Preparation Of Carotenoids-containing Functional Feed By Neurospora Sitophila Solid-state Fermentation

As a by-product of agricultural production,bran has the characteristics of high yield and wide sources,but bran itself has high fiber content and is not easy to digest as feed.Microbial fermentation can increase the content of dietary fiber,carotenoids,phenolic acids and other nutrients in bran,making it a functional feed with added value.In this thesis,Neurospora sitophila was used as a fermentation strain to produce carotenoid-containing functional feed through solid-state fermentation.Carotenoid yields was used as an optimization index.The medium conditions and fermentation conditions were optimized.Based on this,the functional fermentation block containing carotenoids was prepared by open fermentation,and the inducer was selected to further increase the yield of carotenoids.Fermented feed with high nutritional value and good feeding effect was obtained.The main research contents are as follows:?1?The conditions of carotenoids produced from bran by Neurospora sitophila solid-state fermentation were optimized by single-factor test and orthogonal experiment.The results showed that the optimal conditions were 12.50 g of bran in a 250 mL conical flask and KH₂PO₄ was 0.25 g,MgSO₄ addition amount was 0.2%of bran quality,bean dregs addition amount was 2%of bran quality,medium water content?w/v?was 85%,and inoculation amount was 15%?w/v?.After 96 h incubation at 30?,the yield of carotenoids under optimization condition was 147.38?g/g.?2?Based on the results of sterilization solid-state fermentation,the fermentation conditions of feed block by the method of open fermentation was studied.The single factor test showed that the inoculation amount of the feed block was 20%,the water content was 85%,the specific gravity of the feed block was 0.15 g/cm³,2%?w/v?molasses was added,and the fermentation was carried out for 6 days to obtain a higher carotenoid yeild.According to the response surface optimization results and the actual production conditions,the fermentation conditions of the obtained feed blocks were inoculated amount of 19%,87%of medium water contend?w/v?,0.16 g/cm³ of feed block specific gravity,and fermentation time of 6 days.Compared with the sterilization fermentation,the water evaporation speed of the open fermentation was faster,the water can be used by the microorganism was reduced,and the feed block was relatively dense,and the air permeability was poor,so the carotenoid yield was reduced.Under these conditions,the carotenoid yield was 66.38?g/g.Under the optimized solid-state fermentation condition of the feed block,the yield of carotenoids was further increased by 57.57%by using Rhodotorula sterilized cell homogenate as a inducer,and the yield was further increased by 13.13%by Saccharomyces cerevisiaeas sterilized cell homogenate as a inducer.Therefore,Rhodotorula was further studied as the inducer.The cell wall containing polysaccharides,monosaccharide components,and some intracellular substances might increase the carotenoids yield to 29.76%compared with the blank control group.The no biological activity Rhodotorula cell homogenate obtained by high temperature sterilization was used as inductor.When the homogenate inductor concentration of the sterilized Rhodotorula cell was 2 g/mL,the quality of bran was 32 g and the volume of feed block was 200 cm³,the yield of carotenoids increased by 57.20%compared with the control group.When the inducer was added after 48 h fermentation,the yield of carotenoids was increased by 25.91%compared with the control group.?3?Through a comparative analysis of the nutritional components before and after the fermentation,the crude fiber content of the bran feed block of Neurospora sitophila fermentation was reduced by 19.45%.At the same time,by the degradation of cellulase and lignin enzyme,the content of reducing sugar was increased by 2 times?including reducing sugar content in molasses?,and the soluble dietary fiber was increased by 1 times.The biomass of medium increased by 1.6 times,the content of soluble protein increased by 51.05%,and the content of crude protein increased by 46.15%.Phenolic acid was released under the synergistic action of ferulic acid esterase and xylanase,and the free phenolic acid content was increased by62.10%compared with that before fermentation.The above results showed that the fermentation of wheat bran by Neurospora sitophila could produce high content of carotenoids,and the contents of reducing sugar,crude protein,soluble protein,phenolic acid and soluble dietary fiber were significantly increased.In summary,the functional feed-containing carotenoids obtained from the wheat bran by solid state fermentation of Neurospora sitophila has application significance and can be used in the development and production of fermented feed.