瓜尔豆胶对搅打稀奶油的搅打性能的影响

研究了不同浓度的瓜尔豆胶对搅打稀奶油乳状液的表观黏度、脂肪球粒度、脂肪球界面蛋白浓度、脂肪球部分聚结率、泡沫硬度和搅打起泡率的影响。结果表明，瓜尔豆胶对搅打稀奶油乳状液的表观黏度影响非常显著；瓜尔豆胶浓度过高或过低，都会使得解冻后的乳状液粒径变大；瓜尔豆胶的质量分数越高，脂肪球部分聚结速度越快，泡沫硬度也越大；搅打起泡率随着瓜尔豆胶质量分数增大而降低。     

利用油溶性色素测定搅打乳状液中游离脂肪的方法研究

研究了一种测定搅打乳状液中游离脂肪的新方法，油性色素法。基于油溶性色素油红-O只溶于游离态脂肪的原理建立了测定搅打乳状液中游离脂肪的实验方法并推导出理论计算公式。研究了方法的可行性，结果表明油红-O对典型的食品乳化剂(包括乳清蛋白、酪酝酸钠、Tween-60)和由这些乳化剂稳定的乳状液没有影响。利用该方法测定典型的搅打乳状液植脂鲜奶油中脂肪球部分聚结，经研究证实，油性色素法与传统的溶剂萃取法和浊度法相比，能实际地反映搅打乳状液在搅打过程中脂肪球发生部分聚结的程度，并具有测定结果重现性好、操作方便的优点。     

植脂奶油泡沫结构形成的研究

分别测定植脂奶油乳状液在剪切、充气和搅打作用下脂肪球部分聚结率、电导率、膨胀率的变化,研究了植脂奶油形成泡沫结构的作用机理.结果表明,剪切或充气作用都不能形成稳定的泡沫结构;只有在搅打条件下才能获得60%以上的脂肪球部分聚结率,使植脂奶油由一个黏稠的液体转变为稳定的泡沫结构.     

油脂种类对植脂鲜奶油搅打性能的影响

通过研究不同种类的油脂在植脂鲜奶油搅打过程中脂肪球的部分附聚、搅打时间、搅打起泡率和泡沫稳定性之间的关系。结果表明：不同种类的油脂对搅打性能的影响与其熔点有着密切的关系，其实质是油脂在常温下的固体脂肪指数决定了脂肪球能否发生部分聚结与聚结的程度，熔点为35～43℃的部分氢化植物油的聚结率接近60％，可以达到最佳的部分聚结率，能够形成稳定的泡沫结构；熔点为47～53℃的部分氢化植物油的聚结率超过70％，容易产生过度的部分聚结，形成结构粗糙的泡沫；天然奶油的部分聚结率低于10％；大豆油或者极度氢化油不能发生脂肪球的部分聚结，不能形成稳定的泡沫结构。     

油脂用量对搅打稀奶油的搅打性能和品质的影响

研究了油脂用量对搅打稀奶油的粒度分布、脂肪部分聚结、液相蛋白质浓度、搅打起泡率、质构特性、感官品质和稳定时间的影响。研究表明:随着油脂用量增加,冷却后乳浊液脂肪球粒径增大;搅打过程中脂肪部分聚结速度和脂肪球粒径d4,3均随油脂用量增加而增大,且脂肪部分聚结率与脂肪球粒径d4,3有很好的相关性;液相蛋白质浓度和搅打起泡率降低;搅打稀奶油的质构特性值增加;稳定时间呈先增后减趋势,当油脂用量为23%时,搅打稀奶油的稳定时间最长达到2.7h;搅打稀奶油的感官品质以油脂用量为20%最好,综合考虑,油脂最佳用量范围是20%-23%。     

蛋白质用量对黄油基淡奶油搅打前乳液性质及搅打性能的影响

以黄油为油相制备淡奶油,研究蛋白质用量(1.0%～3.0%)对黄油基淡奶油搅打前乳液性质及搅打性能的影响。研究表明:蛋白质用量为1.0%～2.5%时,随蛋白质用量的增加,搅打前乳液的界面蛋白浓度明显增加,脂肪部分聚结率降低,脂肪球粒径减小,粒度分布曲线变窄,表观黏度升高,乳液的稳定性提高;蛋白质用量由2.5%增加至3.0%时,脂肪部分聚结率增加,脂肪球粒径增大,乳液的稳定性降低。乳液在200 s的搅打过程中,随搅打时间的延长,脂肪部分聚结率不断增加,平均粒径呈现先减小后增大的趋势,搅打起泡率则先升高后降低。蛋白质用量为1.0%～1.5%时,在搅打过程中脂肪部分聚结率、平均粒径、搅打起泡率均快速增加,易出现搅打过度现象,且泡沫稳定性差。蛋白质用量为2.0%～2.5%时,脂肪部分聚结率、平均粒径、搅打起泡率则缓慢增加,而泡沫稳定性较好。蛋白质用量增加至3.0%时,尽管泡沫稳定性较好,但搅打200 s后的脂肪部分聚结率仅有26.45%。因此,将黄油基淡奶油的蛋白质用量控制在2.0%～2.5%范围内较适宜。     

