Application of spray drying technology in solid beverage

Spray drying technology has the advantages of large evaporation area, fast drying speed, low material temperature and easy continuous production It shows strong superiority in food drying Spray drying technology and its main process parameters, spray drying technology in solid beverage are reviewed It will provide some references for further research on solid beverage Research status of spray drying technology in solid beverages the research of spray drying technology started in the early nineteenth Century and has been in the world for more than 100 years As early as 1865, La Mo NT proposed the spray drying method to treat egg products, which was directly transformed into solid powder by liquid atomization and drying in a very short time, and made considerable progress in twentieth Century Spray drying technology started relatively late in our country In 1950s, the spray dryer used in the former Soviet Union used for spray drying of dyes [1? 2] Spray drying technology has been increasingly mature and widely used in food industry, such as milk powder [3], whey powder [4], soy milk powder [5], egg powder, juice powder, instant coffee [6]] and so on Spray drying technology has the advantages of large evaporation area, fast drying speed, low material temperature and easy continuous production It shows strong superiority in food drying It can greatly extend the shelf life of many valuable but difficult to preserve materials, and make some materials easy to pack, store and transport At the same time, the processing technology of some materials is also simplified [7] In recent years, spray drying technology has been widely applied in solid beverages, such as strawberry powder, milk powder, pumpkin powder, tomato powder and all kinds of plant powder processing This paper describes the characteristics of spray drying technology and its application in solid beverage, and discusses the determination of technical parameters for spray drying process, so as to provide some references for further study on its solid beverage 1 spray drying technology and main process parameters 1.1 spray drying technology spray drying is a drying method which is used to process solution, emulsion, suspension and slurry material into powder, granular, hollow spheres or pellet like drying products in a single process [8], mainly using atomizer to disperse material into tiny droplets The process of quickly evaporating solvent to form dry powder product in the hot drying medium The spray drying stage is the atomization of the feed liquid, the fog group is mixed with the hot drying medium, the droplet is evaporated and dried, and the drying product is separated from the drying medium The material solution can be in the form of solution, suspension, emulsion and other liquid that can be delivered by pump, and the dried product can be in the form of powder, granule or agglomerated [9] Compared with the traditional drying methods, spray drying technology has many advantages Its drying speed is fast and the time is short (3~ 10 s) It is especially suitable for drying heat sensitive materials The drying process is completed instantaneously, and the drying products can be directly obtained by liquid, so as to avoid the dust flying in the drying process, and do not need evaporation, crystallization, solid-liquid mechanical separation and so on The product has good dispersibility and solubility, which can greatly retain the color, fragrance, taste and nutrition of raw materials; the production process is simple and the operation and control is convenient However, the spray drying method also has some shortcomings which are not easy to overcome For example, the large power consumption and low heat transfer coefficient lead to low thermal efficiency The dryer has large volume, small operation flexibility, and easy to adhere to the wall (10? 11]) 1.2 spray drying technology main parameters in spray drying, the main influencing factors are spray drying before the homogenization of the material, drying temperature, inlet and outlet pump pressure and so on There are also some other factors, such as sugar and acid ratio, feed temperature and feed flow rate, which affect the yield and solubility of the product The ratio of sugar to acid will have a great impact on the taste and flavor of the product, and if the softening point of sugar, acid, pectin, etc is lower than the drying temperature, it will cause serious wall sticking phenomenon Some embedding agents need to be added for embedding, such as maltodextrin, β - cyclodextrin, soluble starch, ethyl maltol or carrageenan, etc 1 2.1 homogeneous homogenization before spray drying is to homogenate the material's liquid, squeeze the impact and expand the pressure, and make the material thinning, so that the material can be more evenly mixed (12]) Homogenization of the material before spray drying has a great influence on spray drying in a uniform manner So, proper homogenization temperature, homogenization time and pressure are very important Generally, the material can be homogenized at 50 ~ 60 ∀ for 20min If the temperature is too high and the time is too long, the homogenization equipment may be damaged If the temperature is too low and the time is too short, the homogenization effect is not good For the homogenization equipment, under a certain homogenization temperature and pressure, the diameter of fat ball particles will not decrease significantly when homogenization reaches a certain degree, and the emulsification effect will not be improved much At the same time, too long homogenization time is not conducive to improving production efficiency When the homogeneous pressure is in a certain range, the stability of the homogeneous liquid increases significantly with the increase of the homogeneous pressure However, when the homogeneous pressure reaches a certain value, the stability of the homogeneous liquid does not change significantly with the increase of the homogeneous pressure [13] Jiang Changxing et al [14] in the process parameters of pumpkin powder prepared by spray drying method, the optimized homogenization pressure is 25MPa, the effect is good Zhang Yan et al [15] used a homogeneous pressure of 40 MPa in the development of the healthy balsam pear solid beverage Therefore, it is necessary to select appropriate homogeneous pressure according to different materials The general pressure is controlled at 25 ~ 50MPa 1 2.2 inlet and outlet air temperature during