Mesu Lab Instruments (Guangzhou) Co.,Ltd


The important effect of viscosity on dairy products.

Author : MesuLab Date : 6/25/2019 2:31:46 AM
In recent years, low-fat milk has gradually become a popular item on the market because people are worried about eating too much fat. However, due to the degreasing, the taste and texture of the milk are not as good as before. In 1991, Shoemaker Nantz et al. studied the correlation between the viscosity of dairy products and sensory evaluation. The results showed that the creamy taste and the mouthfeel were strongly correlated with the fat content, while the creamy taste and the mouthfeel were strongly correlated with the viscosity of the instrument, which confirmed the correlation between viscosity and sensory analysis. Therefore, in the development of dairy products, quality control, etc., the determination of viscosity is more and more important. One of the important control items in the production process of stirred yoghurt is viscosity. In the process of producing yoghurt, it is inevitable to mechanically process the fermented and solidified yoghurt, such as mixing, cooling, filling and other processes. . If the design of the production line is unreasonable or the process parameters are not properly controlled, the viscosity of the yogurt will be greatly reduced, and stratification will occur in severe cases. Viscosity is also an important indicator for evaluating the quality of yogurt. In addition, the concentration of the end point of the concentration can also be determined by measuring the viscosity during the concentration of the dairy product. There are many types of rotors for viscometers. When measuring the viscosity of dairy products, different rotors can be selected according to different needs, such as paddle rotors and lifting brackets.

Dairy products in the world, due to large consumption, the corresponding rheological research is also more extensive. Studies have shown that the rheological properties of milk are affected by its concentration. The different concentrations not only change the apparent viscosity of the milk, but also change the fluid type of the milk. At lower concentrations, the milk exhibited plasticity (n>1), which became Newtonian fluid at moderate concentrations (n=1), but at higher concentrations, it became non-Newtonian fluid, presenting a pseudoplastic fluid. Characteristic (n<1), that is, as the concentration increases, the value of n gradually decreases from large to large. Although the temperature has an effect on the viscosity of the milk, it has no effect on the flow pattern of the milk. Among all the influencing factors, the concentration convectively plays a decisive role.

The viscosity of yoghurt The main viscous substance is the precipitation of protein in the presence of lactic acid. Therefore, the protein content is naturally thicker and the acidity is also an influencing factor. Therefore, the lactic acid bacteria used (mainly with different acidity) have an effect on this. . Of course, it is also possible to strengthen the viscosity by adding a thickener or containing other excipients. So which factors will affect the viscosity of the late yogurt?

1. Sterilization: The denaturation of whey protein in milk and the reaction with casein will start at a heating temperature of 90-95 ° C, which will reduce water precipitation and increase viscosity to improve product quality.

2. Refrigeration: refrigerating causes some of the curd particles separated by the processing process to recondense into the network structure of the curd particles, and the denatured whey protein swells to cause the water retention rate to rise, so the chilled yogurt can be made. Restore part of the viscosity.

3. Homogenization: Homogenization can make the particles (fat ball, milk protein, etc.) in the raw milk smaller, promote the combination of tiny fat globules and casein micelles, which is beneficial to the increase of protein gel volume and the formation of tender and condensed Milky texture: The homogenized raw milk has a higher viscosity than the unhomogenous raw milk.

4. Conveying and filling: The number of tubes, the flow rate, the length and diameter of the pipeline and the shearing force of the canned head of the filling pump and the conveying pipeline all have an effect on the viscosity of the yogurt. In order to reduce the loss of yogurt viscosity, the filling pump should use a small power screw pump. The pipeline design should be as short as possible, the pipe should be short, the pipe should be large, the turbulence should be controlled during the production process, and the filling machine should be finished. It may be large to ensure the quality of the yogurt.

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