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。     

Influence of whipping temperature on the whipping properties and rheological characteristics of whipped cream

The effects of whipping temperature (5 to 15°C) on the whipping (whipping time and overrun) and rheological properties of whipped cream were studied. Fat globule aggregation (aggregation ratio of fat globules and serum viscosity) and air bubble factors (overrun, diameter, and surface area) were measured to investigate the mechanism of whipping. Whipping time, overrun, and bubble diameters decreased with increasing temperature, with the exception of bubble size at 15°C. The aggregation ratio of fat globules tended to increase with increasing temperature. Changes in hardness and bubble size during storage were relatively small at higher temperatures (12.5 and 15°C). Changes in overrun during storage were relatively small in the middle temperature range (7.5 to 12.5°C). From the results, the temperature range of 7.5 to 12.5°C is recommended for making whipped creams with a good texture, and a specific temperature should be decided when taking into account the preferred overrun. The correlation between the whipped cream strain hardness and serum viscosity was high (R² = 0.906) and persisted throughout the temperature range tested (5 to 15°C). A similar result was obtained at a different whipping speed (140 rpm). The multiple regression analysis in the range of 5 to 12.5°C indicated a high correlation (R² = 0.946) in which a dependent variable was the storage modulus of whipped cream and independent variables were bubble surface area and serum viscosity. Therefore, fat aggregation and air bubble properties are important factors in the development of cream hardness. The results of this study suggest that whipping temperature influences fat globule aggregation and the properties of air bubbles in whipped cream, which alters its rheological properties.     

Effect of hydroxypropyl methylcellulose on the textural and whipping properties of whipped cream

In this work, hydroxypropyl methylcellulose (HPMC) was added into whipped cream for improving its textural and whipping properties. By determination of the particle size distribution, a single peak for the emulsion after homogenization and two distinguishable peaks for the emulsion after whipping for 5 min were observed. With the increase of HPMC level, the average particle size (d_3,2) decreased for the emulsion after homogenization and increased for the emulsion after whipping for 5 min. Both whipping time and HPMC level showed positive effects on the partial coalescence of fat globules. The partial coalescence of whipped cream with 0.125% HPMC after whipping for 5 min reached 56.25%, significantly (P < 0.05) higher than that (4.77%) without whipping treatment. Surface protein concentration was measured to evaluate the change of protein content at the droplet interface. The results indicated that the increase of HPMC level could decrease the surface protein concentration slightly. The overrun of whipped cream slightly increased when the HPMC level increased in the range of 0.025–0.125%. Firmness, cohesiveness, consistency and viscosity of whipped cream were analysed in this work. HPMC showed a positive dose-dependent effect on all these textural properties.     

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.     

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.     

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。     

复配乳化剂HLB值对稀奶油脂肪聚结及结晶的影响

将单,双甘油脂肪酸酯与蔗糖酯按一定比例复配成不同亲水亲油平衡（hydrophile lipophilic balance,HLB）值的乳化剂,研究复配乳化剂HLB值对稀奶油脂肪聚结及结晶影响,并对其乳液性质及打发性质进行表征。结果表明,随着复配乳化剂HLB值的增大,乳液粒径增大且表观黏度升高进而使搅打时间延长;热力学及Avrami等温结晶动力学结果表明,复配乳化剂HLB值为10时,高熔点乳脂熔融温度改善显著,并且结晶速率最快;HLB值为8～10时打发性较好,乳清泄漏率较低,涂抹性较佳。因此,复配乳化剂HLB值应控制在8～10,此时更适用于高品质裱花稀奶油的工业生产。     

Composition of interfacial layers in complex food emulsions before and after aeration: effect of egg to milk protein ratio

Whipped emulsions were prepared at pilot scale from fresh milk, whole egg, and other ingredients, for example, sugars and stabilizers (starch, polysaccharides). Egg content was varied: 4 recipes were studied differing in their egg to milk protein ratio (0, 0.25, 0.38, and 0.68). Protein and fat contents were kept constant by adjusting the recipes with skim-milk powder and fresh cream. Emulsions were prepared by high-pressure homogenization and whipped on a pilot plant. Particle-size distribution determined by laser-light scattering showed an extensive aggregation of fat globules in both mix and whipped emulsions, regardless of recipe. Amount of protein adsorbed at the oil-water interface and protein composition of adsorbed layer were determined after isolation of fat globules. Protein load is strongly increased by the presence of egg in formula. Values obtained for the whipped emulsions were dramatically lower than those obtained for the mix by a factor of 2 to 3. Sodium dodecyl sulfate-PAGE indicated a preferential adsorption of egg proteins over milk proteins at the oil-water interface, regardless of recipe. This phenomenon was more marked in aerated than in unaerated emulsions, showing evidence for desorption of some milk proteins during whipping. Egg proteins stabilize mainly the fat globule surface and ensure emulsion stability before whipping. Air bubble size distribution in whipped emulsions was measured after 15 d storage. When the egg to milk protein ratio is decreased to 0.25, large air cells appear in whipped emulsions during storage, indicating mousse destabilization. The present work allows linking the protein composition of adsorbed layers at the fat globule surface to mousse formula and mousse stability.     

