植物乳杆菌ST-Ⅲ在豆乳中的发酵特性及发酵豆乳的贮藏稳定性

通过测定植物乳杆菌ST-Ⅲ在发酵豆乳过程中的生长曲线、酸化曲线、蛋白水解能力和豆乳表观黏度、终产品感官分值,以及发酵豆乳在不同贮藏温度下植物乳杆菌ST-Ⅲ菌数、pH值、持水力和感官变化,研究植物乳杆菌ST-Ⅲ在豆乳中的发酵特性和发酵豆乳产品的贮藏稳定性。结果显示,植物乳杆菌ST-Ⅲ在豆乳中生长良好,到达发酵终点时的菌数为6.1×108 CFU/mL(对数值为8.78),表观黏度可达0.24Pa·s,感官品质较佳;发酵豆乳在低温(4℃)条件下各指标变化差异较小,贮藏稳定性明显优于常温(25℃)时。表明植物乳杆菌ST-Ⅲ具有发酵豆乳制品的优势与潜力。     

双蛋白干酪发酵剂的筛选及发酵特性研究

为了研究不同发酵剂对牛乳或豆乳的发酵特性,对6株乳酸菌在发酵过程中的酸度、pH、胞外多糖、黏度、游离氨基氮、双乙酰等指标进行了测定。结果表明:在牛乳中,XZ3303的产酸能力最强,QH27-1滴定酸度最高;在豆乳中,QH48-3-2滴定酸度最高,并且在豆乳中的酸度明显高于牛乳。乳酸菌在豆乳中的黏度值都明显高于牛乳,并且豆乳中的黏度变化曲线有二次产黏的现象,有利于发酵乳口感的改善。XZ3303、XZ10303、QH27-1、QH48-3-2发酵乳产双乙酰能力较强;XZ3303和QH27-1产胞外多糖的能力明显高于其他菌株。通过感官分析并结合理化指标综合考虑,选择了在豆乳和牛乳中都能优势生长的L.Lactis subsp.Cremoris QH27-1和L.Lactis subsp.Lactis XZ33032株乳酸菌作为制作双蛋白干酪的发酵剂。     

乳酸菌发酵不同乳基质的凝乳特性研究

探讨了不同乳酸菌发酵不同乳基质时的凝乳特性,为开发混合乳制品及豆乳发酵制品提供理论依据。对8株乳酸菌作用于纯牛乳、混合乳及纯豆乳时的凝乳性能进行了研究;检测了凝乳的粘度、酸度、双乙酰、胞外多糖和pH4.6时的可溶性氮含量。结果表明,以不同基质作为发酵介质时,乳酸菌呈现不同的凝乳特性。     

不同混合发酵方式对发酵豆乳贮藏品质的影响

采用牛乳与豆乳混合后再发酵、牛乳发酵后混入豆乳（发酵牛乳无后酸化处理）和单独发酵牛乳，发酵结束4℃后酸化24 h后再混入豆乳3种混合发酵方式制备发酵混合豆乳，探究3种混合发酵方式对发酵混合豆乳贮藏期品质的影响。结果表明，单独发酵牛乳，发酵结束4℃后酸化24 h后再混入豆乳方式可减缓发酵豆乳在贮藏期的后酸化程度，活菌数保持7 log cfu/mL以上，持水力增加，无乳清析出，提高了发酵豆乳的稳定性，贮藏期内发酵豆乳具有良好的感官，颜色微黄，有光泽，口感润滑，有弹性，具有大豆特有的香气，无豆腥味，贮藏期硬度和胶黏性增加，具有良好的咀嚼特性。因此，单独发酵牛乳，发酵结束4℃后酸化24 h后再混入豆乳方式下的产品稳定性更好。     

