Protein Extraction Process

Brief Introduction of Potato Protein Powder
A large amount of waste water and residue are discharged in the production process of starch. Such pollution-intensive industrial waste water contains a lot of organic substance.The disposal of untreated industry waste in which the COD can reach up to 50000 or more and the Kjeldahl nitrogen is about 3500 will cause severe pollution. In the process of sewage treatment, nitrogen is hard to break down. Even if it can reach the required standard, the cost will be very high and the investment in the equipment of the sewage treatment will be larger, especially for the discharging of the waste water in the production of the potato starch, sewage treatment is difficult to operate normally because of the foam in the waste water. We can extract potato protein from the industry waste water and lower the content of the organic matter by using advanced potato protein separation technology. By eliminating the forming of the foam and reducing the heavy load on the sewage treatment, the discharge can be up to standard and the extracted potato protein can be used as an additive of food or feeding ingredients. Furthermore, potato protein, as a kind of vegetable protein, is more conducive to digestion and absorption.

The potato protein extracted from the potato juice by special coagulation and separation technology is called coagulated potato protein (CPP). It is grayish yellow powder with a good liquidity.

Potato protein powder is a by-product of the potato starch industry. The study founds that it is a high quality protein of early weaned piglets. Under the restriction of international animal husbandry rules that the animal protein feed is forbidden used, the potato protein is of great significance as a high quality vegetable protein feed resource. Potato protein, as a complete and a high nutrition protein, contains 8 kinds of essential amino acids. Since it has a better energy and nutritional value than that of the soybean meal, the potato protein is a high quality and inexpensive natural nitrogen resource with a broad prospect for development.

Potato Protein Applications
1. Biology Feedstuff Application
  Potato protein can be used as an additive of the feed ingredients. On one hand, it can increase the protein content of the feed; on the other hand, it can improve the utilization of the feed and reduce the feeding cost. Not only rich in protein, but potato protein powder has a balance composition of amino acids just like that of skim milk powder and fish meal. The potato protein powder has a digestible energy density of 18.84 MJ/ kg, 74.08 % of crude protein and 76.87% of biological value which are significantly higher than that of soybean meal. Meanwhile, the apparent or true digestibility in most of the amino acids in potato protein powder, especially Glu, Lys, Pro content, are ignificantly higher than that of soybean meal. The ileal true digestibility of Glu, Lys, Pro contents are 20.67%, 5.58% and 8.16%, respectively 194.92%, 110.34% and 94.87% higher than that of the soybean meal. It is thus clear that the potato protein powder has a better energy and nutritional value in protein amino acids than soybean meal.
  
  Potato protein has a high biological nutritional value. It has a high content of protein and amino acids coupled with a better natural composition balance of amino acids in protein, making it particularly suitable in feeding animal pups. Practice shows that potato protein also has a good effect when it is used to feed adult animals, even better than other protein like fish meat, soy protein, so potato protein has already been widely used as an additive of various kinds of animal feed, such as cattle feed, poultry feed, pet feed, and fish feed.
  
  The experiment showed that the digestibility of potato protein powder increases with the increased age of piglets, from 87% in 3 ~ 4 weeks to 93% above in 5 ~ 6 weeks. The average digestion rate of its essential amino acids reaches up to 87.5%, higher than other protein feeds. The continuous improvement of the protein extraction technology will bring new ideas for the potato industry. In recent years, some unscrupulous manufacturers of feed production add melamine to improve the protein content and it has already caused a great damage. And the mad cow disease makes vegetable protein preferable. Compared with the animal protein, the vegetable protein is easier to absorb. So we should develop refined potato protein industry, extend industry chain of the potato starch and open up the domestic market as well as the Asia-Pacific market.
2. Health Food Application
  Lysine content of potato protein is much higher than that of other types of proteins and potato protein nutrition is only slightly inferior to egg protein. Potato protein contains up to 93mg/100g lysine and 32mg/100g tryptophan. Potato protein is rich in polysaccharide protein, normally it is known as the sticky protein, which can prevent deposition of fat in the cardiovascular system to maintain the flexibility of arteries, and also prevent premature atheroma, atrophy of liver and kidney tissue, maintaining lubrication of respiratory and digestive tracts. Like sweet potato protein, potato protein is also used to cure collagen disease and is a valuable health food for the elderly with an important health and physiological functions.
  
