First, the indigo fruit is pulped, then extracted with subcritical water, then enriched by winterization and membrane technology, and finally vacuum freeze-dried by molecular distillation and food freeze dryer equipment to obtain the indigo fruit anthocyanin product, including the following steps:
(1) Using colloid mill to crush and beat the fresh fruit of Indigo chinensis to obtain pulp;
(2) extracting the pulp obtained in step 1 by using subcritical water extraction technology in the presence of antioxidants, and using subcritical water extraction technology to extract the pulp of indigo fruit pulp, the pressure range is 16-20mpa, and the extraction process is carried out. The temperature is 300-340 degree , the pulp:water=1:1-3(m/m), the extraction time is 10-30min, and the extraction is performed twice. The added antioxidant is egcg, and the added amount of the two extraction times is 0.01 percent to 0.05 percent of the weight of the indigo fruit. ;
(3) The feed liquid extracted in step 2 is introduced into a centrifuge for centrifugation, and the centrifuge is collected;
(4) The centrifuge in step 3 is placed at room temperature for stratification, the lower water layer is collected, and the water layer is filtered to obtain filtrate a;
(5) winterize the filtrate a in step 4, and then filter again to obtain filtrate b;
(6) The filtrate b in step 5 is treated with a ceramic membrane and a nanofiltration membrane successively. The pore size of the ceramic membrane is a membrane element with a diameter of 200 nm. The molecular weight cut-off of the nanofiltration membrane is selected as 200-400da, the temperature of the nanofiltration membrane treatment liquid is 23-28 DEG C, and the pressure is 0.3-0.5mpa. to obtain concentrated solution a;
(7) The concentrated solution a in step 6 is concentrated by molecular distillation, the pressure of molecular distillation is 20-30pa, the evaporation temperature is 30-35 degree , the condensation temperature is 0-10 degree , and the material flow rate is 1.0-2.0l/min. to obtain concentrated solution b;
(8) Vacuum freeze-drying the concentrated solution b in step 7. When the food freeze-drying machine is frozen at low temperature, the temperature is -50--40 degree , the vacuum degree is controlled at 10-13pa in the drying stage, and the vacuum freeze-drying is carried out to moisture. The content is below 5 percent . A finished powder containing anthocyanins from indigo fruit is obtained.
