非脂乳固体和脂肪含量对酸牛乳粘度的影响

通过调整酸牛乳配方中非脂乳固体和脂肪的含量,使酸牛乳粘稠度发生变化,找出它们之间的关系。确定最佳粘稠度的配方。     

非脂乳固体和脂肪含量影响酸牛乳粘度的研究

通过调整酸牛奶配方中非脂乳固体和脂肪的含量，使酸牛乳粘稠度发生变化，找出它们之间的关系，确定最佳粘稠度的配方。     

复乳凝胶作为脂肪替代物 对鸡肉肠理化性质的影响

本实验将海带水提多糖以0%、0.25%、0.5%、0.75%、1.00%、1.25%的浓度添加到复乳凝胶中,以改善其持水性和热稳定性。并将1.00%多糖复乳凝胶以0%、15%、30%、45%、60%、75%替代度替代猪背脂,分析其对鸡肉肠持水持油性、乳化稳定性、质构与感官的影响。随着海带多糖浓度的增加,复乳凝胶的持水性和热稳定性增加(P<0.05),当添加量大于1.00%时,硬度、粘聚性、咀嚼性显著降低(P<0.05)。随着复乳凝胶替代猪背脂比例增大,鸡肉肠的持油性、乳化稳定性、硬度和咀嚼性显著提高(P<0.05),L^*值、b^*值逐渐增大,a^*值逐渐降低(P<0.05),当替代度为30%时,脂肪含量为9.29%;替代度为75%时,脂肪含量仅2.68%。感官评定结果显示,当替代度达到60%时,感官评分与对照组相似。由以上结果说明,复乳凝胶可替代鸡肉肠中60%的猪背脂,且保证了产品性质和质量。     

高压对牛乳理化性质和成分的影响

高压食品加工是一种非热杀菌技术,是指在室温或低温下用100-800MPa高压处理食品。与传统的热杀菌比较,它具有很多优点,不仅能杀死微生物钝化酶类,而对食品的营养成分和感官品质改变较小。本文综述了高压处理对牛奶物理化学性质和成分的影响。     

巴氏法测定牛乳脂肪的改进

对测定牛乳脂肪的巴布科克氏法进行了改进，首次定量确定了硫酸的滴加速度，且通过改变离心条件，大大缩短了测定时间，使其更适合于乳品分析。     

高压脉冲电场杀菌对牛乳理化性质影响的研究

高压脉冲电场技术是目前较受关注的非热加工技术之一。本文研究了高压脉冲电场技术对牛乳几种理化性质的影响。结果表明，不同电场条件下，牛乳的pH值、电导率、乳糖含量、蛋白质质量分数差异均不显著。     

脂肪含量对肉糜性质影响

在低脂肉制品制作中脂肪被水所取代 ,通过对不同脂肪含量 (30 %、2 0 %、1 0 % )肉糜乳化稳定性、色泽、质构等性质的测量 ,发现随着脂肪含量的降低 ,产品硬度值下降。各样品产量、成品稳定性与乳化稳定性具有相关性。试验结果表明 ,高温产品各种性质较低温产品差     

酒精阳性水牛乳乳成分及理化性质的研究

本研究连续一年观测了摩拉水牛、尼里-拉菲水牛、一代杂水牛和三品杂水牛4个种水牛乳64%的不同季节的酒精阳性发生率、乳成分、理化性质,并比较了酒精阳性乳、阴性乳与乳样总体的差异。结果表明,纯种河流型水牛(摩拉水牛、尼里-拉菲水牛)乳酒精阳性率低于两个杂交水牛(三品杂水牛、一代杂水牛),各品种水牛乳均以2~4月和8~10月的阳性率为最高。低酸度酒精阳性乳(12~18oT)占据了酒精阳性乳的52.9%~64.1%。酒精阳性乳的乳蛋白、乳固体、非脂乳固体、酸度均显著高于阴性乳和乳样总体平均值,但冰点低于乳样总体平均值。可见不同品种水牛乳不能用同一酒精浓度进行检验;酒精阳性率可反映水牛应激或营养状况;较高的乳蛋白、非脂乳固体、总乳固体、酸度以及较低的冰点是酒精阳性水牛乳的特征;酸度和冰点是品种间酒精阳性率差异的主要因素。     

