To understand the practical value and efficacy of plant essential oils through information review and collection. Collect the effective methods of extracting essential oils in industry and laboratory, choose the most suitable experimental method to make an experimental plan and implement it. According to the results of the experiment to adjust the experimental program, summarize the experience, improve, and carry out the second experiment. Finally, the results of the two experiments were analyzed and a conclusion was drawn about the best method for essential oil extraction. Keywords: essential oil, rose, water vapor, distillation, extraction, essential oils are the source of the fragrance of flowers, have medical benefits, and are also very expensive. After discussion, our group members thought that by collecting information about essential oil extraction, we could deepen our understanding of this extraction industry. By personally selecting and developing an experimental program, we can improve our scientific inquiry. The unpredictable changes brought by the experiment can make us feel the hard work of successful scientific experiments. Finally, we decided that the topic should be: the choice of extraction methods of plant essential oils and experimental investigation. After setting the topic of research study, we first collected information about the extraction methods of plant essential oils. The main extraction methods are: steam distillation, chemical solvent extraction, oil separation (liposuction), freezing compression (pressing), carbon dioxide extraction. This five methods have their own characteristics: water vapor distillation: the operation of the simplest, lower cost, is the most commonly used extraction methods. Chemical solvent (organic matter) extraction method: is a common extraction method for essential oils of flowers. Oleoresin Separation Method (Liposuction Method): is an expensive extraction method for flower essential oils. Freezing and compression method (pressing method): is specifically used to extract essential oils stored in the peel part of the fruit, such as citrus fruits. Carbon Dioxide Extraction: A very expensive method, the quality of the extracted oils is almost perfect and the price is very high. After considering the cost and difficulty of the experiment and combining with the existing experimental conditions of the school, we finally decided to choose the water vapor distillation and organic extraction method to extract essential oils. In the second step, we selected the experimental materials (plant species): among many plants (lemongrass, lavender, rosemary, geranium, tea tree, sandalwood, bergamot, eucalyptus, pine, rose, moonflower, peppermint, etc.), we finally selected rose petals as our experimental materials in terms of the price of the experimental materials, the difficulty of transportation and the prediction of the experimental effect. After the preparation of the experiment is ready, we began to experiment: After discussion, we decided to follow the textbook formulated the first experimental program: materials and appliances: extract, distilled water, alcohol, phenol, NaCl, catheter, conical flasks, distillation equipment, beakers, stoppers, fine glass tubes, thermometers, iron stand, mortar, alcohol lamps, glass rods, etc. Experimental procedures: as shown in the figure assembled the extraction equipment, the rose petals divided into two equal parts. After assembling the extraction equipment as shown in the figure, divide the rose petals equally into two groups (α, γ). The α group petals into the flask, add distilled water to 1/2 place and then light the alcohol lamp. When the water boils, the evaporated gas condenses at the condenser tube and flows out of the bullwheel tube into the conical flask. Collect the extract. Stop collection when about 20 ml of the extract has been collected. Extinguish the alcohol lamp. Divide the extract into 4 groups: a1,a2,a3,a4 in test tubes. Put a spoonful of NaCl in group a1, phenol in group a2, NaCl and phenol in group a3, and a4 as a control. The solution after boiling in the flask (yellow color) was filtered and collected into four equal groups b1,b2,b3,b4, with the same experimental steps as the previous counterparts. γ group petals crushed into a beaker, add ethanol, stir the petals with a glass rod in the ethanol solution, let stand, to be ethanol solution was stained rose color will be divided into 4 groups of solution r1, ,r4, the same experimental steps and group a. All test tubes covered with a rubber stopper, collected after filtration, divided into four equal groups b1, b2, b3, b4, the same experimental steps and corresponding to the former. All test tubes were covered with rubber plugs and sealed. Theoretical basis: After the essential oil is extracted, a turbid liquid will be formed, because the density is similar to the density of the solution, so it is not easy to precipitate. The purpose of adding NaCl is to increase the density of the solution so that the essential oils float in the upper layer of the liquid and can be separated using a split funnel to obtain the essential oils. Phenol and alcohol are added to purify the essential oils by utilizing their solubility in organic solvents. Experimental Note: Groups a and b are used to compare the content of essential oils in the experimental setup and to determine which part of the setup has the highest level of essential oils extracted from it. Horizontally, they are comparing the liquids in the same place in the apparatus to determine which