Study On Browning Factors And Process Optimization Of Casein Purified From Qula

Recently, Casein has been used widely in modern industry and national defence industry, which makes the supply of Casein unable to meet the demand. The Casein made from fresh milk, a kind of powdery or granular material without foul smell, is white or yellowish. But the color of Casein refined by Qula is yellow, even dark brown, which brings limitations for the applications in industry.As raw materials, Casein was produced by a series of engineering procedure such as alkali dissolution, acid precipitation, dry and so forth. The key factor which has caused casein to occur browning reaction in the procedures refined by Qula is studied, and the ingredient of Qula is inspected. The method that applicate HPLC, one of indicator of Maillard's reaction, to determinate the content of 5-hydroxymethylfurfural (5-HMF) in casein made by Qula is established, Based on this method, we detection the content of 5-HMF in the raw material, solution in the procedures refined by Qula and casein produced in different technics conditions. The results indicate in the raw material there is 5-HMF, whose content can increase obviously by dissolving and drying, and decrease by centrifugalization. The content of 5-HMF is positively correlated with dissolvable temperature, pH, ratio of material and liquid, dry temperature, while negatively with the color and luster of the casein refined by Qula, therefore, the key factor can be determined to be Maillard reaction.The engineering procedure that refines Casein by Qula is optimized. Firstly, high-quailty Qula are shattered to 60 meshes, and are soluted twice. secondly, to promote solution, Qula and water are in ratio of 1:17 at 35℃in which pH is 8.5, and 5mL suppressor SHNa are added , the concentration of which is11%. Then, colloid mill grind two times every 5μm to promote solution, and then centrifugalize the solution for 10 min at 8 000 rmp at 50℃. The last, Qula are dryed for 10 min at the temperature of 50℃by air.The Casein produced in this procedure: L*,a*,b* of the product are 78.14, 5.26, and 17.43, respectively. The production rotio is 98.21%. The quality of sensory, Physical and chemical indicators and microbiologic in produced Casein have been detected, all of which can meet the requests of the QB/T 3781—1999.