33B-4 |
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M. B. A. GLÓRIA, Departamento de Alimentos, Faculdade de Farmácia, Universidade Federal de Minas Gerais, R. Zilah Correa Araujo 416, B. Ouro Preto, Belo Horizonte, 31310-450, Brazil, J. Tavares-Neto, Brazil, and S. M. Vieira, Departamento de Alimentos, Brazil. The authenticity of fruit based products is a concern throughout the world. Several studies were undertaken to determine the levels of juice added to orange-based products, among them, phenolic, betaine, carotenoids and amino acids. However, most of these methods were time consuming and did not provide the required reliability. Some amines are largely distributed in plants. Putrescine, spermine and spermidine are implicated in a number of important physiological processes. Other amines may also be present, however they are specie related. Synephrine, an aromatic amine formed from tyramine, is typically found in citrus. Since it is restricted to citrus, synephrine has been used in chemo taxonomic studies and, therefore, could be used to determine the authenticity of the orange based products. The objective of this work was to develop a HPLC method for the determination of synephrine and to investigate the possibility of using synephrine to determine the levels of orange juice added to soft drink. An ion-pair HPLC procedure for synephrine determination in orange juices and soft drinks was developed and validated. Orange soft drink was prepared with different levels of orange juice - 7.5, 10, 12.5, and 15% and analyzed for synephrine levels. Among conditions investigated, best results were obtained using reversed-phase column, 0.1 M acetate buffer, pH 4.9, with 10 mmol/L octanesulfonic acid sodium salt and 15% acetonitrile and detection at 275 nm. Purification of the samples with Sep pak C18 was required to avoid interference. The method was considered efficient in terms of linearity, detection limit, accuracy and precision. The levels of synephrine detected in the soft drink correlated significantly with the percentage of orange juice added. The percentage of orange juice added during soft drink manufacture could be determined taking into account the levels of synephrine detected in the product.
Session 33B, Citrus Products: General
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