酸奶生产中酵母菌分布及产品污染研究

为研究酸奶中污染酵母菌的溯源,以酸奶生产车间为研究对象,确定生产环境中存在的酵母菌,同时对胀包产品中污染的酵母菌进行鉴定。研究结果表明,车间环境中主要存在的酵母菌为热带假丝酵母(Candida tropicalis)、阿氏丝孢酵母(Trichosporon asahii)、中间假丝酵母(Candida intermedia)、葡萄牙棒孢酵母(Clavispora lusitaniae)和产朊假丝酵母(Candida utilis),设备管路和表面基本上无酵母菌的污染,胀包产品中污染酵母菌主要为中间假丝酵母(Candida intermedia)、葡萄牙棒孢酵母(Clavispora lusitaniae)、产朊假丝酵母(Candida utilis)、热带假丝酵母(Candida tropicalis)。产品中污染的酵母菌主要来自于灌装间空气和包材间的空气中。这一研究为车间环境消毒的关键控制点提供了理论依据。     

利用高通量测序技术分析传统面引子中的酵母菌多样性

面引子是传统面食加工中发酵剂,酵母菌是面引子中的重要微生物之一,对其研究大多集中于传统分离培养法,文章旨在采用新一代高通量测序技术揭示传统面引子中的酵母菌群落结构特征。从我国吉林省、山东省、山西省、陕西省、甘肃省以及河南省收集18个面引子样品,基于宏基因组采用PCR扩增ITS1区,Illumina Miseq测序,云平台分析样品中酵母菌群落。结果表明样品中共有12个属16种酵母菌,分别是酿酒酵母、Kazachstania bulderi、异常威克汉姆酵母、光滑假丝酵母、矮小假丝酵母、清酒假丝酵母、近平滑假丝酵母、戴尔凯氏有孢圆酵母、扣囊复膜孢酵母、马克思克鲁维氏酵母、发酵毕赤酵母、Meyerozyma guilliermondii、Trichomonascus ciferrii、Hyphopichia burtonii,未鉴定出的假丝酵母和未鉴定出的酵母。其中酿酒酵母是大多数样品中的优势菌,而Kazachstania bulderi、光滑假丝酵母菌、矮小假丝酵母、清酒假丝酵母、戴尔凯氏有孢圆酵母、异常威克汉姆酵母在少数样品中也有较高的分布。各样品酵母菌群落结构相差不大,而且在类型和地理分布差异也不明显。     

武陵山区桑葚酿酒酵母菌种筛选研究

采用成熟的武陵山桑葚为原料,对其自然发酵液中的酵母菌进行筛选鉴定,经过初筛、复筛,得到4株起酵快、有明显酒香的优良的酵母菌。通过形态观察与生理生化试验鉴定,分别是红酵母属(Rhodotorula)中的胶红酵母(Rhodotorula mucilaginosa)、有孢汉逊酵母属(Hanseniaspora)中的酒有孢汉逊酵母(Hanseniaspora vineae)、假丝酵母属(Candida)中的近平滑假丝酵母(Candida parapsilosis)、酵母属(Saccharomyces)中的酿酒酵母(Saccharomyces cerevisiae)。并对这4种酵母菌进行了生长特性、残糖量、乙醇产量进行研究,为将来利用所筛选的酵母菌取代普通市售的葡萄酒酵母在桑葚酿酒工艺中的应用研究奠定了理论基础。     

双菌混合发酵丢糟生产微生物油脂的研究

探索利用假丝酵母和皮状丝孢酵母混合发酵丢糟生产微生物油脂的最佳工艺条件.在对假丝酵母和皮状丝孢进行驯化培养的基础上,设定假丝酵母和皮状丝孢酵母的比例、接种量、培养温度、培养时间为4个因素,进行L9(34)正交试验,通过测定油脂含量,获得油脂生产的最佳工艺条件.研究结果表明,双菌发酵丢糟生产微生物油脂的最佳工艺条件:假丝酵母和皮状丝孢酵母的比例为1:1,接种量为9％,培养温度为32℃,培养时间为4d,在该条件下测得每1000g丢糟发酵物中油脂含量为21.14g.     

