Effect of Thermal Treatment on Synephrine, Ascorbic Acid and Sugar Content of Citrus aurantium (Bitter Orange) Juice

Objective / Purpose: The aim of this study was to understand the change of synephrine, ascorbic acid and sugar contents after thermal treatment of peeled and grated Citrus aurantium (Bitter Orange) Juice. Material and Methods: Citrus aurantium was extracted either by peeling or grating methods. Clarification of juice was achieved by a pectic enzyme. After filtration, juices were thermally treated using rotary evaporator until 67ºBrix. Synephrine, sugar and ascorbic acid analysis were performed with a HPLC system. Results: All compounds’ amounts, except synephrine, changed significantly after thermal treatment. The results, given as dry matter based, were as below. Synephrine contents of fruit juice and concentrated juice of grated bitter oranges were 14.15 g/L and 12.88 g/L, respectively. Ascorbic acid contents of fruit juice and concentrated juices of grated sample were 6.33 and 5.85 g/L, respectively. Synephrine content of peeled fruit juice and concentrated samples were 12.84 and 10.64 g/L, respectively. Ascorbic acid content of peeled fruit juice and concentrated samples were 5.28 and 4.31 g/L, respectively. Conclusion: Thermal treatment has no significant effect on synephrine content of fruit juices. Ascorbic acid content decreased significantly after thermal treatment. Moreover, glucose and fructose content of samples increased and sucrose content diminished significantly.