广西水牛奶和荷斯坦牛奶中蛋白质和氨基酸的含量及组成分析

目的研究广西区内生水牛奶和荷斯坦生牛奶中蛋白质、氨基酸含量及其组成特性,分析水牛奶和荷斯坦牛奶的差异。方法采用盐酸水解法处理牛奶样品,通过氨基酸自动分析仪测定氨基酸含量,分析水牛奶和荷斯坦牛奶氨基酸的含量和组成;通过凯氏定氮法测定牛奶中蛋白质含量。结果 18份牛奶样品中蛋白质、氨基酸的测定结果表明,生水牛奶的蛋白质和氨基酸含量均高于荷斯坦生牛奶,而水牛奶和荷斯坦牛奶中各氨基酸含量占氨基酸总量的比值相近。结论该方法为广西生水牛奶和荷斯坦生牛奶的鉴别提供参考。     

广西水牛奶与荷斯坦牛奶工艺学特性比较

为了探索、比较广西水牛奶与荷斯坦牛奶的工艺学特性,对二者的缓冲容量、表面张力、粒度分布、稳定系数进行了比较分析。结果表明,广西水牛奶的缓冲容量和粒径分别是荷斯坦牛奶的1.1倍和2倍。在研究范围内,广西水牛奶在pH值为6.8时缓冲容量最大,温度50℃时表面张力最小,pH值为4.7时稳定系数最小;而荷斯坦牛奶在pH值为6.6时缓冲容量最大,温度为50℃时表面张力最小,pH值为4.6时稳定系数最小。广西水牛奶的粒径分布在91.28~458.7 nm之间,荷斯坦牛奶的粒径主要分布为91.28~190.1 nm之间,因此,认为两种牛奶的工艺学参数存在多方面的差异。     

粒径分析法快速判定均质工艺对水牛奶稳定性的影响

比较了水牛奶与荷斯坦牛奶粒径分布,并采用粒径分析法研究了均质工艺对水牛奶粒径分布的影响,结果表明:水牛奶脂肪粒径大于荷斯坦牛奶,水牛奶经65 ℃和24 MPa的均质工艺处理后,稳定性较好;粒径分析法是一种快速、准确的判定乳品稳定性的方法.     

不同品种原料乳理化特性分析

主要分析荷斯坦牛、牦牛、娟珊牛、摩拉水牛、尼里-拉菲水牛、Ⅰ代杂交水牛、高代杂交水牛等7个品种的原料乳的常规营养成分,并对原料乳中蛋白质和氨基酸组成及牛乳缓冲能力进行测定。结果显示：摩拉水牛、尼里-拉菲水牛、Ⅰ代杂交水牛和高代杂交水牛的乳脂肪含量分别为6.86%、7.99%、8.34%、8.69%,蛋白质含量分别为5.75%、5.14%、5.78%、5.58%,干物质含量分别为17.07%、18.79%、19.73%、19.88%,显著高于其他3种牛乳;牦牛和娟珊牛乳中乳糖含量分别为5.09%、5.17%,显著高于其他5种牛乳。SDS-PAGE显示：水牛乳中除含有牛乳血清蛋白(BSA)、α-酪蛋白(α-CN)、β-酪蛋白(β-CN)、κ-酪蛋白(κ-CN)、β-乳球蛋白(β-Lg)和α-乳白蛋白(α-La)主要蛋白外,还含有一些未定性蛋白;且水牛乳具有最好的缓冲性能,其次是牦牛乳和娟珊牛乳,荷斯坦牛乳缓冲性能最差。     

广西水牛奶脂肪含量对感官特性的影响

以荷斯坦牛奶为对照品,分析了广西水牛奶的主要成分、理化指标和粒径分布特点,发现两种牛奶的非脂乳固体、酸度、pH值等指标并无明显差异．水牛奶的蛋白质、脂肪、总固形物质量分数及电导率明显高于荷斯坦牛奶,特别是脂肪质量分数差异尤为明显。两种牛奶脂肪在粒经分布上也表现出不同的特点,水牛奶的脂肪粒径在0．5～20μm之间,而荷斯坦牛奶的粒径在0．5～10μm之间。为此,进一步比较分析了不同脂肪质量分数水牛奶的感官差异．发现水牛奶的风味受脂肪质量分数很大的影响．提示在开发水牛奶产品时应注意调节脂肪质量分数。     

新品类水牛奶京城品鉴

记者近期获悉，在京城的超市里热卖一种水牛奶。据介绍，该水牛奶是由皇氏甲天下乳业股份有限公司生产出品的。摩拉菲尔水牛奶奶香浓郁，口感醇厚，完全有别于普通牛奶，相比较普通牛奶，水牛奶挂壁厚、不起泡，这源于水牛奶奶质优良，营养干物质含量高，更为浓稠。     

