Propolis is a natural resinous substance produced by honeybees that has become very popular in recent years due to its medicinal properties. It possesses antimicrobial, anti-inflammatory, and antioxidant properties, making it a highly sought-after ingredient in the food and pharmaceutical industries. Propolis can be extracted from beehives using various methods, including solvent extraction, supercritical fluid extraction (SFE), microwave-assisted extraction (MAE), and ultrasound-assisted extraction (UAE). In this article, we will compare and contrast these four methods based on their efficiency, safety, and environmental impact.
Solvent Extraction
This is the traditional method of propolis extraction, which involves the use of organic solvents such as ethanol, methanol, and chloroform to dissolve the resin. The solvent is added to the propolis in a ratio of 5-10:1 (solvent:propolis), and the mixture is heated, stirred, and filtered to obtain a propolis extract. The extract is then concentrated and dried to remove the solvent.
Solvent extraction has several advantages, including its simplicity, low cost, and high extraction yield. However, it also has several drawbacks, including the use of toxic solvents, which can be harmful to human health and the environment. In addition, the extraction process is time-consuming and labor-intensive, requiring several steps to obtain a pure propolis extract.
Supercritical Fluid Extraction
Supercritical fluid extraction (SFE) is a modern extraction method that uses supercritical fluids such as carbon dioxide (CO2) to extract propolis. In this method, the propolis is placed in a vessel, and CO2 is applied under high pressure to extract the resin. The extracted resin is then collected, and the CO2 is recycled.
SFE has several advantages over solvent extraction, including its high efficiency, cost-effectiveness, and safety. It does not require the use of toxic solvents, and the extracted resin is of high quality. However, it also has some limitations, including the need for high-pressure equipment and the possibility of extracting unwanted compounds if the pressure is too high.
Microwave-Assisted Extraction
Microwave-assisted extraction (MAE) is another modern method of propolis extraction that uses microwaves to extract the resin. In this method, the propolis is mixed with a solvent in a vessel, and the mixture is then exposed to microwave radiation. The heat generated by the microwaves causes the resin to dissolve in the solvent, and the extract is collected and purified.
MAE has several advantages, including its high speed, low cost, and high extraction yield. It is also safe and environmentally friendly, as it does not require the use of toxic solvents. However, it also has some limitations, including the need for specialized microwave equipment and the possibility of overheating the mixture, which can result in the degradation of the extracted resin.
Ultrasound-Assisted Extraction
Ultrasound-assisted extraction (UAE) is a novel method of propolis extraction that uses high-frequency ultrasound waves to extract the resin. In this method, the propolis is mixed with a solvent in a vessel, and the mixture is then exposed to ultrasound waves. The waves generate cavitation bubbles in the mixture, which cause the resin to be released from the propolis and dissolve in the solvent. The extract is then collected and purified.
UAE has several advantages over other extraction methods, including its high efficiency, low cost, and high extraction yield. It is also safe and environmentally friendly, as it does not require the use of toxic solvents. However, it also has some limitations, including the need for specialized equipment and the possibility of overheating the mixture, which can result in the degradation of the extracted resin.
Comparison of Methods
The four methods of propolis extraction have their advantages and limitations, as summarized in Table 1. Solvent extraction has the highest yield, but it is also the most time-consuming and requires the use of toxic solvents. SFE is the most efficient and safe method, but it requires specialized equipment. MAE is fast and cost-effective, but it requires specialized equipment and can result in the degradation of the extracted resin. UAE is also fast and cost-effective, with the added advantage of not requiring toxic solvents, but it also requires specialized equipment.
Comparison of propolis extraction methods
| Method | Advantages | Limitations |
|---|---|---|
| Solvent Extraction | High yield | Toxic solvents; time-consuming |
| Supercritical Fluid Extraction | Efficient; safe; high-quality extract | High-pressure equipment; possibility of extracting unwanted compounds |
| Microwave-Assisted Extraction | Fast; low cost; high yield | Specialized equipment; possibility of overheating/extract degradation |
| Ultrasound-Assisted Extraction | Fast; low cost; high yield; environmentally friendly | Specialized equipment; possibility of overheating/extract degradation |
In conclusion, the method of propolis extraction used depends on the specific application and the availability of equipment and resources. While solvent extraction remains the most widely used method due to its simplicity and low cost, it is important to consider the potential health and environmental risks associated with toxic solvents. Supercritical fluid extraction is a promising alternative that offers high efficiency, safety, and quality of the extracted resin. However, the cost of specialized equipment may be a limiting factor.
