extraction of phenolic compounds and natural antioxidants from coffee silverskin using the polyol-based microwave-assisted extraction method

Polyol-Based Microwave-Assisted Extraction for Phenolic and Antioxidant Yields

Nowadays, there is a global trend towards environmental awareness in the beauty industry, leading manufacturers to focus on green technology for extracting plant components using sustainable alternatives1. Typically, traditional solvents such as ethanol, methanol, and hexane are used to extract plant phenolic components and natural antioxidants2. Nevertheless, the presence of solvent residues within plant extracts poses a potential risk to human health, inducing skin and eye irritation3, particularly concerning their intended application in cosmetics. Consequently, it is challenging to eliminate such solvent residues from the extracts, a process that demands considerable investment in time, energy, and human resources4. Recently, superheated water, ionic liquids, deep eutectic solvents, and bio-derived solvents have emerged as promising approaches for green solvent extraction5. However, their use is still limited by product separation in aqueous-based processes. To address these challenges, the development of ready-to-use extracts emerges as a viable solution6.
Polyols are often used in cosmetic formulations as humectants because of their good polarity and ability to retain moisture from the environment7. In addition, polyols such as glycerin, propylene glycol, butylene glycol, methylpropanediol, isopentyldiol, pentylene glycol, 1,2-hexanediol, and hexylene glycol can be utilized for plant extractions. They are considered non-toxic, biodegradable, environmentally friendly, non-reactive, and safe solvents for use in plant extraction8. Additionally, polyols can withstand the heat generated during microwave-assisted extraction (MAE) due to their elevated boiling points and polarity9. These polyols are generally recognized as safe (GRAS) chemicals by the United States Food and Drug Administration (FDA). Unlike conventional solvents such as ethanol or methanol, which may require rigorous removal from the extract due to their potentially harmful effects, polyols offer the advantage of minimizing the energy, time, and costs associated with solvent removal processes10. This not only streamlines the extraction process but also enhances the overall efficiency and sustainability of the extraction method. Previous investigations have employed polyols such as propylene glycol and butylene glycol as solvents in the extraction of bioactive compounds from Camellia sinensis flowers10 and coffee pulp11, revealing significant potential for their role as sustainable alternative solvents in the plant extraction process. Thus, the continued development and optimization of a polyols-water solvent system holds the potential for significant advancements in green chemistry and sustainable industrial practices.
Generally, bioactive compounds found in plants are synthesized as secondary metabolites. These compounds can be categorized into three primary groups: terpenes and terpenoids, alkaloids, and phenolic compounds12. Various extraction methods are utilized under different conditions to isolate specific bioactive compounds from plants. Bioactive compounds from plant materials can be extracted using either conventional or non-conventional techniques. Traditional methods include maceration, reflux extraction, and hydro-distillation, while non-conventional methods consist of ultrasound-assisted extraction, enzyme-assisted extraction, microwave-assisted extraction (MAE), pulsed electric field-assisted extraction, supercritical fluid extraction, and pressurized liquid extraction13. These non-conventional methods are designed to enhance safety by utilizing safer solvents and auxiliaries, improving energy efficiency, preventing degradation of the bioactive components, and reducing environmental pollution14.
Furthermore, MAE is among the sophisticated green technologies for extracting bioactive compounds from plants. Conventional extraction procedures require significant amounts of time, energy, and high temperatures, which over time might degrade heat-sensitive bioactive compounds13. In contrast to conventional thermal extractions, MAE facilitates the extraction of bioactive compounds by generating localized heating within the sample, disrupting cell structures, and enhancing mass transfer, thereby increasing the efficiency of compound extraction. Heat is transferred from inside the plant cells by microwaves, which operate on the water molecules within the plant components13. Moreover, MAE has advanced to improve the extraction and separation of active compounds, increasing product yield, enhancing extraction efficiency, requiring fewer chemicals, and saving time and energy while preventing the destruction of bioactive compounds15.
This research focuses on the extraction of plant phenolic compounds and natural antioxidants through microwave-assisted extraction (MAE) using different types of polyols as solvents. The total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activities (DPPH, ABTS, and FRAP) of polyol-based MAE extracts are determined. Additionally, polyol-based MAE is compared with MAE using conventional solvents such as water and ethanol. This research is expected to contribute to the development of environmentally sustainable extraction technology for natural components, promoting sustainability by reducing reliance on hazardous chemicals, shortening processing times, and minimizing energy consumption in raw material production for potential applications within the cosmetics industry.

