Study On Extraction,structural Characterization And In Vitro Fermentation Of Insoluble Dietary Fiber From Rosa Roxburghii Tratt Fruit

In the present study,the insoluble dietary fiber of Rosa roxburghii Tratt pomace(RI)was extractied,and modified,and the physicochemical,structural and in vitro fermentation characteristics of insoluble dietary fiber(IDF)were measured.The results will be helpful to provide a theoretical basis for the development of health products with high RI content.The main results are as follows:Ultrasonic assisted water extraction method was used to isolate the RI,and the extraction process was optimized by response surface analysis.The RI yield was taken as the response value,and the optimal extraction condition was 184 W of ultrasonic power,14.7 min of ultrasonic time is,49.5℃of ultrasonic temperature is and 1:16.25(g/m L)solid-liquid ratio.Under this condition,the maximum yield of RI was 76.00%.Then the basic chemical components of Rosa roxburghii Tratt fruit pomace(R)and RI were quantitatively detected.Ultrasonic assisted water extraction method improved the purity of IDF,and the main components were cellulose,hemicellulose,lignin and pectin.RI was modified by high pressure(10 MPa,50 MPa,90 MPa)homogenization and three samples with different high pressures were obtained:HPRI-10,HPRI-50 and HPRI-90.The particle size analysis and specific surface area results showed that high-pressure homogeneous treatment reduced the particle size and increased the specific surface area of RI.Scanning electron microscopy(SEM)analysis indiacted that R and RI samples showed granular shapes with intact structure,whereas HPRI-10,HPRI-50 and HPRI-90 had a flaky appearance and fiber structure became looser with the increase of homogeneous pressure.Furthermore,Fourier-transform infrared spectrometry(FTIR)and X-ray diffractometry(XRD)results showed that the structure and crystallinity remained unchanged after high-pressure homogenization.Derivative thermogravimetry(DTG)showed these five samples showed a significant peak at 345~oC with a rapid weight loss rate.The peak values of RI,HPRI-10,HPRI-50 and HPRI-90 were greater than R,and the pyrolysis temperature was higher..Thermogravimetry(TG)showed that R,RI and high-pressure homogenized modified IDF were suitable for processing below 300℃.In addition,the water holding capacity(WHC),oil holding capacity(OHC)and swelling power(SW)were enhanced for all samples,and the HPRI-90 sample had the largest augmentation,indicating that high-pressure homogenization treatment played a critical role in the improvement of the physiochemical properties of the dietary fiber of Rosa roxburghii Tratt fruit pomace.In vitro fermentation characteristics were studied with R,RI and HPRI-90 as subsubstances,FOS and carbohydrate free as positive and negative controls respectively,and the content of gas and short-chain fatty acid(SCFAs)was detected at different fermentation time points(0,4,8,12 and 24 h).Compared with FOS,the amount of gas produced by in vitro fermentation of R,RI and HPRI-90 decreased at each time point,and the gas production rate was relatively slow.The gas production rate of R fermentation was higher than that of RI and HPRI-90.By using 16S r RNA gene sequencing technology to analyze the intestinal microbial composition after fermentation for 24 h,it was found that R,RI and HPRI-90groups significantly reduced the ratio of Firmicides to Bacteroides,and RI and HPRI-90groups promoted the growth and reproduction of Bacteroides and Faprococcus.