Leaching Cottonseed Meat With A Single-phase Mixing Solvent Containing Methanol And Hexane

Cottonseed meat is rich in oil and protein. Because the current prepress-leachingtechnique preferred oil to meal, it not only left the toxin gossypol in meal, but alsochanged the protein quality in meal during its high temperature processing. For thesereasons the protein in cottonseed has not been utilized reasonably.A new invented technique named two liquid phase solvent (TPS) extraction couldproduce high-level oil and toxin-free meal simultaneously. On the other hand, thistechnology had its own disadvantages. First, the current extractor which was widelyused could not adapt to TPS technique because of bad permeability of meal. Secondly,the cost was increased for consuming lots of methanol.A new idea was born that using one phase mixing solvent (methanol dissolved inhexane) to extract cottonseed meat. To verify the feasibility of the idea, some researchwork had been done and the main issuers are as follows:1. A cascade experiment were carried out to simulate a multistage countercurrentleaching process. The results are as follows:1)Effect of leaching time. As one of an important factor, the longer the leachingtime, the better the leaching result. Considering efficiency, suitable leaching time was40 min every stage.2) Leaching temperature was important to result. After study, 50℃ was properwhich was accordant with that using hexane to extract oil.3) Selection of leaching stages. Obviously, the more the leaching stages, the betterthe leaching results. In general, 4 theoretical stages would lead to a meal with residualoil about 1.25% and free gossypol (FG) below 100 mg/kg.4) Effect of the ratio of hexane to cottonseed meat on leaching result was obvious.Under leaching temperature 50℃, The ratio 6.7 (ml /g) would lead to a meal with oil1.25%.5) Proper ratio of methanol to cottonseed meat was 2 ml/g. High ratio wouldincrease cost. On the other hand, too low ratio could lead to high-level FG content in imeal. When the ratio was 2 ml/g, FG content was 92 mg/kg below the FAO standard600 mg/kg.The proper process parameters are as follow: series N=4, temperature 50℃, timefor every stage 40 min, ratio of methanol to cottonseed 2 ml/g, ratio of hexane tocottonseed 6.7 ml/g. Under these conditions , residual oil in meal about 1.25%, FGcontent about 92 mg/kg, bound gossypol about content 3620 mg/kg. Cottonseed mealobtained with above process could reach feed standard.2.Calculation of theoretical stages for a leacher. The Baker equation was used tocalculate the theoretical stages for a given leacher needed to fulfil a leaching task. Acomparison and the experiment was made and average stage efficiency of experimentwas 81.75%.