| Pomegranate is one of the most widely cultivated local specialty fruits in China.The peel of it,accounting for about 30%of the total weight,is rich in a variety of natural active ingredients.Dietary fiber is one of the essential nutrients to keep a balanced diet.It is not only benefit for keeping intestinal health,maintaining blood glucose balance,reducing blood lipids and cholesterol,but also can control weight,prevent against colon cancer,diabetes and coronary heart disease etc..Studies on dietary fiber in pomegranate peel have not been reported.In this dissertation,the extraction steps,physicochemical properties,hypolipidemic activity in vitro of PPIDF were studied.And a functional chewable tablets were developed based on the mentioned above work.The main contents are included as follows:(1)Alkali extraction was used to extract insoluble dietary fiber from the pomegranate peel.The concentration of NaOH solution,material ratio,extraction time and temperature were selected for single factor experiments.The optimal extraction conditions were chosen by using response surface methodology.The results are as follows:The concentration of NaOH 6%,ratio of liquid to solid 24.4(mL/g),extraction time 51 min and temperature 60 ?.The extraction yield was 30.42±0.32%(n=3)under the obtained conditions,which was 0.39%of the prediction error of the model.The water holding capacity and swelling power of PPIDF were 4.84 g/g and 3.99 mL/g respectively,which indicated that it was a kind of dietary fiber with relatively high activity.(2)The extracted PPIDF was used as raw material to study hypolipidemic activity in vitro by simulating the gastrointestinal environment.The adsorption of oil is expressed by the adsorption of soybean oil,the result was 1.32 g/g.PPIDF can reduce fat by combining with cholesterol micelle to form sediment.When the dosage is 150 mg,the binding capacity reaches the maximum,which is 4.44 mg/g.The kinetic curves of PPIDF to bile salts adsorption indicated that 60 min is the most suitable time for cholate adsorption.And the binding rates and combining quantity of PPIDF to sodium glycocholate and sodium taurocholate were 36.58%,1.4269 mg/g and 46.27%,1.9903 mg/g,respectively.The adsorption capacity of sodium taurocholate and sodium glycocholate was 2.8175 mg/g and 2.5356 mg/g during the optimal addition amount(180 mg)of PPIDF.Freeundlich isotherm equation was used to describe the binding behavior of PPIDF to cholate(180 mg,60 min),it shows that PPIDF adsorption of choleate is not the main mechanism of its lipid lowering.Half inhibition of quantity(IC50 ? 275.42 mg)was obtained by the equation of PPIDF to inhibitory effect of pancreatic lipase.It was found that PPIDF reacted with the substrate emulsion firstly,which obstructed the interaction of substrate emulsion and pancreatic lipase,thus the activity of lipase was inhibited.Lineweaver-burk diagram showed that the inhibitory effect of PPIDF on pancreatic lipase was competitive inhibition.The hypolipidemic mechanism of PPIDF in vitro is mainly achieved by binding to cholesterol micelles to form precipitates and inhibit pancreatic lipase activity.(3)The PPIDF extracted by alkali was used as raw material to develop a functional chewable tablets with hypolipidemic activity.The optimized formula is as follows:35%of dietary fiber,26%of flavoring agent,20%of maltodextrin,15%of xanthan gum,1%of magnesium stearate,50%concentration of edible alcohol.The average weight and hardness of chewable tablets were 0.6305 g and 8.7095 kg,which having moderate hardness,smooth surface,uniform color,sweet and sour taste. |
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