01
Solid beverage processing methods
Freeze drying, fluidized bed granulation and spray drying are three main processing methods in the production of solid drinks at present. Freeze drying is an advanced drying process that can effectively retain the nutrients and flavor components of materials, but it has high investment and limited application; Fluidized bed granulation is suitable for drying low juice or juice free materials; The spray drying technology is suitable for drying liquid materials with high fruit juice content. Because of the low heating temperature and short time of the materials, the nutrition and flavor components of the materials can be well preserved. Other processing methods of solid drinks include spray freeze drying, vacuum drying, etc. 1. Freeze-drying method
Freeze drying is the process of freezing water in a material into solid ice, which, under vacuum conditions, directly sublimates into water vapor and escapes, thereby removing water from the material. Its characteristic is that the nutrients and volatile components are well preserved, but the processing cost is extremely high. Therefore, the production of solid beverages using freeze-drying method is still rare, and only a few products with high added value, such as Instant Tea Powder and coffee powder, are used. 2. Fluidized bed granulation
There are four types of granulation technologies: wet granulation, dry granulation, rapid stirring granulation, and fluidized bed granulation. Fluidized bed granulation, also known as boiling granulation, is a new granulation technology that combines the three steps of mixing, granulation, and drying of conventional wet granulation in a closed container. It can greatly reduce the amount of auxiliary materials, produce uniformly sized particles, and achieve good results. There are generally three mechanisms for particle growth in fluidized bed granulation - agglomeration, coating, and cumulative granulation. In the process of fluidized bed granulation, these three effects often work together to promote particle growth. The purpose of food industry granulation is mainly to solve the problem of instant solubility, improve appearance, fluidity, facilitate packaging, and thus increase the value of goods. At present, instant fruit and vegetable solid beverages produced in China generally adopt the methods of mixing, granulation, and drying, using a swing granulator for granulation. However, the main disadvantage of directly using a swing granulator to process solid beverages is its high content of excipients. 3. Spray drying
Spray drying is the process of using atomizer to disperse the feed liquid into small droplets, and quickly evaporate the solvent in the hot drying medium to form dry powder. The feed liquid can be in the form of liquid that can be transported by pumps such as solution, suspension, emulsion, etc. The dried products can be in the form of powder, granule or agglomerated particles. The production range of spray dried solid drinks is very wide. In addition to milk powder, instant soybean powder and tomato powder widely used in production, there are also reports of litchi powder, lotus root powder, banana powder, strawberry powder, etc. The powder processed by spray drying has small nutrition loss and good color. In addition to direct preparation, it can also be used as an ingredient. However, the powder after spray drying is generally small in particle size and poor in compatibility, and can be directly blended only after granulation. Instant milk powder is one of the most typical solid drinks that can be quickly dissolved in hot and cold water by agglomeration granulation after spray drying, and its research is also the most popular.
02
Research Progress on Instant Solubility of Solid Beverages
1. Definition of instant solubility of solid beverages
The solid beverage preparation process requires good color, flavor, and stability, and the speed of its dissolution process directly determines its quality. The broad definition of instant solubility includes two meanings. The first is a solid beverage that can quickly and completely dissolve in water, such as instant tea, orange crystals, fruit chestnuts, etc., which can be completely dissolved in water; Another type refers to the formation of a uniformly dispersed suspension after rapid dispersion, such as soy milk powder, milk powder, etc. 2. The blending process of solid beverages
The mixing process of powder is divided into four steps: wetting, sinking, and dispersion. Finally, the powder with good solubility is dissolved and infiltrated into water under capillary action. The dissolution process can be completed in a few seconds. However, if there are hydrophobic groups on the surface of the material, the powder is difficult to wet. Generally, binders such as maltodextrin and surfactants such as lecithin granulation (such as milk powder) are used to improve the solubility. 3. Theoretical research on the blending properties of solid beverages
The dissolution process of solid beverages is essentially a mass transfer process, in which water is transferred from the aqueous phase to the surface of the particles, and then diffuses into the interior of the particles. The particles are dissolved from the inner and outer surfaces of the particles, and the dissolved particles enter the aqueous phase and diffuse from the inside to the outer surface of the particles. They are then transferred from the outer surface of the particles to the aqueous phase through diffusion or convection until the particles are completely dissolved. According to molecular mass transfer theory, the factors that affect mass transfer rate include the inner and outer surface area of particles, particle diameter, liquid film thickness, concentration difference from the inside of particles to the surface of particles, concentration difference of dissolved particles in the aqueous phase from the surface of particles to the outside of the liquid film, diffusion coefficient, etc. Increasing the inner and outer specific surface area of particles, reducing the diameter of small particles and liquid film thickness, and improving diffusion or convective mass transfer coefficients are all beneficial for particle dissolution. Generally speaking, the smaller the particle size, the larger the specific surface area of the particles and the faster the dissolution rate; But the particle size is small, and the gaps between particles are also small. When the particles dissolve on the surface, they stick together, preventing water from spreading inside the powder. Moreover, the particle size is small, the bulk density is light, and it floats on the liquid surface, relatively reducing the wetting area, and the dissolution rate is not fast.
03
Research progress on the properties of solid beverage powder
The properties of powder include the flowability and cohesiveness of powder particles, particle size and distribution, particle shape, apparent density, surface properties, static charge, moisture content, etc. It directly affects the storage, packaging, and processing of powder. The flowability of powder plays a significant role in processing, packaging, such as flow, transportation, mixing, compression, and packaging between storage tanks and grain silos. Therefore, measuring the flowability of powder is of great significance for powder engineering. The industrial processing of powders requires reliable and consistent flowability, so that the storage and feeding silos do not overflow or produce dust. There are frictional forces, static frictional forces, adhesion forces, and cohesive forces between powder particles during flow, among which the adhesion force is caused by intermolecular attraction between particles, also known as van der Waals force; The gravitational force caused by the anisotropic static charge carried by particles; Capillary force of attached moisture; The mechanical biting force caused by the uneven surface of particles, sometimes these forces coexist. Represent and measure the mechanical properties of the flow or stillness between powders, represented by the friction angle. Jenike was the first to use the shear chamber method to measure the flow characteristics of powders in 1964, and later developed the annular shear chamber method, which can measure the internal friction force of the powder itself. The particle shape, surface composition, particle size, and moisture content also have a significant impact on the flowability and caking of the powder. The higher the moisture content, the more liquid bridges between the powders increase, the stronger the adhesion force, and the worse the flowability. Among them, particle size has the greatest impact on the flowability of the powder. 04
Research progress in fruit and vegetable composite solid beverages
At present, there is relatively little research on fruit and vegetable composite powders, and single powder research is still the main focus. In order to compensate for the nutritional, color, or flavor deficiencies of a certain fruit and vegetable in production, several fruits and vegetables are often mixed together for processing, and the processing of solid fruit and vegetable beverages is no exception. At present, research on the processing of fruit and vegetable composite powder is mainly focused on technology, and theoretical research is weak.
Shaanxi Huike Botanical Development Co., Ltd. a integrated enterprise which is focus on natural products, Plant extract related products and services.We mainly focus on pharmaceutical, functional food, Freeze-dried powder,Natural Pigment,Homology of medicine and food,beverages and other business services.
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2024-05-11
Shaanxi Huike Botanical Development Co., Ltd.
