Profiles of Organic Acid and Volatile Compounds in Acid-Type Cheeses Containing Herbs and Spices (Surk Cheese)

A study was conducted to evaluate the basic chemical composition, organic acids, volatile compound profiles, and overall acceptability of Surk cheese (acid cheese). The organic acids were determined by reverse phase high performance liqued chromatography method, and volatile compounds were analyzed by static headspace/gas chromatography/mass spectrometry technique. A total of 134 volatile compounds, including 42 esters, 40 terpenes, 15 alcohos, 11 free fatty acids, 6 ketones, 5 aldehydes, 4 alkenes, 4 phenyl propanoids, 3 phenolics, and 4 other compounds, were identified in the Surk cheeses. The main compounds were found to be carvacrol, γ-terpinene, p-cymene, hexanoic acid, octanoic acid, decanoic acid, butanoic acid, and eugenol. The mean total organic acid content of the Surk cheese was 1.71 g/100 g. The main organic acid in the Surk cheese was lactic acid (1067 mg/100 g), followed by acetic, propionic, oxalic, formic, citric, pyruvic, orotic, hippuric, and uric acids.     

Influence of pulsed electric field treatments on the volatile compounds of milk in comparison with pasteurized processing

Effects of pulsed electric field (PEF) treatments on the volatile profiles of milk were studied and compared with pasteurized treatment of high temperature short time (HTST) (75 °C, 15 s). Volatile compounds were extracted by solid-phase micro-extraction (SPME) and identified by gas chromatography/mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O). A total of 37 volatile compounds were determined by GC-MS, and 19 volatile compounds were considered to be major contributors to the characteristic flavor of milk samples. PEF treatment resulted in an increase in aldehydes. Milk treated with PEF at 30 kV/cm showed the highest content of pentanal, hexanal, and nonanal, while heptanal and decanal contents were lower than in pasteurized milk, but higher than in raw milk. All the methyl ketones detected in PEF milk were lower than in pasteurized milk. No significant differences in acids (acetic acid, butanoic acid, hexanoic acid, octanoic acid, and decanoic acid), lactones, and alcohols were observed between pasteurized and PEF-treated samples; however, 2(5H)-furanone was only detected in PEF-treated milk. Although GC-MS results showed that there were some volatile differences between pasteurized and PEF-treated milk, GC-O data showed no significant difference between the 2 samples.     

圆根酸菜风味成分分析

目的 研究川西地区传统圆根酸菜风味成分。方法 采用高效液相色谱和顶空固相微萃取-气相色谱-质谱联用技术测定圆根酸菜的有机酸和挥发性物质。结果 圆根酸菜中共检测出5种有机酸,乙酸和乳酸是主要有机酸。乙酸风味强度值最高,对酸菜呈味贡献最大,其次是乳酸和琥珀酸。此外,苹果酸和柠檬酸也是影响圆根酸菜呈味贡献的重要因素。圆根酸菜中共检测到挥发性物质263种,主要包括酮类、酯类、醛类、酸类和醇类。44种挥发性物质是所有样品共有的,占挥发性物质含量的76.07~88.19%。5-羟甲基糠醛和4-丙基苯酚是主要的挥发性物质,分别占挥发性物质含量的33.4%和28.1%。结论 该研究结果为提升圆根酸菜的风味和品质提供一定的理论依据。     

Fermentation Quality Characteristics and Flavor Formation Changes During the Process of Pickled Wax Gourd in Eastern Zhejiang

Using pickled brine as samples of natural pickled wax gourd at different stages of 0, 5, 10, 15, and 20 d, respectively, pH value, reducing sugar content, number of lactic acid bacteria and total bacteria, as well as organic acid content and volatile components, were investigated in this study. As a consequence, the lactic acid and acetic acid concentration increased with the decreasing of pH and sugar exhaustion through the pickling process. A total of 60 kinds of volatile compounds were detected, including 12 alcohols, 6 acids, 11 aldehydes, 12 ketones, 4 esters, 6 silicones, and 9 other compounds. At the end of 20 days fermentation, the abundant volatile compounds were identified including alcohols (47.58%), acids (36.00%), and esters (5.94%), with the highest content of acetic acid (27.97%), followed by ethanol (23.69%). The contributions of these compositions were clarified by electronic nose technology method combined with principal components analysis.     

