【作者】 夏玲君；

【导师】 宋焕禄；

【作者基本信息】 北京工商大学 ， 生物化工， 2007， 硕士

【摘要】 本论文以牛肉蛋白酶解液为基础,与氨基酸、还原糖等物质进行Maillard反应制备风味良好的牛肉香精。然后采用国际先进的香味分析技术GC-O (gas chromatography-olfactometry,气相色谱-吸闻),对其香成分进行分析,以鉴别其中的香味活性化合物。同时,采用稀释技术AEDA (aroma extract dilution analysis,香味提取物稀释分析)筛选其关键芳香化合物。选择Flavourzyme(F)和Protamex(P)组合酶对牛肉蛋白进行酶解,酶与底物质量比为3‰,底物浓度为40%,通过正交设计安排酶解实验,得到其最佳工艺条件为:酶解温度55℃,pH 6.0,F:P为1:2。由于酶解度最大的酶解液不一定能使Maillard反应产生好的风味,因而决定选择酶解不同时间的酶解液进行Maillard反应。经过预备实验选取合适的还原糖、氨基酸、不同酶解时间的酶解液及其它原料安排正交实验,以评香员的评分结果,确定Maillard反应的最佳配方为:酶解液酶解时间3.75h,酶解液添加100g ;半胱氨酸(盐酸盐) 0.5g;I+G 0.2g;VB1 1.0g;盐2.0g;丙氨酸0.5g;木糖0.5g;蛋氨酸0.5g;葡萄糖1.0g;脯氨酸1.0g;酵母膏10.0g;甘氨酸2.0g ;丝氨酸1.0g;反应温度110℃;反应时间60min。然而,由此配方得到的牛肉香精牛肉特征味并不十分强烈,考虑脂肪对于肉类特征味的形成有重要的作用,通过单因素实验确定加入15.0g牛脂,从而得到香味柔和、特征味比较浓郁的牛肉香精。GC-O是目前香成分分析中广泛使用的技术,国外已有几十年的发展历史,但在国内该技术尚未见报道。本文利用三种前处理技术即SDE(simultaneous steam distillation/extraction,同时蒸馏提取)、SPME(solid-phase microextraction,固相微萃取)和DHS(dynamic headspace sampling,动态顶空制样)提取牛肉香精的香成分,然后采用GC-O技术进行检测分析。从该牛肉香精香成分中检测到包括醛类、酮类、呋喃类、噻唑类、吡嗪类、酯类等70种香味活性化合物,其中至少在2种方法中都检测到的香味活性化合物有25种。SDE-GCO(同时蒸馏提取物-吸闻)共检测到32种香味活性化合物,SPME-GCO(固相微萃取-吸闻)共检测到23种香味活性化合物,DHS-GCO(动态顶空制样-吸闻)共检测到48种香味活性化合物。从检测结果可以看出DHS-GCO检测到最多的香味活性化合物,这种方法在香成分提取分析中具有优势,所提取的香味化合物能够很好地代表食品的原始香味。不过,将三种方法的检测结果结合起来才能更全面地了解该牛肉香精中的香味活性化合物。AEDA技术是GC-O方法中一种常用的稀释技术,本文采用该技术来鉴别牛肉香精中的关键芳香活性化合物。在SDE-GCO、SPME-GCO、DHS-GCO这三种方法中都鉴别到2-甲基-3-呋喃硫醇、3-甲硫基丙醛、2-呋喃甲硫醇具有最高的FD因子,这3种化合物在相关牛肉香气的文献报道中也被鉴定具有高的稀释因子,是该牛肉香精中对整体香味作出重要贡献的关键芳香活性化合物。此外,其它一些具有肉香、硫香、蘑菇香、爆米花香的醛类、酮类、含硫类、含氮类香味活性化合物也被鉴别出具有高的FD因子,是该牛肉香精中比较重要的香味化合物。香味活性化合物甲基丙基二硫化物、甲基烯丙基二硫化物、3-巯基-2-丁酮、噻唑、丁醇、2,3,5,6-四甲基吡嗪、1-壬烯-3-酮、(E,E)-2,4-庚二烯醛、2-甲基丁酸乙酯、2-戊基呋喃、2-十一烯醛都是首次利用GC-O技术在牛肉香成分中被鉴别出来的。在本文中以GC-O技术为创新点,进行了牛肉香精制备及其香成分检测分析的一系列工作,旨在为风味分析提供一些参考,以使该技术能在国内风味分析领域得以推广。更多还原

【Abstract】 This paper depended on enzymatic hydrolysates of beef protein, amino acid and reducing sugars to prepare flavoring whose aroma was closed to the natural beef aroma via Maillard reaction. For the selection of aroma-active components from this beef flavoring, a valuable analytical method gas chromatography-olfactometry(GC-O) was used. Then, the key aroma compounds were screened by aroma extract dilution analysis (AEDA).The enzymatic experiments were arranged by orthogonal designs to seek the best enzymatic conditions. Protamex and Flavorzyme were screened to hydrolyte beef protein. E/S was 3‰, the most suitable enzymatic conditions were determined as follows: temperature was 55℃, pH was 6, F:P was 1:2. Since the enzymatic hydrolysates with the highest DH were not actually suitable for the Maillard reaction to product the best flavoring, enzymatic hydrolysates with different DH were used in the Maillard experiments. According to the sensory evaluation of the flavorings, the best conditions of Maillard reaction were found. The results was as follows: the enzymatic time 3.75h,enzymatic hydrolysates 100.0g ; Cys 0.5g; I+G 0.2g; VB1 1.0g; NaCl 2.0g;Ala 0.5g; Xylose 0.5g; Met 0.5g; Glucose 1.0g; Pro 1.0g; YE 10.0g; Gly 2.0g ; Ser 1.0g; reaction temperature 110℃; reaction time 60min; but the characteristic aroma of the beef flavoring was not strong, so some beef tallow was necessary. 15.0g beef tallow was determined to add the Maillard reaction system.. In the paper, aroma extracts were prepared by SDE (simultaneous steam distillation/extraction), SPME (solid-phase micro-extraction) and DHS (dynamic headspace sampling) and then analyzed by GC-O. GC-O was a useful and powerful tool for research food aroma, but hardly used in the homeland. 70 odor-active compounds were found in the beef flavoring, and 32 odor-active compounds were identified by SDE-GCO, 23 odor-active compounds were identified by SPME-GCO and 48 odor-active compounds were detected by DHS-GCO. Application of DHS-GCO obviously identified more aroma compounds, but the combination of these three methods would get the comprehensive results.GC-O based on AEDA was applied for the identification of key aroma compounds. The highest FD factors were found for 2-methyl-3-furanthiol, 3-methylthiopropanal and 2-furanmethanethiol. These three aroma components were identified with the highest FD factors in the application of all prepared methods. They were the key aroma compounds in the beef flavoring, and had been reported as the key aroma compounds in the references related to beef aroma. Some aldehydes, ketones, sulfur-containing compounds also had high FD factors. All of these compounds played an important role in the overall aroma of this beef flavoring.Aroma-active components methyl propyl disufide, 3-mercapto-2-butanone, ethyl-2-methylbutyrate, allyl methyl disulfide, thiozale, butanol, 1-nonen-3-one, 2,3,5,6-tetramethylpyrazine, (E,E)-2,4-heptadienal, 2-undecenal and 2-pentylfuran were all identified for the first time in beef aroma by GC-O.更多还原