalteau) and antioxidant activity (ABTS assay).
SFE were carried out using a laboratory-built system equipped with a 25 mL stainless steel vessel filled with 13 g of CH. A total of 7 extractions were carried out with the following variables considered: extraction temperature (40-50ºC) and extraction pressure (100-400 bar). In most of the cases, the extraction solvent was CO2 with 10% of ethanol as modifier. A constant flow rate of 0.5 L/min CO2 was set and each run was finished when 100 L of CO2 were measured in the flow totalizer.
For UAE a total of 9 extractions were carried out according to a simple factorial experimental design of 3 levels with 2 factors, whose independent variables were: extraction time (15-30-60 minutes) and power (54-108-180 watts). An ethanol-water mixture (75:25) was used as solvent, with a ratio of 50 mg CH/mL.
Extraction yield, total phenolic content, caffeine content (quaternary pump HPLC coupled to a diode array detector)and antioxidant activity (ABTS and ORAC assays) of the extracts were considered as response variables.
The best supercritical extract was obtained at 50ºC and 300 bar with the following values: 5.1 %wt; 41.6 mg GAE/g; 88.7 umol/g (caffeine content); 384.7 umol/g (ABTS assay); 806.2 umol/g (ORAC assay).
The best ultrasound extract was obtained at 60 min and 180 W with the following values: 8.8 %wt; 36.8 mg GAE/g; 62.7 umol/g (caffeine content); 491.1 umol/g (ABTS assay); 1012.4 umol/g (ORAC assay).
Results reinforce the use of green extraction technologies to obtain antioxidants compounds from natural sources.