酪蛋白和工艺对再制稀奶油稳定性的影响

本研究主要通过测定再制稀奶油的粒径、界面蛋白含量、黏度、微流变性质分析胶束酪蛋白浓缩粉(micelle casein concentrate,MCC)、酪蛋白酸钙(calcium caseinate,CaC)粉及工艺(灭菌、二次均质)对再制稀奶油稳定性的影响。结果表明:蛋白添加量为1.0%(质量分数,后同)和2.0%时,MCC再制稀奶油的失稳系数分别为0.396±0.011、0.032±0.001,说明稳定性随蛋白添加量的增加而提高,而CaC再制稀奶油稳定性的变化规律与之相反。灭菌后,MCC再制稀奶油脂肪球粒径D3,2、界面蛋白含量及黏度显著增加(P0.05),均方根位移(mean square displacement,MSD)明显降低,CaC再制稀奶油与MCC再制稀奶油的变化明显不同,除界面蛋白含量由3.9～5.5 mg/m~2增至5.2～7.0 mg/m~2外,粒径D3,2、黏度及MSD(2.0%CaC再制稀奶油除外)无明显变化。二次均质后,MCC再制稀奶油脂肪球粒径D3,2、界面蛋白含量及黏度显著下降(P0.05),MSD明显增加,而CaC再制稀奶油样品中除1.0%CaC再制稀奶油粒径D3,2由(2.80±0.10)μm下降至(2.06±0.11)μm外,其他理化性质变化不明显。虽然MCC乳化能力较CaC低,但其在添加量2.0%时制备的稀奶油稳定性最好。工艺会导致再制稀奶油(尤其是MCC再制稀奶油)理化性质间平衡的改变,再制稀奶油的稳定性也随之改变。     

单硬脂酸甘油酯对酪蛋白再制稀奶油乳化稳定性的影响

分析单硬脂酸甘油酯（glycerin monostearate，GMS）对胶束酪蛋白（micellar casein，MCN）再制稀奶油（recombined dairy creams，RDCs）、酪蛋白酸钙（calcium caseinate，CaC）-RDCs及酪蛋白酸钠（sodium caseinate，NaC）-RDCs乳化稳定性的影响。结果表明：GMS可通过与酪蛋白共同吸附在油水界面上使RDCs的脂肪球分散程度改变，因而乳化稳定性也相应改变。对于MCN-RDCs，GMS可显著增加RDCs的相分离时间，其中2.5% MCN-RDCs的乳化稳定性最大，相分离时间从474 s显著增加至4 622 s。CaC-RDCs中，蛋白添加量为0.5%～2.0%时，GMS的添加使CaC-RDCs的相分离时间由167～483 s增加至177～517 s；而2.5% CaC-RDCs的相分离时间有所下降。NaC-RDCs中，GMS的添加使0.5% NaC-RDCs的相分离时间由1 245 s增加至1 460 s；NaC-RDCs添加量大于1.0%时，相分离时间有不同程度下降。可见，GMS可增加MCN-RDCs的乳化稳定性；而其对CaC-RDCs和NaC-RDCs乳化稳定性的影响与蛋白含量有关，当CaC和NaC添加量分别为0.5%～2.0%、0.5%时，GMS才可增加RDCs体系的乳化稳定性。     

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。     

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。     

均质压力对UHT搅打稀奶油品质的影响

以新鲜稀奶油为主要原料,考察了不同的均质压力对UHT搅打稀奶油的脂肪球粒径、流变学特性、搅打特性的影响,分析了各评价指标之间的相关性。结果表明,UHT搅打稀奶油最适均质压力范围为3～5 MPa;随着均质压力的增大(1～9 MPa),脂肪球粒径减小,但打发成型所需时间增加;在α=0.01水平上,粒径与搅打时间、起泡率显著相关;在α=0.05水平上搅打时间与起泡率显著相关。     

二段均质压力对黄油基搅打稀奶油品质的影响

该文在黄油基搅打稀奶油经高压均质、热处理后分别使用1.0~5.0 MPa压力进行二段均质处理,并以未经二段均质处理的产品为对照,比较经不同二段均质压力处理后产品稳定性及搅打品质的变化。实验发现,对照产品脂肪球粒度分布出现明显双峰现象,乳液稳定性差,搅打时间为372.00 s,起泡率仅193.70%,并且在光学显微镜下观察到大量絮凝的脂肪球簇;当二段均质压力在1.0~ 3.0 MPa范围内增大,产品脂肪球平均粒径减小,产品稳定性增强,搅打时间缩短,打发率上升,絮凝的脂肪球簇的数量明显减少;当二段均质压力达到3.0 MPa,产品粒度分布趋于稳定,搅打时间仅需306.50 s,起泡率达235.10%,光学显微镜下未观察到明显絮凝现象。相比对照组,经3.0 MPa压力处理后的产品稳定性更好,搅打成型时间由372.00 s缩短至306.50 s,起泡率由193.70%提高至235.10%,实验结果表明,在搅打稀奶油生产中使用3.0 MPa压力进行二段均质可有效阻止乳液脂肪球絮凝,提高产品的稳定性及搅打品质,可满足工业生产高品质搅打稀奶油的要求。     