利用开菲尔粒制备酸豆乳酒的最佳发酵条件

利用传统酸牛乳酒 (Kefir)的发酵剂———开菲尔粒 (KefirGrains)制作的发酵剂 ,对豆乳与牛乳的混合原料进行发酵 ,采用L16 (4 5)正交试验设计筛选制备酸豆乳酒 (一种新型发酵豆乳制品 )的最佳发酵条件。结果表明 ,豆乳与鲜牛乳的搭配比例是 8∶2 ,接种量为 3 % ,发酵温度 2 5℃ ,发酵时间 1 4h ,添加 1 0 %的白砂糖。产品的酸度为 83°T ,乙醇含量为 0 2 6%。     

萌发大豆制备益生菌发酵豆乳流变特性的研究

以萌发大豆作为主要原料,经瑞士乳杆菌(Lactobacillus helveticus B02)、保加利亚乳杆菌(Lactobacillus bulgaricus AS1.1482)和嗜热链球菌(Streptococcus thermophilus IFFI 6038)组合发酵制成发酵豆乳,研究益生菌发酵豆乳的发酵特性及流变特性。结果表明,大豆经萌发后,游离氨基酸总量增加了近2倍;与未萌发大豆制成的发酵豆乳相比,萌发大豆发酵豆乳中乳酸菌菌落总数显著增加,产生更多的游离H离子及有机酸,且其剪切稀化作用减弱,表观黏度显著下降,更为接近发酵纯牛乳的流变特性。大豆萌发后制成发酵豆乳,可促进乳酸菌的生长及产酸,有助于改善发酵豆乳的流变特性。     

牛乳和豆乳配比对酸奶品质特性的影响

为了探究牛乳与豆乳配比对酸奶理化性质、流变学特性、微观结构和感官特性的影响,将不同质量配比(100∶0、75∶25、50∶50、25∶75、0∶100)的牛乳与豆乳混合,加入1 g/L直投式发酵剂,在43℃条件下发酵至pH=4.8,在4℃条件下贮存并进行分析。结果表明,随豆乳比例的增加,酸奶中蛋白质含量增加,脂肪含量降低。与纯牛乳酸奶相比,混合乳酸奶的发酵时间缩短,持水力降低,储能模量和损耗模量增加;纯豆乳酸奶的持水力、储能模量和损耗模量居中。纯牛乳或纯豆乳制备的酸奶具有光滑规整的微观结构,混合乳酸奶微观结构粗糙,有大量的微孔。整体上,50%牛乳和50%豆乳制备的酸奶在28 d贮存期内具有良好的风味、较高的感官分数和贮存稳定性。     

干酪乳杆菌纯种发酵大豆乳培养基的优化调配

从益生菌乳制品中自行分离选育出的生长繁殖力强、发酵活力高的干酪乳杆菌(05-20)为试验菌株,研究了牛乳和蔗糖在大豆乳中的添加量对干酪乳杆菌在大豆乳中发酵的凝乳时间、凝乳时活菌数、pH值、滴定酸度及产品感官风味的影响,通过方差分析确定了发酵培养基中牛乳和蔗糖的最适添加量分别为20%和7%,完成了以大豆乳作为干酪乳杆菌最佳载体的初步探索,为进一步研制开发益生菌发酵大豆乳制品奠定了基础.     

绿茶混合软质干酪质量控制研究

研究了绿茶粉豆乳混合干酪的制作工艺,试验结果表明,绿茶混合干酪的最佳工艺条件应为:绿茶粉加入量1%,豆乳添加量为20%,混合乳采用75℃杀菌15s,冷却后加入2%的发酵剂,其中保菌和嗜菌比例为2:3,发酵温度为35℃.当发酵乳pH值达到5.6时停止发酵,发酵后牛乳加入0.04?Clo<,2>和0.02%混合凝乳酶(动物凝乳酶和微生物凝乳酶比例为4:1),35℃条件下凝乳65 min后经排乳清,加盐后熟化得到干酪产品,产品风味较好.出品率为9.12%.     

