Preparation Of Monascus Dietary Fiber By Fermentation And Its Application In Bread

The output of agricultural product processing residues in China is huge,but the utilization efficiency is low extremely.Agricultural product residues such as okara,wheat bran and pear residue could be used by microorganisms to ferment,extract effective ingredients such as dietary fiber（DF）,which can not only turn the waste residue into treasure,but also reduce environmental pressure.The study found that okara,wheat bran and pear residue could be fermented by Monascus to produceMonascus pigments while extracting dietary fiber,which not only reduces theproduction cost of Monascus pigments,but also increases the value of agricultural products.In this paper,okara,wheat bran and pear residue were used as substrates to prepare Monascus dietary fiber by liquid fermentation of Monascus.The process and physical and chemical properties of different Monascus dietary fiber were studied,and the effect of the Monascus dietary fiber on bread quality was analyzed.The main research contents and results are as follows:（1）Study on the preparation of Monascus okara dietary fiber（MODF）,Monascus wheat bran dietary fiber（MBDF）and Monascus pear residue dietary fiber（MPDF）by liquid fermentation of Monascus.Using single factor and orthogonal test design methods,using soluble dietary fiber（SDF）yield and color value of Monascus pigments as indicators,the best process for preparing fermented MODF,MBDF and MPDF by liquid fermentation of Monascus was determined.MODF:material-liquid ratio is 1:15,inoculums is 10%,fermentation time is 7 d,glucose addition is 2%,under this condition,the yield of Monascus okara SDF（MOSDF）is 7.62%,and the color value of Monascus pigments is 254 u·m L^-1.MBDF:material-liquid ratio is 1:15,inoculums is 10%,fermentation time is 6 d,glucose addition is 1.5%,under thiscondition the yield of Monascus wheat bran SDF（MBSDF）is 6.49%,the color value of Monascus pigments is 218 u·m L^-1.MPDF:material-liquid ratio is 1:15,theinoculums is 10%,the fermentation time is 6 d,and the glucose addition is 1.5%.The yield of Monascus pear residue SDF（MPSDF）was 6.75%,and the color value ofMonascus pigments is 230 u·m L^-1.（2）Research on physicochemical properties and structural characterization of MODF,MBDF and MPDF.Scanning electron microscopy and X-ray diffractionspectroscopy analysis showed that the fermentation of Monascus destroyed the matrix of insoluble dietary fiber（IDF）in okara,wheat bran,and pear residue,which exposed the internal structure and reduced the crystallinity.Infrared spectroscopy anddifferential scanning calorimetry analysis showed that intramolecular hydrogen bond breakage and oligosaccharide increase in okara,wheat bran and pear residue.Theresults showed that the fermentation of Monascus increased the content of MOSDF from 4.3 g/100 g to 7.7 g/100 g,the content of MBSDF from 10.7 g/100 g to 16.5g/100 g,and the content of MPSDF from 8.9 g/100 g increased to 12.6 g/100 g.The water holding capacity,oil holding capacity and swelling capacity of Monascusdietary fiber have been improved.UV-Vis spectroscopy analysis showed that theMonascus okara fermentation broth（MOFB）mainly contained orange pigments with a color value of 258.8 u·m L^-1,and the Monascus wheat bran fermentation broth（MBFB）mainly contained yellow pigments with a color value of 236.6 u·m L^-1.The Monascus pear residue fermentation broth（MPFB）mainly contains orange pigments with a value is 248.2 u·m L^-1.Liquid fermentation Monascus fully utilizes thebiological characteristics of okara,wheat bran and pear residue,and improves the structure and function of the dietary fiber of okara,wheat bran and pear residue.In addition,the content of citrinin in Monascus seed broth and fermented products was determined by HPLC.The content of citrinin in the Monascus seed broth,MOFB,MBFB and MPFB was 0.98 ug·m L^-1 and 0.94 ug·m L^-1,0.88 ug·m L^-1 and 0.90ug·m L^-1,respectively.（3）Effects of MODF,MBDF and MPDF on the quality of dough and bread.When the amount of MBDF is 1.0‰,the dough has the longest stable time and the weakest degree is 7.0 min and 29,respectively.At this time,the dough is not easy to rheology,and the processing performance is the best.Adding MODF and MPDF to flour will increase the degree of dough weakening.When they are added in an amount of 2.0‰,the weakening degree is the largest,and the weakening degrees are 57 and59,respectively,which will adversely affect the processing quality of the dough.When 1.0‰MODF,1.5‰MBDF and 1.0‰MPDF are added to flour,the dough has the largest tensile resistance and elongation,the dough is sticky,and the horizontaland vertical elasticity is good.The bread has the best appearance,taste and flavor,and the bread has the highest acceptable rating.Through the above research on the key technologies for the preparation ofMODF,MBDF and MPDF by liquid fermented of Monascus,the basic mechanism of the utilization of agricultural waste residues by Monascus liquid fermentation can be preliminarily explored.It provides a research foundation for the comprehensiveutilization of okara,wheat bran and pear residue dietary fiber.