不同乳酸菌发酵豆浆挥发性气味物质的差异性分析

不同乳酸菌因代谢特征存在差异,故在发酵豆浆过程中产生的挥发性气味物质组成亦有差异。采用pH值测定、GCMS定性、定量分析植物乳杆菌、干酪乳杆菌、德式乳杆菌、发酵乳杆菌、嗜热链球菌5种乳酸菌在发酵豆浆过程中的产酸能力及挥发性气味物质的差异性。结果表明,干酪乳杆菌和嗜热链球菌在豆浆发酵过程中的产酸能力较强;5种乳酸菌发酵豆浆中挥发性气味物质的含量与组成数量均显著增加,其中干酪乳杆菌、植物乳杆菌、德式乳杆菌和发酵乳杆菌4种乳酸菌发酵豆浆挥发性气味物质组成相近,与未发酵豆浆、嗜热链球菌发酵豆浆之间存在差异。主成分分析显示,未发酵豆浆的特征挥发性气味物质为壬醛、正辛醛、戊醛、正己醛、正戊烷、反-2-辛烯醛、反,反-2,4-癸二烯醛;植物乳杆菌、干酪乳杆菌、德式乳杆菌发酵豆浆的特征挥发性气味物质是叶醇、仲辛酮、反-2-辛烯醛、(E,E)-2,4-庚二烯醛、3-乙基-2-甲基-1,3-己二烯、3-辛烯-2-酮、(2Z)-2-辛基-1-醇、反式-2-辛烯-1-醇;发酵乳杆菌发酵豆浆的特征挥发性气味物质是氯甲酸正辛酯、正庚醇、(2R,3R)-(-)-2,3-丁二醇、3-羟基-2-丁酮、愈创木酚、苯酚;嗜热链球菌发酵豆浆的特征挥发性气味物质是苯酚、芳樟醇、愈创木酚、甲基麦芽酚、2-乙酰基噻唑、2-乙基己醇、异戊醇、正辛醇、苯乙醇、环庚醇、2-壬酮。本研究结果可为乳酸菌发酵豆浆饮料的开发与生产提供理论参考。     

基于HS-GC-IMS和化学计量学分析牦牛乳干酪成熟过程中挥发性风味物质的变化

采用顶空气相色谱-离子迁移谱技术分析在5℃储存条件下成熟的1～180 d牦牛乳干酪中挥发性风味物质的变化。结果共定性鉴定出22种挥发性物质,包括8种酯类、7种酮类、3种醛类、2种醇类和2种其他化合物。不同成熟时间牦牛乳干酪中挥发性风味物质的含量存在明显差异,其中乙偶姻、2-庚酮二聚体、2,3-戊二酮、正戊醛、3-甲基丁醛（单体和二聚体）和乙醇在1 d时的含量最高,己酸乙酯二聚体、乙酸乙酯二聚体、丙酸乙酯、丁酸乙酯、乳酸乙酯、2-戊酮二聚体、2-庚酮单体和2,4,6-三甲基吡啶在成熟180 d时含量最高。化学计量学分析结果表明乙醇、乙偶姻和2-丁酮可作为成熟1～90 d时样品的特征挥发性风味物质,己酸乙酯二聚体、丁酸乙酯、乙酸乙酯二聚体、2-戊酮二聚体和2-庚酮单体可作为成熟180 d时样品的特征挥发性风味物质。研究结果可为牦牛乳干酪的风味改善与品质控制提供参考。     

气相色谱-离子迁移谱结合化学计量学分析成熟时间对牦牛乳干酪挥发性风味物质的影响

采用气相色谱-离子迁移谱技术分析了牦牛乳干酪成熟过程中挥发性风味物质的变化。该研究共鉴定了46个信号峰中的22种挥发性风味物质。不同成熟时间牦牛乳干酪中挥发性风味物质的含量存在明显差异,成熟前期(1 d)乙偶姻和乙醇含量最高;成熟中期(30～90 d)2,4,6-三甲基吡啶、乙酸异戊酯和丁酸乙酯含量随着成熟时间的延长明显增加;成熟后期(120～180 d)丁酸乙酯、己酸乙酯二聚体、乙酸异戊酯和乙酸乙酯二聚体等含量达到最高。偏最小二乘-判别分析筛选出了12种特征挥发性标志物[变量重要性(variable important for the projection, VIP)>1],包括3-甲基-3-丁烯-1-醇、乙酸乙酯二聚体、乙偶姻、乙酸异戊酯、乙醇、丁酸乙酯、2-丁酮、正丁醇、己酸乙酯二聚体、烯丙基腈、2-戊酮和苯甲醛。主成分分析结果能够较好地区分牦牛乳干酪的成熟阶段。该研究结果可为今后牦牛乳干酪的产品开发和品质控制提供参考依据。     

