Studies On The Extraction, Separation And Determination Of Pectin And Biofavonoids In Grapefruit

Grapefruit is one of characteristic fruits in China, which is planted widely. In the past years, the sales have been in trouble with the increasing of yielding of grapefruit abruptly, and more than 20 percent mature grapefruit is too inferior to be edible. At the same time, the grapefruit peel takes up 45 percent of the whole fruit. People always discard the inferior grapefruit or peel in the rivers or lakes in the past, which results in the waste and pollution. The grapefruit peel consists of many components, including pectin, biofavonoids and essential oil, which are used widely in the medicine, food, and chemical engineering. In this paper, the process of separation pectin and biofavonoids from grapefruit peel is developed based on the modern technology of extraction and separation.The research is composed of three main parts:(1). ARP-HPLC method is established for simultaneous determination of naringin and hesperidin in the grapefruit peel after constitutes of flow phase, acidity, flow speed and quantity of injected sample are studied. The method is rapid, accurate and reliable. Simultaneously, spectrophotoetric determination of pectin and biofavonoids is established. Those methods can be used to determine the content of naringin, pectin and biofavonoids in the peel or the extraction in those ranges of linear line.(2) The process of extraction, discoloring, separation of pectin is studied in detail. Due to the factors such as acidity, temperature, time, ratio of the liquid to solid, which will affect the yielding of pectin, the experiments of the single factor and orthogonal experiments are carried out. The result shows that the acidity is the main factor influencing the yield. So pH of the extraction solvent should be maintained to the range of 1 and 2. The optimum parameters of extraction is gained ,which is acidity pH1~2,temperature 100 C,time 100min,the ratio of liquid to solid 20:1.In the process of discoloring, the technology is developed using the macro porous resin as the sorbent. And the factors such as the type ofresin, acidity, temperature of discoloring are studied. The quantitative relation among quantity of resin, volume of pectin solution and absorptivity of pigment is established.In the process of precipitation of pectin, the ethanol-precipitation method is adopted. The acidity, content of precipitator, content of pectin solution and time of precipitation are discussed. Spray drying method is compared to ethanol-precipitation.(3 ) In order to make use of grapefruit peel and optimize the process of pectin , preparation of biofavonoids is researched. The factors such as temperature, content of ethanol, which influence the extraction of biofavonoids, are studied by experiments of single factor and orthogonal experiments. The optimum terms of extraction are gained. Then solution of extraction is discolored by extraction method and the biofavonoids are enriched and separated using the macro porous resin. The result showed that the adsorption isotherm could be described with the Langmuir isotherms equation. The static maximum adsorbing capacity for biofavonoids is 32.6 mg mg-1 while the concentration is 2.7 mg mL-1.The dynamic adsorbing capacity for biofavonoids is 23.8 mg 'mg-1 when the flow velocity is 2BV 'h-1.The optimal eluting solvent is 60% EtOH-H2O with pHlO. The eluting ratio overpass 85% when the flow speed is (1 ~2 ) BV h-1.The study will be a new way and a new idea for grapefruit exploiting.