【作者】 黄强；

【导师】 郑建仙；

【作者基本信息】 华南理工大学 ， 食品科学， 2010， 硕士

【摘要】 L-抗坏血酸(维生素C)几乎是所有动物维持生命必需物质,但L-抗坏血酸也是食品和饲料原料中最不稳定维生素,容易受到光、热、氧、湿气、pH、金属离子、紫外线等影响,使效价明显下降。相关研究表明在饲料制粒及存放过程中约有80-98%L-抗坏血酸被破坏。近些年,开发以L-抗坏血酸-2-多聚磷酸酯(AsPP)为代表具有强抗氧化能力L-抗坏血酸衍生物正受到越来越多国内外研究者重视。本论文采用直接酰化法,以L-抗坏血酸为原料,三偏磷酸钠(STMP)为磷酸化试剂,以氯化钙为催化剂,运用单因素实验方法考察原料配比、催化剂用量、pH值、温度、时间等因素对AsPP产率和纯度影响,并在单因素实验基础上进行正交实验从而确定AsPP最佳合成工艺:n(L-抗坏血酸):n(三偏磷酸钠):n(催化剂)为1:1.1:0.2、反应体系pH值为8.0、反应温度为30℃、反应时间为30min。由于目前饲料工业上生产AsPP工艺大多需要采用蒸发干燥或喷雾干燥法才能从反应液状态制得粉剂状态产品,工艺复杂且浪费能量。本实验通过向反应液加入有机溶剂以改变反应液相平衡从而使AsPP从反应液中沉淀析出。通过单因素考察有机溶剂种类、有机溶剂与反应液体积比、温度、料液pH值、时间、有机溶剂质量分数等对AsPP得率、纯度影响。在单因素实验基础上,通过响应面法实验进一步优化AsPP晶析制备工艺条件:以95%乙醇为有机溶剂、料液pH值6.74、料液体积比为2.25:1、温度为30.15℃,在此最优工艺下AsPP得率理论预测值为89.38%,效价理论预测值为41.90%。并采用紫外光谱扫描、红外光谱扫描等方法对产物进行鉴定和结构表征。论文对制备出的AsPP主要理化性质进行研究,包括室温下在纯水中溶解度、溶解平衡时间、熔点和pH值、温度、放置时间、溶液离子等对稳定性影响,并与L-抗坏血酸和L-抗坏血酸-2-单磷酸酯钠(SAP)稳定性进行比较研究,从而论证AsPP优越性能:在25℃时,AsPP在纯水中4小时达溶解平衡,溶解度为18.98mg/mL,AsPP粉沫熔点为221～224℃。AsPP无论在酸性、碱性还是中性溶液中都比较稳定,尤其是在pH=10碱性溶液中最稳定,存放3个月后,保存率依然高达88.6%;AsPP具有较强抗高温能力,在140℃条件下处理5min,依然有66.86%保存率;AsPP在重金属溶液中具有较强稳定性,AsPP在含Cu2+、Fe3+重金属溶液中保存90d后,保存率分别为53.7%、47.5%;在添加氧化剂H2O2情况下,AsPP在第90d后,保存率为44.3%。更多还原

【Abstract】 L-ascorbic acid (vitamin C) is the most unstable vitamin among the food and feed raw materials,but it is vulnerable to light,heat,oxygen,moisture,pH,metal ions and ultraviolet radiation et al,so that the effect decreases quickly.Relevant researches suggest there is about 80-98 percent of L-ascorbic acid was destroyed during the feed pelleting and storage.In recent years,the development of ascorbyl polyphosphate (AsPP) which is one of the L-ascorbic acid derivatives with a strong antioxidant capacity is being payed more and more attention by the domestic and foreign researchers.In this paper,the direct acylation method was applied to obtain AsPP using L-ascorbic acid and Sodium Trimetaphosphate.By studying the effects of material molar ratio,reaction temperature,pH,amount of catalyst,reaction time on the AsPP yield and purity to optimize the best reaction conditions,and used orthogonal experiment to abtain the optimum technological condition of preparating AsPP on the base of single factor experiments,the result shows that n(L-ascorbic acid):n(Sodium Tripolyphosphate):n(catalyst) was 1:1.1:0.2,pH value of reaction system was 8.0,the reaction temperature was 30℃,reaction time was 30min.As the current process of production AsPP powder from the reaction mixture in the feed industry is by evaporation drying or spray drying method,which is complex and a waste of energy,so in this study we used the method of adding some organic solvents to the reaction solution to change the phase equilibrium so that the AsPP can be precipitated from the reaction solution.In this study the effects of organic solvent kind,volume ratio of organic solvents to reaction solution,temperature,pH value,alcohol precipitation time,mass fraction of the organic solvent on the yield and purity of AsPP were investigated by single factor experiment,and used response surface method to further optimize the preparation process of AsPP powder,and the result shows that 95% ethanol was the organic solvents,liquid pH value was 6.74,volume ratio of organic solvents to reaction solution was 2.25:1,the temperature was 30.15℃.Under this optimal process the AsPP theoretical predictive yield value is 89.38%,the theoretical predictive titer value is 41.90%.And by using UV scanning,IR scanning et al to identified the product is AsPP.This paper also studyed some major physical and chemical properties of AsPP,including the solubility in pure water at room temperature,the dissolution equilibrium time,the melting point and the effects of pH,temperature,storage time,the solution ions on the stability of AsPP. By comparing the stability of AsPP with L-ascorbic acid and Ascorbyl monophosphate sodium(SAP) to demonstrate the superiority of AsPP.The result shows that the dissolution equilibrium time at 25℃is 4 hours,the solubility is 18.98mg/mL,the melting point of AsPP powder is 221 ~ 224℃.AsPP is quite stable regardless of in the acidity,the alkalinity or the neutral solution, particularly is stablest in the alkazid solution with pH10,the survival rate still reached as high as 88.6% after depositing for 3 months;and AsPP has a strong anti-high temperature ability, its survival rate was 66.86% after being processed at 140℃for 5minites;AsPP also has a strong antioxidant ability in the heavy metal solution,the survival rates respectively was 53.7% and 47.5% after being deposited in CuSO4 solution and Fe2(SO4)3 solution for 90 days;AsPP still had a 44.3% survival rate after being deposited in water which was added with 30%H2O2 for 90days.更多还原