Inhibition of Enzymatic Browning in Fresh Fruit and Vegetable Juices by Soluble and Insoluble Forms of β-Cyclodextrin Alone or in Combination with Phosphates

Soluble and insoluble forms of β-cyclodextrin (β-CD) can be used to inhibit enzymatic browning of fresh raw apple, pear, white grape, and celery juice. The anti-browning effects of soluble CDs were concentration-dependent. Concentrations (1−1.5% w/v) of soluble (un-derivatized, hydroxyethyl, or maltosyl) β-CD substantially inhibited browning of Granny Smith apple juice held at room temperature for several hours while untreated juice browned in minutes. Higher concentrations (4−10%) of soluble β-CD derivatives completely inhibited the browning of apple juice held for 1 day under these conditions. The effectiveness of β-CD was greatly enhanced by the presence of phosphate-containing compounds. Hence, only 1% levels of soluble β-CD (in the presence of 0.25−0.5% phosphate compound) completely inhibited browning in apple juice held for 1 day at room temperature or for up to 2−3 weeks at 4 °C. Treatment of apple, pear, white grape, and celery juice with an insoluble form of β-CD, either in a batchwise or flow-through process, resulted in juices free of CDs that resisted browning indefinitely. Keywords: Enzymatic browning; inhibition; cyclodextrins; vegetable and fruit juice; phosphates; phytic acid