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.     

搅打充气对搅打奶油流变特性的影响

研究了搅打充气对搅打奶油流变特性的影响,分析其变化规律及探讨搅打充气与搅打奶油结构之间的内在联系。结果表明:搅打奶油属于假塑性流体,其表观黏度、屈服应力、触变性和黏弹性(G~*)均随搅打充气进行而增加,而相对恢复率呈先增大后减小趋势。在蠕变-回复测试中,蠕变柔量随搅打充气进行逐渐减小;推迟时间先增大后减小,到了搅打过度阶段又重新增大;回复率呈先增大后减小趋势。     

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.     

搅打植脂奶油粉的制备及其性能

介绍了植脂奶油粉的制备工艺及配方,制备的植脂奶油粉在搅打时不仅具有较高的起泡率,而且具有较好的可塑性、硬挺性和稳定性,通过多次试验,在室温15-18℃下搅打7min,起泡率达3．5,硬度为0．50N,24h内无脱水收缩现象。制备的植脂奶油粉具有良好的搅打效果。     

菊糖作为脂肪替代品在植脂掼奶油中的应用

研究了菊糖取代脂肪率对植脂掼奶油的影响,通过对植脂掼奶油的打发率、泡沫稳定性、融点、屈服应力、触变性、储能模量、损耗模量和感官评定等几个指标的测定发现:以菊糖取代50%的脂肪得到的植脂掼奶油具有与全脂样品相似的性质。     

Dynamic rheological properties of dough as affected by amylases from various sources

The effect of alpha-amylases from cereal, fungal, and bacterial sources on dough dynamic rheological properties was investigated. Dynamic rheological study of flour-and-water doughs during resting period showed significant changes in dough rheological properties as a function of alpha-amylases. Addition of alpha-amylases caused a time-dependent decrease in G', storage modulus. The enzyme action on starch during baking increased viscous flow properties. These changes were temperature-dependent. The thermal inactivation temperature of alpha-amylase plays an important role in modification of starch. Rheological changes in dough will alter the machinability of the dough and the quality of end products.     

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 galactomannan addition on rheological,physicochemical, and microbial properties of cultured sour cream

Food Science and Biotechnology - Sour cream is a popular fermented dairy product and galactomannans are widely used in the food industry to improve texture and stability. In this study, it was...     

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.     

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.     

Mechanical and rheological properties of fresh egg pasta as affected by shell egg production factors

The aim of this work was to study the influence of hen age and housing system on egg performances in fresh pasta production, focusing on mechanical and rheological properties of pasta. Samples of pasta were prepared with eggs laid by Hy‐Line Brown hens (from 27 to 68 weeks old) housed in conventional cage, barn and organic systems. Only hen age significantly affected pasta properties. In particular, as regards raw pasta, the loosest structure was obtained using eggs laid by the youngest hens (27–30 weeks old). On the contrary, in cooked pasta, the weakest structure was observed when eggs were laid by hens aged 53–68 weeks. However, differences, although significant, were small and thus most likely not sensorially perceivable. Significant correlations were found between mechanical and rheological properties of raw fresh egg pasta, meaning that small deformation measurements are as valuable as large deformation tests for the characterisation of this product.     

Functional properties of whey proteins affected by heat treatment and hydrodynamic high-pressure shearing

Two batches of native whey proteins (WP) were subjected to microfluidization or heat denaturation accompanied by microfluidization, followed by spray drying. Powders were assessed for their solubility, heat stability, coagulation time, and emulsifying and foaming properties. Effects of denaturation and shearing were examined by particle size analysis, differential scanning calorimetry, reducing and nonreducing sodium dodecyl sulfate-PAGE, and size exclusion-HPLC. Heat treatment significantly decreased solubility, whereas the number of microfluidization passes markedly improved solubility. The combined effect of heat and pressure significantly increased heat coagulation time. Emulsifying activity index substantially increased upon heat denaturation and was further enhanced by microfluidization. Emulsion stability appeared unaffected by the combined treatment, but the concentration of adsorbed protein on fat droplets was significantly increased. Foaming properties were diminished by heating. Particle size distribution patterns, sodium dodecyl sulfate-PAGE, and size exclusion-HPLC revealed disappearance of major WP and creation of relatively higher, as well as smaller, molecular weight aggregates as a result of the 2 treatments. The use of heat and microfluidization in combination could be used to stabilize WP against heat by producing microparticulated species that have different surface and colloidal properties compared with native WP. These results have implications for the use of WP as an additive in heat-processed foods.     

