动物饲用高产蛋白酵母菌株培养条件的优化

采用正交试验法,对动物饲用高产蛋白酵母菌的生长条件进行了研究,探讨了温度、pH值、蔗糖质量浓度、装液量对酵母菌生长的影响。并测定酵母在自然pH值条件下、蔗糖质量浓度20 g/L,装液量2/5,培养条件30℃,摇床转速180 r/min的生长曲线。结果表明,对筛选酵母在30℃,pH值为6.5,蔗糖质量浓度20 g/L,装液量在100 mL/250 mL的条件下生长较优。其中温度为影响生物量的主要因素。通过对酵母生长曲线的测定得出筛选酵母的对数生长期在6～16h,之后逐渐达到稳定期。利用血细胞计数板方法对在优化条件下培养48 h的酵母菌进行计数,含酵母1.09×1010个。与市售酵母菌数相比基本一致。     

中空纤维膜分离酵母提取液中活性成分的初步研究

以啤酒废酵母为原料,研究了中空纤维膜(微滤和超滤)分离酵母提取液中活性成分的工艺.基于超滤机理分析了操作压力、温度、pH值和料液浓度对膜通量的影响,得到超滤工艺最佳条件:压力为0.105MPa,温度、pH值和料液浓度分别为24℃、6.0、3.0%.在此条件下,膜通量为18.42 L/m2·h,海藻糖透过率为96.36%,蛋白质截留率为94.50%.经高效液相色谱(HPLC)验证,实现了酵母提取液中活性成分的分离.     

酱醪生香酵母的选育及其生长动力学研究

该研究从酱醪中筛选耐盐生香酵母，结合形态学观察、生理生化试验及分子生物学技术对其进行鉴定及耐盐性分析，采用单因素试验及响应面试验对其培养条件进行优化，并对其生长动力学进行研究。结果表明，筛选获得一株耐盐生香酵母(编号为Flae04)，经鉴定为鲁氏接合酵母(Zygosaccharomyces rouxii)，该菌株可耐受20%的盐浓度；其最适培养条件为接种量1%，初始pH值5.7，培养温度28℃，培养时间48 h，转速181 r/min。在此优化条件下，酵母Flae04的细胞数为3.33×10⁸ CFU/mL；基于Logistic方程与类LuedekingPiret方程分别建立细胞生长动力学模型和底物消耗动力学模型，相关系数R2分别为0.997和0.995，说明试验值与模型拟合良好，表明所建模型能较好的反映该酵母分批培养的生长规律。     

酱醪中产香酵母菌筛选及用于低盐固态发酵酱油增香研究

从天然发酵酱醪中分离筛选到一株产香酵母JM01,经鉴定为球拟酵母属的球形球拟酵母.研究了该菌的耐盐性,在16%氯化钠麦芽汁培养基中JM01生长良好,细胞数可达108个/mL.并研究了该菌在低盐固态发酵酱油中生长特性,发现其最适生长条件:温度25℃～ 28℃,pH值为4.5～5.5,接种量4%(v/v),葡糖糖添加浓度4%(w/v),该条件下摇瓶发酵30h～33h制得JM01种子液.根据JM01生长特性,确定了生酱油增香工艺操作要点.增香发酵后酱油酯香、醇香浓郁,风味得到了极大的改善.     

一株有氧条件下高产乙醇酵母的筛选、鉴定及其生物学特性研究

采用平板涂布法从老白干香型大曲中获得一株有氧条件下高产乙醇酵母菌株,命名为YF1914。通过菌落形态、细胞显微结构、生理生化特性和26S rDNA D1/D2区方法对其进行鉴定,借助液体培养方式考察其乙醇耐受性、葡萄糖耐受性、乙酸耐受性、生长温度和pH等生物学特性。结果表明,该菌株为酿酒酵母(Saccharomyces cerevisiae)属于乙醇高耐受性酵母,耐受乙醇最高体积分数为18%,同时还具有较高的NaCl和葡萄糖耐受性,最高耐受质量分数分别为15%和80%,在温度为20~50 ℃和pH1~10能够生长,具有宽广的温度和pH适应性。综上,该酵母这些优良特性有利于其在未来白酒酿造方式变化中发挥作用。     

啤酒酵母发酵产有机酸的生理代谢机制

以微波破壁和高效液相色谱法,对通风发酵过程中的啤酒酵母细胞胞外、胞内六种有机酸含量的动态变化进行了跟踪检测。研究结果表明,酵母细胞对一部分有机酸有着非常亲缘性的代谢途径和生理机制;柠檬酸等某些有机酸在酵母细胞衰老凋亡时作为碳底物代谢,存在着非常严格的精确保守性、经济效能性调控机制。     