副干酪乳杆菌对发酵香肠风味的作用研究

以副干酪乳杆菌作为发酵剂,研究其在滋味(可溶性物质)和香气(挥发性化合物)两方面对发酵香肠风味的改善情况。采用电子鼻分析未添加发酵剂的香肠—自然发酵(1#)与添加发酵剂的香肠(2#)的香气组成,并利用气相色谱-质谱法(GC-MS)和氨基酸自动分析仪测定其挥发性成分及可溶性呈味物质的含量。结果表明,添加副干酪乳杆菌的发酵香肠较未添加的氨基酸的含量有所提高,谷氨酸、天门冬氨酸、甘氨酸、丝氨酸、丙氨酸等呈味氨基酸含量增加明显。醇、酸、酯、酮类等挥发性成分物质增加,说明副干酪乳杆菌可以很好的改善发酵香肠的风味。     

乳酸菌强化发酵对刺梨果醋风味品质的影响

以刺梨汁为主要原料,通过液态发酵的方式,将酵母菌分别搭配三株不同乳酸菌（鼠李糖乳杆菌H3、副干酪乳杆菌SR10-1、植物乳杆菌LP）进行混菌酒精发酵,再接种巴士醋杆菌进行醋酸发酵制备刺梨果醋。为了探究乳酸菌强化发酵对刺梨果醋风味品质的影响,采用顶空固相微萃取-气相色谱-质谱联用技术（HS-SPME-GC-MS）,分析不同乳酸菌强化发酵刺梨果醋挥发性风味物质组成及理化指标的差异。结果表明,酵母菌发酵组与乳酸菌强化发酵组差异明显。从4组刺梨果醋样品中共检测出49种挥发性风味物质,其中酵母菌组有30种、鼠李糖乳杆菌H3组有41种、副干酪乳杆菌SR10-1组有37种、植物乳杆菌LP组有41种,各组共有挥发性物质22种,分别含有0种、2种、1种和5种特有挥发性物质,挥发性风味物质的总质量浓度高低依次为：鼠李糖乳杆菌H3组>植物乳杆菌LP组>副干酪乳杆菌SR10-1组>酵母菌组,乳酸菌强化组的挥发性风味物质种类和含量明显高于酵母菌组,其醇类、醛类和烃类总质量浓度减少,酸类和酯类总质量浓度有所增加,且乳酸菌强化组中总酸、乳酸、总黄酮、总多酚含量和SOD活力均高于酵母菌组,说明接种乳...     

酿酒酵母Y-8对发酵香肠品质与风味的影响

为改善发酵香肠的品质与风味,将酿酒酵母Y-8接种到发酵香肠中,探究不同比例酿酒酵母(Saccharomyces cerevisiae)Y-8与植物乳植杆菌(Lactiplantibacillus plantarum)Z43复配对发酵香肠理化性质、挥发性风味物质与脂肪酸的影响。分别通过气相色谱-离子迁移谱、气相色谱-质谱联用技术测定挥发性风味物质与脂肪酸。结果表明：添加酿酒酵母Y-8可以促进发酵香肠中酯类和醇类物质产生、降低乙酸含量、提高最终pH值、增加油酸相对含量、快速降低肠杆菌数;使用正交偏最小二乘判别分析建立模型,结合变量投影重要性(variable importance projection,VIP)值筛选出17种差异挥发性风味物质(VIP>1),可以对不同比例酿酒酵母Y-8与植物乳植杆菌Z43复配发酵香肠做出很好地区分;植物乳植杆菌Z43与酿酒酵母Y-8以20∶1(植物乳植杆菌Z43接种量为10⁷ CFU/g)比例复配发酵香肠感官综合评分最高、色度值最大,硬度显著高于其他组(P<0.05),且3-羟基-2-丁酮含量明显高于其余3组;接种酿酒酵母...     

