Detection of coffee adulteration with soybean and corn by capillary electrophoresis-tandem mass spectrometry

Author(s)

Daniel, Daniela ^{[1, 2]} ; Lopes, Fernando Silva ^[2] ; dos Santos, Vagner Bezerra ^[3] ; do Lago, Claudimir Lucio ^[2]

Affiliation

^[1] Agilent Technol, Alameda Araguaia, 1142, BR-06455000 Barueri, SP - Brazil

^[2] Univ Sao Paulo, Inst Quim, Dept Quim Fundamental, Ave Prof Lineu Prestes, 748, BR-05508000 Sao Paulo, SP - Brazil

^[3] Univ Fed Para, Inst Ciencias Exatas & Nat, Rua Augusto Correa, 01 Setor Basico, BR-66075110 Belem, PA - Brazil

• Document type: Journal article
• Source: Food Chemistry; v. 243, p. 305-310, MAR 15 2018.
• Web of Science Citations: 9

Abstract

The detection of coffee adulteration with soybean and corn by capillary electrophoresis-tandem mass spectrometry was accomplished by evaluating the monosaccharides profile obtained after acid hydrolysis of the samples. The acid hydrolysis, using H2SO4 as a catalyst, increases the ionic strength of the sample impairing the electrophoretic separation. Therefore, Ba(OH)(2) was used to both neutralize the medium and reduce the content of sulfate by precipitation of BaSO4. The best separation of nine determined monosaccharides (fucose, galactose, arabinose, glucose, rhamnose, xylose, mannose, fructose and ribose) plus inositol as internal standard was obtained in 500 mmol.L-1 triethylamine, pH 12.3. The monosaccharides are separated as anionic species at this pH. The proposed method is simple, fast (< 12.0 min), present linear calibration curves (r(2) = 0.995), and relative standard deviation for replicate injections lower than 5%. The LOQ for all monosaccharides was lower than 0.01 mmol.L-1, which is in accordance with the tolerable limits for coffee. Principal component analysis (PCA) was used to evaluate interrelationships between the monosaccharide profile and the coffee adulteration with different proportions of soybean and corn. Fucose, galactose, arabinose, glucose, sucrose, rhamnose, xylose, mannose, fructose, and ribose were quantified in packed roast-and-ground commercial coffee samples, and differences between adulterated and unadulterated coffees could be detected. (AU)

• FAPESP's process: 13/14993-1 - Characterization and quantification of monoalkyl carbonates in aqueous medium employing microfluidic devices coupled to a mass spectrometer
• Grantee: Vagner Bezerra dos Santos
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 12/06642-1 - Formation and properties of adducts of organic hydroxy-compounds with carbonate in aqueous medium and biological conditions
• Grantee: Claudimir Lucio Do Lago
• Support Opportunities: Regular Research Grants