发芽大豆复合乳制品的研制

以发芽大豆和牛乳为原料,开发复合乳制品。通过品质分析,确定了复合乳及复合酸乳的制备条件。其中发芽大豆乳与牛乳以4∶6混合,得到的复合乳呈乳白色、外观均一、风味协调,营养丰富。通过对菌种的连续驯化,利用单因素试验与正交试验找到复合乳的最适发酵条件,即混合乳质量比为1∶1,接种量为3%,加糖量为5%。     

Thermal conductivity as influenced by the temperature and apparent viscosity of dairy products

This study aimed to evaluate the rheological behavior and thermal conductivity of dairy products, composed of the same chemical components but with different formulations, as a function of temperature. Subsequently, thermal conductivity was related to the apparent viscosity of yogurt, fermented dairy beverage, and fermented milk. Thermal conductivity measures and rheological tests were performed at 5, 10, 15, 20, and 25°C using linear probe heating and an oscillatory rheometer with concentric cylinder geometry, respectively. The results were compared with those calculated using the parallel, series, and Maxwell-Eucken models as a function of temperature, and the discrepancies in the results are discussed. Linear equations were fitted to evaluate the influence of temperature on the thermal conductivity of the dairy products. The rheological behavior, specifically apparent viscosity versus shear rate, was influenced by temperature. Herschel-Bulkley, power law, and Newton's law models were used to fit the experimental data. The Herschel-Bulkley model best described the adjustments for yogurt, the power law model did so for fermented dairy beverages, and Newton's law model did so for fermented milk and was then used to determine the rheological parameters. Fermented milk showed a Newtonian trend, whereas yogurt and fermented dairy beverage were shear thinning. Apparent viscosity was correlated with temperature by the Arrhenius equation. The formulation influenced the effective thermal conductivity. The relationship between the 2 properties was established by fixing the temperature and expressing conductivity as a function of apparent viscosity. Thermal conductivity increased with viscosity and decreased with increasing temperature.     

Effects of ultra-high pressure treatment on angiotensin-converting enzyme (ACE) inhibitory activity,antioxidant activity,and physicochemical properties of milk fermented with Lactobacillus delbrueckii QS306

The present study investigated the influence of ultra-high pressure (UHP) treatment on angiotensin-converting enzyme inhibitory (ACEI) activity and quality of milk fermented with Lactobacillus delbrueckii QS306 after storage. By varying treatment pressure, duration of pressure treatment, and duration of fermentation, optimal process parameters for the UHP treatment of milk fermented with QS306 to enhance ACEI activity were found to be 400 MPa, 10 min, and 48 h, respectively. The degree of ACE inhibition of the fermented milk was 91.63 ± 0.02%. After UHP treatment, ACEI activity, apparent viscosity, concentrations of polypeptides and volatile aromatic substances, umami, and richness had increased significantly, bitterness and astringency were significantly reduced, and antioxidant properties were maintained. In addition, UHP fermented milk maintained a high level of ACEI activity and good quality during storage. Thus, the data represent a valuable reference for improving the storage quality of fermented milk and research for the future development of dairy products with high ACEI activity.     

环丙沙星残留量对嗜热链球菌grx02发酵乳品质的影响

研究不同环丙沙星残留量对S. thermophilus grx02发酵乳的感官性状、酸度、组织状态和挥发性风味物质的影响。结果显示：当环丙沙星的残留量高于0.4μg/mL时,会对发酵乳的感官质量产生显著的不利影响。当发酵乳中环丙沙星残留量高于0.2μg/mL时会显著降低发酵乳的黏度,增大其脱水收缩性;且环丙沙星残留量为0.1μg/mL时就会降低发酵乳挥发性风味物质的总含量。可见,用于发酵乳制品生产的原料乳中环丙沙星的残留限量应该控制在0.1μg/mL以下。     

