Naringin in Turkish orange juices and its reduction by Naringinase

Turkey is a major producer of fresh oranges and related products. The juice making process involves the debittering of naringin. Few studies have been reported on this compound in the fruits and products in Turkey. Furthermore, the process to remove this bitterness was also of interest in this study. Samples of 97 freshly hand-squeezed orange juice and orange peel juice, 30 commercial orange juice and peel concentrates collected from the Mediterranean Region of Turkey were analyzed for their naringin concentrations by HPLC following the Fisher and Wheaton method. Naringin concentration of 53 juice samples from freshly squeezed orange and 87 peel juice samples ranged from 0.12 to 2.63 mg L-1 and 0.50 to 15.7 mg L-1, respectively. On the other hand, the naringin concentration of the commercial orange juice and peel concentrates were higher and ranged from 0.61 to 19.4 ing L-1 and 95 to 995 mg L-1 for 30 samples, respectively. Due to higher naringin levels in orange peel concentrates, these samples were subjected to a debittering process using free naringinase with a Km value of 0.098 mM naringin, at pH 4.0 and 60°C. After 85 min of debittering process, 35.3% of the naringin was found to be hydrolyzed.