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。     

Fat Content of Milk and Cream and Effects on Fat Globule Stability

Milk fat globules with crystalline fat content were sheared in defined flow conditions in order to ascertain the critical strain rate, which led to destabilization of the fat globules. Based on a fluid-mechanical model which considered the influence of the dispersed phase, a critical shear rate was defined. The model predicted a linear decrease in destabilization shear rate coupled with an increase in fat volume concentration. This interrelationship was confirmed in experiments. Fat globule stability, as related to shear strain rate, increased at decreasing temperatures. Critical shear rates for milk and cream should be calculated at a fat content not exceeding 45% for temperatures between 5 and 20°C. Any motion at higher fat content had a destabilizing effect on fat globules.     

均质法控制PET奶茶脂肪上浮的研究

采用物理方法——均质法控制奶茶中脂肪上浮,研究了不同的产品均质次数和奶粉均质方式对奶茶脂肪上浮的影响。研究结果显示,产品均质次数越多,所制备产品粒径越小,但随着均质次数的增加,粒径减小的幅度减小。奶粉的均质对奶茶产品脂肪上浮没有影响。粒度测量结果与奶茶脂肪上浮趋势一致。     

Modification of Physicochemical Characteristics of Goat Milk Fat by Feeding Protected High Oleic Sunflower Oil Supplements

ABSTRACT: Protein-oil supplements containing high oleic sunflower oil (HOSO) and different proteins were prepared and fed to lactating goats. Milk fat from goats on basal diet had 12.5% oleic acid (C18:1n9), but C18:1n9 increased ( P < 0.05) to 19.0% on the keratin protein-oil supplement diet, 19.2% on the casein protein-oil supplement diet, and 25.2% on dry casein (DC) protein-oil supplements diet. Feeding protein-oil supplements increased ( P < 0.05) levels of triacylglycerols with 46 and 50 carbons in milk fat and decreased ( P < 0.05) solid content in milk fat at 10°C from 34.8% to 23.0% for DC, to 26.5% for casein, and to 29.6% for keratin. The DC protein-oil supplement diet might produce spreadable butter out of the refrigerator.     

牛奶脂肪含量对超声波检测参数的影响

探测了不同温度下不同脂肪含量牛奶的超声特性参数———声速与衰减系数,分析了脂肪含量与超声参数间的关系以及温度对此关系的影响。结果表明:在温度10.9～39.1℃内,声速随脂肪含量的变化不大,其在39.1℃表现出来的最大变化率仅为0.164%,声速/温度随脂肪含量的变化稍大,其表现的变化率为4.29%;而衰减随脂肪含量的增加显著,在39.1℃时,衰减随脂肪含量变化的变化率最大,为113.2%,衰减/温度随脂肪含量变化的变化率为40.4%。这表明衰减随脂肪含量的变化趋势最明显,且温度对衰减的影响也相对较小,因此利用衰减系数作为测定牛奶脂肪含量的主要指标比其他参数更易于检测出脂肪含量上的差异。     

磷脂强化乳脂肪体系对易氧化营养素包埋稳定性的影响

通过添加外源性大豆卵磷脂的方法保护牛乳均质后的脂肪球膜磷脂层，并利用新生成乳脂肪球分别包埋和保护富含多不饱和脂肪酸的鱼油、VE和β-胡萝卜素3 种易氧化营养素。结果表明，外源性磷脂的添加使牛乳均质过程中形成了结构完整、粒径更小、表面电位绝对值更大的油滴。在油脂加速贮藏实验过程中，富含磷脂和鱼油的2 种均质加工乳可减缓鱼油初级和次级氧化的程度，油脂氧化的初期阶段产生的脂质氢过氧化物含量最终分别为1.28 mmol/mL和1.79 mmol/mL，显著低于无外源性磷脂添加的2.81 mmol/mL。2 种磷脂强化乳在次级氧化阶段产生的丙二醛分别为4.29 nmol/mL和6.64 nmol/mL，显著低于无外源性磷脂添加的15.87 nmol/mL。磷脂强化乳中的VE保存率和β-胡萝卜素的保存率在贮藏实验的12 d后分别达到90.80%和71.02%，显著高于无外源磷脂添加的均质乳（80.63%和64.54%），该工艺方法可降低VE和β-胡萝卜素的降解程度。     

