Dissertation
Dissertation > Industrial Technology > Chemical Industry > Other chemical industries > Fermentation industry > Other fermentation industry > Polysaccharides

Study on the Enzymatic Production of Xylooligosaccharides from Apple Pomace

Author HuBiao
Tutor LiuFang
School Central South University of Forestry Science and Technology
Course Agricultural Products Processing and Storage
Keywords XOS Pomace Xylanase TLC Purification
CLC TQ929.2
Type Master's thesis
Year 2010
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As with the promotion of bifidobacteria, are not digested and other physiological characteristics, functional oligosaccharide become a health food R \u0026 D is one of the most popular topics. XOS (xylooligosaccharides XOs), is defined by 2-7 xylose by β-(1 → 4) glycosidic linkage to form a direct bond or a branched oligosaccharides general key, which xylobiose (X2 ) and xylotriose (X3) based. Xylo addition to promoting bifidobacteria added, anti-caries, enhance immunity, lower blood pressure cholesterol and other physiological effects, but also have a valid amount is small, good stability. Apple juice processing is the main byproduct, apple pomace xylan accounted for 25.5% of dry material, which will be xylan if fully utilized, not only can solve the problem of pollution pomace, but also can improve Apple's comprehensive utilization, help to increase economic and social benefits of apple processing plants, more conducive to China's apple industry. Currently, the main raw material used in the preparation of corn cob XOS, about the legal system of each oligosaccharide pomace enzyme studies have not been reported, this study is the best pomace enzymatic hydrolysis process Xylo and for the separation and purification of the product were studied. In this study, using alkaline hydrogen peroxide extraction preparation pomace xylan, then Apple enzymatic hydrolysis of xylan to hydrolysates reducing sugar content, total soluble sugar content and average polymerization hydrolysates as the index in the enzyme concentration, pH, substrate concentration, reaction temperature, reaction time on the hydrolysates impact studies based on the use of orthogonal experiment xylanase enzyme preparation Xylo Apple The optimum conditions, and the use of activated carbon - hydrolysates diatomite column for separation and purification of amorphous pale yellow crystals - Xylo, the main findings are as follows: 1. using alkaline hydrogen peroxide pomace extracting xylan, xylan affect the concentration of hydrogen peroxide extracted, pH, reaction time, reaction temperature orthogonal analysis to determine the optimum conditions: the concentration of hydrogen peroxide 3.0%, pH 12.5 , reaction temperature 50 ℃, reaction time was 8 hours, in this condition undergrowth polysaccharide extracted more than 85%. (2) using xylanase xylanase enzyme Apple, the first of the factors affecting enzymatic effect univariate analysis, using 3,5 - dinitro salicylic acid (DNS) to detect reducing sugar hydrolyzate (RS) of the content, the results showed that: in 1-12 h, the enzymatic liquid RS content increased with time; RS with the increase in substrate concentration rises, the concentration of the substrate when the RS is 4.08% 50.87 mg However, the hydrolysis rate of xylan as substrate concentration and decreases, then selected as the best of 4.08%, and the substrate concentration is no longer orthogonal to consider the interactions; added at 1500 U is the amount of enzyme, RS content and the total soluble sugars (STS) content of the maximum value (63.42 mg, respectively, and 129.85 mg), time average polymerization degree of hydrolysis product (DP) is 2.05; pH 5.0 when the maximum enzyme reactivity, and the time of the DP 2.09, the main product is xylotriose (X3); at 40 ℃, RS content and STS content is almost reaches the maximum value (63.40 mg, respectively, and 134.03 mg), and declined rapidly at 50 ℃. Orthogonal experiment the optimal enzymatic hydrolysis conditions: enzyme dosage 1500 U, solution pH 5.0, temperature 40 ℃, reaction 8 hours, then RS and the STS contents were 6.42 mg / ml and 13.28mg/ml , DP 2.07 3. use of activated carbon - diatomite enzymatic liquid chromatography column for separation and purification, eluting first with deionized water adsorbed on the chromatographic column monosaccharides, salts and other impurities, and then 30% desorption ethanol been XOs, when a volume of 175 m1 is off, XOs began to be eluted into 225 ml when, XOs maximum concentration of the elution 16.79mg/ml, and remains unchanged until the elution volume of 250 m1 began to fall, 375 m1 time, XOs base is completely eluted. 4 XOS (XOs) thin layer chromatography, Apple xylan hydrolysis is the main product by X2, X3, X2 and X3 is greater than the content of the content. After chromatographic separation can be a good solution in the enzymatic removal of monosaccharide composition, get XOs products. Recovery of ethanol by rotary evaporation, and vacuum freeze dried to give a pale yellow amorphous Xylo crystals.

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