【作者】 张朝飞；

【导师】 钟海雁； 李忠海；

【作者基本信息】 中南林学院 ， 农产品加工与贮藏工程， 2005， 硕士

【摘要】 以湖南省永州蓝山县种植的黄花、翠冠、清香、绿宝石、丰水五种砂梨和中南林学院绿之梦苗圃晚熟砂梨品种新高、晚大新高、金秋、爱宕为样品,用常规分析方法进行营养成分分析,原子吸收法选择测定了其中7种矿质元素含量,HPLC ACCQ.Tag法进行氨基酸的测定。结果表明:总糖的范围为5.00～7.49%,蛋白质含量范围为0.11～0.22%,Vc含量范围为4.4～7.2mg/100g,总酸范围为0.14～0.34%;常量元素含量较高的是:钾（丰水）239.1mg/100g,镁（翠冠）21.88mg/100g;微量元素含量较高的是:Fe（清香）2.75mg/100g,Zn（翠冠）11.5mg/100g;含有16～17种氨基酸,其中有6～7种必需氨基酸。 以中南林学院苗圃晚大新高等梨品种为样品对砂梨清、浊汁加工工艺中澄清及护色工艺条件进行了优化,利用Vc与Na₂SO₃、果胶酶为护色剂和澄清剂对砂梨清汁进行护色与澄清等实验,建立了不同酶浓度、温度和酶解时间对出汁率和吸光度的关系,得出适宜工作条件;利用稳定剂及均质处理,获得了浊汁合理的工艺条件。结果表明:砂梨果实经挑选、清洗、热烫、冷却后破碎,在破碎时用质量分数为0.4g·kg^-1的抗坏血酸处理,可防止果汁氧化:褐变而保持淡黄色或黄白色;果胶酶加入量为2.5g·kg^-1,在50℃下酶解90min,出汁率可提高8.1%。在砂梨带肉果汁制作工艺中,采用先真空脱气后均质的工序,可保持果汁色泽,减少Vc的损失;添加稳定剂和均质可以改善饮料的悬浮隐定性。稳定剂用量:CMC-Na浓度为0.20%,或者黄原胶与CMC-Na配合使用,浓度各为0.15%和0.05%。均质条件:高速剪切机以24000rpm均质4min。杀菌处理温度以121℃较为理想,既达到了杀菌的目的,又较好地保持了带肉果汁的稳定性及营养成分。 以晚熟砂梨新高、晚大新高、金秋、爱宕制成的清汁为测定物,以顶空固相微萃取法和气-质联用,3-癸酮为为内标,研究了果汁量、萃取时间、加盐浓度、萃取温度对梨果汁中香气物质萃取的影响,优化了分析条件,建立了快速测定梨果汁中香气物质的方法。优化后的固相微萃取主要条件是:PDMS/DVB/CAR纤维头,梨果汁用量7ml,吸附时间为45min,吸附温度为50℃,加盐量为25g/dL,解吸时间为2min。四种砂梨果汁中共鉴定出30种香气成分,酯类香气成分在金秋、新高、晚大新高、爱宕梨果汁中所占比例分别为:55.60%、63.92%、44.86%、62.66%,构成了梨果汁的主要香气成分。砂梨果汁中特征香气物质为:己酸乙酯,丁酸乙酯,乙酸乙酯、d—柠檬油精、α—萜品油烯、正己醇、正己酮。更多还原

【Abstract】 Ingredients of nutrition of five cultivars of pear from Lanshan country, Hunan, were studied. Seven kinds of mineral element were analysed by atomic absorption spectrometry. And amino acid was determined by HPLC ACCQ. Tag, others were carried out by national standards analytical methods. The results showed that: the range of water content, 86. 2⁹0.4 %; the total sugar content, 5.00⁷.49%; protein, 0.11⁰.22%; Vc, 4.4⁷.2 （mg/100g） and the total acid content, 0. 14⁰. 34%. With respect to the macro-element of content, Kalium （Fengshui pear, 239.1mg/100g） ranks first, Magnesium （cuiguan pear, 21.88mg/100g） ranks second. As to the trace elements, the higher of those are zinc （11. 5mg/100g, Cuiguan pear）, iron （2.75 mg/lOOg, Qingxiang pear）. The 16¹7 kinds of amino acid were found in the samples. Among of them, 6⁷ kinds were essential amino acids.The technology of clarification and protect color of clear Pyrus pyrifolia juice and the stability of the turbid juice were studied. The results showed that 0. 4g · kg^-1 Vc could keep the color of clarified juice as straw yellow; juice extraction was improved from 72.6% to 80. 7% under the incubation of pectinase at the condition of 50°C, 2. 5,g. kg"1, 90min. The dosage of pectinase is the key factor of juice extraction. In the processing of the turbid juice extraction, the color of the pear juice was preserved and the loss of Vc was reduced by using vacuum degassing before homogenization. Stabilizer and homogenization could improve stability of the turbid pear juice. The optimum concentration of stabilizer was 0.20% （CMC-Na）, or the mixture of xanthan gum and CMC-Na was 0. 05% and 0. 15%, respectively. Homogenization was carried out at 24000 r/min for 4 min. The sterilization was performed at 121℃ for 30s.The volatile profile of pear juices was determined by using solid phase microextraction （SPME） coupled with GC-MS. The optimum experiment parameters for SPME were: amount of juice 7 mL, extraction time 45min, extraction temperature 50°C, NaCl concentration 25g/dL. A total of 30 volatile components were identified from the four juice samples. Esters were the dominant constituents in all of the samples. The important compounds which contribute to pear aroma were: ethyl hexanoate, ethyl butanoate, hexyl acetate, hexyl alcohol, hexanone, d- limonene, α — terpinolene.更多还原