method of extraction is more desirable. a2,b2,r4 can be used to compare the effect of alcohol and phenol solutions on the extraction of different loads of essential oils. Experimental results: after 1 week of resting , group a was in the same state as 1 week ago, without any phenomenon. Through the careful observation of group b, found that the bottom of group b3 there is a very small amount of flocculent precipitate, the other groups for the initial yellowish, but have a faint plant flavor. r1,r4 test tube floating in the upper layer of the film like an unidentified substance. There was a strong odor of alcohol when the mouth of the test tube was opened. Perhaps the aroma of the essential oils was diluted, we did not smell the aromatic odor. The result of the first experiment was quite unexpected. This almost declared the experiment a failure. We immediately began to check the problem, carefully analyzed each step of the possible flaws. There are four main points: 1, the flower petals added to the flask were not crushed, which may have an impact on the extraction of essential oils. The result is not obvious. 2, The essential oils were not dissolved in distilled water, resulting in a near-distilled solution after distillation. 3, alcohol odor is too strong, resulting in the aroma of essential oil substances can not be smelled. 4. It was not possible to extract and determine whether the "suspicious substance" was indeed rose essential oil. For the first experiment, we designed our own experimental program 2: Materials and appliances: extracts, alcohol, NaCl, catheter, conical flask, distillation equipment, stopper, thermometer, iron stand, water bath, mortar and so on Experimental steps: as shown in the figure assembled the extraction equipment, will be ground petals into the flask, add the wine exquisitely 1/2 place. Light the alcohol lamp and control the temperature of the alcohol at about 78 degrees Celsius. Collect 10 ml of distillate continuously. The distillate was divided into 2 groups: D1 and D2. D1 was placed in NaCl solution and D2 was the control group. Put the distillate into conical flasks and cover the mouths of the flasks with cling film, making small holes so that the alcohol can evaporate and the dust cannot get in easily. Note: In this experiment, we crushed the petals to avoid problem 1. Since the previous experiment has confirmed that essential oils do dissolve in alcohol (the color of the alcohol changes and a film-like substance is produced), we decided to distill the rose petals while extracting the organic solvents with alcohol, so that the alcohol vapors bring out the essential oils. The essential oils dissolved in alcohol thus avoiding problem 2. Since the boiling point of alcohol is 78 degrees Celsius, in order to avoid the consequences of the essential oils escaping from the bottle due to the high temperature of the liquid (higher than the boiling point of the essential oils) and not being able to be collected, we decided to control the temperature of the liquid at the boiling point of alcohol. This allows the essential oils and alcohol to be distilled "synergistically". For the final strong odor of alcohol and essential oil composition determination of the problem, we decided to use the volatile nature of alcohol to make the alcohol volatile to complete the final purification work. Experimental results and notes: from the conical bottle of liquid can be smelled obvious plant flavor. This indicates that the distillate already contains essential oils (a major breakthrough). After a week of resting found that there is no obvious difference between groups D, E. The liquid is transparent and colorless. There is a faint plant fragrance. As of today, the alcohol in groups D and E has not yet evaporated. No obvious signs of essential oil (flocculent precipitation). Summary of the two experiments: In the first experiment we designed the experimental program as described in the book. The problems of the first experiment were solved in the second self-designed experiment. The immediate effect was the extraction of a liquid with a strong aromatic odor (compared to the first experiment). Although we have not yet been able to use the oils we extracted, we have gained a lot more than 10 test tubes and 2 bottles of fragrant liquid. During the preparation, planning and execution of the two experiments of the research study, we gained a clear understanding of what a true inquiry experiment is all about. The main gains are as follows: We realized that books are not omnipotent: they are only limited to describing the general steps of the experiment, but many important details that are related to the success of the experiment are not detailed. The discoverers of these details were often those who had experienced the failure of the experiment themselves. The lesson we have learned is that we cannot blindly trust the knowledge taught in textbooks. Practice is the only test of truth. With the practical experience of scientific experiments: through the reproduction and improvement of textbook experiments, we designed and executed our own experimental programs. The results of the experiment were not shown to us until the last moment. It was like conducting a real scientific discovery experiment. We had never experienced such an independent inquiry-based experiment from start to finish before. We learned the hard way what it is like to be a real researcher. We experienced much more than just the pleasant aroma of essential oils ...... We learned that successful experimental results are not