Development And Application Of A Tea Seed Oil Refining Plant Based On Inorganic Membrane Separation Technology

Tea seed oil,extracted from the oil seeds of Camellia sinensis,is a high quality edible oil with good flavour,quality and nutritional value,and is widely used in cosmetics,medical and industrial applications.The fresh tea seed crude oil extracted needs to be further refined because of its impurities,dark colour and poor taste.The traditional refining process includes degumming,deacidification,decolourisation and deodorisation,which often requires the use of chemicals such as Na OH for alkaline refining and decolourisation of tea seed crude oil and active white clay(with an earthy smell)for decolourisation,which not only destroys the nutrition of camellia seed oil,but also affects the oil quality to a greater extent and produces alkaline refining waste streams that pollute the environment.In this paper,the inorganic ceramic membrane separation technology is applied to the refining of tea seed oil by using the characteristics of high mechanical strength,narrow pore size distribution,high separation efficiency and easy regeneration and cleaning to achieve the purpose of degumming,deacidification and decolourisation of tea seed crude oil by means of pure physical separation.The research work carried out is mainly as follows:(1)Optimization of refining process conditions.Three types of ceramic membrane tubes(400 nm,200 nm and 100 KD)were selected to test the refining effect of tea seed crude oil and to optimize the temperature.The ceramic film with a pore diameter of100 KD has the best refining effect at a temperature of 70 ℃ and a pressure of 0.2 Mpa.The results showed that: the phospholipid content was reduced from 1.542 mg/g to0.216 mg/g,and the degumming rate reached 85.99%;the acid value was reduced from5.56 mg KOH/g to 1.4 mg KOH/g,and the degumming rate reached 74.82 %;the absorbance was reduced from 4.5 to 3.0,the colour changed from brown to yellow,and the colour was clear,and the acid value and colour both met the relevant indexes of GB/T 11765-2018 in the first grade tea seed oil.(2)Membrane contamination control.Combined with the existing equipment in the laboratory,the study of physical cleaning of ceramic membranes was carried out,and the results showed that the recovery rate of membrane flux of ceramic membranes(400 nm,200 nm)was about 70% and the recovery rate of membrane flux of ceramic membranes(100 KD)was about 65 % through tap water backwashing only.After cleaning by ultrasonic assisted cleaning,the membrane flux recovery rate of ceramic membrane(400 nm,200 nm,100 KD)was 94.56 %,95.23 % and 95.03 % respectively,which was a better cleaning effect.(3)Design and construction of the pilot plant and refining performance testing.On the basis of the laboratory equipment,the pilot plant was designed and optimised,with additional heating,stirring and temperature control systems and pressurised filtration systems.The whole system was intelligently controlled centrally through the control cabinet to ensure the stable operation of the refining process.The refining effect of the pilot plant was tested in combination with laboratory filtration process conditions and at 70 °C,0.2 MPa and 0.4 MPa.The results showed that the refined phospholipid content of 400 nm ceramic membrane tube was 0.356mg/g,the acid value was 2.3 mg KOH/g,the degumming rate and deacidification rate were 76.91 % and 58.63 %,and the colour was yellow;the refined phospholipid content of 200 nm ceramic membrane tube was 0.311 mg/g,the acid value was 1.67 mg KOH/g,the degumming rate and deacidification rate were 79.83 % and 69.96 %,and the color was yellow;the refined phospholipid content of 100 KD ceramic membrane tube was 0.235 mg/g,the acid value was 1.44 mg KOH/g,and the color was yellow.The refined phospholipid content of the 100 KD ceramic membrane tube was 0.235 mg/g with an acid value of 1.44 mg KOH/g,and the degumming and acid removal rates were 84.76 % and 74.1 %,with a yellow colour.At 0.4 MPa,the refined phospholipid content of the 400 nm ceramic membrane tube was 0.352 mg/g,the acid value was 2.25 mg KOH/g,the degumming rate and deacidification rate were 77.17 % and 59.53 %,and the colour was yellow;the refined phospholipid content of the 200 nm ceramic membrane tube was 0.305 mg/g,the acid value was 1.65 mg KOH/g,the degumming rate and deacidification rate were The refined phospholipid content of the 100 KD ceramic membrane tube was 0.232mg/g and the acid value was 1.41 mg KOH/g,and the degumming and deacidification rates were 84.95 % and 74.64 %.The refining effect of 200 nm and 100 KD ceramic membranes is good and meets the GB/T 11765-2018 standard.Combining with the actual situation and considering the refining effect,filtration rate,cleaning cycle and operation cost,0.2 MPa is adopted for tea seed oil refining.