【作者】 张怡；

【导师】 郑宝东； 陈绍军；

【作者基本信息】 福建农林大学 ， 农产品加工及贮藏工程， 2009， 博士

【摘要】 本文较为系统的研究了福建特产柚子品种品质特性、柚苷酶产生菌的筛选及诱变育种、柚子汁功能学特性,并在此基础上研究了高品质柚子汁的生产工艺、柚子加工副产物的综合利用。通过实验研究结果如下:(1)福建特产柚子品种品质特性的研究福建五大特产柚子品种营养品质的研究表明,维生素C是新鲜柚子中含量最高的维生素,蛋氨酸是柚子的第一限制氨基酸。加工品质的研究表明,柚子的深加工具有独特的优势,总酚含量较低,且多酚氧化酶活性低未检出,柚子在加工过程不易出现酶促褐变。柚子果肉中含有较多的果胶,且属于低甲氧基果胶,为榨汁工艺中优选果胶酶类型提供依据。保健品质的研究表明,总黄酮、多糖、SOD含量品种间差异较大。这对开发不同类型柚子保健食品时优选柚子品种具有指导意义。(2)柚苷酶的筛选及诱变育种的研究研究利用柚苷酶平板透明圈筛选方法,加大了透明层与未分解层的颜色对比,便于观察,易测量,检测步骤简化,提高了菌种筛选的效率,改进了柚苷酶产生菌的选育模型。筛选出一株柚苷酶生产菌株A-13,其酶活可达365.31 U /mL,具有较高的酶活力,通过对该菌株的形态特征、培养特征的观察,对照《真菌鉴定手册》判定该菌株为黑曲霉(Aspergillus niger)。通过NTG对出发菌株A-13诱变处理,结合优化后的透明圈筛选法和摇瓶复筛法,筛选得到1株摇瓶发酵单位达876.43U/mL的A-13-62号菌株,比出发菌株的产酶能力提高了近237%。以鼠李糖为产酶诱导剂,确定黑曲霉A-13-62的最佳发酵培养基及最佳发酵条件。发酵培养基配方:豆渣(含水30%～40%)100g,脱脂豆饼粉40g,鼠李糖0.2g,CaCl2 1g,ZnSO4 1g,MgSO4·7H2O 5g,K2HPO4 1g,蒸馏水1000mL;发酵条件为:培养温度30℃、初始pH为5.0、接种量10%、500mL三角瓶装液量为50mL,在此条件下测得酶活可达1017U/mL。对经NTG诱变得到的高产菌株A-13-62进行稳定性考察,数代培养后,酶活稳定在1004U/mL以上,比野生菌株提高了272%。(3)柚子汁加工关键技术的研究果胶酶提取柚汁的最佳工艺条件为:采用果胶酶X1与GM以1:1复合酶解、酶解时间60min的条件下,在柚子原汁pH状态下,酶用量2000IU/kg、酶解温度50℃,出汁率高,达48.9%,出汁率提高近22%。将柚苷酶发酵液冷冻浓缩至酶活力10000IU/mL,作为液体酶制剂,研究柚汁酶法脱苦的最佳工艺条件。结果表明:在柚子原汁pH状态下,酶解时间60min,酶解温度为50℃,加酶量为8000 IU/kg时酶解效果最好。在最佳工艺条件下,果汁的脱苦率达到46.25%,风味优良。柚汁饮料配方为柚子原汁用量30%,柠檬酸用量0.06%,白砂糖用量7.0%,以此调制的饮料酸甜适合,又具柚子特有风味,口感佳。(4)柚子降血脂作用的研究以高血脂模型大鼠研究柚汁的降血脂功效。将SD大鼠分成正常对照、高脂模型组、阳性对照组和柚子汁低、中、高剂量组,即100Bix、200Bix、300Bix柚子汁灌胃1.2mL/100g.bw,测定其甘油三脂(TG)、总胆固醇(TCHO)、高密度脂旦白胆固醇(HDL–C)、低密度脂旦白胆固醇(LDL–C)和载脂蛋白A /载脂蛋白B (ApoA/ApoB)。研究表明,给予高脂血症大鼠服用柚子汁4周,能明显降低大鼠血清脂质含量,改变脂蛋白成分。柚汁高、中和低剂量组TG含量与模型组比较明显降低(p<0.01);柚汁高和中剂量组TCHO含量与模型组比较明显降低(p<0.05或p<0.01));柚汁高、中和低剂量组HDL-C含量与模型组比较明显升高(p<0.01);柚汁高和中剂量组大鼠ApoA/ApoB值与模型组比较明显升高(p<0.05)。表明柚子汁灌胃给药对实验性高脂血症大鼠具有治疗作用。(5)柚子加工副产物综合利用的研究以柚子落果和疏果的青果皮为原料,采用了酸浸提、醇沉淀法,对青果皮提取果胶的最佳工艺条件进行了研究,得到青果皮提取果胶的最佳工艺条件为pH值0.5,提取温度90℃,提取时间80 min,果胶的提取率为3.15%。以柚皮为试验原料,采用乙醇浸提法从柚皮中提取总黄酮,研究柚皮提取总黄酮的最佳工艺条件:在提取温度为90℃的情况下,提取时间2h,乙醇浓度50%,稀释倍数20倍时总黄酮提取率最高,达0.607%。采用超临界CO2萃取技术提取柚籽精油,研究得出其最佳工艺条件为:萃取压力35MPa、萃取温度40℃、CO2流量为16L/h、萃取时间为1h,得率达33.90%。同时利用气象色谱对柚籽精油的脂肪酸成分进行分析,结果表明:精油中饱和脂肪酸占32.11%、不饱和脂肪酸占66.65%,可作为食用油源或功能性芳香油进一步开发。更多还原

【Abstract】 The quality characteristics of Shaddock varieties, the special products of Fujian,screening and mutation breeding of Naringinase producing strain, and function characteristics of Shaddock juice were studied systematically in this paper. Meanwhile on this basis, production technology of high-quality Shaddock juice and comprehensive utilization of Shaddock processing by-products were researched. The research results were as follow.