Concentration of sweet potato anthocyanin pigments by loose reverse osmosis memblane process

Concentration of sweet potato anthocyanin pigments with Loose Reverse Osmosis membrane process. The concentration conditions of sweet potato anthocyanin pigment that used the loose R. O. were studied, obtained from following results: 1) Purple sweet potato "Kyushu No.109" contained color value were 5.6. 2) The optimum pigment extractant for membrane process was 5% acetic acid aqueous solution. 3) Acetic acid and sugar were effected on concentration of pigment solution. 4) The loose R. O. membrane of the 10% NaCl rejections was suitable for pigment concentration. This membrane was well permeated of sugar and acetic acid from pigment liquid. 5) As it was taken 21 hours when on the condition of mean pressure 7.0 Mpa and membrane area 1.52 square meter, 500L of pigment extraction liquid concentrated to 39 VRF. 6) It was considered that 4 square meter membrane area is required to bring concentration to an end in 8 hours. 7) In this case pigment recovery and color value of pigment liquid, which was obtained, was 98% and 32.9. This pigment liquid was strong smelling of acetic acid. 8) It wa possible that acetic acid removes from pigment liquid by diafiltration process, it suited for food