云南不同地区玛咖挥发性成分的GC-MS分析

采用顶空固相微萃取技术对玛咖中挥发性成分进行富集,用气相色谱-质谱联用技术对其化学成分进行分离和鉴定,在云南8 个种植区玛咖样品中共检出挥发性成分69 种,共有的挥发性成分有18 种。这些成分包括酮类12 种、醛类10 种、醇类9 种、酸类7 种、酯类6 种、烯烃类6 种、杂环化合物5 种、腈类4 种、芳香族类4 种、酚类3 种、胺类2 种、硫醚类1 种。含量较高的挥发性成分是异硫氰酸苄酯、苯甲醛、苯乙腈、乙酸、苯甲醇、二甲基硫醚、3-甲氧基-苯甲醛、4-甲氧基苄基异硫氰酸酯。通过统计比较发现了云南8 个不同种植区玛咖挥发性成分存在的差异。     

Effect of ultra-high-temperature steam injection processing on sulfur-containing amino acids in milk

Raw skim milk was processed by a modified No-Bac Unitherm IV System (Cherry-Burrell Corp.) at 143 C for 8 s, vacuum cooled to 71 C, collected, and cooled to 4 C. Raw and ultra-high-temperature processed skim milks were oxidized with performic acid, hydrolyzed with hydrochloric acid, and analyzed for cysteine and cystine (as cysteic acid) and methionine (as methionine sulfone) on a Beckman Automatic Amino Acid Analyzer. A loss of approximately 34% of these amino acids was observed in ultra-high-temperature processed skim milk. Sulfhydryl and disulfide groups determined with Ellman's reagent [5,5'-dithiobis(2-nitrobenzoic acid)] indicated no free sulfhydryls in raw skim milk and .07 mmole per liter in ultra-high-temperature processed skim milk. Loss in total sulfhydryl and disulfide groups was approximately 16% in ultra-high-temperature processed milk. Volatile sulfur compounds were detected by odor in the vapor collected from the vacuum chamber, but they could not be identified. Amino acid analysis of milk deposit collected from the injection section revealed .09 microgram of cysteine and cystine (as cysteic acid) per gram of deposit and no detectable methionine.     

牦牛乳软质干酪成熟期挥发性风味成分分析

采用固相微萃取- 气相色谱- 质谱联用(SPME-GC-MS)对不同成熟时期(30、60、90d)牦牛乳软质干酪挥发性风味物质进行分离鉴定,共检测出45 种化合物,并用峰面积归一化法确定各种化合物的相对百分含量。通过对固相微萃取纤维头和萃取温度的筛选优化实验条件,采用75μm CAR/PDMS(碳分子筛- 聚二甲基硅氧烷)萃取纤维头,50℃条件下吸附不同成熟时期(30、60、90d)干酪的挥发性风味物质效果较好。检测出的挥发性风味物质主要是酸类、醇类、酮类,其次为酯类和醛类化合物,酸类物质构成了牦牛乳软质干酪的主体特征风味。乙酸、丁酸、己酸成为干酪中的优势风味物质。     

SAFE-GC-MS分析酸牛奶挥发性成分

采用溶剂辅助风味蒸发法萃取原味酸牛奶挥发性成分,利用气相色谱-质谱联用法结合保留指数、标准品对照对挥发性成分进行定性分析,采用面积归一化法加邻二氯苯作内标定量,共鉴定出挥发性成分52 种,其中酸12 种、醛2 种、酮5 种、醇2 种、酯3 种、内酯2 种、烯烃4 种、烷烃17 种、其他5 种。其中,对酸牛奶风味影响较大的可能有乙酸、丁酸、己酸、辛酸、癸酸、9-癸稀酸、乙偶姻、2-壬酮、2-十一酮、壬醛、香兰素、3-甲基-2-丁烯-1-醇、十六硫醇、丁位癸内酯、丁位十二内酯等。     