大豆蛋白与酪蛋白比例对搅打稀奶油稳定性影响的研究

研究了大豆蛋白与酪蛋白不同配比对搅打稀奶油乳浊液的表观粘度及搅打过程中的液相蛋白浓度、脂肪部分聚结、搅打起泡率的变化和泡沫稳定性的影响,并在此基础上探讨了其作用机理。结果表明:大豆蛋白比例的增大能增加界面膜的粘弹性,抑制脂肪球的部分聚结,提高泡沫结构的稳定性,当大豆蛋白与酪蛋白比例为4∶1时,搅打稀奶油可以获得最佳的稳定性。     

乳化剂用量对搅打稀奶油搅打性能和品质的影响机理研究

研究了乳化剂用量对搅打稀奶油的乳浊液粒度分布、脂肪球部分聚结、液相蛋白浓度、感官品质和泡沫稳定性的影响。研究结果表明:乳浊液冷却及解冻后脂肪球粒径随乳化剂用量增加而减小,随着乳化剂用量增加,脂肪部分聚结速度和液相蛋白质浓度增加速度加快,搅打起泡率和感官品质以乳化剂用量为0.60%时最好,搅打稀奶油稳定时间随乳化剂用量增加呈先增加后下降趋势,当乳化剂用量为0.60%时,稳定时间达到最大2.4h。综合考虑,当乳化剂HLB值为7,乳化剂用量为0.60%时,搅打稀奶油搅打性能和品质最佳。     

黄油-代可可脂基奶油生产工艺优化及其晶型形成分析

在分析油脂用量对黄油-代可可脂基奶油品质影响的基础上,通过正交试验研究油脂用量、黄油-代可可脂质量比和均质压力对奶油搅打性能、质构特性、脂肪球部分聚结率、结晶特性等的影响。结果表明,在油脂用量30%、黄油-代可可脂质量比2∶3、均质压力60?MPa的条件下,能保证脂肪部分聚结的发生,并保持搅打稀奶油较好的感官特性、起泡性和结晶特性。60?MPa的均质压力保证了体系的稳定性,使大量游离脂肪球产生从而促进脂肪部分聚结。晶型形成分析结果表明,在优化条件下,原料乳浊液X-射线衍射峰峰形由较宽、较尖锐变为峰形适中均匀,适宜搅打稀奶油的β’晶型晶体明显增多,搅打稀奶油乳浊液在低温条件下发生脂肪结晶,表现为脂肪晶体尺寸增大。     

二次均质工艺中一次均质压力对黄油基搅打稀奶油品质的影响

以无盐黄油和脱脂乳为原料制备黄油基搅打稀奶油,采用二次均质工艺,研究了一次均质压力（二次均质压力不变）对黄油基搅打稀奶油的粒径、脂肪部分聚结率、流变学特性、搅打性能的影响,分析了各评价指标之间的相关性。结果表明,黄油基搅打稀奶油的一次均质压力在10.0~15.0 MPa时,随着均质压力的增大,脂肪球粒径D4,3由1.85 μm逐渐减小到1.57 μm,且在15.0 MPa时脂肪球粒径D4,3达到最小为1.57 μm;黄油基搅打稀奶油的脂肪部分聚结率随着一次均质压力的增大逐渐增大,由13.74%增大到17.53%;搅打时间随着均质压力的增大逐渐由314 s减小到265 s且一次均质压力在15.0 MPa时搅打时间最少为265 s;泡沫稳定性由78.09%逐渐增加到87.26%,且泡沫稳定性在15.0 MPa时泡沫稳定性达到最大87.26%。因此将黄油基搅打稀奶油的一次均质压力控制在10.0~15.0 MPa范围内较适宜。     

Tempering of dairy emulsions: Partial coalescence and whipping properties

This study investigates the effect of applying a time–temperature profile to natural and recombined cream to influence partial coalescence and, consequently, the whipping quality. To date, no clear relationship exists between the consequences of tempering on a microstructural level, partial coalescence, and whipping properties. Milk fat crystallisation was analysed using differential scanning calorimetry and the internal arrangement of fat crystals was visualised with cryo-scanning electron microscopy. Shear-induced partial coalescence and whipping properties were studied. Shear-induced partial coalescence was promoted, attributed to the observed changes in the fat crystal network. The effects on whipping properties were different for natural and recombined cream and thus dependent upon the interfacial composition. Consolidation of the partially coalesced fat droplet network by tempering increased the stability of whipped recombined cream during cold storage. Tempering is a promising tool to alter the susceptibility to partial coalescence by changing the internal fat crystal network, and influencing whippability.     

