Study On Physicochemical Properties And Processing Of Potato Dietary Fiber

China has abundant resources of potato,the planting area and production rank first in the world.Especially since the Ministry of Agriculture proposed strategy potato staple food in January 2015,potatoes are raised to strategic positions.Potato is an important raw material for potato starch,which not only brings economic benefits but also produces a large amount of potato residue.Potato residue is rich in dietary fiber.In order to respond the potato staple food strategy positively,it is very important to improve the comprehensive utilization of potato residue.In this study,dietary fiber was extracted from dried potato residues from 6 varieties potato,using an enzymatic hydrolysis method.The chemical composition,physicochemical properties and microstructure of dried potato residue(DPR)and potato dietary fiber(PDF)were studied.The effects of microwave and atmospheric cooking treatment on PDF were also studied.The main results are as follows:There were significant differences in nutritional composition of different varieties of potato(P<0.05).The contents of dry materia were between 18.17 % and 29.99 %,starch were between 10.36 % and 21.02 %,vitamin C were between 8.59 mg/100 g and 12.47 mg/100 g and reducing sugar were low(<0.5%).The chemical composition of DPR from different varieties were significantly different(P<0.05).The contents of total dietary fiber(TDF)in Shepody and Black Rose were 43.16 % and 31.87 %,respectively.The highest yield of PDF was extracted from Shepody(62.19 %),and the lowest was White Rose(42.99 %),Black Rose was 51.27 %(ranked fourth).The WHC,OHC,SC and cholesterol absorption capacity of PDF were significantly higher than those of DPR(P<0.05),while the GAC and Pb2+ adsorption capacity of PDF were significantly lower than those of DPR(P<0.05).The structures of DPR were compact,while PDF became loose and folded after hydrolysis.There were many holes and the surface area were increased,so PDF can adsorb more substances.For Black Rose,the content of starch in dietary fiber was the lowest;the protein was 7.69 %,which significantly lower than that in the White Rose(P<0.05)and the cellulose was 21.30 %.There were no significant difference(P>0.05)between lignin in Black Rose and White Rose,which had the highest content of lignin.The content of pectin was significantly higher than that of other varieties(P<0.05).The WHC of PDF of Black Rose was 4.21 g/g,OHC was 1.46 g/g,SC was 7.87 mL/g and GAC was 9.47 mmol/g.The cholesterol adsorption capacity of PDF for Black Rose was 5.23 mg/g at pH 2,and pH 7 was 7.83 mg/g.The adsorption of PDF to Pb2+ was 0.4318 mg/g at pH 2,and was 0.4399 mg/g at pH 7.It can be seen that the physical and chemical properties of Black Rose PDF are in a good level in the 6 varieties,so Black Rose is a kind of potato resources suitable for extracting PDF.The contents of TDF,IDF and SDF in PDF were affected by microwave and atomospheric steam.The TDF content in PDF were increased by microwave treatment and atomospheric steam,but the difference were not significant(P>0.05).Microwave treatment increased the content of PDF in IDF,while reduced by atomospheric steam.After two treatments,the content of SDF in the PDF increased from 6.57 % to 14.88 %(microwave)(P<0.05)and from 8.26 % to 16.54 %(natural cooking)?In chemical composition,the cellulose content of PDF were increased by microwave treatment,while the atomospheric steam treatment decreased.Lignin were stable,and the content were not significant(P>0.05).The content of pectin in PDF were increased by two kinds of processing methods,and the effect of atomospheric steam was significant(P<0.05)?In terms of physicochemical properties,microwave treatment increased the PDF of WHC,and reduced by atomospheric steam.The two processing methods could improve the PDF of OHC in different degrees,but there were no significant difference compared with the control(P>0.05).The SC of Shepody,White Rose,Kexin No.1 PDF were increases by microwave treatment,while the Black Rose,Favorita PDF decreased,but the difference were not significant(P>0.05).It was reduced by atomospheric steam.The GAC(P<0.05)were significantly increased by microwave and atomospheric steam,and the effect of atomospheric steam was significantly better than that of PDF(P<0.05)?The effect of microwave treatment on the adsorption of nitrite by PDF were higher than that of atomospheric steam.The effects of two processing methods on PDF of CEC were significant(P<0.05).In general,Kexin No.1 PDF have better quality,food added this PDF are suitable for atomospheric steam(locking water and oil)and microwave cooking(locking oil and lowing blood pressure).Before and after cooking,Shepody and Black Rose PDF have excellent performance in reducing blood pressure.