Key technical points of plant protein beverage production equipment
With the continuous expansion of beverage market demand, plant protein drinks made of crops or plant fruits as the main raw materials developed rapidly, such as Chengde's almond juice, Shanghai's longevity milk and Haikou's coconut juice, which are regarded as high-grade nutritional drinks and are popular, especially almond juice and soybean milk. Because vegetable protein beverage is different from general acid beverage and has its own characteristics, its production and processing are relatively complex, and it is easy to appear stratification, deterioration and other problems in production. This paper discusses the key technical problems in the production of soymilk, peanut milk and almond juice, hoping to play a role in attracting valuable products.
I. raw material pretreatment process
1. Pretreatment of peanut kernel
The key point of peanut kernel pretreatment is baking. Peanut contains trypsin and anti nutritive trypsin inhibitor. After heat treatment, the anti nutritive factors are destroyed or lose their activity. The roasted peanuts are good for removing the red coat and avoiding the change of the color of the finished products. Moreover, the roasted peanuts at high temperature can produce a variety of pleasant aroma and make the finished products have a better flavor. The temperature and time of baking peanuts have a great influence on the quality of the products. Generally, it is better to control the temperature at 110 ℃ ~ 130 ℃ and 20 min ~ 30 min. If the temperature is too high, it will produce burnt taste and seriously affect the dissolution rate of protein; if the temperature is too low, it will produce bad smell and the finished product will have fishy smell.
2. Pretreatment of soybean
The key point of soybean pretreatment is enzyme inactivation. In the process of soybean processing, it is easy to form peculiar smell substance, which is generally believed to be originated from the oxidation of unsaturated fatty acids in soybean, and lipoxygenase is the main factor to promote the oxidation of unsaturated fatty acids. Most of the lipoxygenase existed in cotyledons near the soybean epidermis. Therefore, the method of heating can be used before the soybean is broken, heating for 7S ~ 8s under high temperature steam at 120 ℃. It can inactivate the lipoxygenase in soybean epidermis without any effect.
3. Pretreatment of almond
The key point of almond pretreatment is peeling and Debittering. Amygdalin, which contains 3% of amygdalin, can destroy the enzymes in human cells after entering the human body, so that it can not absorb the dissolved oxygen in the blood, resulting in the body's anoxia and asphyxia. Therefore, the almond dew processed from bitter almond must be debittered and detoxified first. The solubility of Amygdalin in water is relatively large, so it is suitable to use warm water immersion method to remove bitterness and detoxification, that is, to control the water temperature to 50 ℃ ~ 60 ℃, the water consumption is about 3 times of the quality of raw materials, which needs to be turned over frequently, and the water should be changed once or twice a day, generally taking 5-7 days. If the immersion is not complete, the product not only has a strong smell. Moreover, it is spicy to drink. If you drink too much, you may be poisoned. Therefore, you must ensure that bitter almonds are completely free from bitterness and poison before entering the next process.
II. Impact of pH value on products
1. Effect of pH value on protein yield
Plant protein drinks contain a certain amount of protein. The yield of protein directly affects the input-output ratio of raw materials, that is, the cost of products. Generally speaking, the protein is easy to dissolve in alkaline condition, that is to say, the protein yield is relatively high when the pH value of the slurry is high. However, if the pH value is too high, it will make the product bitter and astringent, so the pH value of the slurry grinding water should be generally controlled at about 7.5.
2. Influence of pH value on product stability
In the process of processing and storage, vegetable protein drinks are prone to stratification, which is mainly due to the change of pH value. In general, the closer the pH value of the solution is to the isoelectric point of the protein, the easier it is to make the protein agglomerate and produce precipitation or floating phenomenon. The isoelectric point of peanut protein is about 5.5 ~ 6.5, that of soybean protein is about 4.3, and that of almond protein is about 5.0. In order to promote the full dissolution of plant protein, improve its hydration ability, and ensure the stability of plant protein beverage, the pH value of emulsion should be kept away from the isoelectric point of the plant protein on the premise of not affecting the taste and flavor of the product, so as to avoid the stratification of the product in the process of processing and sterilization.
III. use of emulsifier
Vegetable protein beverage is a complex emulsion composed of colloidal solution of plant protein and oil in water emulsion. In the unstable thermodynamics system, it is easy to break, flocculate, merge, break and other demulsification. In order to reduce or avoid the above phenomenon, the use of emulsifier is one of the effective methods. An ideal emulsifier formula should have a strong affinity with both water and oil phases. Usually, a single emulsifier is difficult to achieve this ideal state. Two or more emulsifiers with different HLB values can often play a complementary role in rational use.
1. Peanut milk and almond dew are the composite Emulsifying Stabilizers because of their high fat content. In order to achieve the balance of hydrophilicity and lipophilicity, the oil / water emulsifier sucrose ester stabilizer hb0.4 ~ 0.5% with strong hydrophilicity can be used to obtain satisfactory results.
2. There is a high content of protein in soy milk, which has a certain degree of emulsification. When heated, soy protein is easily denatured by heat, which destroys the secondary bond of the primary, secondary, tertiary and quaternary structures that maintain the spatial conformation of protein molecules, forming a new conformation and forming a precipitate. Therefore, by adjusting the salt balance of the emulsion, that is to say, adding phosphate, and controlling the pH value and homogenizing pressure at the same time, the two bactericidal precipitation can be effectively prevented.