| Microwave-assisted extraction is a promising extraction method by coupling the microwave heating with chemical extraction technique. Recently, MAE has been widely employed for the extraction of compounds from various parts of plants because it decreases the extraction time, improves the extraction efficiency and selectivity, and reduces the amount of energy and solvent discharged into the surroundings. Microwave extraction has high purity and quality, and effectively preserves the functional ingredients of foods, medicines and other chemicals. The main results are as follows:1. Microwave-assisted extraction of polyphenols from teaThis study demonstrated a promising method for quickly extracting tea polyphenol (TP) by microwave-assisted extraction technology. Some influential parameters, including MAE temperature, microwave power, concentration of extraction solvent, MAE time and the solid/liquid ratio, were investigated. The optimum condition of MAE was obtained by dual extraction with 60% ethanol (v/v) and the solid/liquid ratio 1:12 g/mL at 80℃for 10 minutes under the microwave power 600 W. The yield of TP was 96.5% under the described condition. Compared with the hot reflux extraction, the extraction time was saved 3 times, the energy consumption was one fourth that of UAE and the yield of TP was increased by 17.5%.2. Microwave-assisted extraction of flavonoids from radix puerariaMicrowave-assisted extraction method was adopted for extracting the effective ingredient-flavonoids from radix pueraria. Several factors, such as the MAE temperature, microwave power, concentration of extraction solvent, MAE time and the solid/liquid ratio, were investigated by using HPLC and UV methods. The optimum condition of MAE was obtained by 60% ethanol water solvent and the solid/liquid ratios 1:20 g/mL at 80℃for 15 minutes under the microwave power 400W. The extraction percentage of flavonoids was 96% under the described condition and puerarin was 99%. Compared with the hot reflux extraction, the extraction time was saved 2 times, the energy consumption was one third that of UAE and the yield of flavonoids was increased by 17%. The preliminary extract technology of flavonoids from radix pueraria was established in our study.3. Microwave-assisted extraction of RKX using a high efficient continuous dynamic countercurrent pilot-scale extraction machineRKX was extracted by a high efficient continuous dynamic countercurrent pilot-scale extraction machine. The microwave countercurrent organically combines microwave and traditional countercurrent extraction equipment, can safely run for a long time without break and the maintenance is easy. RKX water extract and RKX ethanol extract prepared according to conventional technology and RKX laboratory-scale test were tested by the HPLC fingerprint chromatogram method.8 main common peaks in water extract and 3 main common peaks in ethanol extract were selected and signed. The area range of these common peaks was calculated. According to fingerprint chromatogram obtained by conventional technology, the feasibility of using MAE to extract RKX was tested. The results showed that the main common peaks area were within the range when MAE process for water extract and ethanol extract were carrying out under 85℃for 14 minutes with power of 39 kW and solid/liquid ratio 1:14, and 70℃for 4 minutes with power of 39 kW and solid/liquid ratio 1:8, respectively.4. Microwave-assisted extraction of TanshinoneⅡA from the residue of Salvia miltiorrhiza bunge using a high efficient continuous dynamic countercurrent pilot-scale extraction machineAccording to conventional technology and laboratory-scale test, TanshinoneⅡA was extracted from the residue of Salvia miltiorrhiza bunge by a high efficient continuous dynamic countercurrent pilot-scale extraction machine. The optimum condition of MAE was obtained with 80% ethanol (v/v) and the solid/liquid ratios 1:9 (g/mL) at 70℃for 4 minutes under the microwave power 39kW. The yield of tanshinoneⅡA was 0.68%.
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