【作者】 衣宇佳；

【导师】 汤坚；

【作者基本信息】 江南大学 ， 食品科学， 2008， 硕士

【摘要】 干酪的营养价值丰富,风味独特,是乳制品中的精华。干酪是西方国家的传统食品,应用于人们的日常饮食,消费量极大。而目前我国的干酪市场被进口产品所占领,且品种少、价格高。受消费习惯的影响,分析设备昂贵等原因,国内对干酪及其风味的研究相对滞后,但随着对外交流的日益加强,中国人的饮食结构也在发生巨大变化,我国政府也日益重视新型乳制品干酪的开发研制工作。因此,为降低对干酪研究的盲目性,加快干酪的国产化进程,本文以国产原制类契达干酪为原料,以其特征风味为主要指标,采用固相微萃取、同时蒸馏萃取、气相色谱-嗅觉测量法、电子感官分析等方法对国产干酪的风味进行分析,主要研究内容和结果如下:为了避免不同样品制备方法带来的结果上的偏差,确定合适的样品处理方法,首先筛选了适合国产干酪挥发性风味组分的分析方法,优化了分析条件,并比较了两种方法的优劣。实验结果表明,同时蒸馏萃取法(SDE)较佳的条件为:以乙醚为溶剂,蒸馏3小时;固相微萃取法(SPME)较佳的条件为:采用75μmCAR/PDMS萃取头,40℃下吸附40min,250℃下解吸2min。采用各自较优的操作条件,SDE法检出的化合物最多,为65种,SPME法可检出62种化合物。SDE法对高沸点、低挥发性成分的分离比较有利,SPME法对醇类以及一些低分子量的羧酸和一些含硫化合物的检出效果良好。两种各有优缺的方法检出结果相互补充,共能检出国产干酪中风味化合物100种。为了确定国产原制类契达干酪的风味评价指标,研究了国产干酪的特征风味组分。并采用气相色谱-嗅觉测量法(GC-O)测定了经同时蒸馏萃取法制备的国产干酪抽提物中的气味活性组分。采用了香气抽提稀释分析法(AEDA)定量测量各气味活性组分对国产干酪整体风味的贡献大小。按它们对干酪整体风味的重要性由大到小排序为:①异丁酸= 3-羟基-2-丁酮>②2-壬酮>③2-庚酮= 2-十一酮= 2-十三酮= 2-十五酮=十八醛>④2,3-丁二酮=戊酸=乙酸-1-辛稀-3-醇酯=癸酸=δ-十二内酯=甘油三乙酸酯。由于非挥发性风味组分可以直接影响干酪的滋味,也是形成干酪特征风味的前体物质,为了探索干酪特征风味组分的产生与干酪成熟度之间的关系,研究了干酪成熟过程中的蛋白水解和脂肪水解情况,并对不同成熟度干酪的风味进行了感官评定。结果表明,干酪的风味随成熟时间延长有明显变化,奶油味和腐臭味是干酪的重要气味;苦味和咸味在滋味中最强;经HPLC及GC-MS分离不同成熟度干酪中的游离氨基酸及游离脂肪酸,结果表明氨基酸及脂肪酸种类及含量的变化对干酪的特征风味有重要影响。SPME/GC-MS对不同成熟度干酪的风味组分提取,结果表明:干酪成熟至90d时,对干酪特征风味组分贡献较大的化合物检测到7种,分别为:2,3-丁二酮、3-羟基-2-丁酮、2-庚酮、2-壬酮、异丁酸、戊酸和癸酸。而其它辅助特征风味组分可能在干酪成熟后期产生。为了对国产干酪的风味更好的进行客观评价,以建立不同成熟阶段干酪的风味模型,确定国产原制类契达干酪的成熟时间,采用电子感官指纹分析仪(电子鼻、电子舌)对国产干酪不同成熟阶段的气味与滋味特征进行识别,经PCA分析结果表明,低成熟期与中等成熟期干酪的总体风味较接近,与高成熟期干酪的风味相对差异较大;国产类契达干酪基本成熟时间为90天,其气味以奶油味和腐臭味为主,滋味以苦味和咸味为主。更多还原