Physical,textural, and rheological properties of whipped cream affected by milk fat globule membrane protein

This work aims at improving the textural and whipping properties of whipped cream by the addition of milk fat globule membrane protein. The determination of particle size distribution and average diameter of whipped cream showed that the small particle size was shifted to a larger range after milk fat globule membrane protein was added. The average particle size (d_3,2) of whipped cream reached a maximum value of 5.05 µm at 1% milk fat globule membrane protein, while slowly decreased with increasing milk fat globule membrane protein levels from 2% to 5%. In addition, the partial coalescence of fat increased with the increase of milk fat globule membrane protein levels, and the correlation between the whipping time and the overrun of whipped cream was positive. The addition of milk fat globule membrane protein also altered the rheological behaviour of whipped cream, resulting in the increase of modulus G′ and the loss modulus G″. The results also indicated that higher milk fat globule membrane protein level decreased the serum loss of whipped cream while improved its stability. While milk fat globule membrane protein levels had no significant effect on viscosity, its increasing levels effectively improved the hardness, consistency, and viscosity of whipped cream.     

Effect of xanthan gum on the physical properties and textural characteristics of whipped cream

Xanthan gum was used as thickening agent to prepare whipped cream in this work. A dose-dependent effect was observed on the average particle size (d_3,2) of whipped cream. At each xanthan gum level (0.025–0.125%) used, whipping time also showed a positive effect on the average particle size. With the increase of xanthan gum level or whipping time, the partial coalescence of fat in the whipped cream increased gradually. However, xanthan gum level showed no significant effect on the overrun of whipped cream. The textural characteristics of whipped cream were also investigated and the results indicated that a positive correlation was found between xanthan gum level and firmness, cohesiveness or viscosity of whipped cream. A different tendency was detected for consistency. The consistency of whipped cream increased with the increase of xanthan gum level to 0.100%, thereafter decreased.     

Emulsions under shear—the formation and properties of partially coalesced lipid structures

Partial coalescence in semi-crystalline emulsion droplets is essential to the manufacture and quality of many dairy products including ice cream, whipped cream, and butter. In real food emulsions this process occurs under fluctuating temperatures and shear rates and some of the effects of these factors are considered in this work. Two approaches to the problem are reported. In the first, the freeze-thaw stability and shear modulus of a food oil emulsion during a freeze-thaw cycle is related to the volume fraction of dispersed phase. In the second approach the rate of crystallization of emulsified n-hexadecane in the presence of solid n-hexadecane is shown to be independent of applied shear rate. Some ideas on how these approaches may be combined for a fuller understanding of the partial coalescence process are presented.     

Characterisation of ice cream containing flaxseed oil

Five batches of a 12% (w/w) fat ice cream formulation were prepared using different amounts of flaxseed oil (0%, 3%, 6%, 9% and 12% w/w) to replace milkfat. Meltdown rates, texture of ice cream, particle size of fat globules and microstructure of the ice cream were determined. Increasing the proportion of flaxseed oil in ice cream resulted in an increase in the meltdown rate and a decrease in the ice cream hardness. These were attributed to the low melting temperature of flaxseed oil and the varying extent of fat flocculation. In ice cream containing a high proportion of milkfat, the fat globules formed large particles largely due to flocculation rather than partial‐coalescence. The extent of fat flocculation decreased as the proportion of flaxseed oil was increased. Evidence of fat coalescence was observed in ice cream containing 12% flaxseed oil. The fat flocculates stabilised the air cells and strengthened the foam structure of the ice cream.     

Effect of sorbitan monostearate on the physical characteristics and whipping properties of whipped cream

In this work, the effects of sorbitan monostearate (Span 60) level on the particle size distribution, microstructure and apparent viscosity of the emulsion were investigated. Average particle size (d_4,3), surface protein concentration, partial coalescence of fat and overrun of whipped cream during whipping were also determined. As Span 60 level increased (0–0.8%) in emulsion, the apparent viscosity was increased gradually, and the particle size range was narrowed, which was also detected by microstructure. A positive effect of whipping time was observed on the average particle size, partial coalescence of fat, surface protein concentration and overrun during whipping, respectively. An increase of Span 60 level resulted in a reduction of d_4,3 values and partial coalescence of fat during 0–1 min whipping, then increasing after whipping for 2–5 min (0.6% Span 60 as the critical level). A negative behaviour was observed between surface protein concentration and Span 60. Moreover, Span 60 could improve the overrun and organoleptic properties of whipped cream efficiently.