胀袋番茄酱中分离出季也蒙假丝酵母和丛生丝孢酵母

酵母菌是单细胞真菌，广泛存在于自然界。由酵母菌引起食品腐败已有许多报道。本研究从腐败番茄酱中分离出季也蒙假丝酵母（Candida guiliermondii）和丛生丝孢酵母（Trichosporn Pullulans）。     

酱香型大曲中酵母的分离与鉴定

采用传统分离培养方法,对不同颜色和不同存储时间酱香大曲中的酵母菌进行分离,从中共筛选到60株酵母,并通过菌落形态观察、生理生化实验和分子生物学方法对其进行鉴定。结论:酱香大曲中酵母菌的种属有毕赤氏酵母属、伊萨酵母属、假丝酵母属、丝孢酵母属、酵母属、德巴利酵母属和复膜孢酵母属,其中,伊萨酵母属、德巴利酵母属和复膜孢酵母属是首次以传统方法从酱香大曲中分离筛选出,这也表明酱香大曲中酵母具有高度多样性。     

贮藏苹果中酵母菌的分离、初步鉴定及其抑制研究

对苹果中的酵母菌进行分离、纯化与初步鉴定,并用不同的抑制剂对其进行抑制试验研究.结果表明:从苹果中初步分离出酵母菌4株,通过对其形态、培养特征及生物学特性的研究,初步鉴定为酿洒酵母属、出芽短梗霉属、产朊假丝酵母属、皮状丝孢酵母属;山梨酸和苯甲酸钠对此4株菌都有很好的抑制效果,当山梨酸和苯甲酸钠浓度均为0.08%时,对酵母菌的平均抑菌率分别为99.98%和99.78%.     

不同种属酵母菌对发酵挂面品质的影响研究

利用从传统面食发酵剂中分离并纯化的不同种属酵母菌——酿酒酵母(Saccharomyces cerevisiae)、异常威克汉姆酵母(Wickerhamomycesanomalus)、德尔布有孢圆酵母(Torulaspora delbrueckii)和矮小假丝酵母(Candida humilis)为发酵剂制作发酵挂面，并对挂面的蒸煮品质、质构特性和力学特性等品质进行研究。结果表明：不同种属酵母菌在发酵过程中利用还原糖和产酸的能力差异显著；与未添加酵母菌发酵的挂面相比，添加酵母菌发酵可以改善挂面的蒸煮特性和质构特性，添加矮小假丝酵母菌可降低挂面的蒸煮损失，添加酿酒酵母发酵的挂面硬度显著性降低。综合分析利用酿酒酵母作为发酵剂制作的发酵挂面无论是蒸煮特性还是质构特性等均得到明显改善，具有应用于发酵挂面生产的潜力。     

甘蔗内生酵母菌的分离鉴定及发酵性能

为研究甘蔗内生酵母菌的种类并筛选出发酵性能良好的酵母菌株,该文采用组织分离法对甘蔗中的内生酵母菌进行分离,通过形态学、生理生化以及26S rDNA D1/D2区序列分析法进行鉴定。利用杜氏管发酵法初筛产气性能较好的菌株,确定筛选菌株的最适生长条件,然后采用摇瓶发酵法对其进行耐糖、耐盐以及耐酒精等耐受性试验,复筛出发酵性能优良的菌株。结果表明,从甘蔗中共分离得到内生酵母菌63株,鉴定为8种：葡萄有孢汉逊酵母(Hanseniaspora uvarum)、季也蒙毕赤酵母(Meyerozyma guiliermondii)、汉逊德巴利酵母(Debaryomyces hansenii)、嗜油假丝酵母(Candida oleophila)、类筒假丝酵母(Candida zeylanoides)、异常威克汉姆酵母(Wickerhamomyces anomalus)、Cystobasidium minutum以及Papiliotrema terrestris。从63株酵母菌中,筛选一株生长性能和发酵性能优良的菌株J-6,在温度26℃、pH5.0的条件下,24 h时生长速率达到最大值,其最大值为1.99...     