Effect of Sucrose on Physical Properties of Spray‐Dried Whole Milk Powder

ABSTRACT: Spray‐dried whole milk powders were prepared from whole condensed milk with various sucrose concentrations (0%, 2.5%, 5%, 7.5%, and 10% w/w), and their glass transition temperature and some physical properties of importance in chocolate manufacture were evaluated. In milk powder samples, the glass transition temperature and free‐fat content decreased in a nonlinear manner with sucrose addition. Moreover, increasing sucrose concentration reduced the formation of dents on the particle surface. Addition of sucrose in whole condensed milk increased linearly the apparent particle density and in a nonlinear manner the particle size of spray‐dried milk powders. The particle size volume distribution of milk powders with the highest sucrose concentration differed from the log‐normal distribution of the other samples due to the formation of large agglomerates. Neither vacuole volume, nor the amorphous state of milk powders was affected by sucrose addition.     

The Effect of Inclusion of Naked Oats in the Concentrate Offered to Dairy Cows on Milk Production,Milk Fat Composition and Properties

Dairy cows in early or mid-lactation were offered naked oats- or barley-based concentrates in addition to ad libitum access to grass silage in a continuous design experiment of 10 weeks duration. Concentrates were formulated on an isonitrogenous basis and contained either 500 g barley or 565 g naked oats kg⁻¹ concentrates as the principal energy source in the concentrate. Concentrate type had no effect on silage intake, milk yield or milk protein concentration. However, nitrogen and modified acid detergent fibre digestibility were significantly reduced by inclusion of naked oats and this was reflected in a significant reduction in milk fat concentration. Milk fat from early lactation cows on the naked oats diet contained the highest proportion of unsaturated and the lowest proportion of saturated fatty acids. Sensory and instrumental analyses determined that this milk fat produced the softest, most spreadable butter. This was supported by solid fat content results. The degree of change in milk fat composition due to diet was similar irrespective of stage of lactation but milk fat compositions with the control treatment differed with stage of lactation. Dietary effects were established by the end of the first week of the trial and persisted for the 10-week trial period.     

Physical and Sensory Properties of Milk Chocolate Formulated with Anhydrous Milk Fat Fractions

Maximum additions of milk fat that produced temperable milk chocolates were anhydrous milk fat (AMF), middle-melting fraction (MMF) or low-melting fraction (LMF) up to 40 wt % total fat, and high-melting fraction (HMF) up to 35%. The solid fat content (SFC), melting point, melting enthalpy, instrumental and sensory hardness of milk chocolates decreased with increasing milk fat addition. No differences in sensory attributes sweetness, milk powder, chocolate, butter flavor or thickness of melt were observed. Chocolate with 40% MMF or LMF had greater milk flavor than that with 12.2% HMF. Onset of melt correlated (r = 0.96) with melting enthalpy. No differences between types of milk fat (AMF, HMF, MMF, LMF) were observed for any textural attribute assessed.     

Carbohydrate or Protein Based Fat Mimicker Effects on Ice Milk Properties

Batches of ice milks (2–5% milk fat) made with a carbohydrate- or a protein-based fat mimicker were compared to conventional ice milk (4.8% milk fat). Rheological, freezing, and melting properties were evaluated. The carbohydrate-based fat mimicker changed rheological properties, resulting in higher viscosities, greater deviations from Newtonian flow, and higher consistency indices. Less air was incorporated in the mix containing the carbohydrate-based fat mimicker than in the control or the mix with protein-based fat mimicker, The protein-based fat mimicker mix had rheological and melting properties similar to those of the control but achieved higher air incorporation than did the control.