Study On Removing Effect Of Phospholipids In Crude Soybean Oil By Phospholipase C

As a new method, removal of phospholipids by enzymes has many advantages. Com-pared to the tradition water and acid methods, enzymatic method uses little chemicals, waterand electricity consumption, simple operation and little loss of oil. Phospholipids can be hy-drolyzed by phospholipase C （PLC） to diacylglycerols （DAG） and phosphate esters. Com-pared to phospholipids-removing by phospholipase A（PLA）, phospholipids-removing by PLCcan be completed fast. More little loss of oil and increase of DAG content can be gotten afterPLC reaction. Therefore, phospholipids-removing by PLC is a promising method. Processoptimization and factors of PLC reaction have been studied in this thesis.First, the selectivity of PLC was studied. After analyzing the PLC reaction results ofthree kinds of crude soybean oil with high, middle and low phosphorus content, conclusionwas drawn that PLC reaction was fast.85.0%of phosphorus was removed in0.5h and theremoval of hydratable phospholipids （HP） was much higher than nonhydratable phospholipids（NHP） during the first0.5h. High remove of HP in crude oil with high HP/NHP value whilelow remove of HP in oil with low HP/NHP value was gotten by PLC degumming. PLC reac-tion was suitable for crude soybean oil with low phosphorus content and HP/NHP.The process was optimized.The temperature was set at50℃, time1h, enzyme dosage30mg/kg, pH5.0, water content3%and stirring speed300r/min. The phosphorus contentwas21.2mg/kg in reacted oil while the DAG was0.32%. The results of orthogonal experi-ment were: enzyme dosage30mg/kg, temperature50℃, water content2%, stirring speed200r/min, pH5.0. The phosphorus content was17.0mg/kg in reacted oil while the DAG was0.33%.Three kind factors were studied to reduce the phosphorus deeply. The predominant effectof45%（w/w） citric acid pretreatment before PLC reaction was to adjust pH. Compared to theresults of reacted EDTA chelated oil by PLC, Mg²⁺,Ca²⁺,Fe³⁺,Zn²⁺,Cu²⁺all had suppressingeffects on PLC reaction. The suppressing effect increased with the increase of ion concentra-tion, especially Fe³⁺. When PLC and PLA were used together to phospholipids-removing, thephosphorus content reduced under5mg/kg after0.5h, no matter the reaction condition andratio of PLC/PLA. The enhancement resulted from the increasing of contact area. No obviousenhancement was observed when non-ion surfactant Span20, Span40, Span80, Tween20andTween80were added, neither solvent-phase degumming by PLC.Finally, scale-up experiment demonstrated that there was no evident amplification effect,which layed a foundation for industrialization of PLC degumming.