不同发酵剂对Mozzarella干酪品质的影响

采用嗜热链球菌和嗜热乳杆菌作为Mozzarella干酪的发酵剂，研究单一嗜热链球菌发酵剂与嗜热链球菌和嗜热乳杆菌组成的混合发酵剂对Mozzarella干酪品质的影响。结果表明，混合菌作发酵剂制得的干酪品质优于用单一嗜热链球菌作发酵剂的干酪。     

发酵剂、氯化钙及凝乳酶添加量对白牦牛乳Mozzarella干酪质构的影响

以白牦牛乳为原料制作Mozzarella干酪,在单因素试验基础上采用Box-Behnken响应面法对发酵剂、CaCl_2、凝乳酶添加量进行优化,利用质构综合评分筛选最佳的工艺参数。结果表明,白牦牛乳Mozzarella干酪的最佳工艺参数为:发酵剂添加量0.24 g/L、CaCl_2添加量0.23 g/L、凝乳酶添加量0.04 g/L,此时白牦牛乳Mozzarella干酪质构综合评分为11.095,出品率为20.53%,感官评分为93.67。此工艺条件下制作的白牦牛乳Mozzarella干酪香味浓郁,质地均匀,软硬适度。     

组合赋权法结合响应面分析法优化娟姗牛奶Mozzarella干酪制作工艺

以娟姗牛奶为原料乳,制作Mozzarella干酪,采用组合赋权法综合评价娟姗牛奶Mozzarella干酪的质量品质,并通过响应面分析法优化娟姗牛奶Mozzarella干酪的制作工艺。结果表明,Mozzarella干酪的色泽、风味、质构、特征结构的组合权重分别为0.052、0.427、0.351、0.170,质构指标中的硬度、弹性、凝聚性的组合权重分别为0.742、0.095、0.163,特征结构指标中的拉伸性、融化性、油脂析出性的组合权重分别为0.372、0.334、0.294。响应面分析法优化发现娟姗牛奶Mozzarella干酪的最佳工艺参数为:发酵剂添加量0.020%,拉伸温度76℃,拉伸时间3min,在此条件下娟姗牛奶Mozzarella干酪的理论综合值为15.97,实验验证综合值为15.99,模型拟合程度较高。     

适合Mozzarella干酪生产用菌种的筛选

概述了Mozzarella干酪的特点以及适合生产Mozzarella干酪用菌种所具备的特性,从实验室现有的优良纯化菌种中筛选出适合Mozzarella干酪生产所用的菌种。经过对各株菌种的产酸性能、黏度、双乙酰质量浓度、胞外多糖质量浓度以及pH值为4.6可溶性氮的测定最终优选出两株优良的菌种,分别是保加利亚乳杆菌和嗜热链球菌。     

模拟胃肠液环境下Mozzarella干酪提取液抗氧化活性

为评价干酪成熟过程中形成的活性肽及存活的发酵剂菌种对人体的抗氧化作用,对不同菌种组合Mozzarella干酪的蒸馏水、pH4.6醋酸缓冲液和12%三氯乙酸（TCA）提取液在模拟胃肠液环境下对DPPH自由基的清除率以及还原力进行测定。结果表明,所有不同菌种组合Mozzarella干酪的不同溶剂提取液在模拟胃肠液的环境下具有一定的抗氧化活性,并且模拟肠液的抗氧化活性大大低于模拟胃液环境,活性下降最高达88.35%。添加干酪乳杆菌（Lactobacillus casei）LPC-37的3号Mozzarella干酪提取液在模拟胃肠液环境下的抗氧化活性高于其他Mozzarella干酪,其水、pH4.6醋酸缓冲液、12%TCA提取液在模拟肠液环境下对DPPH清除率分别为73.96%、30.28%、70.27%,还原力分别为0.37、0.18、0.18。     

Mozzarella干酪功能特性的研究进展

本文概述了Mozzarella干酪的功能特性,并对影响Mozzarella干酪功能特性的原料乳及其处理方式、乳酸菌种和发酵剂、生产工艺条件等因素进行分析,提出了我国南方奶水牛养殖地区发展水牛乳Mozzarella加工产业化的设想和有利条件.     