发酵乳的最新进展

综述了发酵乳在科学、枝术和市场方面最新进展。介绍了在分子水平和菌株水平的乳酸菌和益生菌的菌种鉴定、乳酸菌和新益生菌株的安全性、乳酸菌胞外多糖、减少发酵乳生产过程中黏度降低的因素，以及乳酸菌和益生菌的功能保健作用。根据近年来消费者对酸奶的温和味道、香气和质地更高的要求，叙述了酸奶和其他发酵乳新产品开发的进展。     

中国主要牧区特色干制发酵乳制品细菌多样性和游离氨基酸及脂肪酸特征性分析

为研究我国主要牧区特色干制发酵乳制品中细菌、游离氨基酸、脂肪酸组成及其相关性,通过高通量测序技术对新疆酸奶疙瘩、西藏曲拉、内蒙古奶渣子和云南乳扇中细菌16S rDNA V4-V5区测序,利用气相色谱-质谱联用技术和液相色谱技术分别测定脂肪酸和游离氨基酸含量,最后再利用冗余分析研究细菌群落与α多样性、脂肪酸和游离氨基酸的相关性。高通量测序结果表明,干制发酵乳制品样本共获得2 421 338条reads,其中clean reads为1 871 524条,云南乳扇中细菌Chao1指数和Shannon指数均明显高于其他3个地区的干制乳制品样品。细菌群落组成分析发现,不同干制乳制品样品的菌群组成差异较大,4个地区的干制乳制品中的菌群均以Firmicutes为主,其中新疆酸奶疙瘩的Firmicutes相对最高,西藏曲拉的Proteobacteria相对于其他地区的干制乳制品占比最高。在属水平上,不同地区的干制乳品主要以Lactococcus或Lactobacillus为主。脂肪酸分析发现,云南乳扇中的16种脂肪酸均高于其他3个地区。对游离氨基酸进行分析,共检出24种游离氨基酸,其中新疆酸奶疙瘩的游...     

Capsular and slime-polysaccharide production by Lactobacillus rhamnosus JAAS8 isolated from Chinese sauerkraut: Potential application in fermented milk products

Exopolysaccharides (EPSs) produced by lactic acid bacteria (LAB) play an important role in the improvement of the physical properties of fermented dairy products. To find EPS-producing LAB strains with potential industrial applications, a Lactobacillus rhamnosus strain, L. rhamnosus JAAS8, that is capable of producing two forms of EPS when grown in MRS broth or semi-defined medium with glucose as a carbon source was isolated and identified from Chinese sauerkraut. The capsular-polysaccharide (CPS) present surrounding the bacterial surface of L. rhamnosus JAAS8 was observed by both optical microscopy and transmission electron microscopy. The slime-polysaccharide (SPS) present in the growth medium was produced mainly during the exponential growth phase, while the CPS was produced only in fermentation. Monosaccharide analysis of the purified polysaccharide samples showed that the CPS was composed of galactose and N-acetylglucosamine in a molar ratio of 5:1, and the SPS was composed of galactose, glucose and N-acetylglucosamine in a molar ratio of 4:1:1. The use of L. rhamnosus JAAS8 could be considered for potential applications in the dairy industry to improve the rheological properties of fermented milk products by increasing their water-holding capacity and viscosity.     

