Marta Muñoz-Colmenero1, Jose Luis Martínez2, Agustín Roca1, Eva García-Vázquez1. 1. Laboratory of Genetics of natural resources, Area of Genetics, Department of Functional Biology, University of Oviedo, Asturias, Spain. 2. Sequencing Unit of the University of Oviedo, Asturias, Spain.
Abstract
BACKGROUND: Commercial candies are consumed by all population age sectors worldwide. Methods for quality control and composition authentication are therefore needed for best compliance with consumers' preferences. In this study applications of DNA-based methodology for candy quality control have been tested. Eighteen samples of commercial candies (marshmallows, gumdrops, jelly, sherbet, gelatin-based desserts) produced by five countries were analyzed to identify the component species by polymerase chain reaction, cloning and sequencing of 16S rRNA and ribulose -1,5-diphosphate carboxylase oxygenase genes, and the species determined from BLAST comparison with universal databases and phylogenetic analysis. RESULTS: Positive DNA extraction and amplification of the target genes were obtained for 94% of candies assayed, even those containing as little as <0.0005 ng µL(-1) DNA concentration. The results demonstrated that the species detected from DNA were compatible with the information provided on candy labels only in a few products. DNA traces of undeclared species, including fish, were found in most samples, and two products were labeled as vegetarian but contained porcine DNA. CONCLUSION: Based on the inaccuracy found on the labels of sweets we recommend the use of DNA tests for quality control of these popular sweets. DNA tests have been useful in this field but next-generation sequencing methods could be more effective.
BACKGROUND: Commercial candies are consumed by all population age sectors worldwide. Methods for quality control and composition authentication are therefore needed for best compliance with consumers' preferences. In this study applications of DNA-based methodology for candy quality control have been tested. Eighteen samples of commercial candies (marshmallows, gumdrops, jelly, sherbet, gelatin-based desserts) produced by five countries were analyzed to identify the component species by polymerase chain reaction, cloning and sequencing of 16S rRNA and ribulose -1,5-diphosphate carboxylase oxygenase genes, and the species determined from BLAST comparison with universal databases and phylogenetic analysis. RESULTS: Positive DNA extraction and amplification of the target genes were obtained for 94% of candies assayed, even those containing as little as <0.0005 ng µL(-1) DNA concentration. The results demonstrated that the species detected from DNA were compatible with the information provided on candy labels only in a few products. DNA traces of undeclared species, including fish, were found in most samples, and two products were labeled as vegetarian but contained porcine DNA. CONCLUSION: Based on the inaccuracy found on the labels of sweets we recommend the use of DNA tests for quality control of these popular sweets. DNA tests have been useful in this field but next-generation sequencing methods could be more effective.