Microwave-assisted extraction and ultrasound-assisted extraction are both fast and cost-effective methods that do not require toxic solvents, making them environmentally friendly alternatives. However, they do require specialized equipment and have the potential to overheat the mixture, which can impact the quality of the extracted resin.
In conclusion, the optimization method for propolis extraction depends on several factors, including efficiency, safety, cost, and environmental impact. Each method has its advantages and limitations, and it is important to carefully assess each option before selecting the most appropriate one for a particular application. Table 2 below provides a summary of the key factors to consider when selecting a propolis extraction method.
Key factors to consider when selecting a propolis extraction method
| Factor | Importance | Method |
|---|---|---|
| Efficiency | High | Supercritical fluid extraction |
| Safety | High | Supercritical fluid extraction, ultrasound-assisted extraction, microwave-assisted extraction |
| Cost | Low | Solvent extraction, microwave-assisted extraction, ultrasound-assisted extraction |
| Environmental impact | Low | Supercritical fluid extraction, ultrasound-assisted extraction, microwave-assisted extraction |
Overall, the choice of propolis extraction method is a crucial factor in ensuring the quality and safety of the final product. While each method has its unique advantages and limitations, it is important to consider the specific requirements of the application and weigh the tradeoffs carefully. With the increasing demand for natural and sustainable ingredients, it is likely that more research will be done to develop new and innovative extraction methods in the future.
Propolis CO2 Extraction Process
Laboratory equipment: L-01 small co2 extraction machine
- Pulverization degree:60 mesh
- Extraction pressure: 30 MPa
- Extraction temperature: 50°C
- Separation pressure I: 14 MPa
- Separation I temperature: 45°C
- Separation pressure II: 8 MPa
- Separation II temperature: 40°C
- Extraction time: 90 min
Two extraction methods of propolis
Ethanol extraction
Propolis raw materials → impurity removal → freezing, crushing → 95% ethanol solution soaking for 60 minutes → filtering → drying → alcohol extraction of propolis
CO2 extraction method
Propolis raw material→freezing, crushing→supercritical CO2 extraction→separation of supercritical CO2 extract→CO2 raffinate (residue)→supercritical CO2+ethanol (entrainer) extraction→extract evaporating ethanol→supercritical CO2+ethanol extract
CO2 extraction process vs. ethanol
In terms of yield, traditional ethanol extraction has the highest yield, supercritical CO2+alcohol extraction is the second, and supercritical CO2 is the lowest;
The content of total flavonoids, the main bioactive components of propolis, is the highest in supercritical CO2 + alcohol extraction, followed by traditional ethanol extraction, and supercritical CO2 is the lowest.
If only the total flavonoid content is used as the quality comparison, the propolis obtained by the supercritical CO2 + alcohol extraction process has the optimization quality.
Further reading
Propolis
Propolis is a resin collected by bees from plant spores and tree trunks, mixed with bee mandibular gland secretions and beeswax to form an aromatic viscous gel-like isoform.
Its chemical composition is complex, containing phenols, acids, alcohols, esters, phenols, ethers, terpenes, enes, sterols, and many trace elements.
Research of propolis
In recent years, a large number of studies done by domestic and foreign scholars have shown that propolis has important physiological effects in the treatment of cardiovascular, diabetes, skin diseases, gastrointestinal diseases, anti-cancer, immune enhancement, antibacterial and anti-inflammatory, etc.
So it is used in modern medicine and health food research fields. Get more and more research and application.
CO2 extraction process
The supercritical co2 extraction process has developed rapidly in recent decades.