益生性植物乳杆菌对切达干酪挥发性风味形成的影响

将分离自西藏灵菇的益生性植物乳杆菌1-2通过在杀菌乳中添加活菌数8.0、9.0（lg（CFU/mL））和在排乳清后添加于凝乳块8.0（lg（CFU/g））的方式分别加入到切达干酪中,考察植物乳杆菌活菌数量、添加方式和成熟时间对干酪挥发性风味物质组成的影响。利用固相微萃取和气相色谱-质谱联用技术检测出对照组干酪的风味物质26种,益生菌干酪组风味物质30种,添加植物乳杆菌1-2可产生乙苯、十二烷、己醇和丙酮4种挥发性风味物质。成熟时间对干酪风味的影响最大,随成熟时间的延长,益生菌干酪组中苯含量显著增加,而对照组干酪在成熟12周时才检测到苯。益生菌添加量和添加方式对干酪挥发性风味的影响相似,丁酸受益生菌活菌数和添加方式的影响最大,益生菌干酪组成熟12周时,丁酸含量最高达对照组的3.96倍（P＜0.05）。在杀菌乳中添加益生菌活菌数8.0（lg（CFU/mL））组和9.0（lg（CFU/mL））组干酪中挥发性风味物质含量有显著差异,但在杀菌乳中添加高活菌数9.0（lg（CFU/mL））和在排乳清后添加低活菌数8.0（lg（CFU/g））于凝乳块中对干酪挥发性风味的形成具有相似的影响。本研究结果为改进益生菌干酪的加工工艺和风味品质提供了实验依据。     

Mozzarella干酪成熟过程中风味变化的研究

通过对pH值为4.6的可溶性成分的HPLC分离,发现干酪成熟过程中大分子的肤类逐渐减少,小分子的肽类和氨基酸逐渐增多,对成熟干酪中的挥发性物质进行GC-MS分析.结果表明,鉴定出许多重要的风味化合物,如:2-甲基-3戊醇、3-甲基丁醛、壬醛、苯甲醛、2-庚酮和2-壬酮、3-羟基-2-丁酮、辛酸、丁酸乙酯、己酸乙酯、二甲基二硫醚等.在Mozzarella干酪的成熟过程中,醛、酮、酯的数量增多,而烃、酸、醇的种类逐渐减少.     

对添加附属发酵剂干酪的感官分析

对添加附属发酵剂SP-3的干酪进行感官评定,结果表明,筛选得到的植物乳杆菌SP-3作为附属发酵剂,对半硬质干酪的风味产生影响.同时,对照组干酪的主要风味特征为易于接受的坚果风味和奶香风味.     

一种植物乳杆菌对干酪模型成熟中微生物及蛋白质水解的影响

采用无菌条件下生产的新鲜干酪凝块制作干酪模型,以WSN,12%TCASN和氨基酸含量等为指标测定植物乳杆菌SP-3对其的促熟作用。微生物测定表明SP-3在干酪模型的成熟过程中(12d)能保持较高的浓度;WSN结果表明SP-3对干酪中蛋白质的初级水解无显著影响;12%TCASN的结果表明SP-3影响了干酪中小肽的形成;5%PTA-SN和总游离氨基酸浓度测定结果表明植物乳杆菌SP-3促进了体系中游离氨基酸的产生;游离氨基酸的分析显示谷氨酸、亮氨酸、组氨酸的含量明显高于对照组,而丝氨酸、赖氨酸、脯氨酸的含量低于对照组。以上结果表明,植物乳杆菌SP-3能加快干酪体系中蛋白质的水解进程,具有促进干酪成熟的作用。     

Production of volatile compounds by Rhizopus oligosporus during soybean and barley tempeh fermentation

Rhizopus oligosporus Saito can ferment soybeans or cereal grains to tempeh, a sliceable cake with improved nutritional properties. Volatiles produced by different R. oligosporus strains grown on malt extract agar (MEA), barley and soybean were investigated. The effect of co-cultivation with Lactobacillus plantarum on the production of volatiles was also studied. Volatile compounds were collected in situ by headspace diffusion and identified by GC-MS. The ten R. oligosporus strains that had different colony morphologies on MEA produced very similar volatile profiles, except for slight variations among the minor volatile compounds (e.g. sesquiterpenes). Likewise, practically no differences in volatile profiles were observed between three of the strains grown on soybeans. In contrast, the R. oligosporus volatile profile on soybean was different from that on barley from the same strain. Co-cultivation with L. plantarum did not influence volatile production by R. oligosporus. The dominant compounds produced on all three substrates were ethanol, acetone, ethyl acetate, 2-butanone, 2-methyl-1-propanol, 3-methyl-1-butanol and 2-methyl-1-butanol. Acetaldehyde and 2-methyl-propanal were also produced on MEA and barley, while 2-pentanone, methyl acetate, 2-butanol and 3-methyl-3-buten-1-ol were observed on soybeans. Ethanol, 2-methyl-1-butanol and 3-methyl-1-butanol were the most abundant volatile compounds produced on MEA and barley, while 2-butanone was the dominant volatile metabolite on soybean. The mushroom odour compounds, 3-octanone and 1-octen-3-ol, were only detected from soybean and soybean tempeh.     

