Study On Enzymatic Degumming Process Of Rice Bran Oil And Properties Of Degumming Products Phospholipids

Enzymatic degumming of edible oil has the advantages of high safety,thorough degumming,high oil yield,and low wastewater discharge.However,enzymatic degumming has not yet been widely promoted.One important reason is that there are shortcomings in the application of a single enzyme in industry:phospholipase A₁ can enzymatically hydrolyze most phospholipids,but requires a long enzymatic hydrolysis time;The enzymatic hydrolysis rate of phospholipase C is fast,but it can only hydrolyze phosphatidylcholine（PC）and phosphatidylethanolamine（PE）.The preparation of a composite enzyme from PLA₁ and PLC can integrate the respective degumming advantages of the two phospholipases,achieving a dual improvement in degumming efficiency and degumming effect.In this paper,using rice crude oil as raw material,the optimal degumming conditions for the complex enzyme composed of phospholipase A₁ and phospholipase C were determined through a single factor experiment,and the degumming effect of silicon dioxide combined with the complex enzyme was studied.Then,the effects of acid degumming,single enzyme PLA₁degumming,single enzyme PLC degumming,composite enzyme degumming,and silicon dioxide combined with composite enzyme degumming on the quality of rice oil degummed oil were compared and studied.Finally,using acid degumming and enzymatic degumming oil residue as raw materials to extract phospholipids,the extraction process was optimized,and the effects of different degumming methods on the structure and properties of phospholipids（HLB value,emulsification stability,antioxidant stability,bacteriostasis）were compared and studied.This provides a theoretical basis for the application of enzymatic degumming technology in the rice oil processing industry.The main research results are as follows:1.Study on enzymatic degumming process of rice bran oil.The phospholipid composition and distribution of rice crude oil are characterized by high phosphorus and high NHP values.Simple hydration or acid degumming cannot reduce the phosphorus content of the crude oil to 10 mg/kg.The effects of process parameters such as complex enzyme reaction temperature,p H value,reaction time,enzyme complex ratio,and enzyme addition amount on the degumming of rice crude oil were investigated through single factor experiments.The optimal conditions for complex enzyme degumming were determined:reaction temperature 50℃,reaction p H 5.0,reaction time 3 h,enzyme complex ratio PLA₁:PLC=1:2,and enzyme addition amount 2 m L/100 g.Under this condition,the phosphorus content of rice oil was reduced to 5.96 mg/kg,and the degumming rate was 98.5%,which was about 16%higher than that of acid degumming.The oil yield of composite enzyme was 96.72%,and that of single enzyme was 96.25%,96.04%,both higher than that of acid degumming by 95.37%.Compared with acid degumming,it could significantly increase revenue.Silicon dioxide can be used as an adsorbent in the degumming of rice oil.At 35℃,when the addition amount is 2.5%,47%of phospholipids can be removed.Under the optimal process conditions,silicon dioxide combined with complex enzyme degumming can reduce the amount of phospholipase added by 25%.2.The effect of different degumming methods on the quality of rice oil.Compared to crude oil,there was no significant difference in the peroxide value and iodine value of different degummed oils.The water content of acid degumming oil is significantly higher than that of crude oil and enzymatic degumming oil,and the acid value of acid degumming oil is significantly lower than that of enzymatic degumming oil.Different degumming methods have no significant impact on the fatty acid content of the crude oil,but can cause varying degrees of loss of the active components in the crude oil,with total phenol loss rates ranging from 15.49%to22.17%.The sterol loss rate is 6.27%～8.25%,the tocopherol loss rate is6.62%～6.96%,the oryzanol loss rate is 11.80%～15.27%,and the squalene loss rate is18.52%～18.76%.There was no significant difference in the content of tocopherols and squalene among the degummed oils.The content of total phenols,total sterols,and oryzanol in the acid degummed oil was significantly higher than that in the enzymatic degummed oil.The total phenol content of acid degumming oil is 6.82%,3.85%,5.16%,5.73%higher than that of single enzyme PLA₁ degumming oil,single enzyme PLC degumming oil,composite enzyme degumming oil,and silicon dioxide combined composite enzyme degumming oil,respectively;The total sterol content is1.97%,1.08%,0.93%,1.25%higher,and the oryzanol content is 3.47%,2.08%,2.77%,2.10%higher.After degumming,the oxidation induction time of the crude oil increased from 5.69h to 10.04h,and the oxidation stability of enzymatic degummed crude oil was significantly higher than that of acid degummed crude oil.In summary,the quality of each degummed oil varies greatly,and enzymatic degumming improves the quality of the crude oil.3.Study on the separation and properties of phospholipids from oil residue products from different degumming processes of rice crude oil.The solvent method was used to enrich and purify phospholipids from oil residues.After optimizing the process,the yield of phospholipids was 81.24%,which was 14%higher than the original scheme.The infrared spectrum results showed that the purified degumming product was phospholipid,and the difference in phospholipid functional groups between acid degumming and enzymatic degumming was significant,indicating that phospholipase hydrolyzed phospholipids during the degumming process to produce different modified phospholipids.The purified phospholipid meets the national phospholipid standard and meets the test requirements.After enzymatic treatment,the HLB of phospholipids is 9～10,and the HLB of natural phospholipids is 7.After enzymatic treatment,the emulsification stability and antioxidant performance of modified phospholipids are greatly improved compared to natural phospholipids.All phospholipids have a certain inhibitory effect on Staphylococcus aureus and Escherichia coli,and the antibacterial activity of phospholipids treated by enzymatic method is greatly improved compared to natural phospholipids.This indicates that phospholipids treated by enzymatic method have a wider application range compared to natural phospholipids.