副干酪乳杆菌水牛奶酸奶品质及其通便功能的评价

研究了含副干酪乳杆菌LYO 50 DCU-S的水牛奶酸奶品质及其润肠通便作用。实验对副干酪乳杆菌、保加利亚乳杆菌和嗜热链球菌混合发酵的水牛奶酸奶在1、7、14、21 d的发酵过程中的活菌数、p H值、酸度、黏度、持水力、感官指标等分别进行测定,将其与保加利亚乳杆菌和嗜热链球菌混合发酵的水牛奶酸奶进行对比分析,探究了LYO 50 DCU-S是否可作为附属发酵剂应用到水牛奶酸奶生产中。将昆明种雄性小鼠分为空白组、模型组、对照组和3个副干酪乳杆菌给药组。使用复方地芬诺酯建立小鼠便秘模型,副干酪乳杆菌水牛奶酸奶给药7 d后,便秘小鼠首次排便时间缩短;连续15 d灌胃副干酪乳杆菌水牛奶酸奶后,便秘小鼠墨汁推进率显著增加。结果表明,将副干酪乳杆菌LYO 50 DCU-S作为附属菌应用到水牛奶酸奶生产中具有可行性,副干酪乳杆菌LYO 50DCU-S可显著改善水牛奶酸奶的润肠通便功能。     

混合乳干酪生产工艺研究(2)混合乳干酪生产最佳工艺参数优化

本试验在已筛选出的发酵剂菌种、最佳凝乳酶和钙化合物的基础上,又综合考虑了影响混合乳(豆乳和牛乳)干酪的几大因素,即豆乳添加量,发酵剂添加量,乳酸钙添加量和凝乳酶添加量,由此优化出混合乳干酪生产的最佳工艺参数.结果表明最佳发酵剂为干酪乳杆菌99108+嗜热链球菌(11),最佳凝乳酶为皱胃酶,最佳钙化合物为乳酸钙,而70%大豆豆乳与30%牛乳混合,添加4%发酵剂,0.2%乳酸钙和0.015%皱胃酶则为最佳的工艺参数.     

快速成熟切达干酪复合发酵剂的筛选

以促进切达干酪成熟为目的,筛选发酵菌种,菌种添加量、菌种比例,确定发酵剂对切达干酪促熟的影响。利用响应面中心旋转组合设计,优化出具有促熟效果的复合发酵剂的最佳配比,即:保加利亚乳杆菌(Lb)添加量为0.92 kg/100 kg原料乳,嗜热链球菌(St)添加量为0.77 kg/100 kg原料乳,瑞士乳杆菌(Lh)添加量为1.08 kg/100 kg原料乳,复合发酵剂的总添加量2.77%。使用优化的复合发酵剂,通过验证试验加工的切达干酪与R704商业发酵剂对照样比对,结果复合发酵剂具有显著的促熟效果(P0.01)。     

应用模糊数学方法评价水牛乳Mozzarella干酪发酵剂

以发酵剂的产酸性能、黏度大小、双乙酰含量、pH4.6可溶性氮含量、滋味等五项为评价指标,应用模糊数学综合评价方法评价水牛乳Mozzarella干酪发酵剂中球菌与杆菌比例。结果表明,Lb.与St.以1∶1.2的比率混合时,模糊概率达0.83,菌种的综合品质最好,且与其它比率的菌种在统计学上存在显著差异(p<0.05)。     