Author Spotlight: Eco-Friendly Extraction of Bioactive Compounds Using Polyol-Based Microwave-Assisted Techniques

Microwave-Assisted Extraction of Phenolic Compounds and Antioxidants for Cosmetic Applications Using Polyol-Based Technology

This research talks about finding eco-friendly ways to extract plant bioactive compounds. We are testing how well microwave assisted extraction with the polyol-based solvents work for extracting plants bioactive substances, especially phenol compounds. Additionally, exploring this method could lead to more efficient and effective extraction technique for the cosmetic industries.Today's cosmetic research is also about using green technology and green chemistry. Nonconventional extraction techniques such as microwave-assist extraction, and extraction, have been interestingly employed to extract plants bioactive compounds. However, organic solvents are still commonly utilized for bioactive component extraction.Using polyol-based solvent for microwave assistant extraction turned out to be more effective than using traditional solvent like water and ethanol. The results show that the plant extract obtained with polyol have higher level of phenolic content for the flavanoid content and antioxidant activity. Compared to those extracted with conventional solvent.Our procedure stands out because it is beneficial, environmentally friendly and safe for human health. It is also more energy efficient and cost effective than traditional processes, making it an excellent alternative for sustainable and simple production. Our finding show that polyols combined with unconventional extraction methods can extract phenol compounds.The next challenge is whether this extraction method can be used to extract other plant, secondary metabolized, and if it can be commercialized to extract bioactive compounds for cosmetic purposes.

Extraction of Phenolic Compounds and Natural Antioxidants from Coffee Silverskin Using the Polyol-Based Microwave-Assisted Extraction Method

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.

extraction-phenolic-compounds-natural-antioxidants-from-coffee

Research

JoVE Journal

Chemistry

The utilization of polyols as green solvents for extracting bioactive compounds from plant materials has gained attention due to their safety and inert behavior with plant bioactive chemicals. This study explores the sustainable extraction of phenolic compounds and natural antioxidants from coffee silverskin using the microwave-assisted extraction (MAE) method with polyol-based solvents: glycerin, propylene glycol (PG), butylene glycol (BG), methylpropanediol (MPD), isopentyldiol (IPD), pentylene glycol, 1,2-hexanediol, and hexylene glycol (HG). A comparative analysis was conducted on conventional and non-conventional solvent extractions, focusing on their impact on the bioactive compounds of MAE, encompassing parameters such as total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activities like the 1,1-diphenyl-2-picrylhydrazyl radical scavenging assay (DPPH), the 2,2&#8242;-azino-bis(-3-ethylbenzothiazoline-6-sulphonic acid) radical scavenging assay (ABTS), and the ferric reducing antioxidant power assay (FRAP). The highest values were observed for TPC with aqueous-1,2-hexanediol extraction (52.0 &#177; 3.0 mg GAE/g sample), TFC with aqueous-1,2-hexanediol extraction (20.0 &#177; 1.7 mg QE/g sample), DPPH with aqueous-HG&#160;extraction (13.6 &#177; 0.3 mg TE/g sample), ABTS with aqueous-pentylene glycol extraction (8.2 &#177; 0.1 mg TE/g sample), and FRAP with aqueous-HG extraction (21.1 &#177; 1.3 mg Fe (II) E/g sample). This research aims to advance eco-friendly extraction technology through natural plant components, promoting sustainability by minimizing hazardous chemical use while reducing time and energy consumption, with potential applications in cosmetics.

This protocol details the utilization of a polyol-based microwave-assisted extraction method for extracting phenolic compounds and natural antioxidants, representing a practical and environmentally sustainable approach to the development of ready-to-use extracts.

The utilization of polyols as green solvents for extracting bioactive compounds from plant materials has gained attention due to their safety and inert ...