【作者】 詹萍；

【导师】 张晓鸣；

【作者基本信息】 江南大学 ， 食品科学， 2013， 博士

【摘要】 羊肉加工副产物(骨骼、尾油及肚油等)资源极其丰富，但其深加工利用技术匮乏。目前国内羊肉香精产品普遍存在天然感差、留香时间短、特征风味不明显等问题，严重制约羊肉香精产业化的发展，因此开发天然、高附加值产品势在必行。本文以羊肉加工副产品的开发利用为目标，在构建羊肉特征风味指纹图谱的基础上，采用酶解技术和调控氧化技术等手段，通过羊骨可控酶解和羊脂定向氧化，开发高品质的天然羊肉香精。主要研究内容如下：采用SPME-GC-MS和GC-O分析技术同时结合聚类分析的方法建立了羊肉特征风味指纹图谱。利用色谱指纹图谱相似度和主成分分析对所建的羊肉风味指纹图谱可靠性进行评定，结果表明利用所建立的指纹图谱信息可以有效评价待测样品与合格样品偏离程度；另外采用PLS-DA方法分别建立了不同种类肉类产品的定性判别模型，不同种类肉类样品分类变量的模型预测值与实测值相关系数均在0.89以上，对检测集样本的识别率为100%。通过对未参与建模的样品进行分析，结果表明利用所建羊肉指纹信息结合PLS-DA判别分析法能有效地检测和准确地判别羊肉和其他肉类产品，同时可以准确的对掺假样品进行识别，为羊肉的品质评价、质量控制及羊肉香精的制备提供科学依据与方法。以水解度和可溶性氮含量为指标，筛选出合适的蛋白酶，通过二次通用旋转回归设计建立了羊骨蛋白Alcalase酶与Flavourzyme酶双酶分步酶解的回归模型。以感官分析为指标，结合GC-MS-O分析，考察不同水解度羊骨蛋白酶解液作为Maillard反应底物对MPF产品的影响，结果如下：以不同水解度羊骨酶解液为前体制备的MPF产品在某一个或几个感官属性相对较强，其中水解度在25.92%的MPF样本表现出明显的羊肉味、肉味和烤香，水解度在30.89%的MPF样本则表现出较高的仿真度和回味感，结果证实水解度在25.92%～30.89%的羊骨蛋白酶解液为前体制备的样品可以产生种类较多的香气活性物质。对选定的36种代表羊肉风味特征风味物质和感官分析数据进行PLSR相关性分析，再次证实水解度在25.92%～30.89%的羊骨蛋白酶解液可作为Maillard反应的最适反应底物，其酶解工艺条件如下：在底物浓度为20%的羊骨粉中，经热处理后降温到55℃，调节pH为8.5，加入3000U/g(蛋白质)的Alcalase酶水解3h～4h，再加入3000U/g(蛋白质)～3500U/g(蛋白质)的Flavourzyme酶，酶解2.5h～3h。对不同氧化条件下获得的羊脂的化学指标（PV、p-AV和AV）和氧化过程中各种挥发性化合物成分的变化进行了研究，结果表明：氧化温度和氧化时间对于羊脂中挥发性化合物种类和含量具有显著影响。利用PLSR分析建立了各种挥发性化合物与化学指标之间的相关性模型，找出了各个化学指标与具体的挥发性成分的显著相关性，掌握了羊脂的氧化规律，为实施羊脂的定向调控氧化提供依据。通过描述性感官分析和GC-MS分析，比较了未氧化羊脂和不同氧化状态羊脂的Maillard反应产品，结果表明，在热反应过程中氧化羊脂对于模拟或加强羊肉特征风味具有重要作用。以不同氧化程度的羊脂为前体制备的羊肉香精产品在某一个或几个感官属性相对较强，通过温和氧化羊脂（S5）制备的羊肉香精（MFS5）表现出明显的羊肉味、肉味、脂肪香和高的仿真度。结合电子鼻响应值、感官分析数据和19种重要化合物的相关性分析确证了温和氧化羊脂作为Maillard反应的前体可以产生羊肉特征风味。温和氧化羊脂的制备工艺条件如下：称取100g羊脂，反应温度为140℃，空气流速为60L/(h·100g)脂肪，氧化3h，此条件下获得的温和氧化羊脂的P.V.、A.V.和p-A.V.分别为287.61meq/kg·羊脂、5.11mgKOH/g、262.52。考察不同反应条件对Maillard制备的MPF的影响，结果表明pH、反应温度和反应时间对于MPF样品整体风味具有显著的影响，过高或过低的pH和反应温度以及过短或过长的反应时间均不利于MPF整体风味的呈香。采用均匀设计实验优化了制备MPF风味基料的模式Maillard反应体系，具体反应配方为：羊骨蛋白酶解液（DH%=25%，底物浓度为20%）100.0g、半胱氨酸1.369g、丙氨酸0.2g、牛磺酸2.5g、硫胺素2.5g、葡萄糖4.0g、HVP1.428g、氧化羊脂（PV287.61meq/kg、p-AV262.52、AV5.11mgKOH/g）12.0g；模式体系反应的最优条件为反应初始pH6.5、反应温度125℃、反应时间180min。该Maillard反应模式体系可以制备出特征风味明显、香气协调的天然高品质的羊肉香精。更多还原