基于化学分析和智能感官方法对不同产地川醋特征风味物质的比较分析

研究通过化学分子分析和智能感官等方法对四川不同产地晒醋品质进行比较分析。采用氨基酸自动分析仪、高效液相色谱（HPLC）、固相微萃取气相色谱与质谱联用（SPME-GC-MS）等化学分析方法对样品氨基酸、有机酸、挥发性有机物（VOCs）的种类和含量进行测定分析。通过感官评价,利用电子鼻、电子舌等智能感官结合主成分分析（PCA）和聚类分析（CA）进行表征。结果表明,四种川醋pH3.08～3.29,总酸度16.40%～18.07%,色泽中a*和b*有显著差异（P<0.05）;共检出17种氨基酸,其中,丙氨酸和谷氨酸含量最高;测定乙酸、酒石酸等9种有机酸,总含量在22.44～70.06 mg/mL,其中,乙酸和乳酸占总有机酸的50%以上,自贡醋样品的有机酸含量最高（70.06 mg/mL）;共检出150多种挥发性有机化合物,其中,酸类（21.56%～44.34%）含量最丰富,眉山醋样中酯类和苯二氮类化合物等种类和相对含量较高;电子鼻、电子舌PCA的前两个主成分之和超过累计方差的98%,电子鼻CA分析显示自贡和眉山醋样差异较大,可能与其感官评价中的涩味及挥发性有机物中酮类、杂环类等的数量有关,电子舌CA分析显示自贡与眉山和南充醋样差异较大,则可能是由pH、总氨基酸、必需氨基酸、有机酸和总酸的差异引起的。通过化学分析、感官分析、智能感官评价结合化学计量法,可以用来表征样品因原料、工艺、配方等因素引起差异的相关性。本研究为建立可靠的中国食醋风味表征提供实用参考,为食醋质量和真实性评价提供了有效依据。     

完全发酵与适度发酵苹果醋主要成分的差异性分析

研究苹果醋分别采用适度发酵和完全发酵时主要成分及芳香物质种类和含量的差异性。采用福林-酚法、高效液相色谱法、固相微萃取结合气相色谱-质谱联用分别测定2种发酵方式苹果醋中总酚、有机酸含量和芳香成分。结果表明,适度发酵苹果醋总酚含量比完全发酵高21%;2种果醋的有机酸种类完全一致,但适度发酵法中的酒石酸、柠檬酸和富马酸含量更高,而丙酮酸、苹果酸、α-酮戊二酸、乳酸、乙酸和琥珀酸的含量则略低于完全发酵的醋样。适度发酵苹果醋芳香物质种类更丰富,检测到37种芳香成分,其中保留了不少原果香气,如香茅醇、橙花醇、乙酸丁酯、乙酸-4-甲基-3-己酯和乙酸二甲基丁酯等。适度发酵可减少苹果醋总酚的损失,同时保留了更多的苹果原香物质,是值得探索改善苹果醋品质的途径。     

顶空固相微萃取-气相色谱-质谱联用法分析山楂果醋易挥发成分

采用顶空固相微萃取和气相色谱-质谱联用法对山楂果醋易挥发性成分进行提取分析,通过与NIST 05 a.L谱库比对,鉴定得到各个组分,应用峰面积归一化法测定各成分的相对含量。共分离得到49 种化合物,结构鉴定出36 种化合物,占总易挥发成分总量的98.91%,对山楂果醋易挥发性成分贡献较大的依次是：酯类化合物11 种,占40.12%;酸类化合物6 种,占33.63%;醇类化合物11 种,占21.79%。此外,醛类化合物1 种,占0.05%;酮类化合物2 种,占0.57%;其他类5 种,占1.55%。初步确定乙酸、乙酸乙酯、乙醇、乙酸-3-甲基丁酯、苯甲酸乙酯、3-甲基丁醇、己酸乙酯、己酸、苯甲酸、乙酸-1-甲基丙酯、2-丁醇、苯乙醇、辛酸、2-甲氧基-4-甲基苯酚是山楂果醋的主要香气成分。以期为山楂果醋的香气特征研究提供科学依据,为山楂果醋品质感官评价体系的建立和山楂果醋产业发展提供参考。     

UHT热处理对牛奶中风味物质的影响

结合固相微萃取(SPME)及气相色谱-质谱(GC-MS)研究UHT热处理后牛奶的风味变化,并与原料牛乳风味特征进行对比。结果表明:新鲜原料乳中可以检测到50种挥发性风味物质,其中酸类最多,其他还包括醛,醇,酮,酚,酯等。牛乳经过137℃,4 s加热杀菌后,挥发性风味物质有75种,除上述风味化合物外,酯类和酮类数量明显增加,其中甲基酮,3-羟基-2-呋喃酮,δ-癸内酯,γ-十二内酯是UHT乳中重要挥发性风味物质,对形成UHT乳特有风味起重要作用。     