内蒙古土默川平原葡萄酒相关酵母多样性研究

考察酿酒葡萄中酵母菌种的多样性,分别采用形态学及基于酵母5.8S rRNA-ITS区域的RFLP分析法对内蒙古土默川平原酿酒葡萄中的酵母菌种进行了鉴定.结果表明,该地区葡萄酒相关酵母分属于5个属的6个酵母菌种,分别为葡萄汁有孢汉逊酵母(Hanseniaspora uvarum)、酿酒酵母(Saccharomyces cerevisiae)、东方伊萨酵母(Issatchenkia orientalis)、克鲁维毕赤酵母(Pichia kluyveri)、异常毕赤酵母(Pichia anomala)及星形假丝酵母(Candida stellata).实验表明,该地区酿酒葡萄中的酵母菌种具有多样性;此外,采用形态学及分子生物学相结合的方法可以快速、准确地对酵母菌种进行鉴定.     

橙汁腐败酵母菌的分子鉴定及其形态特征分析

目的：结合多种酵母菌鉴定方法,分析腐败橙汁中酵母菌的种类,为快速检测和控制商品橙汁中酵母菌污染奠定基础,也为酵母菌种类的快速鉴定提供参考。方法：以分离自腐败橙汁的8株酵母菌株为材料,观察菌落和细胞形态。用引物ITS1/ITS4扩增菌株5.8S rDNA 及其ITS间隔区(5.8S-ITS),对扩增产物用HhaⅠ、Hae Ⅲ 和 HinfⅠ进行限制性酶切片段多态性(RFLP)分析和测序;用引物NL1/NL4扩增26S rDNA D1/D2区并测序。结果：菌落特征观察将菌株初分为6组,细胞学观察粗分为3组,分子方法都分成4组。用限制性内切酶HhaⅠ、Hae Ⅲ和HinfⅠ对5.8S-ITS区产物进行 RFLP分析,观察到4种不同的图谱类型。5.8S-ITS 区和26S rDNA D1/D2区的序列分析结果相似,8株分离菌与GenBank中的4种酵母菌参考菌株序列一致性达99%以上。分离株与参考菌株以两区序列构建的NJ系统树都分成4枝：Y1与克鲁维毕赤酵母(Pichia kluyveri),Y12-3、Y18-1与发酵毕赤酵母(Pichia fermentans),Y22、Y23、Y26和Y56与Meyerozyma guilliermondii,Y47与Wickerhamomyces anomalus分别聚为一枝。结论：结合形态分析和核酸分析,将8株腐败橙汁分离菌鉴定为P. kluyveri var. kluyveri、P. fermentans、M. guilliermondii和W. anomalus 4个种,其中M. guilliermondii在腐败橙汁中首见报道;ITS- RFLP分析、26S rDNA D1/D2区测序与菌株形态特征结合能有效鉴定酵母菌,核糖体DNA分析可鉴定酵母到生物学种,菌落形态特征可反映种以下的遗传差异,因此,采用分子方法鉴定时不能忽视形态特征分析的重要性。     

A medium for the impedimetric detection of yeasts in foods

A mycological medium, CBAS, was developed for the detection of yeasts in foods using polarization capacitance (Cpol) measurements. The signal obtained due to the growth of yeasts in CBAS provided earlier detections and stronger responses than the signals produced by these yeasts in other common media. Of several impedance components evaluated, Cpol provided the most useful signal for yeasts in CBAS. Further investigation showed that pH change was responsible for approximately 50% of the Cpol signal. Cpol detection times correlated highly with plate counts of a yeast isolated from orange juice when tested in CBAS (r = ?0·99) and in a 1:10 dilution of orange juice in CBAS (r = ?0.94). A concentration of 10² yeast cfu ml⁺¹ in a 1:10 dilution of orange juice in CBAS was detected within 26 h by Cpol in contrast with a 3 to 5 day plate count.     

