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Applied research in the sugar cane juice clarification process of alkaline pectinase

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Tutor: FanJiaHeng
School: Kunming University of Science and Technology
Course: Of Food Science
Keywords: alkaline pectinase,clarification,sugarcane juice,drying
CLC: TS244.2
Type: Master's thesis
Year:  2010
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The paper described that an alkaline pectinase were used to clarify mixed cane juice. First of all, the different carbon sources on fermentation inducer of alkaline pectinase were examined. The effects of reaction temperature, of pH and time on the pectinase activity, and the thermal stability of the alkaline pectinase were determined accordingly. Then, the experiments, such as alkaline pectinase clarifying juice, the dosage of crude enzyme liquid, reaction time, juice pH, reaction temperature on the effect of clarifying, and applying the response surface method to optimize the design of the experiment, exploring the optimum reaction conditions of clarification and juice viscosity, transmittance, optical rotation, pectin content, changes in brix were done. Finally, a various stabilizers and preservatives added to enhance the preservation time were studied. The main findings are as follows:1. Adopted the condition:pomelo skin 4.0 g, bran 1.0 g, peptone 0.3 g, KH2PO415 mg, Na2CO30.15 g, water 20 mL. Through solid fermentation crude enzyme solution of alkaline pectinase enzyme are obtained. The activity of the alkaline pectinase enzyme is 8.721U/mg, which can be used in cane sugar industry because it can¡¯t invert sucrose. The properties of the crude enzyme liquid were analized. The optimal reaction temperature is 50¡æ, the optimum pH value is 10.5.2. The crude enzyme liquid of alkaline pectinase used in juice clarification was studied by the orthogonal experiment results. The reaction temperature is 47¡æ, pH 9.3, enzyme dosage 3mL(144U), reaction time 30min. Viscosity of cane juice from 4.6 mPa¡€S increased to 1.13 mPa¡€S, light transmission rate of cane juice increases from 24.1% to 88.5%. Preliminary determination:100mL cane juice contains pectin of 565mg and the enzymatic reactions can decrease 70% pectin. The concentration of original cane juice is 18.42 "Bx, which contains pectin 2.1% Bx. After reaction, pectin content decreased to 0.5% Bx.3. After purification grade test results show that the use of ammonium sulfate fractionation, the crude extract specific activity was 63.73U/mg, enzyme activity recovery was 59.8%, crude enzyme purified 7.38 times; the use of ethanol precipitation, the enzyme specific activity was 51.46U/mg, recovery was 51.8%, purification 5.96 times; using acetone precipitation when the enzyme specific activity was 52.62U/mg, recovery was 55.7%, purified multiple of 6.10 times.4. 100mL crude liquid enzyme after extract treatment, get about 0.8g dry enzyme preparation; Vacuum constant temperature drying treatment total activity of the original crude extract for 56% of total activity, specific activities for the 4.94U/mg; vacuum freeze-drying treatment, the total vitality of the original crude extract of 91% of the total activity, specific activity was 8.19U/mg.
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