搅打稀奶油的乳液特征和打发性能研究

为了对搅打稀奶油的科学应用提供参考,以19款市售代表性搅打稀奶油（常温型、冷藏型和冷冻型产品）为研究对象,通过分析乳液的离心乳析率、黏度、粒径和微观结构研究其乳液的质量,通过分析打发时间、起泡率、泄漏率和裱花性能研究其打发性能。结果显示：常温型产品的离心乳析率为22.17%～32.68%,显著高于冷藏型产品的离心乳析率(1.36%～13.09%)和冷冻型产品的离心乳析率(2.97%～12.87%);常温型和冷藏型产品的黏度、粒径分布特征接近,呈流动性较好且脂肪球分布较均匀的乳液,而冷冻型产品相对黏稠且乳液中无明显脂肪球结构;常温型产品和冷藏型产品的打发时间在13244～291.28 s之间（只有1款冷藏型产品打发时间为79.49 s）,起泡率在111.49%～202.50%之间（只有2款冷藏型产品起泡率分别为92.30%、328.25%）,部分有泡沫泄漏,裱花维持能力较弱;而冷冻型产品打发时间为89.91～158.52 s,起泡率在240.39%～27815%,无泡沫泄漏,裱花维持能力强。综合而言,常温型搅打稀奶油的乳液相对不稳定,打发性能与冷藏型搅打稀奶油接近,而冷冻型搅打稀奶油的打发性能最强。     

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%。     

不同乳化剂对大豆基搅打稀奶油的影响

本研究以大豆油体为原料,探究了不同乳化剂(大豆皂苷、大豆卵磷脂、大豆多糖、吐温80)对大豆基搅打稀奶油的粒径分布、粘度、乳状液稳定性、搅打起泡率、泡沫稳定性的影响。结果表明,不同乳化剂对大豆基搅打奶油的乳状液特性和搅打特性有一定影响。添加吐温80的大豆基搅打稀奶油有较小的粒径分布,ζ-电位为-30.3 mV,粘度比加其他大豆乳化剂的小,而且搅打起泡性最高,达到112.4%,但是泡沫稳定性只有2.1%。添加大豆乳化剂的大豆基搅打稀奶油具有类似的乳状液特性,但是添加大豆卵磷脂的大豆基搅打稀奶油比其他两种大豆乳化剂具有更高的膨胀率(134.5%),而添加大豆多糖的大豆基搅打稀奶油具有更好的泡沫稳定性(1.2%)。     

酪蛋白酸钠-甘油二酯软奶酪的制备及其特性分析

目的：探究以酪蛋白酸钠（Sodium caseinate,SC）与纳米纤维素（Nano-crystalline cellulose,NCC）为壁材包埋甘油二酯（Diacylglycerol,DAG）的条件,改善开发功能性发酵乳制品品质。方法：以乳脂为原料,通过酶解反应制备出DAG,以SC与NCC为壁材制备水包油型DAG乳液,筛选乳液最佳制备条件下的SC和NCC添加量、粒径大小、均质压力,以及对添加了DAG纳米乳液的软奶酪进行流变分析、质构分析和感官分析,探究它们之间的稳定性差异,并作为脂肪替代物制备软奶酪。结果：采用高压均质法制备酪蛋白酸钠复合纤维素甘油二酯乳液的最佳条件为：NCC含量1.5%,SC含量5%,芯壁比1:1,均质压力100 MPa,此时DAG乳液均为水包油型,粒径大小在100～240 nm之间。通过分析软奶酪的特性,证实随着DAG乳液添加量的增加,软奶酪的弹性变大,硬度、稠度、粘聚性均出现先升后降的趋势,其中当DAG纳米乳液添加量为2%时,软奶酪品质显著高于其他组。结论：在NCC含量1.5%,SC含量5%,芯壁比1:1,均质压力100 MPa的条件下,DAG纳米乳液包埋率...     