(1)Study on quality characteristics of Shaddock variety in FujianThe study on nutrients quality of Shaddock showed that Vitamin C was the highest content of vitamin, and methionine was the first-limiting amino acid in fresh Shaddock.The study on processing quality shows that deep processing of Shaddock has unique advantages because of the lower total phenolic content and few polyphenol oxidase activity. It meaned enzymatic browning hardly occurred during processing. Shaddock flesh contained more pectin, which was a low-methoxyl pectin, that provided evidence for selecting the pectinase type for preparing juicing.The study on health-care quality showed that total flavonoids, polysaccharides, and SOD content varied among different varieties, which was significant for selecting optimal variety to exploit different types of Shaddock health-care food.(2)Study on screening and mutation breeding of Naringinase producing strainThe efficiency of screening and establishing the breeding model of Naringinase producing strain was improved by transparent plates method through color comparison of transparent layer and non-decomposed layer which had convenience for observation and measurement. One Naringinase producing strain, A-13,whose enzyme activity was up to 365.31 U /mL has been screened. Meanwhile, it was judged as Aspergillus niger by its morphological and cultural characteristics according to the <MANUAL OF FUNGI IDENTIFICATION>.By NTG mutagenic treatment of original strain A-13 together with optimization of transparent circle method and screening and breeding with shake bottle, mutant A-13-62 was obtained, whose enzyme activity was up to 876.43 U /mL. The yield of enzyme of this mutant produced was 237% higher than that of original strain by shake flask culture method.The optimal fermentation medium and conditions of mutant A-13-62 has been confirmd with rhamnose as enzyme inducing agent. The optimal fermentation medium formula was as follow: 100g bean dregs(moisture 30%～40% ), 40g defatted bean cake flour, 0.2g rhamnose, 1g CaCl2, 1g ZnSO4, 5g MgSO4·7H2O, 1g K2HPO4, 1000mL distilled water. The optimum fermentation conditions: fermentation temperature 30℃, initial pH 5.0, fermented with 10%,50mL in 500mL triangle bottle,the enzyme activity of A-13-62 was 1017U/mL.The stability of high-yield strains A-13-62 by NTG mutagenic treatment was studied. Cultivated for several generations, A-13-62 reached a stable enzyme activity level of 1004U/mL, 272% higher than that of wild strains.(3)Study on critical Technology of Shaddock juice processingThe optimal process of Shaddock juice extraction with pectinase were put forward as follow: composite enzyme for hydrolysis (pectinaseX1 and GM with ratio of 1:1 ), hydrolysis time for 60 min, unchanged pH of raw juice, enzyme dosage 2000IU/kg, hydrolysis temperature 50℃.Under these conditions, the juice yield was improved by 22%,up to 48.9%.Fermentation broth of Naringinase was frozen and concentrated for enzyme activity 10000IU/mL as liquid enzyme,which was used to study the optimal conditions of debittering Shaddock juice by enzymatic method.And the results showed that: in the conditions of unchanged pH of raw juice, hydrolysis time for 60 min, enzymatic hydrolysis temperature 50℃, enzyme concentration 8000IU/kg, the hydrolysis was best and juice debittering ratio reached 46.25% with good flavor.The Shaddock juice drink had sweet-sour, dense tastes and peculiar flavor with the formula : Shaddock raw juice 20%,citric acid 0.06%,sugar 7.0%.