To begin, place the diluted 60%solvents for microwave assisted extraction on the working platform. Weigh 0.67 grams of the coffee silver skin and mix with 20 milliliters of extraction solvent at a one is to 30 ratio in a reaction container. Add a magnetic stir bar to the vessel to ensure uniform distribution of the heat and solvent within the sample.
Close the vessel firmly with a special tool and place it into the microwave assisted extraction chamber. To set up the method, click on the toolbox icon on the top bar of the monitor and select the SK eT rotor in the accessory section. Then click on the stir and type 20%to set the stirring rate.
Click on the door lock sector and set it to activate at temperatures exceeding 80 degrees Celsius. Then click on the table icon on the top bar and set the temperature gradient T1 to an extraction duration of 10 minutes. Microwave power to 1800 watts and temperature to 120 degrees Celsius.
To activate the stir, click on the stir button and wait until the green light appears. Set the blower fan speed to level three. To hold the extraction time, select the desired extraction temperature T2 by setting the extraction duration to 15 minutes, the microwave power to 1800 watts and the temperature to 120 degrees Celsius.
Now, click on the cooling button at the lower left corner of the screen and select the cooling time of 10 minutes. Click the Save icon at the top right corner of the screen. Start the extraction process by choosing the number of vessels used.
Following extraction, centrifuge extracts at 9072g for 15 minutes at four degrees Celsius. Collect the supernatant with a 10 milliliter glass pipette and store it at minus 20 degrees Celsius. Dilute the coffee silver skin extracts tenfold with distilled water in a 96 well plate.
Mix 10 microliters of the diluted sample with 20 microliters of undiluted folin-ciocalteu reagent, and allow them to react for three minutes. Next, add 100 microliters of 7.5%sodium carbonate solution to the mixture in each well of a 96 well plate. Prepare different concentrations for the gallic acid standard concentration range by diluting with distilled water.
Mix them with 20 microliters of folin-ciocalteu reagent, and allow them to react for three minutes. Next, add 100 microliters of 7.5%sodium carbonate solution to the mixture in each well of a 96 well plate. Incubate the reaction for 30 minutes in the dark at room temperature.
On a microplate reader, measure the absorbance of the reaction mixture at 765 nanometers. Plot the standard calibration curve using the concentrations of the standard and absorbance at 765 nanometers. Express the results as milligrams of gallic acid equivalent per gram of the sample.
Aqueous 1, 2 hexanediol extraction yielded the highest total phenolic content and water extraction yielded the lowest. Aqueous 1, 2 hexanediol extraction yielded the highest total flavonoid content and aqueous isopentyldiol extraction yielded the lowest. Aqueous hexylene glycol extraction exhibited the highest DPPH assay value and aqueous ethanol extraction exhibited the lowest.
Aqueous pentylene glycol extraction resulted in the highest ABTS assay value and water extraction resulted in the lowest. Aqueous hexylene glycol extraction showed the highest FRAP value and water extraction showed the lowest.