Volatile compounds in uninoculated and inoculated table olives with Lactobacillus plantarum (Olea europaea L., cv. Moresca and Kalamata)

Table olives' flavour plays an important role in consumer's acceptability and it depends on various factors such as varieties, intrinsic characteristics, ripening of fruit and processing technologies. Flavour biogenesis is also influenced by addition in brine medium of lactic acid bacteria as inoculants, which reduce spoilage risks and improve sensory characteristics. In this work, flavour profiles of uninoculated and inoculated table olives with Lactobacillus plantarum (cv. Moresca and Kalamata) have been analytically characterised and compared. Twenty-one volatile compounds comprise alcohols, aldehydes, ketones, esters as well as acids formed during Greek-style olive fermentation (3 months brining after) have been characterised by gas chromatography and GC/mass spectrometry. Very high contents of ethanol and appreciable amounts of ethyl acetate, isobutanol, 2-butanone, 1-propanol and 1-hexanol were revealed in all samples with a significant increase in inoculated samples with respect to uninoculated ones. Also 1-butanol, 3-pentanol, 3-hydroxy-2-butanone, cis-3-hexen-1-ol and 2-butanol which were present in lower amounts, disclosed a meaningful increase in inoculated samples of both varieties, especially in Moresca inoculated sample. Acetic acid, isopentanol, 2-pentanol, propyl acetate, ethyl propanoate and 4-penten-1-ol showed a significant increase in inoculated Kalamata sample. These results showed that inoculation of brine medium with lactic acid bacteria starters significantly influenced aroma profiles of both varieties, in particular an increase in concentration of various flavour compounds has been revealed in inoculated table olives.     

Headspace flavour compounds produced by yeasts and lactobacilli during fermentation of preferments and bread doughs.

Production of volatile flavour compounds during fermentation with pure cultures of Saccharomyces cerevisiae and Candida guilliermondii, Lactobacillus brevis and Lactobacillus plantarum have been investigated, using wheat doughs and several preferements as substrates. For yeast, preferments consisted of 10% (w/v) glucose, maltose and sucrose solutions, whereas for lactobacilli they consisted of supplemented and unsupplemented (3% and 10% (w/v)) glucose solutions, and a 10% (w/v) wheat flour slurry. Seven volatile compounds (acetaldehyde, acetone, ethyl acetate, ethanol, hexanal+isobutyl alcohol, and propanol) were detected when using yeasts. All these compounds, except propanol, appeared for all the substrates assayed, with ethanol as the predominant component. Generally, S. cerevisiae produced higher amounts of the different components than C. guilliermondii. Both yeasts produced larger amounts of volatile flavour compounds during fermentation in glucose and sucrose solutions than in maltose or wheat dough. In general the yeasts examined produced more flavour components than the lactobacilli. For the lactobacilli the highest number of volatile flavour compounds were observed for substrates containing flour.     

Characterization of flavour and volatile compounds of fermented squid using electronic nose and HPMS in combination with GC-MS

The present study investigated the flavour characteristics and key volatile components of fermented squid (Dosidicus gigas) as well as their formation mechanism by three different starter cultures of lactic acid bacteria (LAB) and natural squid. The sensory assessment, volatile compounds, as well as the amino acids of the mixed fermented squid were detected using pickled brine as samples of fermented squid. A total 88 types of volatile compounds were found in four samples by 0–72 h of fermentation. After fermentation by LAB, the volatile compounds of squid showed that the fermented squid with different started cultures differed mainly in terms of numbers of alcohols, ketones, and esters. Furthermore, the amounts of volatile compounds among three starter cultures were also obviously different. Gas Chromatography-Mass Spectrometer (GC-MS) analysis indicated that the mixed fermentation process contained relatively higher (+)-limonene (11.71%) (lemon scent) and 3-hydroxy-2-butanone (5.72%) (creamy taste). These compounds were not detected in the control group. The main flavour compounds of nonanal and 2, 4-decadienal were gradually reduced. Meanwhile, 2, 3-butanedione, 2-heptanone, 2-pentylfuran, and nonanoic acid are the key flavour components. The total principal component is 94.01%, which were clarified by electronic nose in combination with principal components analysis. After mixed fermentation by LAB, the total amino acid (TAA) content reached 85.36 g/100 g, which was almost twice the amount of the control, especially in aspartate, glutamate, and threonine. Our results indicated that LAB has obvious effects on deodorization and flavour promotion during the fermentation of squid. This study provided an important basis for the further development and utilization of squid.     