新疆传统乳制品中优良乳酸菌的筛选及多菌株发酵剂的研究

从新疆地区采集的46份传统乳制品中分离获得的612株乳酸菌,根据菌株来源、培养条件,形态特征、凝乳状态和产酸特性,选择其中20株乳酸菌进行生理生化鉴定和酸奶发酵试验,结果表明,分离株中3株为链球菌,4株为乳球菌,13株为乳杆菌,平均发酵产酸速率在8.11~12.43oT/h,不同菌株在酸乳冷藏期间表现出不同的后酸化活性,冷藏15d滴定酸度提高了6.3%~55.7%。不同菌株凝乳时黏度在272~1085cp,多数菌株发酵乳在冷藏期间黏度呈上升趋势,球菌的产黏能力普遍低于杆菌。气相色谱分析结果显示不同菌株发酵乳中丁二酮在3.51~68.74mg/L,乙醛在3.51~68.74mg/L,丙酮在0.87~48.35mg/L,乙酸乙酯在0~103.68mg/L,异戊醇都未检出。经过混合菌株发酵生产酸乳比较,发现以S.thermophilusX1、S.thermophilusX5、L.plantarumY5和L.delbrueckii bulgaricussubsp.Y10按1∶1∶1∶1比例组合作为发酵剂,生产的酸乳组织状态较好、风味独特、后酸化弱。     

干酪乳杆菌纯种发酵燕麦乳工艺及其产品质量分析

针对目前益生菌发酵乳制品多为混合菌种发酵动物源乳制品的研究现状,本研究以燕麦为主要原料,通过制备纯燕麦乳,酶解,添加20％牛乳和7％蔗糖以及适量乳化剂与稳定剂,组成发酵培养基,以发酵乳制品中选育出的生长繁殖力强,发酵活力高的干酪乳杆菌05-20为试验菌株,研究接种量、发酵温度、发酵时间等单因素对干酪乳杆菌纯种发酵燕麦乳...     

Processing properties of yogurt as affected by the EPS produced by Leuconostoc mesenteroides XR1

The aim of this study was to examine the fermentation characteristics of a novel Leuconostoc mesenteroides strain (XR1) and to investigate the effect of XR1 exopolysaccharides (EPS) on the microstructure, texture and rheological properties of yoghurt. The novel Leuconostoc mesenteroides strain (XR1) was isolated from wild kefir grains obtained from Xinjiang Province. The results showed that XR1 had good EPS production capacity and favourable fermentation performance. The addition of XR1 EPS to fermented milk effectively improved the water-holding capacity (WHC) of the fermented milk and changed its microstructure. In subsequent fermentation studies, the XR1 strain was found to be a compatible strain, and the steric barrier formed between XR1 EPS and the fermented milk proteins enhanced its viscoelastic properties. Rheology studies indicated that fermented milk supplemented with EPS possessed a higher modulus (G’, G’’ ) and complex viscosity. Thus, these results indicate that XR1 EPS are useful as a natural organic additive that can replace chemical additives in dairy products.     

基于16S rDNA高通量测序方法比较新疆西北部地区乳品中微生物的多样性

为更加全面地了解新疆特色乳品中微生物多样性,比较不同动物来源的原奶和酸奶的细菌群落结构,运用高通量测序技术,对乳品中细菌16S r DNA V4-V5区测序,进而对新疆克州和塔城地区牛奶、驼奶、马奶、羊奶、酸牛奶、酸驼奶和酸马奶7种乳品中细菌群落组成和多样性进行分析。研究共获得539 557条有效序列,379个OTU。多样性分析表明,原奶样品中细菌Shannon-Wiener指数明显高于酸奶样品。微生物群落组成分析发现,不同乳品之间菌群组成差异较大。7种乳品中的菌群均以厚壁菌门和变形菌门为主,但原奶样品主要以变形菌门为主,而酸奶样品主要以厚壁菌门为主。在属水平上,牛奶主要以假单胞菌属(Pseudomonas)为主,驼奶主要以埃希菌属-志贺菌属(Escherichia-Shigella),马奶主要以明串珠菌属(Leuconostoc)为主,羊奶中的优势菌属为乳球菌属(Lactococcus),而酸牛奶、酸驼奶和酸马奶都是以乳杆菌属(Lactobacillus)为优势菌属。不同动物来源的原奶和酸奶样品中的微生物多样性存在显著差异,并且原奶中检测到的环境污染菌和致病菌(或条件致病菌)的丰度也相对较高。本研究结果将为准确评估乳品中的微生物群落对新疆地区少数民族健康的影响提供一定的数据基础。