高产RNA酿酒酵母培养条件及发酵培养基的优化

RNA是食品工业鲜味物质酵母抽提物的重要鲜味成分。以酿酒酵母J-5为试验菌株,以菌株细胞内RNA积累量和生物量为指标,通过单因素试验和正交试验对高产RNA酿酒酵母基础发酵培养基的碳氮磷源成分进行优化,同时对摇瓶培养条件进行了优化。结果得到最优发酵培养基配方为:葡萄糖5%,酵母浸粉1%,(NH4)2SO41.5%,KH2PO40.2%。最佳培养条件为:初始pH 5.0,培养温度30℃,转速为200r/min。在此培养基上生长,菌体RNA积累量提高到12.6%以上,细胞干重超过12.2g/L。     

超声波辅助提取青梅有机酸及其成分分析

利用超声波技术提取青梅中的有机酸,在探究超声温度、超声时间、料液比及超声功率对提取总有机酸得率影响的基础上,用正交试验优化得到最佳工艺;并对比超声波辅助提取液与乙醇回流提取液中,有机酸种类、含量以及香气成分的差异。结果表明,超声波辅助提取最佳条件为:超声温度70℃,超声时间20 min,料液比1∶15(g/mL),超声功率320 W,在此条件下青梅果肉(干重)总有机酸得率为35.07%;采用高效液相色谱(high-performance liquid chromatography,HPLC)测定提取液中8种主要有机酸含量,与乙醇回流法相比,苹果酸、柠檬酸、酒石酸、乳酸和乙酸显著提高;对提取液的香气成分进行气相色谱-质谱(gas chromatography-mass spectrometry,GC/MS)分析表明,青梅有机酸提取液特征香气成分为酸类物质,与乙醇回流相比,超声波提取青梅特征香气成分的提取率和保留率显著提高。     

天然酱醪中产β-苯乙醇酵母菌的分离鉴定、发酵条件优化及其应用

为了提升酱油品质,开展筛选产β-苯乙醇的酵母菌,并应用在高盐稀态发酵酱油酿造的研究。从天然酱醪中筛选出产β-苯乙醇的酵母菌株J13,对其进行形态学观察、生理生化实验及分子生物学鉴定,通过耐盐性、pH耐受性及温度耐受性分析研究Z. rouxii 13的生物学特性,并采用单因素和正交试验对培养基成分及发酵条件进行优化,在最优发酵条件下培养Z. rouxii 13,获得风味液并应用到高盐稀态发酵酱油的酿造工艺中。结果表明,J13鉴定为鲁氏接合酵母（Zygosaccharomyces rouxii）,并命名为Z. rouxii 13,能在含盐量较高（18%NaCl）条件下生长,最适pH为4～8及最适温度为20～35℃,其产β-苯乙醇的最优发酵条件为：L-苯丙氨酸4 g/L、葡萄糖30 g/L、蛋白胨10 g/L、硫酸镁0.5 g/L、磷酸氢二钾5 g/L、NaCl 50 g/L、pH6.0,温度28℃,在此条件下β-苯乙醇含量达到1.40 g/L。该风味液用于酱油酿造获得成品的感官评定结果表明,相比不添加风味液的空白对照组,风味液组的酱香和醇厚感更突出,鲜味及整体评价更佳。     

胞内pH法评价酵母活性的研究

酵母细胞内pH与酵母生长和发酵状况密切相关，用胞内质子的释放能力可以衡量酵母细胞的生理状态。为了测定质子在酵母生理条件下的释放能力．在较低pH下，利用荧光法来测量胞内pH，简称ICP法。通过发酵试验证明，ICP法对于准确地评估啤酒生产过程中酵母细胞活性的细微区别，是非常有效的。     

Effect of drying and proline addition on aroma volatile compounds of acid‐hydrolysed rice bran protein concentrate

Rice bran protein concentrate (RBPc) was hydrolysed by 0.5 N aqueous HCl at 95 °C for 12 h. The liquid hydrolysate obtained was prepared as hydrolysate powder by spray drying. Aroma volatile compounds in liquid hydrolysate and its hydrolysate powder were tentatively identified by GC‐MS. Furfural and vanillin were found in both hydrolysates with high concentration, and vanillin showed the highest odour activity value. Hexanal was present in only liquid hydrolysate. Concentrations of carboxylic acids and heterocyclic compounds, especially 2‐methoxy‐6‐methylpyrazine, increased after drying. Amino acid composition of the hydrolysate powder showed high aspartic acid and glutamic acid. Aroma volatile compounds of hydrolysate powder prepared by the addition of proline at pH 6.0 (Pro6.0‐H) and pH 7.5 (Pro7.5‐H) before drying were investigated. Furaneol was found only in Pro6.0‐H, but it was not detected in Pro7.5‐H and hydrolysate powder without proline addition. Pro7.5‐H had higher furfural and vanillin concentrations than Pro6.0‐H.     

