Fermentation For Preparing Oil Tea Meal Soluble Dietary Fiber By Trichoderma Reesei

The oil tea meal is a by-product of oil tea,but the utilization rate is very low at present.The oil tea meal is abundant in our country,but the content of soluble dietary fiber(SDF)in oil tea meal is low,so it is of great significance to improve the extraction rate of SDF in oil tea meal.Trichoderma reesei has strong cellulase ability,in this paper,the fermentation conditions of the Trichoderma reesei were optimized by single factor experiments and response surface analysis.The mutant strains of the Trichoderma reesei was breeded,which improved the activity of cellulose,by using nitrogen ion beam induced mutation.The SDF was prepared by using hot water extraction,the original and mutant strain strains fermentation,and the properties of the three kinds of SDF were analyzed.1.The effect of the oil tea meal ratio,the content of microcrystalline cellulose,the inoculum concentration and pH on the cellulase activity of Trichoderma reesei were studied.A model was established by Box-Behnken experimental design and analyzed by response surface methodology to optimize the fermentation conditions,on the basis of single factor experiments.The results showed that the optimal fermentation conditions were as follows:oil tea meal ratio 8.6%,microcrystalline cellulose content 0.93%,inoculation concentration 12.48%,pH 4.9.Under this conditions,the carboxymethyl cellulase activity(CMCA)was 8.47U/mL,the microcrystalline cellulase activity(MCCA)was 9.28U/mL,the cellobiase activity(CBA)was 5.05U/mL,and the filter paper activity(PFA)was 5.44U/mL.2.The mutant strain of the Trichoderma reesei was breeded to improve the activity of cellulose by selecting different dose of nitrogen ion beam.The results showed that the strain curve for survival was"saddle" type after nitrogen ion beam inducing.The "saddle ridge"appeared at the mutation dose of 50×1014 N+/cm2,and the survival rate was 33.34%.The 20 strains of different mutation dose were selected to determine the activity of carboxymethyl cellulose.When the mutation dose was 50×1014 N+/cm2,the positive mutation rate was 20%by calculating the mutation rate.The nine positive mutant strains were studied in genetic stabilities of five generations.It was found that the CMCA of N-50-15 was 6.65±0.22U/mL,higher than that of the all other remaining strains,and the CMCA of N-50-15 was 30.39%higher than the original strain.3.The extraction rates of SDF were prepared by using hot water extraction,the original strain and mutant strain N-50-15 fermentation.The results showed that the extraction rate of the mutant strain of N-50-15 was 3.81g/100g,which was 170.23%higher than the extraction rate of the hot water 1.41g/100g and 74.17%higher than the extraction rate of original strain 2.19g/100g.After glucopolysaccharide gel G-200 purification of SDF,by using liquid chromatogram analysis,the molecular weight distribution of SDF3-1 which prepared by the mutant strain N-50-15 fermentation was in 7～972KDa,less than SDF 1-land SDF2-1 which respectively prepared by the hot water extraction and the original strains fermentation.Through the monosaccharide analysis,it was found that the monosaccharide components of SDF 1-1 mainly were glucose,galactose and xylose,the monosaccharide components of SDF2-1 and SDF3-1 mainly were galactose and xylose.The properties of the three kinds of SDF were further compared with the indexes of water-holding capacity,expansion capacity and superoxide anion free radical removal rate and reduction ability.The results showed that compared with SDF 1-1 and SDF2-1,the water-holding capacity and expansive capacity of SDF3-1 were higher,2.50±0.30g/g and 0.88±0.14 mL/g respectively.The antioxidant capacity of the three kinds of SDF wae:SDF3-1>SDF2-1>SDF1-1,the superoxide anion free radical removal rate of SDF3-1 was 62.94%.It is indicated that SDF3-1 has better physiological activity and nutritional health value.Through the analysis of infrared spectrums,it was found that the infrared spectrums of three kinds of SDF were very similar,and the main absorption peak were-OH,C-H stretching vibration.The pyrana ring characteristic absorption peak of SDF2-1 and SDF3-1 were more than SDF 1-1,which showed SDF2-1 and SDF3-1 possibly had more hydrophilic groups.