加热条件下海蜇伞部物性学参数的变化

为了研究海蜇伞部的流变学特性,本文采用质构仪测定海蜇伞部在不同加热条件(50、80、90、100℃)下物性学参数(弹性模量E0、粘性模量η1、应力松弛时间τ1、破断强度、硬度、弹性等)。结果表明:在不同的加热温度下海蜇伞部的物性学参数变化显著,随温度的上升呈现先增大后减少的趋势。鲜活样品的各特征参数(E0、τ1、η1、破断强度)明显小于在50℃加热处理的样品。随着温度的升高,加热样品的粘性模量η1呈增大趋势;相对于其它加热样品,80℃加热的样品弹性模量E0最大。这些变化主要是由于样品失水和在加热过程中胶原蛋白状态不同所引起的。     

Effect of substituting whey cream for sweet cream on the textural and rheological properties of cream cheese

In the manufacture of cream cheese, sweet cream and milk are blended to prepare the cream cheese mix, although other ingredients such as condensed skim milk and skim milk powder may also be included. Whey cream (WC) is an underutilized fat source, which has smaller fat droplets and slightly different chemical composition than sweet cream. This study investigated the rheological and textural properties of cream cheeses manufactured by substituting sweet cream with various levels of WC. Three different cream cheese mixes were prepared: control mix (CC; 0% WC), cream cheese mixes containing 25% WC (25WC; i.e., 75% sweet cream), and cream cheese mixes with 75% WC (75WC; i.e., 25% sweet cream). The CC, 25WC, and 75WC mixes were then used to manufacture cream cheeses. We also studied the effect of WC on the initial step in cream cheese manufacture (i.e., the acid gelation process monitored using dynamic small amplitude rheology). Acid gels were also prepared with added denatured whey proteins or membrane proteins/phospholipids (PL) to evaluate how these components affected gel properties. The rheological, textural, and sensory properties of cream cheeses were also measured. The WC samples had significantly higher levels of PL and insoluble protein compared with sweet cream. An increase in the level of WC reduced the rate of acid gel development, similar to the effect of whey phospholipid concentrate added to mixes. In cream cheese, an increase in the level of added WC resulted in significantly lower storage modulus values at temperatures <20°C. Texture results, obtained from instrumental and sensory analyses, showed that high level of WC resulted in significantly lower firmness or hardness values and higher stickiness compared with cream cheeses made with 25WC or CC cream cheeses. The softer, less elastic gels or cheeses resulting from the use of high levels of WC are likely due to the presence of components such as PL and proteins from the native milk fat globule membrane. The use of low levels of WC in cream cheese did not alter the texture, whereas high levels of WC could be used if manufacturers want to produce more spreadable products.     

Microstructure and rheological properties of psyllium polysaccharide gel

The strong gelling property of psyllium polysaccharides is closely related to its health benefits and applications, such as use as a binding agent in the landscape industry. However, information about gelling properties of psyllium polysaccharides is very limited. To explore the gel properties of psyllium, the alkaline extracted gel fraction (AEG) of psyllium polysaccharides was studied in this investigation. The rheological and low-temperature electron microscopy methods including cryo-scanning electron microscopy (Cryo-SEM) and freeze-substitution for transmission electron microscopy (TEM) were used to investigate Ca²⁺ influence on the gel properties of AEG. AEG formed a weak gel with a fibrous appearance. AEG did not have a sharp melting point and exhibited no thermal hysteresis during heating and cooling procedure. The origin of this gelling behaviour was due to the fibrillar gel structure of psyllium polysaccharide. It was found that Ca²⁺ had a significant influence on the gel properties and microstructure. Elastic modulus G′ of gel increased as Ca²⁺ concentration increased. Critical strain S at first increased and then decreased as Ca²⁺ concentration increased. AEG gel became more resistant to temperature change on addition of Ca²⁺. Psyllium gel changed to aggregated gel with added Ca²⁺. The strands of gel appeared thicker and the density of the junction zone increased with increasing Ca²⁺ concentration as revealed by SEM and TEM. The changing bulk gelling properties of psyllium polysaccharide by adding Ca²⁺ was attributed to the change in gel structure.     

Microstructure,textural and sensorial properties of durum wheat bread as affected by yeast content

In this study, breads varying in yeast content and therefore leading to distinct cellular structures are investigated. Firstly, X-ray microtomography is used to characterize not only the final cellular structure, but also the process of development of microstructure during the fermentation stage. With μCT, image analysis of the full 3-D microstructure, measuring the size, shape, networking/connectivity and distribution of various phases was possible. These measurements represent the full 3-D microstructure, which is not always possible by 2-D image analysis using statistical techniques. Secondly, the textural properties of the baked bread were obtained by compression tests and finally, the sensorial quality of the final product is also evaluated and correlated with the above properties. Results showed that an increase of the yeast content increased the percentage volume of pores and decreased the force required for compression of the bread sample and the tenacity. Moreover, a larger quantity of smaller sized pores led to a firmer bread structure. Regarding the sensorial properties, none of the investigated microstructural parameters were significantly correlated with the overall quality of the bread. In fact, the overall quality was more strongly affected from other parameters such as odor and appearance attributes.