Preparation Of Dietary Fiber From Pomegranate Marcs (Seed) And Its Antiobesity Function

In this paper,the process conditions of ultrasonic extraction and alkaline modification of dietary fiber were optimized in pomegranate marcs(seed)(PMs).The chemical composition,physicochemical properties and structural properties of PMs,extracted dietary fiber(EDF)and modified dietary fiber(MDF)were evaluated.The method of evaluating the lipid-lowering effects of PMs,EDF and MDF on caenorhabditis elegans(C.elegans)was established.The experiment may provide theoretical basis and technical support for the comprehensive development and utilization of PMs.The main research contents and results were as follows:1.In the single experiments,the ratio of liquid-solid(RLS),ultrasonic temperature(UT),ultrasonic time(Ut),and ultrasonic power(UP)had significant effects on total dietary fiber(TDF)content of PMs.The extraction conditions were optimized by response surface methodology(RSM)were RLS of 36:1,UT of 50 ℃,Ut of 10 min,and UP of 500 W.Under these conditions,the TDF content in EDF was 58.99%.2.The study of alkaline modification of EDF showed that NaOH concentration,RLS,modification time and modification temperature had significant effects on the yield of soluble dietary fiber(SDF).On the basis of single-factor tests,the modified conditions of EDF optimized by RSM were as follows: NaOH concentration was 1.5%,RLS was 38.5:1,modification time was 45 min,modification temperature was 45 °C.Under these conditions,the SDF yield reached 73.58 %.3.The chemical composition analysis of PMs,EDF and MDF showed that compared with PMs,the fat and protein contents in EDF decreased by 1.90 % and 1.18 %,while the contents in MDF decreased by 5.08 % and 4.69 %,respectively.The contents of TDF and SDF in EDF increased by 12.99 % and 11.18 %.The contents of TDF and SDF in MDF increased by 17.93 % and 12.80 %.The contents of other monosaccharides in EDF and MDF decreased to certain extent except for xylose.In the mineral elements,the content of Na increased significantly,while the content of K decreased.The composition of amino acids in PMs,EDF,and MDF was basically the same.The contents of total amino acids and essential amino acids in EDF decreased by 82.29 % and 92.24 %,respectively,while the contents of total amino acids and essential amino acids in MDF decreased by 69.30 % and 63.75 %,respectively.These results showed that EDF and MDF with higher purity and SDF content can be obtained after extraction and modification.4.The physicochemical properties of PMs,EDF,and MDF showed that the water holding capacity,swelling capacity,and oil holding capacity of EDF increased by 15.61 %、365.85 % and 52.52 %,while MDF increased by 33.24 %、374.39 % and 155.40 % compared to PMs.The water holding capacity,swelling capacity,and oil holding capacity of MDF increased by 15.25 %、1.83 % and 67.45 %,respectively,compared with EDF.These results indicated that the modification was beneficial to improve the physicochemical properties of dietary fiber.5.The accumulation density of PMs,EDF and MDF were 2.17、1.67 and 1.98 g/mL respectively.It was indicated that the surface structure of EDF and MDF were looser than that of PMs,consistented with the results of scanning electron microscope.The infrared spectrum analysis showed that more hydrophilic groups were exposed in EDF and MDF than that of PMs,resulting in absorbing more water.It was consistented with the results of thermal stability analysis,which showed that more bound water were lost in the EDF and MDF during heating process.These results showed that the hydration properties of EDF and MDF were improved.6.PMs,EDF and MDF were added into the NGM culture medium by determining the content of fatty acid triglyceride in C.elegans for evaluating their lipid-lowering fuctions.The results showed that the contents of fatty acid triglyceride in BX160 C.elegans were no significantly reduced by PMs,EDF and MDF,while the contents of fatty acid triglyceride in wild C.elegans was significantly decreased.The lipid-lowering fuctions of EDF and MDF were better than that of PMs.Moreover,MDF had the higher lipid-lowering fuction compared with that of EDF.For example,0.2 mg/mL of PMs,EDF,and MDF could reduce fatty acid triglycerides in the wild-type nematode by 8.97 %,29.66 %,and 71.72 %,respectively.