Utilização dos isótopos estáveis de carbono e nitrogênio na detecção de adulteração e avaliação energética de bebidas de laranja
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Data
2005-12-12
Autores
Queiroz, Elvio Cardoso [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
O presente trabalho analisou, através da metodologia dos isótopos estáveis de carbono e nitrogênio, bebidas comerciais de laranja para detectar adulterações. Sob esta ótica, foram analisadas 33 bebidas comercializadas no mercado brasileiro e verificou se as mesmas estavam em conformidade com os padrões de identidade e qualidade da legislação brasileira. Primeiramente, foram coletados sucos concentrados sem adição de açúcar, sucos integrais fresco de laranja (in natura) e bebidas comerciais. As análises do teor isotópico de carbono-13 foram realizadas nos sucos e nas suas frações: açúcar purificado, polpa lavada com água e polpa lavada com acetona. Os sólidos insolúveis (polpa) foram usados como padrão interno para a quantificação da quantidade de açúcar de cana misturada à bebida comercial de laranja. A variabilidade do enriquecimento relativo natural do carbono nas amostras de laranja, tanto para os sucos concentrados, quanto para os sucos integrais frescos, mostrou-se alta, variando de -26,44 a -28,13 e -25,02 até -28,88 , respectivamente. O balanço de massa isotópico, que considerou a contribuição dos açúcares na constituição dos sólidos solúveis (açúcar da fruta / °Brix da fruta) e (açúcar de cana / °Brix do açúcar de cana), permitiu a quantificação de fonte C3 em bebidas comerciais com erro da ordem de 3%, devido a variabilidade isotópica da polpa. As análises isotópicas das bebidas comerciais mostraram que uma amostra de suco de laranja integral apresentou adição de açúcar, o que é proibido para esta classe de suco; uma amostra de suco concentrado apresentou 40% de adição de açúcar de cana, quando para este tipo de suco, é permitido no máximo 10% em relação ao seu °Brix; uma amostra de suco adoçado de laranja apresentou porcentual de carbono C3 menor do que o mínimo permitido por lei, que para esta classe de suco...
The present work analysed commercial orange beverages to detect adulteration. The methodology of stable carbon and nitrogen isotopes was used. Thirty-three orange beverages commercialised on the Brazilian market were evaluated for compliance with identity and quality standards of the Brazilian legislation. Frozen concentrated orange juices with no sugar addition and freshly squeezed orange juices were collected. The analysis of the carbon-13 isotope signal was carried out for the juice and its fractions: orange juice sugars, pulp washed with water and pulp washed with acetone. The insoluble solids content (pulp) was used as the internal standard for the quantification of the amount of sugar cane mixed with the commercial orange beverages. The variability of enrichment 13C/12C in the orange samples was high for both frozen concentrated orange juices and for freshly squeezed orange juices, showing values from -26.44 to -28.13' and from -25.02 to -28.88', respectively. The isotopic mass balance that considered the contribution of the sugars to the soluble solids content (fruit sugar / fruit °Brix) and (cane-sugar / cane-sugar °Brix), allowed for the quantification of C3 in the commercial beverages with an error to the order of 3%, due to isotopic variability of the pulp. The isotopic analysis showed that one sample of freshly squeezed orange juice presented sugar addition, which is forbidden for this kind of juice. One sample of commercial frozen concentrated orange juice presented 40% of sugar cane. For this kind of juice, the maximum addition permitted is 10% in relation to its °Brix. One sample of sweetened orange juice showed a C3 carbon percentage lower than that allowed by law for this type of juice (maximum of 10% sugar in relation to the mass of the juice)...(Complete abstract click electronic access below)
The present work analysed commercial orange beverages to detect adulteration. The methodology of stable carbon and nitrogen isotopes was used. Thirty-three orange beverages commercialised on the Brazilian market were evaluated for compliance with identity and quality standards of the Brazilian legislation. Frozen concentrated orange juices with no sugar addition and freshly squeezed orange juices were collected. The analysis of the carbon-13 isotope signal was carried out for the juice and its fractions: orange juice sugars, pulp washed with water and pulp washed with acetone. The insoluble solids content (pulp) was used as the internal standard for the quantification of the amount of sugar cane mixed with the commercial orange beverages. The variability of enrichment 13C/12C in the orange samples was high for both frozen concentrated orange juices and for freshly squeezed orange juices, showing values from -26.44 to -28.13' and from -25.02 to -28.88', respectively. The isotopic mass balance that considered the contribution of the sugars to the soluble solids content (fruit sugar / fruit °Brix) and (cane-sugar / cane-sugar °Brix), allowed for the quantification of C3 in the commercial beverages with an error to the order of 3%, due to isotopic variability of the pulp. The isotopic analysis showed that one sample of freshly squeezed orange juice presented sugar addition, which is forbidden for this kind of juice. One sample of commercial frozen concentrated orange juice presented 40% of sugar cane. For this kind of juice, the maximum addition permitted is 10% in relation to its °Brix. One sample of sweetened orange juice showed a C3 carbon percentage lower than that allowed by law for this type of juice (maximum of 10% sugar in relation to the mass of the juice)...(Complete abstract click electronic access below)
Descrição
Palavras-chave
Suco de laranja, Carbono - Isotopos, Nitrogenio - Isotopos, Adulterações, Alimentos - Teor calorico, Orange juice
Como citar
QUEIROZ, Elvio Cardoso. Utilização dos isótopos estáveis de carbono e nitrogênio na detecção de adulteração e avaliação energética de bebidas de laranja. 2005. ix, 73 f. Tese (doutorado) - Universidade Estadual Paulista, Faculdade de Ciências Angronômicas, 2005.