Characterization of volatile compounds and organic acids in ultra-high-temperature milk packaged in tetra brik cartons

A study was conducted to evaluate the basic chemical composition, organic acids and volatile compound profiles of ultra-high-temperature milk samples sold in Turkey. The organic acids were determined by reverse-phase high-performance liquid chromatography method, and volatile compounds were analyzed by headspace solid phase micro-extraction/gas chromatography/mass spectrometry technique. A total of 43 volatile compounds including 4 aldehydes, 5 alcohols, 10 ketones, 9 acids, 9 aromatic hydrocarbons, 3 nitrogenous, 2 sulfur containing compounds, and 1 alkane hydrocarbon, were identified in the ultra-high-temperature milk samples. The main compounds were found to be oxime methoxy phenyl, 2-heptanone, 2-mercapto-4-phenylthiazole, 2-amino-5-ethoxycarbonyl benzophenone, acetic acid, 2,6,10,14-tetramethyl pentadecane, and 2-nonanone. The main organic acid in the ultra-high-temperature milk was citric acid a mean value of 133 mg/100 mL, followed by formic, lactic, succinic, oxalic, acetic, orotic, propionic, pyruvic, hippuric, and uric acids.     

美拉德反应对金枪鱼红肉酶解液挥发性物质和游离氨基酸的影响

为了高值化利用金枪鱼红肉这一蛋白质资源,利用气相色谱-质谱联用(GC-MS)和高效液相色谱(HPLC),研究美拉德反应对金枪鱼红肉酶解液挥发性物质和游离氨基酸的影响。GC-MS结果表明,金枪鱼红肉酶解液中共检测出19种挥发性化合物,其中未加热的酶解液中有10种,而经过不同时间(30、60和90 min)加热的酶解液中,分别检测出12种、15种和15种,其中呋喃类物质的含量随反应时间延长显著增加。HPLC分析表明,随着加热时间的增加,酶解液中呈味氨基酸总量均上升,但是鲜味和甜味氨基酸的比例呈下降趋势,苦味氨基酸则呈上升趋势。表明,美拉德反应赋予酶解液更加丰富的风味的同时,却使其呈现更多的苦味。     

固相微萃取技术(SPME)分析羊奶中挥发性化合物

采用固相微萃取技术(SPME)提取羊奶中的挥发性化合物,经气相色谱质谱联用仪进行测定分析,实验结果表明,羊奶中挥发性化合物共检测到42种,主要成分为挥发性脂肪酸,酯类、醇和酮类,还含有一些其他挥发性化合物.其中挥发性脂肪酸有10种,主要由短链脂肪酸和中等长度碳链脂肪酸组成.酯类物质有16种,主要包括邻苯二甲酸二丁酯、邻苯二甲酸二乙酯、14-甲基一十五酸甲酯和己二酸二(2-乙基)乙酯等.另外挥发性醇类和酮类物质共7种,其它挥发性化合物9种.     

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.     

Effect of phenolic acids on glucose and organic acid metabolism by lactic acid bacteria from wine

The influence of phenolic (p-coumaric, caffeic, ferulic, gallic and protocatechuic) acids on glucose and organic acid metabolism by two strains of wine lactic acid bacteria (Oenococcus oeni VF and Lactobacillus hilgardii 5) was investigated. Cultures were grown in modified MRS medium supplemented with different phenolic acids. Cellular growth was monitored and metabolite concentrations were determined by HPLC-RI. Despite the strong inhibitory effect of most tested phenolic acids on the growth of O. oeni VF, the malolactic activity of this strain was not considerably affected by these compounds. While less affected in its growth, the capacity of L. hilgardii 5 to degrade malic acid was clearly diminished. Except for gallic acid, the addition of phenolic acids delayed the metabolism of glucose and citric acid in both strains tested. It was also found that the presence of hydroxycinnamic acids (p-coumaric, caffeic and ferulic) increased the yield of lactic and acetic acid production from glucose by O. oeni VF and not by L. hilgardii 5. The results show that important oenological characteristics of wine lactic acid bacteria, such as the malolactic activity and the production of volatile organic acids, may be differently affected by the presence of phenolic acids, depending on the bacterial species or strain.     