spray drying, the inlet temperature of dry air will undoubtedly affect the utilization rate of energy, and this factor also affects the quality of products Although spray drying is a suitable drying method for heat sensitive materials, temperature is still a must factor for many heat sensitive materials [16] Moreover, different materials need different inlet and outlet temperatures when spray drying Chen Qingxiang et al [16] in spray drying process of papaya spray drying, the optimum inlet air temperature is 160 Zhang Yan et al [15] in the development of health type balsam pear solid beverage, the inlet air temperature is 190~ 200, the exhaust temperature is 95~ 98, and so on [17] in the study of spray drying technology for jujube powder, the inlet air temperature is 135, and the outlet temperature is 80 If the air inlet temperature is too high, the material may be coking If the air inlet temperature is too low, the drying effect may not be achieved Therefore, we must choose the appropriate inlet temperature to achieve a better spray effect According to different materials, the air inlet temperature is generally controlled at 140 ~ 200 ∀ [9], while the air outlet temperature does not need to be set, but the general air outlet temperature should be controlled at 60 ~ 90 ∀ 1 the pressure of the 2.3 feed pump and the pressure of the material pump have a great influence on the spray drying effect When the air source pressure increases, the ejecting speed of the material increases, and the amount of compressed air increases As a result, the particle size of the physicochemical liquid drops decreases and the specific surface area increases After the particles contact with the hot air, the water evaporates rapidly, resulting in the serious phenomenon of powder run off, the yield of the product decreases, and the appearance quality of the product, such as the particle size and fluidity, is greatly affected However, when the air pressure decreases, the particle size of atomized droplets increases, the specific surface area decreases, and the drying speed slows down Therefore, the appropriate feed pump pressure must be selected The general pressure shall be controlled between 0.12 and 0.21mpa [13] 2 the application of spray drying technology in solid beverages Solid beverage refers to products made from sugar (or without sugar), fruit juice (or without fruit juice), plant extracts and other ingredients as raw materials, processed into powder, granular or bulk and washed after being washed Solid beverage also refers to the granular, scaly or powdery beverage with water content less than 3% and certain shape, which can be drunk only after being washed and dissolved [19] Solid beverage can be produced by spray drying, vacuum drying, microwave drying and oven drying However, because of its unique advantages, spray drying plays a very important role in the processing of solid beverages, especially in the production of powdered solid beverages 2.1 the application of spray drying technology in instant tea drinks Kurban Jean [20]] optimized the spray drying technology of chrysanthemum instant tea by orthogonal test The optimum process was 200 180kPa, the spray pressure was 180kPa, and the relative density of the liquid was 1.05 Zhou Tianshan et al [21] in the processing of bitter bitter cold soluble instant green tea, the spray drying parameters were: the inlet temperature was 135, the outlet temperature was 75, and the injection rate was 10mL/ min Tan Hongbin et al [22] pointed out in the production of instant tea powder that when the air inlet temperature is 250 ∀ and the pressure nozzle is used, and the operating pressure is 2.5-3.0mpa, beaded particles can be obtained Zhou Jianhua [23]'s spray conditions used in the development of mulberry instant tea are: the feed liquid temperature is 45~ 50, the inlet air temperature is 200~ 220, the exhaust temperature is 80~ 90, the drying chamber temperature keeps 85~ 95, and the rotation speed is 800~ 1500 r/ min 2.2 spray drying technology in the production of fruit and vegetable powder, Li Guo [24] taro as raw material, blanching, beating, homogenizing and spray drying technology to produce taro powder, its spray drying process is air inlet temperature of 140~ 180, the outlet temperature is 80~ 100, and the atomization speed is 15 000~ 30000 r/ min Liu Wenhui and so on [25] pumpkin as raw material, by softening, beating, mixing, homogenizing and spray drying technology to produce pumpkin powder, the spray drying process conditions are imported temperature 135, export temperature 75, air intake 0 9m3 / min, feed temperature 60 Huang Hui, et al [26]] with litchi juice as raw material, maltodextrin, sucrose, carboxymethyl cellulose sodium (CMC), and cyclodextrin as excipients, a litchi solid beverage was made by homogenizing and spray drying, and homogenized 15min was obtained at 20MP, and then at inlet temperature 125, outlet temperature 80 and pressure 80MPa The spray drying effect is better when the wind speed is 0 85m3 / min Chen Rucai [27] uses spray drying technology to produce wild papaya instant solid drink The best spray parameters are inlet temperature 173 and outlet temperature 73 Wang Zenan et al [28] in the study of strawberry powder spray drying process parameters and drying agent ingredients, it is concluded that the spray drying effect is better when the inlet air temperature is 200, the feed flow rate is 60mL/ min, and the nozzle speed is 25000 r/ min 3 in the future, the application of spray drying technology in the production and processing of solid beverage is more and more extensive, and because of its advantages, it not only overcomes the shortcomings of the material not easy to store, but also preserves the nutritional value of the material, which provides better protection for people's health Moreover, with the improvement of people's living standards and the acceleration of life rhythm, people have higher and higher requirements for the color, fragrance and taste of food, and more and more demand for convenient and nutritious food [29] High quality solid drinks are easy to preserve, easy to eat, adjustable and nutritious, which meet people's needs Spray drying, the droplet surface temperature is not high, so for food flavor, contain vitamins and so on can continue to preserve, especially for heat sensitive food It is easy to store, transport and use after being dried into powder products [30 × 31] Therefore, spray drying is a good way to produce solid beverages meanwhile