The aims of this study were to develop the method of isotope analysisto quantify the carbon of the C3 photosynthetic cycle in commercialclarifi ed apple juices and to measure the legal limit based onBrazilian legislation in order to identify the beverages that do notconform to the guidelines of the Ministry of Agriculture, Livestock andFood Supply (MAPA). This beverage was produced in a laboratory,according to Brazilian legislation. Adulterated juices with a sugarcanequantity above the legal limit were also produced. Isotope analysesmeasured the relative isotope enrichment of clarifi ed apple juicesand their purifi ed sugar fraction. From these results the C3 sourceconcentration was estimated by means of the isotope dilutionequation. To determine the existence of adulteration in commercialjuices it was necessary to create a legal limit according to Brazilianlegislation. Two commercial brands of clarifi ed juice were analyzed.Taking the C3 source concentration and the ºBrix of commercialclarifi ed juices, together with the legal limit, it was possible to verifythat one sample certainly contained more sugarcane than thequantity established by the MAPA. The development of a legal limitwas an important methodological innovation that made it possible toidentify the beverages that did not conform to Brazilian legislation.The methodology developed proved effi cient for quantifying thecarbon of C3 origin in commercial clarifi ed apple juices.
ISOTOPE ANALYSIS METHOD (δ13C) IN CLARIFIED APPLE JUICE