  Potato protein is a pure protein concentrate, with a variety of balanced amino acids and a high nutritional value. It is rich in protein, crude fiber, carbohydrates and can provide human beings with nutritional elements. Potato protein contains a lot of stick protein which is a polysaccharide mixture. The rich content of dietary fiber, up to 11.7% of the protein samples, can enhance intestinal function, enable feces, lower blood cholesterol, adjust blood sugar, control weight and prevent colon cancer and so on. It is believed that with the update of the potato protein extraction technology, potato protein will serve as a new cognitive health food.
3. Industrial Fermentation Application
  Potato protein can also be used as nitrogen sources for industrial fermentation. Potato protein has an irreplaceable advantage especially when small particles of protein are needed.
  
  Now, the price of potato protein in the European market is about 1100-1300 euros /ton (content is of 60%) while the domestic price is 8000-11000 yuan /ton. Some feed manufacturers have already used it.
Status of Potato Protein Powder Processing Industry
The lack of the protein resources is one of the most difficult issues in today’s feed industry. Thus, it is urgent to find new protein resources and develop high quality and low price protein feed ingredients.

China is a main country of potato production and potato starch processing, but potato protein powder has not been paid enough attention by the starch manufactures and livestock workers which result in a huge resource waste.

Due to the big differences between the process in the production of potato protein at home and from abroad, we are still lack of the research of feeding weaned piglets with our potato protein powder.

Processing Flow
1. Preheating Unit of Rraw Material
  The cellular fluid from the multi-level cyclone unit is pumped into the preheating section of the protein recycling unit by screw pump. In this section, the fluid will be heated to 40℃. There are many plate heat exchangers in this section, one of which is clean. The hot water from the protein flocculation & dehydration unit is used as the heat sources of the heat exchangers. The heat exchangers operate with semi-automatic closed CIP system for cleaning. Though the acid can be added in the production, but as the waste is bad for the environment and harmful to eyes, we do not suggest adding acid.
2. Flocculation Unit of Raw Material
  Heated cellular fluid is fed into a steam ejector and then is heated to 112℃ with a pressure up to 5-6bar. After staying in the coil for 1 minute, the protein in the cellular fluid will be flocculated.
3. Dehydration Unit
  Flocculated protein is transported to the horizontal spiral centrifuge for dewatering where the protein is dewatered into 38% dry matter content. As a heat resource of the preheating of the cellular fluid, separated water is cooled in the preheater.
4. Drying Unit
  Air through the filter is heated to the required temperature by a heat exchanger and then is sent into the spin flash dryer by a draft fan. Dewatered wet material is fed into the double helix feeder by a spiral conveyor and is smashed by flash drying to ensure the rapid heat exchange and improve the drying efficiency. The material is dried in the cyclone dryer. The dried protein powder is separated with the air in the cyclone separator and moist air is discharged by the draft fan.
5. Screening & Warehousing Unit
  The protein powder is conveyed into well-distributed hopper by finished product spiral, and then the starch is conveyed to the bucket elevator through the lever feeder below the well-distributed hopper, finally the starch is conveyed into the two-way conveying screw. If the water content of protein is not up to the standard, the protein powder will be sent back to the well-distributed hopper; if it meets the requirement, the powder is sent into a two-bin vibrating flat sieve where the powder is sifted and classified to remove the coarse particle in the powder and ensure the required fineness. After screening, the protein powder is directly stored in a silo.
  
  The balance of the product can be guaranteed by the well-distributed hopper. If the starch after being dried is too dry or too wet, the desired water content can be reached by the circulation of the well-distributed hopper. In particular, when the air dryer operates unstably after boosting, the well-distributed hopper ensures the high quality of the starch with standard water content.
6. Weighing & Packaging Unit
  The moisture content of the protein powder after being dried and cooled can be up to 12%. Then the protein powder in the hopper is conveyed to the automatic packing machine where the protein powder is packed 25kg per bag after setting.