Análise isotópica da variabilidade natural do carbono-13 e avaliação energética em néctares de pêssego – Prunus persica (L.) Batsch
Data
2008-09-03
Autores
Nogueira, Andressa Milene Parente [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
O presente trabalho teve como objetivo desenvolver uma metodologia de análise isotópica para quantificação do carbono proveniente de plantas dos ciclos fotossintéticos C3 (pêssego) e C4 (cana-de-açúcar) com o propósito de detectar possíveis adulterações em néctares de pêssego comercializados no Brasil, além de verificar a veracidade dos valores energéticos informados nos rótulos desses produtos. Para isso, foram produzidos néctares de pêssego, em laboratório, conforme os padrões de identidade e qualidade estabelecidos pela legislação brasileira (bebidas-padrão) e produtos adulterados (com quantidade insuficiente de polpa), nos quais foram calculadas as concentrações de carbono C3, de forma teórica. Esses néctares foram analisados físico-quimicamente para °Brix, pH, acidez titulável e ratio, além da análise isotópica, na qual foi mensurado o enriquecimento isotópico relativo da bebida como um todo e de suas frações (açúcares purificados e sólidos insolúveis). Com base nestes resultados, estimou-se a quantidade de fonte C3 prática nessas bebidas. Os resultados práticos foram comparados com os teóricos para avaliar a precisão do método isotópico ( 13C). Também foi avaliada a influência do uso de aditivos permitidos por lei e das equações de diluição isotópica (simples e com fator de correção) na quantificação de fonte C3. Posteriormente, com base na legislação, foi possível criar um limite de legalidade (% de fonte C3 mínima no produto). A análise isotópica dos néctares de pêssego comerciais forneceu a concentração de carbono C3 dessas bebidas, a qual foi comparada com o limite de legalidade, verificando se os fabricantes dos produtos comerciais estão cumprindo com as normas da legislação vigente. Para bebidas ricas em sólidos insolúveis, como é o caso dos produtos de pêssego, deve-se utilizar...
This work aimed to develop an isotope analysis methodology to quantify carbon C3 (peach) and C4 (sugar cane) in order to detect likely adulteration in peach nectars sold in Brazil, and also to verify the energetic values informed on the label of these products. Adulterated products (with insufficient amount of pulp) and peach nectars were produced in laboratory according to identity and quality standards established by the Brazilian legislation (standard beverage) to calculate theoretically the C3 carbon concentration. These nectars were physically-chemically analyzed for °Brix, pH, titratable acidity and ratio, besides the isotopic analysis, when the relative isotopic enrichment of the whole beverage and its fractions were measured (purified sugars and insoluble solids). Based on these results, the amount of practical C3 source in these beverages was estimated. Practical and theoretical results were compared to evaluate the isotopic method precision ( 13C). The influence of using additives permitted by law and of equations of isotopic dilution (simple and with correction factor) in quantification of C3 source was also evaluated. Later, based on the legislation, a which was compared to the limit of legality, verifying if the commercial producers are respecting the current legislation rules. For beverages rich in insoluble solids, such as peach products, the beverage isotopic value must be used as a whole in dp in the equation of simple isotopic dilution for C3 source quantification. The additives didn’t interfere in results of conventional products, but interfered in light. Out of the eleven trademarks of commercial peach nectars analyzed, only three could be considered legal according to the law, while all seven trademarks of light nectars were adulterate; it was concluded that the methodology of isotopic analysis for this product has shown to be efficient to detect... (Complete abstract, click access below)
This work aimed to develop an isotope analysis methodology to quantify carbon C3 (peach) and C4 (sugar cane) in order to detect likely adulteration in peach nectars sold in Brazil, and also to verify the energetic values informed on the label of these products. Adulterated products (with insufficient amount of pulp) and peach nectars were produced in laboratory according to identity and quality standards established by the Brazilian legislation (standard beverage) to calculate theoretically the C3 carbon concentration. These nectars were physically-chemically analyzed for °Brix, pH, titratable acidity and ratio, besides the isotopic analysis, when the relative isotopic enrichment of the whole beverage and its fractions were measured (purified sugars and insoluble solids). Based on these results, the amount of practical C3 source in these beverages was estimated. Practical and theoretical results were compared to evaluate the isotopic method precision ( 13C). The influence of using additives permitted by law and of equations of isotopic dilution (simple and with correction factor) in quantification of C3 source was also evaluated. Later, based on the legislation, a which was compared to the limit of legality, verifying if the commercial producers are respecting the current legislation rules. For beverages rich in insoluble solids, such as peach products, the beverage isotopic value must be used as a whole in dp in the equation of simple isotopic dilution for C3 source quantification. The additives didn’t interfere in results of conventional products, but interfered in light. Out of the eleven trademarks of commercial peach nectars analyzed, only three could be considered legal according to the law, while all seven trademarks of light nectars were adulterate; it was concluded that the methodology of isotopic analysis for this product has shown to be efficient to detect... (Complete abstract, click access below)
Descrição
Palavras-chave
Frutas, Bebidas - Legislação, Pessego, Carbono - Isotopos, Legislation, Fruit, Beverage, Isotope
Como citar
NOGUEIRA, Andressa Milene Parente. Análise isotópica da variabilidade natural do carbono-13 e avaliação energética em néctares de pêssego – Prunus persica (L.) Batsch. 2008. xiii, 77 f. Dissertação (mestrado) - Universidade Estadual Paulista, Faculdade de Ciências Agronômicas de Botucatu, 2008.