Tomato powder processing technology

Ripe tomatoes can be eaten fresh or processed into a range of products such as tomato puree, tomato pulp, tomato sauce, tomato sauce, tomato powder, ketchup, tomato soup, and tomato sauce. In the past 10 years, with the improvement of people's living standards, the food industry has also begun to develop rapidly. Food industry ingredients market and condiment market demand for tomato powder is also increasing.
The tomato powder processing process is: tomato→cleaning→selection→thermal crushing→beating→vacuum concentrating→drying
(1) Raw material selection: Use fresh, ripe, bright color red, pest-free tomatoes as raw materials.
(b) Cleaning: Remove sediment, residual pesticides, and microorganisms attached to the fruit.
(c) Picking: Remove rotten, spotted or badly colored tomatoes.
(D) Thermal fragmentation: The tomato crushing method includes thermal fragmentation and cold fragmentation. Thermal fragmentation refers to a treatment method in which the tomato is heated to 85°C immediately after being crushed. Because of the thermal cracking method, the pectin esterase and polygalacturonase in the tomato pulp can be passivated in time, the pectic substance is retained in a large amount, and the resulting tomato product has a higher consistency.
(five) Beating: The purpose of beating is to remove the skin and seeds of the tomato. The two-channel or three-track beater is used for beating. The screen size of the first beater is 0.8-1.0 cm. The screen diameter of the second beater is generally 0.4-0.6 cm. The speed of the beater is generally 800 to 1200 rpm. The amount of pomace obtained after beating should generally be controlled at 4% to 5%.
(f) Vacuum concentration: Concentration methods include vacuum concentration and atmospheric concentration. Atmospheric Concentration Due to the high concentration temperature, the tomato pulp is heated to cause a decrease in color, flavor, and product quality. In vacuum concentration, the temperature is about 50°C and the vacuum is 670 mmHg or more.
(7) There are many methods for drying tomato concentrates in tomato concentrates, including freeze-drying, puffing and drying, roller drying, foam layer drying, and spray drying.
(1) Freeze-Drying Method: This method uses a low temperature to freeze the tomato concentrate, and then sublimates it under high vacuum to dry it. The resulting tomatoes still retain their original structure without compromising its original shape and size. Therefore, the freeze-dried particles have a porous structure that retains the space originally occupied by moisture without collapsing, thereby facilitating rapid rehydration of the product. However, this method consumes large amounts of energy and the freeze-drying equipment is very expensive, resulting in high product costs.
(2) Expanding and drying method: Expanding and drying method uses a puffing drying device to dry the tomato concentrate. Dehydration is normally required at an absolute pressure of 2.6 mm Hg. The temperature of the tomato concentrate is usually 60 to 70 °C. In order for the final product to have a moisture content of 3%, the drying time is usually 90 minutes to 5 hours. The product is allowed to cool before the vacuum is removed to avoid collapse of the bulk structure of the product because the resulting tomato powder is thermoplastic. The structure of tomato powder prepared by this method is relatively rigid, the volume is similar to that of the concentrate, and the reconstitution performance of the product is poor. In addition, the expansion must be carried out under vacuum conditions, and the cost is relatively high, resulting in a relatively expensive product.
(3) Spray drying method: Before spray drying, tomato concentrated slurry should be homogenized. The homogeneous pressure is generally 150-200 kg/cm2. Drying is usually carried out using a centrifugal or two-fluid spray dryer with a cooling jacket (a double-walled tower wall that can be used to cool the inner wall by air cooling); if the heating medium is pre-dehumidified dry air, Then when the drying temperature is generally about 150 ~ 160 °C, the outlet temperature is 77 ~ 85 °C, the feed concentration is generally 20% ~ 30%.

There are already some modified spray drying machines on the market that can be used to process fruit and vegetable powders. Some use air as the drying gas, and use a moderate inlet air temperature of 75~95°C for drying, which can increase the production speed. Others use dry air as the dehumidified air at a lower inlet air temperature (25-50). °C) Drying. However, the towers of all these spray-drying equipments for drying tomatoes are very high, which increases the cost for setting up factories.
(4) Foam layer drying method: The key to this drying method is to form a stable solution in the tomato concentrate by adding foaming substances such as soy protein, globulin, fatty acid esters, sugar esters and glycerol monostearate. foam. The temperature of the gas in the dryer is approximately 93°C, and the speed is approximately 100-130 m/s. It is added in a countercurrent manner. The drying time is determined by the characteristics of the product and the drying conditions used. Generally, the drying time is 15 to 18 minutes.
(5) Drum drying method: The rotation speed of the drum is generally 3.5 revolutions per minute, the vapor pressure is 3.5 kg/cm2, and the distance between the rollers is 0.2 mm. In order to enable the water vapor generated during drying to be rapidly taken away, human air is needed. The flow of human circulation is opposite to the direction of rotation of the drum, that is, the person in circulation; and the humidity of the air in the material collection area is controlled to be 15% to 20%. However, this drying method does not really achieve the purpose of drying the tomato powder. Because the resulting product has a moisture content of at least 7%, it needs to be dried in a stream of air at 20°C for more than 24 hours. Otherwise, the color, flavor, and nutritional value of products with a moisture content of 7% or more will be severely reduced during storage.