Nogueira, Andressa Milene Parente [UNESP]Figueira, Ricardo [UNESP]Ducatti, Carlos [UNESP]Venturini Filho, Waldemar Gastoni [UNESP]2018-12-112018-12-112018-12-112018-12-112016-01-01Boletim Centro de Pesquisa de Processamento de Alimentos, v. 34, n. 2, 2016.1983-97740102-0323http://hdl.handle.net/11449/180904The aim of this study was to quantify the carbon of C3 photosynthetic cycle in guava commercial pulps, tropical juices and nectars through the carbon stable isotope technique to identify the beverages at odds with Brazilian law. The isotope analyzes were performed in the following materials: cane sugar, additives, laboratory-fabricated beverages and commercial beverages. After preparation, the samples were packed in tin capsules and inserted into the elemental analyzer (EA 1108 - CHN - Fisons Elemental Analyzer) to determine the relative isotope enrichment in Isotopic Ratios Mass Spectrometer (IRMS) (Delta S Finnigan Mat). To estimate the error of the isotope method were produced in laboratory sweetened tropical juices and nectars according to their Identity and Quality Pattern (PIQ) and also adulterated beverages with amount of pulp below of the established by Brazilian law. In these beverages was measured the theoretical percentage and determined in IRMS the practical percentage of C3 source. The difference between these measurements represented the error of the method. To determine the legality of commercial beverages was measured the Legal Limit (LL) according to the PIQ of each beverage. The LL provided the minimum concentration of C3 source that a beverage must contain to be considered legal by the Brazilian legislation. Eighteen brands of guava non-alcoholic beverages were analyzed. Four brands were classified as adulterated. The technique that uses carbon stable isotopes to check adulteration in beverages allowed identifying with security the fraudulent products. The legal limit was an important methodological innovation that made it possible to identify adulterated beverages.porAdulterationBeverageCarbon-13IRMSIsotopePsidium guajavaArtigo10.5380/bceppa.v34i2.59323Acesso restrito2-s2.0-850323369222-s2.0-85015968279