Features of DGCSP Production Process
Low temperature is kept for cottonseed treatment throughout the process so as to avoid protein denaturation to the maximum degree and so as to ensure DGCSP nutritional potency.
The powder content of the cottonseed flake from the preparatory section is small, which is well suited for oil extraction and gossypol removal. Optimal Control of the temperatures at Various points in preparatory section could yield product with high level of digestibility and nutrition.
Application of one-step oil extraction process for cottonseed and use of drag–chain extractor are suited for spraying extraction of cottonseed flake with low residual oil. The de-oiled wet cottonseed meal was sent to another specialized soaking and repeating extractor and in methanol of low concentration, gossypol, sugar and other anti-nutritional factors are removed.
The degossypolization based on soaking in methanol of low concentration (85-90%) makes it possible to thoroughly remove gossypol in short period of time (about 35 minutes) & with little protein denaturation.
The above process has successfully overcome the defect of certain process which has to depend on long time soaking in methanol and then drying to avoid worsen testing result of free gossypol. Certain process produces large amount of alcoholic denatured and thermal denatured gossypol and meanwhile amino acid combines with gossypol and other anti-nutritional factors thus decreasing amino acid content in protein and decreasing digestibility.
By application of soaking degossypolization process, residual oil in the meal could be further extracted to reduce oil residue in protein to less than 10%. By using methanol of low concentration, gossypol is removed while other anti-nutritional factors could also be removed such as aflatoxin, tannin, phytic acid, and various sugars. The moisture contained in methanol could extract out other water-soluble anti-nutritional factors to further improve nutritive level of the product.
By using liquid extractor, the methanol in wet cottonseed meal is removed not only to maximize the decreasing or methanol content in wet meal, to lighten the load of the dryer and to cut down coal consumption but also more importantly, to avoid protein thermal denaturation and alcoholic denaturation to its maximum to produce the product with high amino acid content and with better digestibility.
Since the liquid extractor has extruded out most methanol and moisture, only one low-temperature disc dryer is used to get the drying result. By using one-step drying process, the drying time is shortened and protein denaturation is small. In this way, the energy consumption for drying is economized and the nutritional level of DGCSP is maintained.
By using the originated humidifier over which he Company own Independent intellectual Property, the residual solvent in cottonseed meal is further recovered to reduce solvent consumption and the moisture content in cottonseed meal is rationally regulated to yield in a cost-effective way a type of DGCSP product with little protein denaturation, high nutritional level and moderate moisture content.
The film evaporator is used to recover methanol to avoid liquid overflow in rectifying column so that the process is stabled.
The low temperature process makes it possible that pigment is not solidified into DGCSP nor into cottonseed oil. Therefore, the pigment contact is low in crude oil to wholly guarantee oil quality and the color of DGCSP is light yellow or yellow.
The whole process of oil extraction , gossypol removal and solvent recovery is under slight negative pressure. Quantitive emission of tail gas under control. A series of measures are taken to ensure the separation and recovery of the solvent to minimize solvent consumption and to further ensure the project to have objective economic benefits.
The whole processing system is under automatic control, which makes production more stable and process parameter regulation more accurate and as a result, which achieves the effect of energy saving, consumption decreasing and product quality improvement.