Calibration of infrared milk analyzers: modified milk versus producer milk

Mid-infrared (MIR) milk analyzers are traditionally calibrated using sets of preserved raw individual producer milk samples. The goal of this study was to determine if the use of sets of preserved pasteurized modified milks improved calibration performance of MIR milk analyzers compared with calibration sets of producer milks. The preserved pasteurized modified milk sets exhibited more consistent day-to-day and set-to-set calibration slope and intercept values for all components compared with the preserved raw producer milk calibration sets. Pasteurized modified milk calibration samples achieved smaller confidence interval (CI) around the regression line (i.e., calibration uncertainty). Use of modified milk calibration sets with a larger component range, more even distribution of component concentrations within the ranges, and the lower correlation of fat and protein concentrations than producer milk calibration sets produced a smaller 95% CI for the regression line due to the elimination of moderate and high leverage samples. The CI for the producer calibration sets were about 2 to 12 times greater than the CI for the modified milk calibration sets, depending on the component. Modified milk calibration samples have the potential to produce MIR milk analyzer calibrations that will perform better in validation checks than producer milk-based calibrations by reducing the mean difference and standard deviation of the difference between instrument values and reference chemistry.     

毛细管电泳法对乳及乳制品中乳源蛋白的研究

采用毛细管电泳方法对原料乳、市售鲜奶、不同厂家的巴氏灭菌乳、不同厂家和产地超高温灭菌乳(UHT)、调味乳、乳酸饮料、复原乳、酸奶、奶粉中蛋白成分进行检测。选择聚乙烯醇涂层毛细管,采用柠檬酸缓冲体系,在紫外检测214nm、分离电压20kV条件下对乳及乳制品中的α一乳白蛋白(α-La)、β一乳球蛋白(β-Lg)、α-酪蛋白(α-CN)、β-酪蛋白(β-CN)和k-酪蛋白(k-CN)进行分离测定。结果表明:五种蛋白的含量在原料乳(巴氏灭菌乳、市售鲜奶)、UHT乳、酸奶、调味乳、乳酸饮料、复原乳中依次降低,而UHT乳含量随保质期的增加而减少,奶粉中蛋白质含量因其适应人群而有差异。乳及乳制品中蛋白质的含量与其存在形式、产地及加工工艺相关。     

鲜乳及乳粉糊精掺假问题

目前,我国鲜牛（羊）乳及乳制品掺假是一个较为普遍的现象。鲜乳掺假会增加乳品加工企业的原料收购费及贮存、运输和加工成本,还严重威胁着产品质量,甚至决定着企业的生存和发展。俗话说“千里之堤,溃于蚁穴”,事实上,确有不少企业因无力控制乳原料掺假等等质量问题,在群雄逐鹿的乳品及冷饮市场竞争中不堪一击,不得不偃旗息鼓,被迫抱怨退出！而有的企业,则以低价倾销假冒伪劣乳制品的手段来打击竞争对手、占领市场,极大的破坏了乳品行业的利益,消弱了乳制品市场发展的后劲。然而,鲜乳及乳制品掺假不单是产品质量问题、企业声誉…     

Reduction of milk and milk product wastage

The paper examines the assessment of waste control based on effluent monitoring and the results of a BOD test for 'milk equivalent' measurement are interpreted and evaluated. The importance of reliable flow measurement is stressed and a table is given showing wastage from various dairy operations and methods of reducing losses recommended.     

Effects of milk powders in milk chocolate

The physical characteristics of milk powders used in chocolate can have significant impact on the processing conditions needed to make that chocolate and the physical and organoleptic properties of the finished product. Four milk powders with different particle characteristics (size, shape, density) and "free" milk fat levels (easily extracted with organic solvent) were evaluated for their effect on the processing conditions and characteristics of chocolates in which they were used. Many aspects of chocolate manufacture and storage (tempering conditions, melt rheology, hardness, bloom stability) were dependent on the level of free milk fat in the milk powder. However, particle characteristics of the milk powder also influenced the physical and sensory properties of the final products.     