Shelf-life prediction of fresh blood orange juice

Fresh blood orange juice is successful on the market because of its taste and nutritional value. Yet, it requires accurate control of the cold chain during storage and distribution. A kinetic study was carried out both on growth of spoilage microorganisms (i.e. yeasts) and on decrease of nutritional value (i.e. ascorbic acid and anthocyanin contents) of pasteurised fresh blood orange juice. Kinetic equations were used to set up mathematical models to predict shelf-life of pasteurised fresh blood orange juice under isothermal and non-isothermal conditions. The mathematical model was also able to predict yeast growth in unpasteurised fresh blood orange juice during shelf-life.     

Influence of calcium lactate on the fate of spoilage and pathogenic microorganisms in orange juice

Calcium lactate is used by the beverage industry as a source of calcium to fortify fruit juice. The objective of this study was to evaluate the influence of various concentrations of calcium lactate on the fate of pathogenic and spoilage microorganisms in orange juice. Commercial nonfortified orange juice was supplemented with calcium lactate at a concentration equivalent to 0, 5, 10, 15, 20, 25, or 30% dietary reference intake. The pH of each fortified juice was adjusted to 3.6 or 4.1. The prepared juice samples were inoculated separately with a three-strain mixture of salmonellae, a three-strain mixture of spoilage yeasts, and three single strains of spoilage bacteria including Alicyclobacillus acidoterrestris, Lactobacillus plantarum, and Lactobacillus sake. The contaminated juice was stored at 4 and 10 degrees C, respectively, for 6 to 7 weeks and assayed once a week for populations of salmonellae, spoilage yeasts, or spoilage bacteria. The results indicated that A. acidoterrestris was inhibited in all juice stored at 4 degrees C and low-pH juice stored at 10 degrees C. The bacterium, however, was able to grow at 10 degrees C in the high-pH juice with calcium lactate concentrations equivalent to 0 and 5% dietary reference intake. The cells of L. sake declined and eventually died off in low-pH juice stored at 4 and 10 degrees C and in high pH stored at 4 degrees C. But the organism flourished at 10 degrees C in the high-pH juice containing 0, 10, and 20% dietary reference intake of calcium lactate. The populations of L. plantarum remained approximately stable in low- as well as in high-pH juice stored at both 4 and 10 degrees C. While inhibited at 4 degrees C, the spoilage yeasts grew at 10 degrees C. Salmonellae died off in all juice stored at 4 degrees C and in low-pH juice stored at 10 degrees C. However, they persisted in the high-pH juice stored at 10 degrees C except in the samples that contained 20 to 30% dietary reference intake of calcium lactate.     

橙汁中两株条件致病酵母的形态及分子鉴定

目的：为建立更加完善的橙汁酵母菌检测体系,进一步精确监控市售橙汁质量,对市售橙汁中分离的两株酵母菌Y25、Y32进行菌落动态发育和细胞特征的观察。方法：以NL1和NL4为引物,对分离到的两株酵母菌基因组进行26S rDNA D1/D2区域序列扩增。结果：酵母菌的菌落形态随培养时间延长发生变化,菌落发育形态和菌体细胞特征对菌株鉴定具有直观、简洁的优点;PCR扩增后的基因碱基序列经GeneBank公布的同源基因碱基序列比对后,相似度在99%以上。结论：把分离到的Y25、Y32鉴定为汉逊德巴利酵母(Debaryomyces hansenii)和近平滑假丝酵母(Candida parapsilosis)。形态学与分子技术的结合使鉴定结果更为准确可靠,将为橙汁中其他腐败微生物的鉴定与监控提供有价值的借鉴。     

Survival and Recovery of Thermally Stressed Yeast in Orange Juice

Injury and survival of thermally stressed yeast in orange juice were assessed by plating on plate count agar, acidified potato dextrose agar, and orange serum agar. Thermally stressed yeast were found to have reduced plate counts on both orange serum agar and acidified potato dextrose agar in comparison to plate count agar. Severely injured populations were not able to repair injury in orange juice held at 25°C but survived storage at 25, 6, and -18°C.     

