Process for extracting soybean protein isolate

The process of extracting soybean protein isolate is mainly through the steps of water mill leaching, acid precipitation separation, plate and frame pressure filtration, special preparation, air drying and other steps to obtain soybean protein isolate. The pH value of the acid precipitation is alkali-dissolved, the pH value of the acid precipitation is improved, and the drying method is changed, so that the invention has the advantages of simple and easy process, low production cost, fine product texture and good viscosity, etc. Under the premise of ensuring product quality , Significantly reduces equipment investment, increases product output, saves energy and improves production efficiency.

Process for extracting soybean protein isolate

01 The technical field The present invention relates to a kind of soybean deep processing field, especially a kind of method for extracting soybean protein isolate.

02 Technical background soybean is one of crops with higher protein content, and the isolated protein extracted from soybean is rich in eight essential amino acids such as lysine, tryptophan, valine and other amino acids, and has water retention properties. , adhesion, gel, oil absorption and emulsifying properties, it is a good basic raw material for a variety of food processing. At present, the conventional process of "dry pulverization, heating extraction, centrifugal separation, and spray drying" is commonly used in the production of soybean protein isolate at home and abroad. The main content of this process and its shortcomings are as follows:

1. Dry pulverization and extraction: conventional The process is to directly pulverize the soybean meal, and then add water, heat and alkali for extraction. This method has the following shortcomings:

(1) Since the pulverized soybean meal is a dry powder, a water-absorbing and swelling process is required. In order to promote its water-absorbing and dissolving, the extraction water must be heated to about 60 °C, which consumes a lot of energy.

(2) The extraction time of each batch still needs 2 to 4 hours, and there must be many extraction containers required for continuous operation, which increases the investment in equipment.

(3) Soybean meal powder will inevitably begin to oxidize after contacting with the solvent, and there are usually no preventive measures in the conventional process, which will directly affect the quality of the product.

(4) The produced product has poor viscosity and insufficient protein dissolution.

2. Alkali-solution leaching: The leaching method used in the conventional process is that both leachings are carried out at the same pH value, and the pH value is 8.0 to 9.0. During leaching, the pH value has an impact on the yield and functionality of the isolated protein. The higher the pH value, the higher the yield, but the viscosity and gel properties of the product decrease. Therefore, the extraction method of the conventional process affects either the yield of the product or the functionality of the product.

3. Filtration and slag removal: The leached suspension must remove insoluble matter, that is, slag. The conventional process is to use a spiral decanter centrifuge or a self-cleaning disc centrifuge to filter and remove slag. The price of a spiral decanter centrifuge is about 430,000 to 780,000 yuan. Therefore, the conventional process has the shortcomings of large equipment investment and high power consumption, and often a small amount of residue is left after filtering and removing slag.

4. Acid precipitation: When acid precipitation is carried out in the conventional process, the pH value is about 4.5. In the product obtained by acid precipitation at this pH value, the content of phytic acid is higher. As we all know, phytic acid is an anti-nutritional factor that affects the body's absorption of calcium and also affects the dissolution of protein. Therefore, it should be excluded as much as possible in the production process.

5. Separation, decolorization, washing, neutralization: the sediment after acid precipitation, the conventional process is to remove the whey with a decanter centrifuge, break the separated protein glue block, add water to wash, and then repeat the separation to obtain the protein glue block, The protein glue block is pulverized again, decolorized, deodorized and sterilized at high temperature, then neutralized with alkali, and adjusted to a slurry with a concentration of 15% for drying. The process is cumbersome and only increases the consumption of equipment and energy.

6. Spray drying: To dry the protein slurry with a water content of 85% into powder, the conventional process is carried out by using a spray dryer and a matching boiler. This will inevitably lead to high investment in equipment. A set of spray dryers and supporting boilers worth 1.2 million yuan can only dry 100 kilograms of finished products per hour, thereby increasing the manufacturing cost.

In a word, the existing conventional extraction process of soybean protein isolate has large one-time investment, high energy consumption, high production cost and long investment recovery period. Taking the construction of a production line with an annual output of 3,000 tons as an example, the conventional process requires 70 million yuan, the comprehensive production cost is 14,000 yuan per ton, and the investment recovery period is 5 to 8 years.