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%)。     

Influence of processing and κ-carrageenan on properties of whipping cream

The aim of this work was to characterise the influence of ultra-high-temperature (UHT) treatment and high-pressure homogenisation on functional properties of whipping cream (30% fat content) in relation to adding κ-carrageenan (0%, 0.02% and 0.04% in milk plasma). The determination of the particle size distribution, which was measured by laser diffraction and verified by microscopic observation, indicated that the diameter of fat globules decreased significantly by homogenisation but clusters of small fat globules were produced before the carrageenan–casein micelles aggregates. The viscosity of cream was increased and the thixotropic behaviour was observed both by adding carrageenan and by homogenisation. The homogenisation significantly increased colloidal stability during storage and milk plasmas’ release was minimised in combination with carrageenan addition. The most influenced functional properties were: the whippability, which was significantly impaired by homogenisation, and the stability of whipped foam, which was significantly improved with the increase of the carrageenan concentration.     

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。     

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.     

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%。     

Effects of fermentation by Bifidobacterium bifidum on the rheology and physical properties of ice cream mixes made with cow and vegetable milks

Fermented and nonfermented probiotic ice creams were made by incubating Bifidobacterium bifidum (Bb‐12) culture in ice cream mixes with cow, soya, coconut and composite milks (combinations of coconut or cow milks with soya milk). The changes in ice cream‐eating qualities and physical properties (melting rate, apparent viscosity, hysteresis, fat globule size, zeta potential, microscopic structure and freezing behaviour) were evaluated. In general, fermentation decreased the melting rate and total acceptability of ice creams but increased the apparent viscosity, hysteresis, particle size and freezable water. For fermented ice creams containing composite milk, those containing cow milk showed a higher percentage change than those containing coconut milk in respect of hysteresis, particle size and freezable water; however, the apparent viscosity was not affected.     

Improvement of storage stability and foaming properties of cream by addition of carrageenan and milk constituents

The increasing automation in the dairy industry and the longer guaranteed shelf life of the packed products of cream lead to a loss in the quality of liquid and whipped cream associated with the formation of irreversible plugs, too long whipping times and high degrees of liquid separation of the whipped product. In test series 0.015% carrageenan, 0.25% protein—fat as the dry matter (whey proteins with high-melting milk fat fractions) or a combination of both were added to homogenized and unhomogenized, pasteurized or ultra-high temperature treated (UHT) cream from the winter and summer feeding period (fat content: 30%). The creaming behaviour after storage at 7 or 20°C was characterized by determining the fat content in different layers of a cream package. In cream samples without additives ünstirrable layers had been formed after 2–7 weeks, in particular during the long storage times of UHT cream without cooling. A desired (i.e. low) degree of creaming of the liquid cream as well as little separation in the whipped product could be achieved for all samples only by means of a combination of carrageenan and protein—fat powder. Of the rather varying carrageenan fractions examined, a combination of similar proportions of kappa- and iota-carrageenan has proved to be particularly effective without excessively increasing viscosity.     

Physicochemical properties and application of micronized cornstarch in low fat cream

With normal cornstarch (CS) as material, micronized starch was prepared first by acid hydrolyzed pretreatment and then ball-milling (HMS). A control sample (MS) was prepared by ball-milling without pretreatment. Particle size and shape of micronized starch were investigated, and its application in low fat cream was studied. The Maltase cross of HMS granules almost disappeared and the particle size clearly decreased. It was evident that acid-lintnerised starch granules were more susceptible to break down upon milling. However, the granules would aggregate with an increase in milling time. Compared with full-fat cream, the apparent viscosity of low-fat cream increased, while fat globules partial coalescence rate, overrun and textural properties decreased with the increasing of the fat replacement rate. The average particle size of whipped cream increased with the increase of whipping time. Results indicate that a 15% fat replacement rate would produce cream with good foaming and storage stability.     

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.     

MICROSTRUCTURE AND RHEOLOGICAL BEHAVIOR OF WHIPPING CREAM

The mechanism of the formation of a rigid foam structure during whipping of reconstituted whipping cream was investigated. The rheological properties of whipped cream were estimated from an analysis of shear creep curves by a four element model. The values of each element increased exponentially during the process of whipping. From cryo-SEM observation, the surface of air bubbles consisted of a thin membrane which was penetrated by fat globules. Also, fat globules in the serum were joined together by free fat to form a framework structure.
The relationship between the rheological properties and microstructure of whipped cream was deduced from the rheological properties of two model systems. It is believed that whipped cream is a mixed matrix of a SOB O/W structure and a stiffer W/O structure.     

Impact of cream washing on fat globules and milk fat globule membrane proteins

Milk proteins, contained within the aqueous phase surrounding fat globules, should be removed before analysis of the composition of the native milk fat globule membrane (MFGM). The effect of the conditions applied during washing of cream on MFGM integrity has not been fully studied, and factors potentially effecting a modification of MFGM structure have not been systematically assessed so far. In this study, a cream separator was used to investigate the impact of cream washing on milk fat globule stability and the corresponding loss of MFGM proteins. Flow velocity, fat content, and type of washing solution were varied. Particle size measurements and protein analyses were carried out after each washing step to determine fat globule coalescence, removal of skim milk proteins, and efficiency of MFGM isolation. Significant differences in fat globule stability and protein amount in the MFGM isolates were measured using different washing conditions.     

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。