Investigations on milk flow and milk yield from teats with milk flow disorders

The objective of this study was to investigate peak milk flow, average milk flow, and milk yield in teats with milk flow disorders. A total of 100 hard milking teats were studied in 97 cows. Teats with milk flow disorders were examined endoscopically. Quarter milk flow and quarter milk yield were examined with four Lactocorders attached to a quarter milking machine. Peak milk flow, average milk flow, and milk yield were measured in all teats of the udder before treatment of the affected teat, as well as 1 and 6 mo later. Teats with milk flow disorders were compared to all other teats of the same udder. Before treatment, peak milk flow from affected teats was 20%, average milk flow 14%, and milk yield 53% of the control teats, adjusted for other significant explanatory variables. Milk flow and milk yield increased after surgical treatment of the affected teats. Six months after treatment peak milk flow was 79%, average milk flow 76%, milk yield was 71% compared with control teats. We conclude from these findings that teat endoscopy and measuring quarter milk flow and milk yield with Lactocorders are useful tools for examining teats with milk flow disorders.     

山羊奶与牛奶和人奶营养成分的比较

对山羊奶、牛奶和人奶中蛋白质、脂肪、维生素、矿物质等主要营养成分进行了比较,分析了3种奶中主要营养成分的差别。通过比较发现,山羊奶在总体营养成分方面优于牛奶,更接近人奶。但山羊奶存在铁、叶酸和维生素B12含量较低以及羊奶膻味的问题,应在营养上对这方面加以重视。     

生乳中豆浆、米汤掺假鉴别及其定量测定

为鉴别生乳掺假,采用非线性化学指纹图谱技术,建立基于"溴酸钠+硫酸锰+硫酸+丙酮"稳态体系的不同奶源地的纯生乳及掺入不同量豆浆、米汤的生乳的非线性化学指纹图谱,利用指纹图谱的直观特征信息能很好地将掺豆浆、米汤的生乳鉴别出来,并能对掺假物的种类进行判断。根据掺假生乳指纹图谱参数信息与掺假量的关系,可对生乳中掺入豆浆、米汤的相对含量进行评估。非线性化学指纹图谱技术为原料乳中豆浆、米汤的掺假鉴别及掺入物质的相对含量的评价提供了一种新的方法。     

Nitrate-reducing microorganisms in milk products and human milk

The quantitative determination of nitrate-reducing microorganisms in food is important because of their role in the formation of N-nitroso compounds and methemoglobin. The total counts of microorganisms and the counts of nitrate-reducing microorganisms were assayed in various milk products and in human milk by the method of the most probable numbers using nitrate broth medium. The mean value and standard deviation of the nitrate-reducing microorganisms were the following: in pasteurized milk 3.4 +/- 1.1 log/ml (in spring and summer 4.2 +/- 1.1, and in winter 2.8 +/- 0.6 log/ml), in kefir "Tallinn' 2.9 +/- 1.1 log/ml, in fat kefir 2.9 +/- +/- 0.7 log/ml, in sour milk 3.9 +/- 0.5 log/ml, in fresh milk 4.6 +/- 0.6 log/ml and in human milk 2.7 +/- +/- 1.1 log/ml. The amount of nitrate-reducing microorganisms in pasteurized milk of the spring-summer period and in fresh milk was significantly higher than in human milk. The mean count of nitrate-reducing microorganisms in human milk is regarded as a maximum permitted count of these organisms in milk for bottle-fed sucklings. For them and for atrophic gastritis patients pasteurized or fresh milk should be boiled.     

含24种乳抗体免疫乳的制备

以24株人肠道病原菌（包括病原性大肠杆菌12株、沙门氏菌8株、志贺氏菌3株、小肠结肠炎耶尔森氏菌1株）作为抗原，对乳牛进行系统免疫，免疫乳与非免疫乳乳中IgG含量无显著差异。系统免疫并不增加乳中IgG的含量，但IgG的抗体特异性大大增强，所得的免疫初乳中乳抗体对24种不同病原菌的凝集价为2^8-2^12，为普通初乳中乳抗体凝集价的32－256倍；免疫常乳中乳抗体对24种不同病原菌的凝集价为2^5-2^8，为普通乳中乳抗体凝集价的8－128倍。