| Summary: | 碩士 === 中國醫藥大學 === 營養學系碩士班 === 102 === Bitter melon is vulnerable to pest damage in the planting process. Meanwhile, postharvest ripening of bitter melon in storage, transport and selling process can lead the vegetable to decay and to the loss of commercial value. Lycopene, which has biological activity to prevent cardiovascular disease and reduce the risk of prostate cancer, increases gradually in bitter melon in postharvest ripening as the color of fruit changes from deep green to yellow and the aril turns from white to dark red.
The experiment first obtained lycopene, the experiment material, by exploring different lycopene levels of ripening bitter melon. Ultrasonic extraction, reverse phase elution chromatography and supercritical anti-solvent (SAS) pulverization were employed to isolate and precipitate lycopene. Concentration of lycopene increased from 13.6% of the ultrasonic extract to 98.1% of the elution fraction by an ethanol to acetone ratio of 5 to 1. SAS method produced particulates containing 988.13 mg/g of lycopene with recovery of 98.38%. Effects of three SAS operating parameters on the precipitated amount, lycopene recovery, particle mean size and morphology of the precipitates were also obtained from experiments. The operating conditions were set at 8 to 12 MPa of pressure, 35 to 45 °C of temperature, 0.2 to 0.4 ml/min of feeding flow rate, 10 mg/mL of feeding concentration, 20 min of feeding time and 15 l/min of CO2 flow rate. The mean particle size decreased with increasing pressure and temperature. SAS pulverization of lycopene produced nano-sized particulates which have higher rate of dissolution in a simulated intestinal solution. Given the same operating condition of the SAS pulverization process, a co-precipitate of lycopene with lecithin, mixed by a lycopene to lecithin ratio of 4 to 1 and dissolved in the intestinal fluid containing 5 mg/ml tween 20, generated the highest dissolution rate of 87.5%. While a consistent sample which was dissolved into intestinal fluid without tween 20 only generated dissolution rate of 72.9%.
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