Using Real-Time PCR as a tool for monitoring the authenticity of commercial coffees
Thiago Ferreira1, Adriana Farah2, Tatiane C Oliveira3
1Programa de Pós-graduação em Ciência de Alimentos, Instituto de Química, Universidade Federal do Rio de Janeiro, Avenida Athos da Silveira Ramos 149 Bloco A - 7° andar, Rio de Janeiro 21941-902, Brazil; Programa de Pós-graduação em Nutrição and Núcleo de Pesquisa em Café Prof. Luiz Carlos Trugo (NUPECAFÉ), Instituto de Nutrição, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho, 373 - Centro de Ciências da Saúde, Rio de Janeiro 21941-902, Brazil; Laboratório de Diagnóstico Molecular, Embrapa Agroindústria de Alimentos, Av. das Américas, 29501, Guaratiba, Rio de Janeiro 23020-470, Brazil.
Abstract:
Coffee is one of the main food products commercialized in the world. Its considerable market value among food products makes it susceptible to adulteration, especially with cereals. Therefore, the objective of this study was to develop a method based on Real-Time Polymerase Chain Reaction (PCR) for detection of cereals in commercial ground roast and soluble coffees. After comparison with standard curves obtained by serial dilution of DNA extracted from barley, corn and rice, the method was sensitive and specific to quantify down to 0.6 pg, 14 pg and 16 pg of barley, corn and rice DNA, respectively. To verify the applicability of the method, 30 commercial samples obtained in different countries were evaluated and those classified as gourmets or superior did not present the tested cereals DNA. However, barley was detected in various traditional (cheaper) samples from South America. In addition, corn and rice were also detected in different samples. Real-Time PCR showed to be suitable for detection of food adulterants in commercial ground roast and soluble coffees.
