Study On Clarification Of Litchi Juice By Using Ceramic Membrane And Browning Decreasing Technology

This research argues for the feasibility of clarifying litchi juice with inorgance membrane. Permeation flux influenced with different parameters including pore size, pressure, temperature and so on. The best pore size and optimal operating conditions were chosen. study systematically the factors of pH, storage temperature, color presrever that affect the browning of litchi juice and set up a color dynamical model during storaging litchi juice.1.The pre-diposal method of filtrating by 200 sieve pore sizes can reduce the membrane pollution and increase the volume flow rate. The optimal pore size is 0.20um and the best operating conditions of clafifying litchi juice are that P=0. 2MPa, T = 30°C, V= 2m/s. After clarifying litchi juice, the membrane is cleaned by 2%NaoH and the permeation rate can recover to about 98. 4%. The litchi juice, that is clarified by inorganic membrane of 0. 2um pore size, its transmittance can reach 97. 2%, turbidity is 8. 3NTU, gets 80. 1% clarifyed juice ,divides 98.8% pectin, cantains good flavor without boiled smell, no any deposit appears in the quality guarantee period ,has a good stability.2. Nonenzymatic browning was the main browning factors in the processing and storage of litchi juice. The factors influencing nonenzymatic browning include temperature and pH. when the pH value of lichi juice is 3.0～4.0 and storaged at low temperature, it can reduce the browning effectly . The study was indicated that 0. 1% citric acid +0.2 % sodium erythorbate +0.02 % EDTA-Na2 could resist nonenzymajic browning remarkably in the juice processing, and, it also found that the condition of lower thermal temperature and vacuum concentrate could decrease nonenzymatic browning.3. Based on the theory of chemokinetics, kinetics model of the color changes was studied during the storage of litchi juice. The model was A-A0 = t·K₀·exp (—Ea/RT). Then the chi- squaer test was employed to compare simutation and experimental date. So this model can use to predict the color changes of litchi juice at different storage temperature , and make control of it.