不同酶水解对乳脂挥发性化合物的影响

采用脂肪酶D、E及角质酶F、G水解3?种不同的乳脂底物（黄油A、黄油B和稀奶油）,测定水解前后乳脂酸值及挥发性化合物组成的变化。结果表明,脂肪酶D、E及角质酶F、G水解引起乳脂酸值的变化不同,质量分数50%的黄油A经脂肪酶E水解后酸值变化最明显,增加量大于40?mg/g。角质酶G仅发挥了极弱的水解作用,水解引起乳脂酸值的变化最小。乳脂底物经脂肪酶和角质酶水解后,挥发性化合物种类皆有明显增加。当以脂肪酶D为水解酶时,乳脂中辛酸含量最高（底物为质量分数93.3%的稀奶油时除外）。当以脂肪酶E为水解酶时,黄油A水解后丁酸、己酸、辛酸和癸酸含量相差不多,是含量最高的4?种脂肪酸;黄油B水解后,其挥发性化合物中,以辛酸为主要产物;稀奶油水解后己酸含量最高。当以角质酶F为水解酶时,2?种黄油水解后己酸含量最高;质量分数93.3%稀奶油水解后,己酸与辛酸是含量最多的2?种脂肪酸;质量分数50%稀奶油水解后,癸酸含量最高。3?种乳脂经3?种不同酶水解后,挥发性化合物组成发生明显变化,丁酸、己酸、辛酸、癸酸4?种游离脂肪酸含量增加。     

Determination of volatile, phenolic, organic acid and sugar components in a Turkish cv. Dortyol (Citrus sinensis L. Osbeck) orange juice

BACKGROUND: Orange flavour is the results of a natural combination of volatile compounds in a well‐balanced system including sugars, acids and phenolic compounds. This paper reports the results of the first determination of aroma, organic acids, sugars, and phenolic components in Dortyol yerli orange juices. RESULTS: A total of 58 volatile components, including esters (nine), terpenes (19), terpenols (13), aldehydes (two), ketones (three), alcohols (four) and acids (eight) were identified and quantified in Dortyol yerli orange juice by GC‐FID and GC‐MS. Organic acids, sugars and phenolic compositions were also determined by HPLC methods. The major organic acid and sugar found were citric acid and sucrose, respectively. With regard to phenolics, 14 compounds were identified and quantified in the orange juice. CONCLUSION: Terpenes and terpenols were found as the main types of volatile components in Dortyol yerli orange juice. In terms of aroma contribution to orange juice, 12 compounds were prominent based on the odour activity values (OAVs). The highest OAV values were recorded for ethyl butanoate, nootkatone, linalool and DL ‐limonene. When we compare the obtained results of cv. Dortyol orange juice with the other orange juice varieties, the composition of Dortyol orange juice was similar to Valencia and Navel orange juices. Copyright © 2011 Society of Chemical Industry     

云南不同烟区烟叶中有机酸及乙醚提取挥发性成分含量研究

研究了云南省不同地区、不同品种及不同成熟度,不同部位烟叶中有机酸及乙醚提取挥发性成分含量.经分析得出,红河地区的烟叶有机酸含量较高,昆明、大理地区较低,但挥发性成分含量相反,大理地区最高,红河地区较低,玉溪、楚雄、昆明居中.评吸得分玉溪、大理地区烟叶相对好于其它地区.品种中以V2的有机酸含量最高,NC82的有机酸含量最低,挥发性成分含量相反,NC82较高,V2较低,云烟85、K326、红花大金元居中.初熟和适熟烟叶中有较高的挥发性成分含量,有机酸含量也较稳定,未熟和过熟烟叶中有机酸和挥发性成分依品种而定.对不同部位的烟叶,上部烟叶有较高的挥发性成分含量,中、下部烟叶次之,有机酸含量则中部叶最高,上、下部叶次之.     

桑葚风味构成特点研究

应用固相微萃取-气质联用技术(solid-phase microextraction-gas chromatography-mass spectrometry,SPME/GCMS)对桑葚的挥发性风味物质分析。结果发现:萃取头为50/30μm DVB/CAR/PDMS,饱和时间30 min,萃取60 min效果最好;在此条件下共鉴定出28种挥发性化合物,包括醛类8种,芳香族化合物6种,酯类6种,醇类4种和酸类4种。同时,对已鉴定出的风味化合物进行定量分析,并结合挥发性物质的气味活度值确定桑葚的香气活性物质,结果包括醛类6种,酯类4种,有机酸类3种,芳香族2种和醇类2种被确定为桑葚的气味活性物质,而异辛醇、糠醛、苯甲醛和己酸的气味活度值(odor activity value,OAV)小于1,对桑葚风味贡献度较小。