【Abstract】 Cheese is the essence of dairy products with high nutritional value and characteristic flavor.Cheese is a traditional food in western countries,applied to people’s daily diet,and the consumption is great.At present,cheese market in China is occupied by imported products with less variety and high prices.Due to the spending habits and the expensive equipments,the research in domestic cheese and its flavor is relatively lag.But with the increasing foreign exchanges,the Chinese people’s diet structure has changed dramatically,the Chinese government is also laying emphasis on development of new dairy products- cheese.Therefore,in order to reduce blindness in the study of cheese and to speed up the process of domestic cheese,domestic cheddar cheese was chosen as the raw materials and its characteristic aroma components as the main evaluation index in this thesis.Solid-phase micro-extraction,simultaneous distillation extraction,gas chromatography olfactrometry and electronic sesory evalution methods were used for analysising domestic cheese flavor.Main contents and the results were as follows:The extraction methods for volatile components of cheese were optimized and compared in order to choose optimum method and avoid the deviation of different method.For simultaneous distillation extraction(SDE),ether was the optimum solvent and extraction time was 3h . For solid-phase micro-extraction(SPME) , the optimum conditions were: :75μmCAR/PDMS as optimum absorption fibre,absorption time 40min and temperature 40℃,while desorption was 2min at 250℃.Under each optimized condition,65 kinds and 62 kinds of compounds were identified respectively by SDE and SPME methods.The former method provided better results in detecting high boiling-point,low volatile compounds and some acids,aldehydes,ketones,esters with long chain.The SPME method was fit for some alcohols,acids with low boiling-point and sulf-containing components.One hundred cheese flavor compounds were indentified when the three methods were used to complement each other.The characteristic flavor of cheese was investigated in order to establish the quality evaluation index of domestic cheddar cheese.The odor-active components in cheese aroma were indentified and characterized by gas chromatography-olfactometry(GC-O).Aroma extract dilution analysis(AEDA) was used to quantify the contribution of each odor-active component to whole cheese flavor profile.The order according to significance to the cheese was①isobutyric acid = 3-hydroxy-2-butone >②2-nonanone >③2-heptanone =2-undecanone = 2-tridecanone = 2-pentadecanone = octadecanal>④2,3-butanedione = pentanoic acid = acetic acid-1-octene-3-olide = decanoic acid =δ-dodecalactone = glycecol triacetate。 As non-volatile flavor components could directly affect the taste of cheese,and they were also precursor substances of characteristic flavor.The protein hydrolysis and fat hydrolysis during the cheese mature process were studied in order to explore the relationship between characteristics flavor components of cheese and its mature time.The sensory evaluation in cheese flavor at different mature time were studied.The results showed that the flavor change obviously with cheese maturity,and the cream and moldy odor wewe main cheese characteristic flavor;bitter and salty taste were the strongest in taste.HPLC and GC-MS were used for analysing in cheese at different mature time.The results showed that the type and content of free amino acid and free fatty acids had effect on characteristic flavor of cheese.SPME/GC-MS was used for studying flavor components in cheese at different mature time.The results showed that:At 90 day,seven kinds of characteristic flavor components made great contribution to cheese flavor profile , and they were: 2,3-Butanedione, 3-hydroxy-2-butone,2-heptanone,2-nonanone,isobutyric acid,pentanoic acid, decanoic acid.And other characteristic flavor components may be assisted in the latter part of mature cheese.In order to made objective evalution to cheese flavor and to create a flavor model in cheese at different stage of maturity,e-sensory fingerprint analysis (electronic nose and electronic tongue)were used for cheese to determine the odor and taste character at different mature time.The PCA analysis showed that low- maturity was close to middle-maturity in cheese flavor profile;while different from relative high maturity cheese flavor.90 days were the mature time for domestic cheddar cheese,and its main odors were cream and moldy,with bitter and salty in taste.更多还原