【作者】 刘生利；

【导师】 杨磊；

【作者基本信息】 广东海洋大学 ， 水产品加工及贮藏工程， 2011， 硕士

【摘要】 随着近海清洁养殖的兴起,鱼、虾、贝和藻立体生态养殖模式成为今后的发展方向,大型海藻---江蓠是立体生态养殖模式的主要藻类。江蓠可食用,主要还是用于提取琼胶。目前,江篱提取琼胶后的残渣直接废弃,污染环境。江篱残渣中富含膳食纤维,是提取膳食纤维的优质原料。利用废弃的残渣提取膳食纤维或进行其他高值化利用,不但可以解决环境污染问题,还可以变废为宝,延长“立体养殖—江蓠—琼胶”的产业链,提升我省高效绿色养殖和加工的环境效益和经济效益。本研究围绕这一目的展开,对残渣的成分进行了分析;通过正交试验法,找到了江篱残渣提取膳食纤维的较佳工艺条件,实现了膳食纤维白度的可控;探索了酶处理方法对膳食纤维理化性能的影响规律,找到了较优的复合酶活化方法,提高了膳食纤维的性能;研究了从残渣制备羧甲基纤维素钠的较优生产工艺,拓宽了残渣的高值化利用范围。主要结论如下:1、成分分析及漂白试验。分析了新鲜江残渣的成分构成,测得其纤维素、半纤维素和木质素的含量分别为:47.21%、18.5%和9.9%,是膳食纤维的优良原料;采用正交试验实验法,筛选出了残渣提取膳食纤维碱性过氧化氢漂白的较佳工艺条件为:温度=60℃,时间=3 h,pH=8.5,通过回归分析,得到漂白剂H2O2浓度与膳食纤维白度的函数关系为:Y=30.85+8.96*X-1.2*X2（X∈（0,4））,R2=0.9951。2、江蓠残渣膳食纤维的活化试验。漂白后的江蓠残渣膳食纤维经过纤维素酶和木聚糖酶处理后,可以改善其膨胀力、持水力,持油力、表面结构等物理性能。研究结果表明:45 u/g纤维素酶和60 u/g木聚糖酶复合酶处理漂白膳食纤维可以使膳食纤维的可溶性膳食纤维含量（SDF）、持油能力（OBC）、膨胀力（SW）和持水力（WHC）分别增加:29%,26%,15%和14%,活化后的江蓠残渣膳食纤维的膨胀力达到4.71 mL/g,持水力648%,白度48.9%,功能性指标超过西方国家麸皮膳食纤维的标准（膨胀力4 mL/g、持水力400%）;通过扫描电镜观察发现,复合酶改性后的膳食纤维的表面结构变得蓬松,有孔隙结构出现,可能是其物理性能改善的原因。3、重金属清除试验。研究了江蓠残渣和其漂白后经纤维素酶和木聚糖酶复合处理样品对Pb²⁺、Cd²⁺的吸附条件,探讨了pH、温度、吸附时间、金属离子初始浓度等因素对其吸附性能的影响。研究结果表明:残渣粉末和经过酶法活化的膳食纤维在pH7对Pb²⁺、Cd²⁺的吸附能力最强,吸附率随着Pb²⁺、Cd²⁺初始金属离子浓度的增大而的降低。残渣粉末和经过酶法活化的膳食纤维对Pb²⁺、Cd²⁺的吸附动力学和热力学分别符合Lagergren方程二级吸附模型和Langmuir吸附方程;单一金属溶液中残渣粉末和经过酶法活化的膳食纤维对Pb²⁺的吸附能力强于Cd²⁺。4、研究了残渣粉末和经过酶法活化的膳食纤维对亚硝酸盐的吸附量分别为:91.4 umol/g和107.7 umol /g;体外模拟胃肠环境下,膳食纤维对有益金属离子Ca²⁺、Mg²⁺具有束缚作用;红外光谱研究表明,膳食纤维吸附作用的主要基团是羟基、羧基、硫酯结构等。5、羧甲基纤维素钠的制备与表征。以取代度为指标得出最优制备条件为:经NaOH（W/W=3:1）25℃碱化处理45 min后,加入氯乙酸（W/W=2.5:1）于65℃进行羧甲基化反应2 h,产品取代度为0.7。更多还原