新品类水牛奶京城品鉴

记者近期获悉,在京城的超市里热卖一种水牛奶。据介绍,该水牛奶是由皇氏甲天下乳业股份有限公司生产出品的。摩拉菲尔水牛奶奶香浓郁,口感醇厚,完全有别于普通牛奶,相比较普通牛奶,水牛奶挂壁厚、不起泡,这源于水牛奶奶质优良,营养干物质含量高,更为浓稠。     

纳米多维对荷斯坦奶牛产奶性能的影响

为研究纳米多维对荷斯坦奶牛产奶量、乳品质和体细胞数的影响,试验选择94头荷斯坦奶牛,采用随机分组的方法分为对照组和试验组,对照组正常饲喂,试验组在饮水中添加纳米多维,测定其对奶牛产奶性能的影响。结果表明,试验组荷斯坦奶牛产奶量、乳脂含量、乳蛋白含量和干物质含量均高于对照组,试验组牛奶中体细胞数低于对照组,说明纳米多维可有效改善牛奶的产奶性能和降低奶牛的体细胞数,显著提高经济效益。     

特色奶没那么神

营养丰富的牛奶不仅是人们餐桌上离不开的好食物,也成为各商家的"必争之地"。于是,羊奶、水牛奶、骆驼奶等其他动物奶出现在人们面前时,往往会把自己打造成"最接近完美的奶"、"奶白金"等看似更胜牛奶一筹的产品。让水牛奶走进人们视线的,是一则近日在媒体上广泛传播的广告。广告中提到,"水牛奶的综合营养价值是普通牛奶(荷斯坦奶牛,即黑白花奶牛产的奶)的近2倍,其铁、锌、维生素等微     

不同品种水牛乳中矿物元素的测定与分析

为阐明不同奶水牛品种的水牛乳在不同泌乳期的微量元素变化,采集了我国摩拉水牛、尼里-拉菲水牛、以及上述两种水牛加本地水牛(即三品种杂交水牛,以下简称"三杂水牛")在泌乳第15,45,150和200 d的乳样,同时采集了荷斯坦奶牛和娟姗牛的乳样,用ICP-AES法分析乳中几种常量和微量元素的质量浓度。结果表明,水牛乳中矿物元素除钾和钠外,各种矿物元素质量浓度均高于荷斯坦和娟姗牛。以平均值计,水牛乳钙、铁、锌的质量浓度分别是荷斯坦牛乳的1.7,13.0和1.7倍。泌乳期是影响水牛乳矿物元素质量浓度的主要因素,其中以早期和末期质量浓度较高。各品种水牛乳间矿物元素质量浓度无显著差异,但尼里-拉菲水牛乳总体偏低。     

广西水牛原料乳微生物和理化指标分析

按不同种群从广西取80个水牛原料乳样品，通过理化和微生物指标检测，对水牛乳营养价值和安全性进行了分析比较．主要理化检测结果如下：脂肪7．32％，蛋白质4．71％，乳糖4．67％。固形物18．42％，灰分0．84％（均为质量分数），pH值为652，密度1.030g／mL。纯种河流型水牛摩拉和尼里-拉菲的脂肪、蛋白质、固形物、灰分舍量显著低于（P〈0.05）河流-沼泽型杂交水牛。微生物检测结果如下（对数值）：细菌总数5．69mL^-1，茅孢菌3．03mL^-1，乳酸菌4．79mL^-1，真菌1．80mL^-1，大肠菌群2．48mL^-1，大肠杆菌1．83mL^-1，金黄色葡萄球菌1.80mL^-1，所有样品中李斯特氏苗均未检出。地区间微生物指标差异较大。微生物含量均在可接受范围之内，但是致病菌的出现说明需要建立相关的卫生质量标准.     

Action of milk clotting enzymes on alphas-caseins from buffalo's and cow's milk.

alphaS-Caseins were isolated from buffalo's and cow's milk and hydrolyzed with rennet, bovine pepsin, microbial proteases from Mucor miebei, Mucor pusillus Lindt, and Endotbia parasitica. The rate of hydrolysis was followed by determining the unaltered alphaS-casein in the digest after acrylamide gel electrophoresis. The rate of hydrolysis of alphaS-casein from the two species with the different enzymes was comparable, being more rapid with microbial enzymes particularly Endotbia parasitica protease. However, the electrophoretic patterns of the degradation products of buffalo's and cow's alphaS-casein produced by microbial rennets were not identical.     

Identification of cow's milk in "buffalo" cheese by duplex polymerase chain reaction

A duplex polymerase chain reaction (PCR) was developed to identify the milk of bovine and buffalo species in cheese products, particularly in mozzarella cheese, a typical Italian cheese made from buffalo's milk. Two sets of primers were designed on the basis of the alignment of the sequence codifying mitochondrial cyt b available in the GenBank database. The primers proved to be species-specific, giving rise to 279-bp (bovine) and 192-bp (buffalo) amplified fragments. Since the amplification conditions for bovine and buffalo primers were identical, a duplex PCR was successfully applied to identify the two species in a single reaction step. This technique, when used to test cheese products from the retail trade, allowed the detection of partial or even total substitution of cow's milk for buffalo's milk, in some cases in samples of cheese misleadingly labeled "pure buffalo" mozzarella.     

