Response Surface Optimization of Water Extraction Technology of Loquat Leaves Extract by Microwave-coupled Laccase

The dried and crushed leaves of loquat were used as raw materials, and the loquat leaves was extracted with water by using an atmospheric pressure microwave reaction synthesis device coupled with enzyme(laccase) (microwave irradiation-enzyme coupling catalysis, MIECC). Under the condition that the amount of laccase(2×10⁴ U/g) was 2%, the effects of microwave power, microwave temperature, microwave time and water-to-material ratio on the yield of loquat leaves extract were studied, the response surface method was used to optimize, and the results showed that: The optimum extraction conditions were microwave power of 530 W, microwave temperature of 54℃, microwave time of 20 min, water-to-material ratio of 22:1 (mL/g), the extract was concentrated in vacuum and dried, and the yield of loquat leaves extract was 30.84%±0.47%.Scanning electron microscope results showed that the microwave-coupled enzymatic method had the greatest damage to the tissue structure of the leaves, and the leaching rate of the active ingredient of the leaves could be effectively improved. Infrared spectroscopy results showed that the triterpenoids in the extract may be ursane type or oleanane type, the extract could be used as a concentrated product raw material for functional food development.