【Abstract】 With the development of offshore cleaning aquaculture, the three-dimensional ecological farming mode combining the cultivation of fish, shrimp, shellfish with seaweeds will become mainstream. Gracilaria, one of a delicious large seaweeds, is a main seaweed in this ecological farming mode. Gracilaria is mainly used as the raw material extracting agar presently. The gracilaria residue extracted which is rich in dietary fiber is directly abandoned and cause environmental pollution. Extracting dietary fiber from the residue or other utilization of high value can not only prevent environmental pollution, but also make the residue become the valued resource. Full use of the residue will extends the industry chain, that is, ecological aquaculture—gracilaria—agar and increase the environmental and economic benefits of the aquaculture. In this study ,the composition of gracilaria residue were analyzed,the result shows that the residue is rich in dietary fiber. The optimum technology of bleaching dietary fiber with alkaline hydrogen peroxide was found by orthogonal method and the whiteness of dietary fiber can be controlled. The physical and chemical properties were improved by biological method. The optimum methods preparing sodium carboxymethylcellulose from the residue is achieved. The main conclusions are as follows:1. The composition of the residue was analyzed. The result shows that the content of cellulose, hemicelluloses and lignin is respectively 47.21%, 18.5% and 9.9%, while it is excellent material of dietary fiber. The optimum technological conditions for bleaching of dietary fiber with alkaline hydrogen peroxide are pH 8.5, 60℃, 3 h. The relationship between whiteness and the concentration of alkaline hydrogen peroxide can be expressed with equation Y=30.85+8.96*X-1.2*X2（X∈（0,4））, R2=0.9951.2. The swelling capacity, water holding capacity, oil binding capacity and surface structure of the dietary fiber can significantly be improved by activation with cellulase and xylanase. The content of soluble dietary fiber, swelling capacity, water holding capacity and oil binding capacity increase 29%, 15% ,14%, 26%. The swelling capacity, water holding capacity and whiteness are up to 4.71 mL/g , 648% and 48.9% respectively, which exceeded the standard of the western nations（4 mL/g and 400% ）. The study of electron micrograph shows the surface of dietary fiber after activation becomes fluffy and porous, this may be the course of the improvement of its physical properties.3. The residue and its bleaching residue treated with cellulose and xylanase are studied to investigate the adoption of two metals ions Pb²⁺and Cd²⁺ in different pH, temperature ,reaction time,initial ions concentration. The result shows that both of them have the highest absorption rate to Cd²⁺ and Pb²⁺ at pH 7 , and absorption rate decrease with the increase of concentrations of initial metals ions. The adsorption kinetics and adsorption thermodynamics of both of them to Cd²⁺ and Pb²⁺ agree with secondary adsorption model of Lagergren equation and Langmuir adsorption equation. In single metal ions solution, the adsorption rate of both of them to Pb²⁺ is much stronger than to Cd²⁺.4. The adsorption dose of the residue and dietary fiber activated with cellulase and xylanase to sodium nitrite was studied, the result shows that the adsorption dose is 91.4 umol/g and 107.7 umol/g, respectively. Under simulating gastrointestinal environment, dietary fiber may hinder Ca²⁺ and Mg²⁺ from adsorption. The study from IR spectra shows that main groups for adsorption to sodium nitrite, Ca²⁺and Mg²⁺ are hydroxy,carboxyl, sulphur acetate structure and so on.5. The preparation of sodium carboxymethylcellulose （CMC） with the residue was studied by orthogonal method. The result shows that the optimal conditions are as follows: the cellulose was alkalized with NaOH （W/W=3:1）at 25℃for 45 min, chloroacetic acid （ClCH2COOH） was added（W/W=2.5:1）, and the temperature was adjusted to 65℃for 2h. The degree of substitution 0.70 is achieved.更多还原