Comparison of the characteristics of teleme cheese made from ewe's, goat's and cow's milk or a mixture of ewe's and goat's milk

Teleme cheeses were manufactured from ewe's, goat's and cow's milk and mixture of ewe's and goat's milk. Physicochemical and biochemical analyses of the cheeses at various stages of ripening and storage were performed. Cheeses made from goat's milk had lower moisture content than those made from other milks. No significant differences in the mean values of protein, salt and water activity (a _w ) of the different cheeses at all ages studied were found. Cheeses from goat's and cow's milk had higher contents of fat and fat in dry matter (FDM) compared to that of cheeses from ewe's milk and mixed milk. Significant differences were observed in the yield and yield on 56% moisture: cheeses from ewe's milk gave the highest yield and cheese from cow's milk the lowest. Significant differences were found in the ashes content of the different cheeses at all ages. No differences in cholesterol and cholesterol/fat contents of the four types of cheeses were found. Main and trace elements showed variability among the four cheeses.     

冷、热榨制油工艺对烟籽油理化指标及主要成分的影响

为探究不同制备方法对烟籽油品质的影响,采用冷榨和热榨两种方法制取烟籽油,对两种方法的出油率,油的理化指标、脂肪酸组成和主要脂质伴随物组成进行了比较分析。结果显示,热榨法制备烟籽油的出油率更高,油的颜色较深,酸值和过氧化值明显高于冷榨油,不皂化物和碘值稍高于冷榨油。冷、热榨油的脂肪酸组成和含量没有差别,但冷榨油的植物甾醇、角鲨烯和维生素含量明显高于热榨油。研究结果为下一步针对烟籽油的性质和成分开发利用提供一定的参考。     

武陵山区葡萄酒品质及感官分析研究

根据国家标准分析了酵母辅助发酵（甲）与自然发酵（乙）两种工艺的葡萄酒的理化指标（糖度、酸度、酒精度和固形物含量）,并进行了微牛物指标的检测,并对其营养元素（钾、钠、镁、钙、锌、铁、铜等）、蛋白质、氨基酸和感官进行了分析。结果表明：两种葡萄酒的各项理化指标均在国家标准规定范围之内,其中甲的固形物含量高出乙5．36％;两种葡萄酒的微,丰物指标均能达到国家标准要求;甲的各种矿物质含量均比乙高,蛋白质含量也高出35．90％,氨基酸含量甲（35．4g／100mL）比乙（33．2g／100mL）高,且铁铜含量均在国家标准规定范围之内;通过观察和品尝,甲的色泽较乙好,且酒香较浓郁。通过对武陵山区葡萄酒的品质和感官的分析研究,为以后的理论研究提供实验数据,同时也为武陵山区葡萄酒大规模的牛产奠定理论基础。     

Application of a polymerase chain reaction to detect adulteration of ovine cheeses with caprine milk

A polymerase chain reaction (PCR) procedure has been applied for the detection of caprine milk in ovine cheeses by using primers targeting the mitochondrial 12S ribosomal RNA gene. The use of a primer pair specific for goat in PCR analysis of cheese samples, enabled the amplification of a goat 122 bp fragment with a sensitivity threshold of approximately 1%, whereas no amplification signal was achieved with sheep's, cow's and water buffalo's milk DNA. This study demonstrates the usefulness of the proposed PCR assay for the qualitative detection of goats’ milk in ewes’ cheeses, and may therefore provide a simple and accurate approach applicable to the authentication of cheese or other dairy products in routine monitoring programs.     

虾壳蛋白质营养价值的评价

采用盐酸处理虾头、壳获得蛋白质含量为７６．５５％、钙１５．２％、磷５．２８％的虾头、壳蛋白质。必需氨基酸指数为８８．１３％。化学分为０．９０１３。大鼠实验结果表明，虾头、壳蛋白的蛋白质功效比值、生物价和蛋白质净利用率依次为２．７９２、３．４７７、８０．７９８％和７８．１５３％。各项指标均与牛奶粉蛋白质无显著性差异（ρ〉０．０５）。表明虾头、壳蛋白具有优良的营养价值。     

Determination of mineral contents in different kinds of milk and estimation of dietary intake in infants.

Concentrations of 11 minerals were determined in six kinds of milk (cow's milk-based formulae, breast-milk, soya milk, bottled milk, dried milk and evaporated milk). The contents of copper, magnesium, molybdenum, aluminium, barium and nickel were higher in soya milk than in any other kinds of milk. Except for nickel in soya milk, the dietary intakes of minerals were below or close to the intake recommended by the FAO/WHO.