What is the current status of spray drying technology in the food industry?

Spray Drying Technology
Spray drying technology research began in the early 19th century, with the spray drying technology in the industry is widely used, people on the basic principles and characteristics of it also carried out in-depth research.
1.1 The principle of spray drying technology spray drying basic principle is that the material through the filter by the pump conveyed to the top of the spray dryer atomizer, the use of atomizers will be dispersed into liquid material droplets, due to the droplets of small radius, the specific surface area and surface free energy is large, and a high degree of dispersion, the droplets of moisture on the surface of the vapor pressure than the same conditions under the plane of the liquid moisture vapor pressure to be large, so the moisture evaporation is extremely fast, the product is rapid! The product is dried quickly.
Dai life and others according to the conservation of mass, conservation of energy and Newton’s second law deduced a one-dimensional bidirectional static mathematical model of the spray drying process, from the theoretical study of the thermal drying mechanism of spray drying, spray drying to improve the technical level of the spray drying of great significance.
1.2 Characteristics of spray drying technology 1.2.1 Drying quickly to ensure product quality. Food contains protein and sugar, and protein is generally kept at 60-80 ℃ for a few minutes will produce denaturation, placed at high temperatures will also produce a Melad reaction. The use of spray drying, only 3-10s can dry the product, which can effectively inhibit the drying process of food thermal denaturation and loss of aromatic components, to ensure the quality of the product.
1.2.2 Dry products have good dispersion, fluidity and solubility. For dry products, dispersibility, fluidity and solubility are important indicators of product quality. In the spray drying process, the drying of the product is carried out in hot air, so the product can basically maintain a similar spherical shape with the droplets, thus having good dispersion, fluidity and solubility.
1.2.3 The production process is simplified, easy to operate and control, and suitable for continuous mass production. Most of the products obtained through spray drying do not need to be crushed and screened, thus reducing the production process and simplifying the production process. Product particle size, bulk density, moisture, within a certain range, you can change the operating conditions for adjustment, control and management are very convenient, and can adapt to the requirements of industrialized large-scale production.
1.2.4 Prevent the occurrence of public hazards, improve the production environment. As spray drying is carried out in a closed container, can avoid the drying process caused by dust flying, avoiding environmental pollution.
1.3 Problems of spray drying spray drying technology advantages are significant, but its shortcomings can not be ignored. Its shortcomings are mainly manifested in the power consumption, volume heat transfer coefficient and thermal efficiency are low, the equipment volume is large, prone to sticky wall phenomenon, a larger one-time investment.
In particular, the sticky wall problem, in the spray drying process, if the sticky wall material due to the long time stay in the hot inner wall, may be scorched or deterioration, affecting product quality. Zhou Xueyong et al. analyzed the types and causes of spray drying sticky wall, put forward three types of spray drying sticky wall: semi-wet material sticky wall, low melting point material hot melt sticky wall and dry powder surface adhesion, and put forward to solve the various types of sticky wall program.
Spray drying in the food industry
2.1 Spray drying in the production of fruit and vegetable powder in the application of China is a large agricultural country, fruit and vegetable industry in the country has become second only to the food pillar industry. Fruit and vegetable powder because of its unique advantages, not only to overcome the shortcomings of fruits and vegetables are not resistant to storage, easy to rot and deteriorate, and can meet the people’s diversification of fruits and vegetables, high-grade and fresh trend of the needs of the people, so there is a broad prospect of development.
Fruit and vegetable powder preparation technology is more, such as, spray drying, hot air drying, vacuum freeze drying, microwave drying, variable temperature differential pressure puffing drying and ultra-micro pulverization technology, etc., but spray drying because of its unique advantages, so that it is in the processing of fruits and vegetables occupies a very important position in the powder.
2.2 Spray drying technology in the application of instant tea beverages Instant tea beverages is a solid beverage tea that can be quickly dissolved in water, because it has a convenient drinking and carrying, water soluble, does not leave residue, pesticide residues, easy to adjust the consistency or easy to blend with other foods and many other features, so more and more favored by the people.
Biqiu Yun to Ganoderma lucidum and black tea as raw materials, using spray drying technology to study the Ganoderma lucidum black tea solid beverage production process conditions, the optimal formula and process conditions for the addition of black tea extract 15%, Ganoderma lucidum extract 35%, citric acid 1%, sugar 8%, maltodextrin 15%; spray drying optimal conditions for the inlet temperature of 180 ℃, outlet temperature of 80 ℃, the inlet temperature of 180 ℃, the outlet temperature of 80 ℃, the inlet temperature of 80 ℃, the inlet temperature of 80 ℃, the inlet temperature of 80 ℃ and the outlet temperature of 80 ℃, the inlet temperature of 80 ℃, The optimal process conditions for spray drying are air inlet temperature of 180 ℃, air outlet temperature of 80 ℃, feed volume of 25ml/min.
2.3 Spray drying in the application of food additives due to certain food additives are susceptible to environmental factors such as light, oxygen, temperature, moisture and food additives themselves exist in the odor, odor, pungency and other bad smell, seriously affecting its application in food, hindering the development of the food industry.
In the 20th century, with the birth of microencapsulation technology, these problems are solved, and the key to microencapsulation technology is spray drying. NgLayTze et al. study the effect of different maltodextrin concentration and spray drying population temperature on the content of dragon fruit beet red pigment, and get the optimal spray-drying conditions are the human inlet temperature of 155 ° C and 20% of the maltodextrin concentration.
2.4 The application of spray drying in health food due to the polyunsaturated fatty acids (DHA and EPA) in fish oil is very easy to oxidize, seriously hindering its application in health food and market demand, and fish oil microencapsulation can not only effectively prevent its oxidation and deterioration, but also able to mask the fishy taste.
2.5 The application of spray drying technology in other food fields With the deepening of spray drying technology research, as well as people’s requirements for the flavor and nutritional value of food continue to improve, there are more and more food products produced by the spray drying method on the market, such as egg yolk powder, grains powder, seasoning powder and so on. Due to the development of the economy, people’s lives improve, many areas of the people’s intake of miscellaneous grains and cereals has been reduced, and miscellaneous grains and cereals are rich in dietary fiber, minerals, etc., which are indispensable to the organism, so cereal powders are highly popular among consumers.
Li Ju-nam spray drying technology as the main carrier, yam, black rice, corn, buckwheat, oranges and other grains and fruits for powder processing, and evaluate the spray drying treatment on the functional active ingredients in which the impact of the spray drying process; with a variety of spray-dried powder as the base material, the blend of four kinds of brewing functional beverages. In addition, spray drying technology is also commonly used in the processing of infant nutritional food, the most common is the processing of infant milk powder.