黄酒生产过程中浸米浆水有机酸含量变化研究

本研究以黄酒生产过程中的糯米浸米浆水产生的有机酸含量为主要研究对象,建立了离子色谱分离电导检测法测定浸米浆水中有机酸的含量,并利用该方法研究了不同产地、包装方式以及浸米时间等因素对糯米浸米浆水中有机酸含量的影响。结果表明:离子色谱分离电导检测法具有良好的线性(R²≥0.9995)、检出限(≤0.1037 mg/L)、回收率(90.23%~97.43%)和重复性(RSD≤3.76%)。不同产地的糯米浸米浆水产生的有机酸含量存在差异,江苏糯米产有机酸含量高于吉林糯米。不同包装方式对有机酸含量有很大的影响,包装糯米有机酸含量明显高于散装糯米。随着浸米时间的延长,米浆水中的有机酸的含量均呈先增长后下降的趋势,浸米温度控制在20~22 ℃时,五种有机酸峰值含量分别为:乳酸10746.03 mg/L,乙酸237.31 mg/L,甲酸17.26 mg/L,苹果酸31.32 mg/L,草酸1706.82 mg/L。     

Volatile Compounds and Chemical Changes in Ultrapasteurized Milk Packaged in Polyethylene Terephthalate Containers

The volatile compounds profile and chemical stability of ultrapasteurized 2% milk bottled in amber polyethylene terephthalate (PET) were studied along with its shelf life of 60 d at 5 °C. Identification of volatile compounds using a solid‐phase microextraction (SPME) technique with gas chromatography‐mass spectrometry was performed in situ in the commercial product. Chemical stability was determined by measuring dissolved oxygen, free sulfhydryl groups, ascorbic acid, and headspace oxygen. The classes of volatile compounds identified were ketones, aldehydes, hydrocarbons, fatty acids, alcohol, and miscellaneous compounds. Volatile compounds found consistently during the storage period were 2‐heptanone, methoxy‐phenyl‐oxime, decane, 1‐ethyl‐2,4‐dimethyl‐benzene, D‐limonene, 2‐nonanone, octanoic acid, dodecane, and 4‐(1,1,3,3, ‐tetramethylbutyl) phenol. Possible products of lipid oxidation, such as hexanal, octanal, and nonanal, were also positively identified. Chemical stability of PET‐bottled milk was demonstrated by the insignificant changes in pH or TA, with the exception of ascorbic acid concentration, which degraded in the product at 60 d of refrigerated storage. Sensory evaluation of the milk samples revealed that there is no noticeable oxidized or rancid off‐flavor at 60 d of storage.     

11 种保健酒中挥发性成分的分析

采用硅胶柱层析法结合气相色谱-质谱联用仪,对中国劲酒、竹叶青酒、张裕至宝三鞭酒、椰岛海王酒等11 种保健酒中的挥发性成分进行了分析,并通过标准品比对和NIST 11谱库检索进行了定性、定量研究。结果表明：11 种保健酒中共鉴定出37 种化合物,醇类6 种、烃类12 种、酯类9 种、醛类4 种、酸类2 种、酮类2 种、含氮化合物和酚类化合物各1 种,其中含量较大的成分有1-丙醇、2-甲基-1-丙醇、3-甲基-1-丁醇、乳酸乙酯、柠檬酸三乙酯、5-羟甲基糠醛和乙酸;通过内标法,对11 种保健酒中的乳酸丙酯进行了定量分析,线性回归方程为y =1.059 3x＋0.01（r=0.995）,含量范围在0.02～0.74 mg/L之间。检出限为0.005 mg/L ,定量限为0.01 mg/L。使用MATLAB 7.0软件,对中国劲酒、阳春牌滋补酒、沱牌枸杞酒以及椰岛海王酒、张裕至宝三鞭酒和竹叶青的挥发性成分进行了进行单因素方差分析和帕累托分析,结果表明：6 种酒样中烃类化合物的含量具有显著性差异;重要挥发性成分有3-甲基-1-丁醇、1-丙醇、2-甲基-1-丙醇、2-丁醇、5-羟甲基糠醛、丁香酚、乳酸乙酯、己酸乙酯、乙酸异戊酯、乙酸苯乙酯、癸酸乙酯、柠檬酸三乙酯、糠醛、肉桂醛、乙酸、苯乙烯、十四烷、十五烷、十六烷、1,4-二甲基苯、二苯胺。     

