| Jerusalem artichoke is rich in inulin,which is one of the main raw materials for the production of fructose-oligosaccharides with prebiotic functions.Inulin was hydrolyzed by endo-inulinase to produce fructose-oligosaccharides with polymerization degree of 2-10.Limited by production cost and market demand,the processing amount of fructoseoligosaccharides from Jerusalem artichokes was much lower than that from sucrose.At this stage,there is still a large amount of Jerusalem artichoke that urgently needs to solve the problem of downstream processing after a high yield and a bumper harvest with the help of a reasonable new way.In addition to inulin,Jerusalem artichoke tubers also contain cellulose,hemicellulose,pectin,polyphenol oxides and other substances.The combination of enzymes is reasonably selected to establish an enzymatic hydrolysis method for preparing fructooligosaccharide-rich syrup from fresh Jerusalem artichoke as raw material.The technology can enrich the types of comprehensive processing products of Jerusalem artichoke and promote the development of the Jerusalem artichoke processing industry.Therefore,in this paper,using fresh Jerusalem artichoke as raw material,the pretreatment and beating technology of Jerusalem artichoke was determined.Established and optimized a new combined enzymatic processing technology with endo-inulinase,endo-glucanase,xylanase,polygalacturonase and tannase derived from Aspergillus niger as the main enzyme molecules,and realized the enzymatic preparation of fructooligosaccharide syrup.The results are the following:(1)Determined the beating process of Jerusalem artichoke suitable for enzymatic hydrolysis.By comparing the effects of different ratio of material to water,beating temperature,and beating time on inulin release,a pre-beating technology for enzymatic hydrolysis of Jerusalem artichoke was established.The optimal pretreatment conditions were as follows: 100 g fresh Jerusalem artichoke,the ratio of material to water is 1:2(w/w),the beating temperature is 50°C,and the beating time is 20 min.At this time,the release rate of inulin was 50.55%.The Jerusalem artichoke pulp prepared by this beating process was added with 15.0 U/g endo-inulinase,and hydrolyzed at 50°C and p H 5.0 for 8 h.The content of fructooligosaccharides was 20.75 g/L,and the hydrolysis rate of inulin was 41.87%.(2)A new combined enzymatic hydrolysis process of Jerusalem artichoke based on tannase,endoglucanase,xylanase,galacturonase and endoinulinase was established.By systematically evaluating the effect of tannase,endoglucanase,xylanase,galacturonase and endo-inulinase on the synergistic enzymatic hydrolysis of Jerusalem artichoke,the optimal enzymatic hydrolysis process was determined as follows: first,enzymatic hydrolysis with 0.1U/g tannase at 50°C and p H 5.0 for 4 h.Then added 0.08 U/g endoglucanase,0.08 U/g xylanase,0.07 U/g galacturonase,and 12.0 U/g endo-inulinase,under the condition of 50℃and p H 5 combined enzymatic hydrolysis for 8 h,in the enzymolysis solution of Jerusalem artichoke,the FOS content reached 38.89 g/L.Compared with only adding endoinulinase,it increased by 87.42%,and the hydrolysis rate of inulin reached 78.46%.(3)Completed the process of trial production of fructooligosaccharide syrup with fresh Jerusalem artichoke as raw material and the nutritional composition of oligosaccharide was systematically evaluated.The optimized enzymolysis process was amplified to 1 kg of fresh Jerusalem artichoke enzymolysis system,and the enzymolysis solution of Jerusalem artichoke was concentrated 2 times.The contents of FOS,total protein and total polyphenols in the syrup were 53.72 g/L,3.37 g/L and 3.11 g/L,respectively.DPPH radical scavenging rate,hydroxyl radical scavenging rate and total antioxidant capacity were82.23%,30.47% and 2.78 μmol/m L.The growth rates of Lactobacillus plantarum,Streptococcus thermophilus and Lactobacillus paracei were increased by 33.33%,60.47%and 148.15% with the prepared oligosaccharides as the only carbon source,respectively. |
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