改性大豆蛋白在植脂奶油中的应用

研究了改性大豆蛋白的乳化性、乳化稳定性、起泡性,以及其替代进口酪朊酸钠应用于植脂奶油对其搅打时间、起泡率、保形性、变粗程度、入口即化感、光泽度、细腻度、油腻感的影响,研究表明,改性大豆蛋白的乳化性、乳化稳定性、起池陛介于进口酪朊蛋白和国产酪朊蛋白问,优于国产大豆分离蛋白;改性大豆蛋白替代进口酪朊酸钠50％应用于植脂奶油产品品质良好。     

High hydrostatic pressure modification of whey protein concentrate for use in low-fat whipping cream improves foaming properties

Whey is the inevitable by-product of cheese production. Whey can be incorporated into a variety of foods, but little has been done to investigate its suitability in whipping cream. The objective of this work was to evaluate the foaming properties of selected low-fat whipping cream formulations containing whey protein concentrate (WPC) that did or did not undergo high hydrostatic pressure (HHP) treatment. Fresh whey was concentrated by ultrafiltration, pasteurized, and standardized to 8.23% total solids and treated with HHP at 300 MPa for 15 min. Viscosity, overrun, and foam stability were determined to assess foaming properties. Sensory evaluation was conducted with 57 panelists using a duo-trio difference test. The optimal whipping time for the selected formulations was 3 min. Whipping cream containing untreated WPC and HHP-treated WPC resulted in greater overrun and foam stability than the control whipping cream without WPC. Panelists distinguished a difference between whipping cream containing untreated WPC and whipping cream containing HHP-treated WPC. High hydrostatic pressure-treated WPC can improve the foaming properties of low-fat whipping cream, which may justify expansion of the use of whey in whipping cream and application of HHP technology in the dairy industry.     

Effect of whey protein concentrate addition on the physical properties of homogenized sweetened dairy creams

The influence on their whipping properties of homogenization at first and second stage pressures of 3.5/1.5 MPa and addition of whey protein concentrate (WPC) powder at three different (0.7, 1.4, and 2.1 wt percentage) concentrations to sweetened and homogenized creams was studied. Homogenization of cream significantly decreased maximum overrun and made the foam microstructure less open, while increasing whipping time, cream and foam lightness (Hunter L -value) and apparent viscosity. It also resulted in a less elastic foam structure with an increased drainage. Addition of WPC decreased the amount of maximum overrun, foam drainage and its lightness in parallel with developing a more compact microstructure. It increased the whipping time, apparent viscosity of unwhipped creams and foams, and resulted in a less elastic foam structure. The apparent viscosity of whipped cream with 2.1 wt percentage WPC, however, was lower than that of whipped cream with 1.4 wt percentage WPC, due most probably to the start up of gel formation at 2.1% WPC concentration in sweetened cream when it was sheared. Fresh foam whipped from sweetened cream with 2.1 wt percentage WPC also tended to have a slightly but not statistically significant lower elastic modulus (G') than fresh foam whipped from sweetened cream with 1.4 wt percentage WPC. This concentration can be considered as the critical value for gel formation in sweetened creams enriched by whey proteins when sheared. This study indicated the potential of WPC powder for reducing foam drainage from whipped homogenized sweetened cream.     

Whipping properties of recombined,additive-free creams

There is increasing industrial interest in the use of the milkfat globule membrane as a food ingredient. The objective of this research was to determine whether the aerosol whipping performance of cream separated into butter and buttermilk, and then recombined, would perform in a manner similar to untreated cream. Churning of cream tempered to different solid fat contents was used to separate butter from buttermilk, which were then recombined at the same ratios as the initial extraction yield, or with 25% extra buttermilk. Differences in milkfat globule size distributions among the recombined creams were apparent; however, their whipping behavior and overrun were similar. Importantly, all recombined creams did not yield properties similar to the original cream, indicating that the unique native milkfat globule membrane structure plays a role in cream performance well beyond its simple presence.     

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.     

Dynamic high pressure-induced gelation in milk protein model systems

The structure-functional properties of milk proteins are relevant in food formulation. Recently, there has been growing interest in dynamic high-pressure homogenization effects on the rheological-structural properties of food macromolecules and proteins. The aim of this work was to evaluate the effects of different homogenization pressures on rheological properties of milk protein model systems. For this purpose, sodium caseinate (SC) and whey protein concentrate (WPC) were dispersed at different concentrations (1, 2, and 4%), pasteurized, and then homogenized at 0, 18 MPa (conventional pressure, CP), 100 MPa (high pressure, HP), and 150 MPa (HP+). Differences in viscosity were observed between WPC and casein dispersions according to concentration, heat treatment, and homogenization pressure. Mechanical spectra described the characteristic behavior of solutions except for the WPC 4% pasteurized sample, in which a network formed but was broken after homogenization. Dispersions with different ratios of WPC and SC were also made. In these systems, pasteurization alone did not determine network formation, whereas homogenization alone promoted cold gelation. A total concentration of at least 4% was required for homogenization-induced gelation in pasteurized and unpasteurized samples. Gels with higher elastic modulus (G′) were obtained in more concentrated samples, and a bell-shaped behavior with the maximum value at HP was observed. The HP treatment produced stronger gels than the CP treatment. Similar G′ values were obtained when different concentrations, pasteurization conditions, and homogenization pressures were combined. Therefore, by setting appropriate process conditions, systems or gels with tailored characteristics may be obtained from dispersions of milk proteins.