不同发酵剂对羊肉发酵香肠理化特性的影响

通过测定添加不同发酵剂羊肉发酵香肠加工和贮藏过程中的pH值,Aw值,水分含量,TBARS值和色泽的变化,研究菌种对羊肉发酵香肠理化特性的影响。第1组为未添加菌种的对照组,第2组为添加植物乳杆菌组,第3组为按1:2添加植物乳杆菌和木糖葡萄球菌的混合组。结果表明:发酵过程中,3组发酵香肠pH值均有所下降,但添加植物乳杆菌和混合组下降较多,在发酵结束后的干燥、成熟和室温贮藏过程中pH值有上升的趋势,对照组pH值上升快,而植物乳杆菌组和混合组pH值上升缓慢。各组Aw值在加工阶段迅速下降,植物乳杆菌组最快,混合组其次。水分含量在发酵结束时变化不大,在随后的干燥、成熟阶段水分含量显著下降,贮藏过程中仍缓慢降低。TBA值在发酵、干燥、成熟和贮藏前2周表现上升趋势,而贮藏4周后TBA值显著下降。植物乳杆菌组和混合菌种组红度值(a)分别为16.91和17.17,均高于对照组;黄度值(b)和(L)明度值均显著低于对照组(P<0.05),而混合组略低于植物乳杆菌组。     

两步固态发酵法酿造功能性豆豉

运用分离自云南传统发酵豆豉的Bacillus subtilis SP-8-5与Lactobacillus plantarum YM-5-2菌株对大豆进行两步固态混合发酵。首先,将菌株B.subtilis SP-8-5接种至经室温浸泡10 h(20℃,质量比为1∶3),110℃(20min)蒸煮处理并冷却至30℃的大豆中,于26℃进行初步发酵42 h;随后再接种L.plantarum YM-5-2,并于30℃发酵2 d,最后置于4℃进行后发酵。经两步固态混合发酵处理后,得到一种纤溶活性较强,生产周期短,保质期相对较长,风味独特且易于被大众接受的新型功能性发酵豆豉。当后发酵时间为21 d时,样品豆豉中B.subtilisSP-8-5活菌数为(5.88±0.53)×108 CFU/g,而L.plantarum YM-5-2活菌数则高达(3.50±0.35)×1011 CFU/g,此时检测豆豉纤溶酶的纤溶圈直径高达(2.99±0.06)cm(37℃,静置培养48 h)。     

发酵香肠菌种的筛选及鉴定

本文从混合发酵剂中筛选菌株,确定用于发酵香肠生产的菌株名称,并对其筛选出的菌种进行生化鉴定,结果如下:RFx1为植物乳杆菌,RF261为德氏乳杆菌,AFx1为变异微球菌,ALx3为肉糖葡萄球菌.     

Physicochemical, microbiological and sensory profiles of fermented milk containing probiotic strains isolated from kefir

A two-strain starter culture containing Lactobacillus plantarum CIDCA 83114, a potential probiotic strain isolated from kefir grains, and Streptococcus thermophilus CIDCA 321 was tested for the preparation of a fermented milk product. Kluyveromyces marxianus CIDCA 8154, a yeast with immunomodulatory properties was included to formulate a three-strain starter culture. Supernatants of enterohaemorragic Escherichia coli, shiga-toxin-producing strain, along with a two-strain or a three-strain starter culture were included in the medium of Vero-cell surface cultures. The results demonstrated that these combinations of microorganisms antagonize the cytopathic action of shiga toxins. The cell concentration of Lb. plantarum did not decrease during fermentation, indicating that the viability of this strain was not affected by low pH, nor did the number of viable bacteria change during 21 days of storage in either fermented products. The number of viable yeasts increases during fermentation and storage. Trained assessors analyzed the general acceptability of fresh fermented milks and considered both acceptable. The milk fermented with the two-strain starter culture was considered acceptable after two week of storage, while the product fermented with the three-strain starter culture remained acceptable for less than one week. The main changes in sensory attributes detected by the trained panel were in sour taste, milky taste and also in fermented attributes. The correlation between different sensory attributes and acceptability indicated that the panel was positively influenced by milky attributes (taste, odour, and flavour) as well as the intensity of flavour. In conclusion, the two-strain starter culture would be the more promising alternative for inclusion of that potential probiotic lactobacillus in a fermented milk product.     

榨菜叶酸菜发酵剂的选择

通过对蔬菜发酵中几种常见乳酸菌的发酵生理特点的研究，筛选出适合榨菜叶发酵酸菜的发酵剂，得出最优混合发酵剂为肠膜明串珠菌3％、短乳杆菌l％、植物乳杆菌1％，可生产出质地、风味俱佳，与自然发酵无明显差别的酸菜，但发酵时间从自然发酵的15d左右缩短为5d左右。