The extraction method of soybean separation protein.

soy is high in protein content and rich in nutrients, generally containing 30% to 50% protein. Soybean protein contains 8 essential
amino acids
, and the proportion is reasonable, but lysine is relatively high, while methionine and cysteine content is lower. Soybean protein has become an important protein resource, especially soybean protein separation protein contains
protein
more than 90%, is an excellent food raw materials.
soy separation protein consists mainly of 11S globulin (Glycinin) and 7S globulin (β-con-glycinin), accounting for about 70% of the entire soybean seed storage protein. The composition, structure and composition of these two globulins are different, and the functional properties of soybean separation proteins are different. Physical and chemical changes occur in the extraction, processing and storage of soybean proteins, which can improve the functional properties of soybean proteins used in food. In this paper, the extraction and modified methods of soybean separation protein are reviewed.
1 soybean separation protein extraction method
1.1 alkali acid sinking method
soybean separation protein traditional extraction method is alkali acid sinking method. Mix the skimmed soybean meal with distilled water at a ratio of 1:10, adjust the pH of the mixture with NaOH for 7-9, stir the soy protein with dipping alkali, centrifuge separation, and adjust the pH of the liquid with thin HCI to 4.5-4.8, sink The protein, centrifugal separation, precipitation re-dissolved in pH7.0-8.0 NaOH solution, spray or frozen
dhealing
is the soybean separation protein, its protein content can reach more than 90%, the yield of 24%-38%.
1.2 membrane separation method
and so on studied the use of membrane separation technology to make soybean separation protein. First with Ca (OH)2's thin solution leaching skimmed soybean meal, protein leaching rate of about 80%. The leachate is circulated
ultrafiltration
, and the concentration of the interceptor can reach about 13%. Spraying or freeze-drying the interceptor liquid, i.e. soy-isolated protein products, the protein content can reach more than 95%. Compared with the traditional alkali acid sinking method, the yield is high, the quality is good, the energy consumption is low, and the pollution of wastewater discharge is also solved to a certain extent.
1.3 bipolar membrane electrolysis
developed on the basis of electrodialysis. The bipolar membrane consists of three layers: an anion exchange film and cation exchange film, and a hydro-hydrosphere in the middle of the yin and yang exchange film. Under the action of current, the water molecules ionized on the bipolar membrane as H and OH-, because the membrane selection through anions or cations, resulting in a decrease in the pH of the solution, to reach the isoelectre of soybean protein and make the protein precipitation. This method does not need to add acid or alkali to adjust the pH of the protein solution, avoid mixing salt ions into the isolated soybean protein, and protect the functionality of the soy protein.
1.4 foaming method
foam separation technology is a new separation technology developed in the last decade. It is based on the difference in surf activity, to separate and purify the material means, is widely used in environmental protection, biological engineering, metallurgical industry and pharmaceutical industry and many other ways, the technology is also an effective way to separate and concentrate proteins and enzymes. Xie Jihong and others studied the separation of soybean protein in yellow pulp water emitted by soy products factory. In this method, the separation of soybean protein is done in a continuous operation of the foam distillation tower, nitrogen from the bottom of the tower into the pool liquid, raw material liquid from the foam interface into the tower, foam exported from the top of the tower and broken into foam liquid, foam liquid is the isolated soybean protein.
.