酸浆豆腐后熟过程中风味物质的形成途径分析

采集不同后熟阶段的酸浆豆腐为样本，对其游离氨基酸、有机酸、挥发性风味物质进行测定。结果显示，游离氨基酸和有机酸是滋味物质的主要来源，其中酸味氨基酸是主要的呈味物质，在不同的后熟阶段占总氨基酸的33%～35%。后熟过程中乳酸、乙酸和柠檬酸3 种有机酸是主要呈味物质且含量最高，其总量约占有机酸总量的50.08%～65.00%。后熟过程中共检测到84 种风味化合物，包括醛类、醇类、酚类、呋喃类等化合物，共同赋予酸浆豆腐独特的酵香风味。     

烘干温度对大枣香气成分及理化指标的影响

为比较不同烘干温度条件下大枣香气成分的变化,采用气相色谱-质谱-嗅觉(gas chromatography-mass spectrometry-olfactometry,GC-MS-O)测量法对80~160℃烘干大枣的香气成分进行分析鉴定,并对不同烘干温度条件下大枣的总糖、还原糖、氨基酸及色泽变化进行分析。结果表明:GC-MS-O共鉴定出99种物质,其中经嗅觉测量法检测出61种。典型的随温度升高相对含量逐渐升高的物质为糠醛、5-甲基呋喃醛、5-羟甲基糠醛、2,3-二氢-3,5-二羟基-6-甲基-4H-吡喃-4-酮、糠醇、2-乙酰基呋喃、3,5-二氢-2-甲基-4H-吡喃-4-酮、4-环戊烯-1,3-二酮。酸类物质如醋酸、2-甲基丁酸、正己酸、正庚酸、羊脂酸、苯甲酸、正癸酸、月桂酸随温度升高相对含量逐渐降低。糖与氨基酸含量随温度升高逐渐降低,色差指数表明当温度超过140℃时,大枣褐变反应剧烈,会产生焦糊。     

核桃分心木水提液易挥发性成分分析

利用4 种不同萃取特性的萃取头,对核桃分心木水提液中易挥发性成分进行萃取,并在HP-5（弱极性）和RTX-WAX（强极性）2 种色谱柱上分离,采用顶空固相微萃取和气相色谱-质谱（gas chromatography-massspectrometry,GC-MS）联用法进行分析,并讨论不同色谱柱和萃取头对分析其易挥发性成分的影响。结果表明：选用不同萃取特性的萃取头,在不同极性色谱柱上分离,经GC-MS分析,共得到结构确定的化合物115 种,其中醇类化合物21 种、酯类化合物18 种、酮类化合物15 种、芳香族化合物14 种、烃类化合物13 种、醛类化合物12 种、酸类化合物6 种、酚类化合物5 种、醚类化合物2 种、其他类型化合物9 种。主要易挥发性成分是乙酸、乙酸乙酯、2,6-二叔丁基-4-甲基苯酚、薄荷醇、雪松醇、2,3-丁二醇、1-己醇、苯乙醇、3-叔丁基-4-羟基苯甲醚、己醛、甘菊蓝。     

骏枣果醋发酵过程中营养品质变化及风味成分分析

以骏枣果酒为原料发酵果醋,对发酵过程中营养品质指标变化及发酵前后挥发性成分进行比较研究。结果表明,36～72 h期间为发酵产酸的主要时期,发酵过程中共检测到醋酸、草酸、柠檬酸、乳酸、琥珀酸、苹果酸6种有机酸,发酵后果醋中醋酸和琥珀酸含量分别为发酵前的15倍和3.7倍,乳酸和草酸含量则显著性降低,总酸味强度是果酒的6.17倍。发酵过程中总酚含量不断下降,维生素C含量先下降后趋于稳定,DPPH自由基清除率和总抗氧化能力显著升高。醋酸发酵前后共检测到挥发性成分65种,其中果醋检测到39种,相比果酒减少8种,果醋中酯类物质相对含量最高为37.42%,其中乙酸乙酯和乙酸异戊酯为主要的酯类物质,其次是酸类物质相对含量为30.69%。