In the pharmaceutical and food industries, the supercritical co2 extraction process is mainly used for the extraction of active ingredients of Chinese herbal medicines, including volatile oils, alkaloids, glycosides, coumarins, and terpenes.
Because of its low critical temperature and low critical pressure (31.0℃, 7.39MPa), carbon dioxide has a strong affinity for medium and low molecular weight and non-polar natural products and is colorless, odorless, non-toxic, non-flammable, and non-explosive, Low expansion, low viscosity, low surface tension, easy separation, low price, easy to produce high-purity gas and other characteristics, is the most widely used supercritical fluid.
Study on Extraction Process of Propolis
The three methods of ethanol extraction, supercritical CO2, and supercritical CO2+ethanol (entrainer) extraction are used to extract and separate the crude propolis raw materials produced in Nileke County, Yili Prefecture, Xinjiang.
The yield of propolis extract is the highest among propolis. An important biologically active ingredient is total flavonoid content.
A preliminary comparative study of the three processes is carried out to provide a basic basis for the in-depth study of propolis refining processes.
Three extraction processes of supercritical CO2, supercritical CO2+ethanol, and ethanol extraction were used to extract and separate crude propolis.
The three processes were compared and analyzed from the yield and the total flavonoid content in the extract.
The results showed that: in terms of yield, the ethanol extraction method was 54%, the supercritical CO2+ alcohol extraction method was 35.46%, and the supercritical CO2 method was 18%; in terms of the total flavonoid content, the supercritical CO2 + alcohol extraction method was 28.46%, ethanol The extraction method is 17.13%, and the supercritical CO2 method is 8.02%.
The extraction method of propolis
Propolis is a purely natural substance with both plant and animal properties. The source of propolis determines that its chemical composition mainly depends on the source tree species, and the source tree species are affected by environmental factors such as geographic location, climate, season, and vegetation.
Therefore, the production of propolis in different regions will inevitably lead to different chemical compositions of propolis, and different extraction processes will inevitably affect the quality of propolis.
Supercritical CO2 extraction method
The raw materials of propolis were pulverized after impurity removal and freezing. 45g of the pulverized propolis samples were accurately weighed and extracted under medium CO2 flow rate, extraction pressure 30MPa, extraction temperature 50°C, extraction time 90min, and two parallel experiments. The following processes are two experiments, and the average yield is taken.
Ethanol extraction
Propolis raw materials → impurity removal → freezing, crushing → 95% ethanol solution soaking for 60 minutes → filtering → drying → alcohol extraction of propolis
Supercritical CO2+ethanol extract
Propolis raw material→freezing, crushing→supercritical CO2 extraction→separation of supercritical CO2 extract→CO2 raffinate (residue)→supercritical CO2+ethanol (entrainer) extraction→extract evaporating ethanol→supercritical CO2+ethanol extract
Determination of Propolis Yield
Weigh 45g of propolis and propolis CO2 extracts, and experiment under three different process conditions: supercritical extraction, ethanol extraction, and supercritical CO2+ethanol extraction, and accurately weigh the extracts to calculate the yield.
Experimental results of propolis supercritical method
According to the optimization industrial production process conditions of propolis by supercritical CO2 method, under laboratory conditions, the yield of propolis extracted by the supercritical CO2 extraction method is 18% and the flavonoid content is 8.02%, which is different from that reported in the literature. It may be the raw material of propolis. The source is different.
Experimental results of ethanol extract of propolis
According to the ratio of propolis sample to solvent ethanol is 1:3, parallel test twice, soaking, filtering, drying, and weighing, the average yield of extract obtained by this method is 54%, and the flavonoid content of propolis is 17.13%. Compared with the supercritical CO2 method, the yield and flavonoid content are improved.
Propolis Supercritical CO2+Alcohol Extraction Test Results
Through the experimental study of different ratios of supercritical CO2 + ethanol entrainer, it is found that with the increase of the ratio of ethanol entrainer, the extraction yield obviously increases.
Under the optimization experimental conditions of this experiment, the yield is 35.46%, which is higher than the supercritical CO2 extraction process, but it is lower than the ethanol extraction method. The flavonoid content is 28.46%, which is the highest among the three methods.