Elongational flow studies of set yogurt

Three series of prepared set yogurt samples were tested using squeezing flow viscometry. Samples were compressed using an Instron UTM at constant deformation rate. The first series containing added caseinates exhibited deformation behaviour of a gel. Firmness was dependent on caseinate concentration. The second series contained skimmed milk powder. Their behaviour was more that of a colloidal dispersion at low added powder content and of a gel at higher added amounts. The third series contained carrageenan salts. Their behaviour was that of a dispersion irrespective of the carrageenan concentration. The consistency of the samples examined was evaluated using plots of stress growth coefficients as function of biaxial strain rate. The results indicated that the technique could be used to distinguish changes in yogurt structure caused by the addition of various additives at various concentration levels, to milk to enhance yogurt consistency.     

Rheological characteristics of tamarind (Tamarindus indica L.) juice concentrates

The steady-shear and small-amplitude oscillatory rheological properties of tamarind (Tamarindus indica L.) juice concentrate (TJC) were studied in the temperature range of 10-90 °C using a controlled-stress rheometer. Under steady-shear deformation tests, shear stress-shear rate data were adequately fitted to the Herschel-Bulkley and Casson model at lower (10-30 °C) and higher (50−90 °C) temperature range, respectively. The Carreau model was applied to describe the shear-thinning behaviour of the concentrate, and the model parameters estimated empirically showed temperature dependence. Oscillatory shear data of TJC revealed predominating viscous behaviour (G″>G′) at lower frequency range while the elastic modulus predominating over the viscous one (G′>G″) at higher frequency range. The Cox-Merz rule that relates steady shear and dynamic material functions was tested and not followed by most of the temperatures. The specific heat of TJC increased with temperature and the glass transition temperature of the product was found to be −70.74 °C.     

新型乳化剂磷胺酯和聚甘油聚蓖麻酸酯在食品工业中的应用

本将介绍两种新型的乳化剂产品：磷胺酯（YN）E442,聚甘油聚篦麻酸酯（PGPR）E476及其在巧克力和冰淇淋涂层中的功能特性。磷胺酯是一种大豆磷脂的替代产品,无味,稳定,安全,除有磷脂的功能外,与聚甘聚蓖麻酸酯有更好的协同作用。聚甘油聚蓖麻酸酯是用甘油和篦麻油聚合得到的多聚物,与磷脂或磷胺酯配合使用可降低巧克力浆料的粘度和屈服应力,并使其具有相当的耐水能力。上述特性在章中进行了阐述并列举了配方实例和对比效果。结论对于巧克力和冰淇淋涂层的生产具有指导和实际意义。     

巧克力专用油脂在烘焙和冰淇淋涂层食品中的应用与发展

巧克力涂层与烘焙类、冰淇淋类等食品的复合型产品一直以来都广受消费者欢迎。而不同的食品类别对涂层巧克力专用油脂的性能和品质要求不同。本文分别对巧克力专用油脂在烘焙和冰淇淋两大涂层类食品中的应用进行分析和探讨,并展望了巧克力涂层专用油脂未来的发展趋势。      

巧克力粟米条的研制

将挤压膨化技术与巧克力涂层技术相结合,对膨化巧克力粟米条的工艺流程、技术操作要点及生产中质量控制方法进行了研究,成功的制作出了巧克力粟米条。      

Viscosity of Molten Milk Chocolate with Lactose from Spray-Dried Whole-Milk Powders

Dry whole-milk powders containing 0, 30, 50 and 70% nominal lactose prepared by spray-drying alone, or followed by post-drying crystallization, were incorporated into milk chocolate to give 0–50% substitution of lactose for sucrose. Increasing the concentration of amorphous lactose from spray-dried powders in the chocolates decreased viscosity, increased particle size of refined chocolate mass, and lowered the concentration of surface-active agents at which a minimum in Casson yield value was observed. Increasing the concentration of crystalline lactose from milk powders in the chocolates increased viscosity, decreased particle size, and increased the concentration of surface-active agents at which a minimum in Casson yield value was observed. Conditions which affect lactose crystallinity in milk powders, such as improper storage and handling prior to use in chocolate production, could be responsible for variations in chocolate viscosity noted sometimes by processors.