【Abstract】 There are a variety of by-products of lamb (such as bones, tail oil and belly oil).However, the usage of these by-products is single due to lack of technology to producehigh-end products and weak effort to develop products. Currently, domestic mutton flavorsusually feel unnatural and the fragrance can only last for a short time. The characteristicflavor is often not obvious. These issues have seriously limited development of motton flavorsindustry. It is imperative to develop natural and high value added products. This study aims atupgrade of byproducts from mutton processing and tries to develop high quality naturalmutton flavors by processing by-products of mutton (i.e. bones and mutton tallow), such ascontrolled enzymatic hydrolysis of bones and oriented oxidation of mutton tallow foodprocessing technology based on the characteristic fingerprint of mutton flavor. The maincontents of this study are as follows:The characteristic fingerprint of mutton flavor based on SPME-GC-MS, GC-O andcluster analysis was prepared. The reliability of characteristic fingerprint of mutton flavor wasassessed according to similarity of the characteristic fingerprint and principal componentanalysis (PCA). The results showed that the proposed characteristic fingerprint can effectivelyevaluate the deviation of testing sample and qualified sample; in addition, a qualitativediscriminant model for different species of meat was developed by use of PLS-DA method.All correlation coefficients of predicted value and actual value of categorical variable fordifferent species of meat samples were above0.89. The samples were100%recognized.Analysis of samples that were not involved in model establishment showed that characteristicinformation of mutton flavors and PLS-DA discriminant analysis together were able toeffectively detect and accurately discriminate mutton and other meat products. In addition,adulterated samples can also be accurately identified. This study will provide a scientific basisand method for quality assessment of mutton, quality control and preparation of muttonflavors.Proper protease was filtered out according to degrees of hydrolysis (DH) and solublenitrogen content. Quadratic general rotational regression model was established for Alcalase(protease of sheep bones) and flavourzyme. The impacts of hydrolysates of sheep boneprotein (SBPH) with different DHs on mutton process flavors (MPF) products were examinedby sensory analysis and GC-MS-O analysis. The results were as follows: when protein SBPHwith different DHs were used as precursors, one or several sensory attributes were relativelystrong; MPF samples presented obvious mutton flavor and roasted smell at DH of25.92%;when DH was30.89%, MPF samples showed high degree of simulation and aftertaste sense.The experimental results demonstrated that SBPH as precursors can be used to producevarious active aroma substances when the DH was in the range of25.92%-30.89%. PLSRcorrelation analysis was conducted for total of36characteristic lamp flavor compounds andsensory data. The correlation analysis results also indicated that hydrolysates of sheep boneswith hydrolysis degree of25.92%-30.89%were the most appropriate substrate for Maillardreaction. The conditions for enzymatic process were as follows: after thermal treatment, the sheep bone meal (20%) was cooled down to55℃. pH vas adjusted to8.5. Alcalase (3000U/gprotein) was added to hydrolyze for3h-4h. Then, flavourzyme (3000-3500U/g protein) wasadded to hydrolyze for2.5h-3h.Chemical index of mutton tallow oxidation (PV, p-AV and AV) and compositions andcontents of all volatile compounds during thermal oxidation process in different conditionswere studied. The results showed that temperature and duration of oxidation greatlyinfluenced the compositions and contents of volatile compounds in mutton tallow. PLSRmodel was developed for each volatile compound and chemical index. The significantcorrelations between chemical index and specific volatile compounds were identified. Theunderstanding of mutton tallow oxidation process provides basis for oriented oxidationregulation of mutton tallow.Both of non-oxidized mutton tallow and oxidized mutton tallow were involved inMaillard reaction. The products were compared through sensory description and GC-MSanalysis. The results showed that oxidized mutton tallow was important to stimulate orstrengthen characteristic mutton flavor in the course of thermal reaction. The MFSs usingmutton tallow with different degrees of oxidation as precursor were strong in one or severalsensory attributes. MFS5prepared with mildly oxidized mutton tallow (S5) presented obvioustaste of mutton and fat, which was a high degree of simulation. The correlation analysisagainst response of electronic nose, sensory data and19kinds of important chemicals alsoindicated that the mildly oxidized mutton tallow, as precursor of Maillard reaction, cangenerate characteristic mutton flavor. The preparation of mildly oxidized mutton tallow wasas follows:100g mutton tallow was oxidized for3h at140℃with air flow rate of60L/h(h·100g). The P.V., A.V. and p-A.V. of mildly oxidized mutton tallow generated in suchcondition were287.61meq/kg·mutton tallow,5.11mg KOH/g and262.52, respectively.The impacts of different conditions on preparation of MPF by Maillard reaction wereinvestigated. The results indicated that pH, temperature and duration had significant impactson flavor of MPF samples. If the pH and temperature were too high or too low, or reactionduration was too long or too short, it was not conducive to flavor of MPF. In addition,uniform design was adopted to optimize the Maillard reaction system for preparation of MPFsubstrates. The integrants of substrates included: protease hydrolyzate of sheep bone(100.0g), cysteine (1.369g), alanine (0.2g), taurine (2.5g), thiamine (2.5g), glucose (4.0g),HVP(1.428g), oxidized mutton tallow(12.0g, PV287.61meq/kg、p-AV262.52、AV5.11mgKOH/g); The optimal reaction condition is as initial pH of6.5,125℃and180min. ThisMaillard reaction system can be used to prepare natural high-quality mutton flavors withobvious characteristic flavor, which provided reference for development of byproducts frommeat processing.更多还原