Prevention and control of browning in Dangshan pear juice concentrate by ion exchange and absorption technologies

Reduction and control of browning in Dangshan pear juice concentrate(PJC) by ion exchange and absorption technologies were studied. 20 °Brix Dangshan pear juice was treated with FPC-21 cation exchange resin and XAD-16 adsorption resin sequentially, and then concentrated to 70 °Brix, browning index(A₄₄₀) and other characteristics were measured during storage. Results show that treating the pear juice with FPC-21 resin can reduced pH value, formol index and browning index. Reduction of pH value enhence the decolor ability of XAD-16 resin on pear juice. Reduction of pH value and formol index can control the browning rate of PJC during storage. 20 °Brix pear juice was treated with FPC-21 resin to reduce the pH value to 4.05, then treated with XAD-16 resin to rise color value(T₄₄₀) up to 85%, and concentrated to 70 °Brix. The color value of PJC is over 45% after storing at 37℃ for 35 d, which can meet the export regulation.