Survey on mycoflora of cow and buffalo dairy products from Southern Italy

Economic losses of dairy products due to spoilage by yeasts have been increasing in European companies because of the reduced use of preservatives, packaging in modified atmospheres, or new formulations that do not strictly control the growth of these organisms. This study reports the results of a survey of yeast species and populations in 145 samples of cow and buffalo dairy products collected in some regions of Southern Italy. Yeasts were isolated from 74% and 57% of cow and buffalo products, respectively. Candida inconspicua was the predominant species in unripened products from cow's milk, while C. famata was detected in medium and long-term ripened dairy products, mostly in association with other yeasts and with moulds belonging to the genus Penicillium. For dairy products produced from buffalo milk, C. inconspicua was the most important yeast frequently isolated from dairy products. Total yeast populations ranged from 5 x 10(2) to 5 x 10(5) cfu/g, indicating a good hygienic quality of the products. The isolation of C. albicans from one stracciatella sample is noteworthy, as this yeast represents a potential contamination by human. Even though yeasts are considered as environmental contaminants, the occurrence of some of them in dairy products at high levels could represent a risk for human health, in particular for immunocompromised patients.     

新疆慕萨莱思自然发酵过程中酵母菌表型多样性及优势菌分析

目的：研究新疆慕萨莱思自然发酵过程中酵母菌种群表型多样性与其优势菌,探讨慕萨莱思传统工艺对其主要菌群结构的影响。方法：来自于新疆阿瓦提一古作坊的慕萨莱思酿制原料、原料处理液及发酵液(自然发酵过程中)共19份样品被用于酵母菌分离,分离株利用WL培养基培养归类,筛选代表株,对代表株进行形态观察、生理生化特征检测与类平均连算法聚类分析,探讨新疆慕萨莱思自然发酵过程中酵母菌表型多样性及优势菌群。结果：分离得到217株酵母菌,13种WL培养类型,8个表观群。13株代表菌株经初步鉴定为7个属,疑似为13个种,表明慕萨莱思酵母菌具有丰富的多样性。Hanseniaspora spp.为葡萄果皮、果汁及皮渣中的优势菌,S.cerevisiae为慕萨莱思自然发酵过程中起发者及唯一一种优势菌,非酿酒酵母偶尔在发酵液中发现。结论：慕萨莱思酿制过程中,葡萄原料原有的酵母菌经熬煮工序几乎被全部杀死,自然发酵中唯一优势菌S.cerevisiae可能来自酿制场所和设备,并具有较高适应能力。     

酸化、低温和添加山梨酸盐贮藏橙汁的研究

本文主要研究了酸化、低温和山梨酸盐结合对橙汁贮藏的影响。结果表明,将橙汁酸化到pH2.0和pH2.5,于5℃下贮藏12周,其细菌总数、酵母和霉菌数明显减少。使用0.03％山梨酸或山梨酸钾并酸化到pH2.5的橙汁,可在10℃下贮藏10周以上。但山梨酸盐会使Vc分解。这表明,Vc含量较高的橙汁中,微生物数量也高。     

Use of Acidification, Low Temperature, and Sorbates for Storage of Orange Juice

The effects of acidification, combination of acidification and low temperature and sorbates on the storage of orange juice were investigated. Acidification of orange juice to pH 2.0 and pH 2.5 followed by storage at 5°C resulted in marked reduction in total plate count and yeast and mold population during twelve weeks of storage. Use of 0.03% sorbic acid or potassium sorbate in combination with acidification at pH 2.5 resulted in preservation of orange juice stored at 10°C over 10 wk period; however, vitamin C degradation was enhanced by the presence of the sorbates. The results also indicated that relatively high concentrations of vitamin C were present in orange juice containing high population of microorganisms.