easy to come by: the members of the group invested a lot of time and energy in the design, implementation and analysis of the two experiments. But the results of the experiment were not so satisfactory. At the same time in the disappointment, calm down and think about it, the world and what major scientific and technological achievements with just two experiments can be successful? The development of science is a process of continuous discovery and improvement, the tears of failure are always accompanied by the smile of success. We want to get the success of the experiment only to continue to summarize the lessons learned, and constantly improve the program, after many failures, success can only be in our favor. And the spirit of persistence to the experiment is unshakeable. Conclusion: We have reached the expected goal of understanding the essential oil extraction industry, completed two experiments, from which we have gained practical experience that can not be obtained from books; from which we have experienced the discovery process of independent inquiry; from which we have learned the hard-won scientific results ...... reached the course objectives, and successfully completed the research study project of the first year of the senior academic year.
C4 plants or carbon four plants. Plants in which the initial product of CO2 assimilation is not the three-carbon compound 3-phosphoglyceric acid, which is part of the photosynthetic carbon cycle, but the four-carbon compounds malic acid or aspartic acid. Also known as C4 plants. Such as corn, sugarcane, etc. In contrast, plants whose initial product is 3-phosphoglyceric acid are called three-carbon plants (C3 plants). Many four-carbon plants have an anatomically specialized structure in which two different types of cells surround the vascular bundles: the inner layer of cells close to the vascular bundles are called sheath cells, and the outer layer of cells surrounding the sheath cells are the chloroplasts. Phosphoenolpyruvate (PEP) in the chloroplasts is combined with CO2 by the enzyme PEP carboxylase to form malate or aspartate. These four-carbon bicarboxylic acids are transferred to the sheath cells and release CO2 by the action of decarboxylase, the latter of which enters the photosynthetic carbon cycle by the action of ribulose bisphosphate (RuBP) carboxylase in the chloroplasts of the sheath cells. This metabolic pathway, in which a four-carbon bicarboxylic acid is formed from PEP and then decarboxylated to release CO2, is called the four-carbon pathway. About 800 species of four-carbon plants have been identified and are widely distributed in 18 different families of flowering plants. Most of them are of tropical origin. Because four-carbon plants can use the ATP produced under strong sunlight to promote the combination of PEP and CO2 to increase the photosynthetic rate under strong light and high temperature, they can partially shrink the stomatal aperture in drought to reduce transpiration water loss, and the degree of reduction in the photosynthetic rate will be relatively small, which improves the utilization rate of water in four-carbon plants. These characteristics have clear selective advantages in dry and hot regions. An important difference between C4 plants and C3 plants is that C4 plants have a very low CO2 compensation point, whereas C3 plants have a very high compensation point, so that C4 plants have a higher survival rate at low CO2 levels. C4 plants In the 1960s, Australian scientists Hatch and Slaughter discovered that tropical green plants such as corn and sugarcane, in addition to having the Calvin cycle like other green plants, have CO2 first fixed through a special pathway. This pathway is also known as the Hatch-Slake pathway. C4 plants are mainly those that live in the arid tropics. In such environments, plants that open their stomata for long periods of time to absorb carbon dioxide will result in too rapid a loss of water through transpiration. Therefore, plants can only open their stomata for short periods of time, and the amount of carbon dioxide intake is necessarily small. The plant must use this small amount of carbon dioxide for photosynthesis to synthesize the substances needed for its own growth. Around the vascular bundles of C4 plant leaves are surrounded by vascular sheaths that case by chloroplasts but do not have basidia or are poorly developed inside. Here, the Calvin cycle is mainly carried out. Its chloroplasts contain a unique enzyme, phosphoenolpyruvate carbon oxidase, which allows carbon dioxide to be assimilated first by a three-carbon compound, phosphoenolpyruvate, to form the four-carbon compound oxaloacetate, which is where the name of the type of dark reaction comes from. This oxaloacetate, after being converted to malate, enters the vascular sheaths, where it breaks down to release carbon dioxide and a molecule of glycerol. The carbon dioxide enters the Calvin cycle, followed by the C3 process. Glycerol is re-synthesized into phosphoenolpyruvate, a process that consumes ATP. The advantage of this type of plant is that CO2 fixation is much more efficient than in C3, which facilitates the growth of plants in arid environments. starch from photosynthesis in C3 plants is stored in the chloroplasts as this is the site of the Calvin cycle, whereas the vascular sheath cells do not contain chloroplasts. In C4 plants, the starch will be stored in the vascular sheath cells because this is where the Calvin cycle occurs in C4 plants. C4 type plants are: corn, corns, white amaranth, chard, cabbage