Sulfated Polysaccharides Inhibit Browning of Apple Juice and Diced Apples

Browning of fresh Granny Smith apple juice was inhibited almost 100% for 24 h at room temperature by the addition of ι-, κ-, or λ-carrageenan, alone (0.25%) or in combination (0.05%) with 0.5% citric acid. The combination of 0.1 % of any of the carrageenans and 0.5% sodium hexametaphosphate was slightly less effective. Browning was also inhibited by amylose sulfate (0.025 %) or xylan sulfate (0.025 %) combined with 0.5% citric acid. Under the assay conditions, citric acid alone inhibited browning approximately 34%, but sodium hexametaphosphate alone did not inhibit browning. The inhibition of browning by these compounds in combination with the carbohydrate polymers was synergistic. The combination of 0.1% of any of the carrageenans and 0.5% citric acid was able to inhibit browning of unpasteurized apple juice containing 0.1 % sodium benzoate for up to 3 months at 3 °C. The combination of 0.5% carrageenan and 0.5% citric acid also inhibited browning in Granny Smith and Red Delicious diced apple fruit. These combinations may have practical application in the prevention of enzymatic browning in fresh, raw apple juice or diced apples.