(4)Study on the effect of Shaddock on reducing blood lipidsThe effect of Shaddock reducing blood lipid was studied with hyperlipemia rats model. Male SD rats were divided into six groups: normal control group, hyperlipemia model group, positive control group,and groups receiving 1.2mL/100g.bw low dose(100Bix), middle dose(200Bix) and high dose(300Bix) Shaddock juice respectively by gastric perfusion. Then detect the concentration of triglyceride(TG), total cholesterol (TCHO), high density lipoprotein(HDL-C),low density lipoprotein(LDL–C), apolipoprotein A/apolipoproteinB(ApoA/ApoB). The results showed that: significant decrease of serum lipids content and changes of lipoprotein composition were found in the hyperlipidemia rats fed with Shaddock juice for 4 weeks. Compared with model group significant decrease of TG was found in low dose(100Bix), middle dose(200Bix) and high dose(300Bix) groups (p<0.01) and also significant decrease of TCHO in high dose(300Bix) and middle dose(200Bix) groups(p<0.05或p<0.01) but HDL-C in high dose(300Bix), middle dose(200Bix) and low dose(100Bix)groups (p<0.01) and ApoA/ApoB in high dose(300Bix) and middle dose(200Bix) groups (p<0.05),were significantly increased. It showed that gastric infusion of Shaddock juice had therapeutic effects on the hyperlipidemia rats.(5)Study on the comprehensive utilization of Shaddock processing by-productsThe optimal processing condition of extracting pectin was studied by using pulp of fallen and thinning unripe fruit as raw material,with acid leaching and alcohol precipitation method. The extraction rate of pectin reached 3.15% at the optimal processing conditions: pH 0.5, extraction temperature 90℃, extraction time 80 min.The optimal processing condition of extracting total flavonoids from shaddock peel was studied with alcohol extraction method. The extraction rate of total flavonoids reached 0.607% at the optimal processing condition: extraction temperature 90℃, extraction time 2h, alcohol concentration 50%, dilution multiple 20.The optimal processing condition of extracting essential oil from shaddock seed was studied by supercritical carbon dioxide. The extraction rate reached 0.607% in the optimal processing condition: extraction pressure 35MPa, extraction temperature 40℃, CO2 flow rate 16L/h, extraction time 1h. Simultaneously the fatty acids analysis of essential oil from shaddock seed with gas chromtography showed that it contained 32.11% saturated fatty acid and 66.65% unsaturated fatty acid ,which were exploitable for edible oil resource.更多还原