Detection of roasted and ground coffee adulteration by HPLC and by amperometric and by post-column derivatization UV-Vis detection.

Coffee is one of the most consumed beverages in the world. Due to its commercial importance, the detection of impurities and foreign matters has been a constant concern in fraud verification, especially because it is difficult to percept adulterations with the naked eye in samples of roasted and ground coffee. In Brazil, the most common additions are roasted materials, such as husks, sticks, corn, wheat middling, soybean, and more recently - acai palm seeds. The performance and correlation of two chromatographic methods, HPLC-HPAEC-PAD and post-column derivatization HPLC-UV-Vis, were compared for carbohydrate analysis in coffee samples. To verify the correlation between the two methods, the principal component analysis for the same mix of triticale and acai seeds in different proportions with coffee was employed. The performance for detecting adulterations in roasted and ground coffee of the two methods was compared.

Identification of a splicing coactivator gene that affects the production of ochratoxin a in Aspergillus carbonarius

Ochratoxin A is a mycotoxin produced by some fungi species. Among them, Aspergillus carbonarius is considered a powerful producer. Genes involved in the ochratoxin A biosynthesis pathway have been identified in some producer species. However, there are few studies that purpose to identify these genes in A. carbonarius. The use of insertion mutants to identify genes associated with certain properties has been increased in the literature. In this work, the region of T-DNA integration was investigated in one A. carbonarius ochratoxin-defective mutant previously obtained by Agrobacterium tumefaciens-mediated transformation, in order to find an association between interrupted gene and the biosynthesis of ochratoxin A. The integration occurred in a gene that possibly encodes a splicing coactivator protein. The analysis of the relative expression of the splicing coativator gene from A. carbonarius wild type strain in four different media showed high correlation between the transcript levels and the ochratoxin A production.

A ocratoxina A é uma micotoxina frequentemente encontrada em uma grande variedade de produtos alimentares e apresenta efeitos nefrotóxicos e potencial carcinogênico para animais e humanos. É naturalmente produzida por algumas espécies fúngicas, como Aspergillus carbonarius, que é considerado um potente produtor. Apesar disso, o número de estudos que visam identificar genes que são essenciais para a biossíntese de ocratoxina em A. carbonarius é ainda reduzido. Um mutante de A. carbonarius com baixa produção de ocratoxina A previamente obtido por transformação mediada por Agrobacterium tumefaciens foi investigado com o objetivo de encontrar uma associação entre o gene interrompido e a biossíntese desta micotoxina. Os resultados mostraram a ocorrência de uma junção não exata entre o T-DNA e o DNA genômico do fungo durante o evento de integração. A integração do T-DNA no genoma do mutante T188 provocou deleção de 727 nucleotídeos. Esta deleção inclui uma porção final do gene coativador de splicing e uma região não-codificante entre este gene e o gene F-actina. A expressão relativa do gene coativador de splicing na linhagem selvagem cultivada em quatro diferentes meios mostrou associação entre a quantidade de ocratoxina A e os níveis dos transcritos.

Chemometric evaluation of adulteration profile in coffee due to corn and husk by determining carbohydrates using HPAEC-PAD.

The detection of impurities in coffee samples already roasted and ground is a constant concern mainly in order to verify the incidence of frauds. Carbohydrates contents are important as variations on original constitutes of different matrixes may be able to reveal the final composition of the product. In this sense, a study is performed in this paper in order to evaluate the quality through concentration of total carbohydrates in Arabic roasted and ground coffee. Chemometric methods were applied in order to verify an adulteration pattern by coffee husk and corn, by the mixture of different amounts of these contaminants to coffee, following a statistical design of Simplex-Centroid. It could be concluded that this method was efficient in distinguishing different matrixes. In pure coffee, higher concentrations were found for galactose and mannose with levels of 8.25% and 9.65% (w/w), respectively. However, in the pure husks, the main carbohydrates were mannitol (with a level of 0.64%), arabinose (with 4.24%), and xylose (with 3.40%). For the corn sample, glucose was detected in greater quantity, with 52.53% (w/w). Models presenting the influence of adulterants incorporated to coffee in the carbohydrate level were obtained.