Contribution of FA profile obtained by high‐resolution GC/chemometric techniques to the authenticity of green and roasted coffee varieties

Abstract

Twenty-four coffee samples of different botanical and geographical origins were analyzed for their FA composition, including trans isomers. The analysis used high-resolution GC/FID/CP Sil 88 capillary column to separate FAME obtained by esterification with BF 3 /methanol. The purpose of this work was to verify whether this parameter could be applied in the discrimination of arabica and robusta coffees, either in green or in roasted stage. Statistical approaches were applied to check the efficiencies of some univariate and multivariate procedures, and the results permitted the conclusion that the FA profile can be used as a coffee variety marker and may inform on the historical background, mainly in terms of heat-processing conditions. Paper no. J9895 in JAOCS 80, 511-517 (June 2003).Of all the species of Coffea available, two have acquired high commercial value, namely, C. arabica Linn. and C. canephora Pierre ex Froehner var. robusta, and are used to prepare coffee drinks. The beans of the preferred species are easily identified by their macroscopic characteristics when in the green stage. After roasting, this distinction is still possible with whole beans, but after milling, when the anatomic characteristics are lost, identification becomes extremely difficult. Since C. arabica and C. robusta display different appeals and have different commercial values, the discrimination of these species is essential to be able to avoid adulteration and to prevent unfair commercial practices (1).To guarantee the authenticity of coffees, several chemical and physical parameters have been tried, namely, hydroxycinnamic acid derivatives (2), unsaponifiable lipid fractions (3,4), furanic aldehydes (5), trace element profiles (6), stable isotope ratios (7), aroma profiles (8), and spectroscopic techniques (9-11).With regard to the FA composition of the two coffee varieties, an unambiguous position among authors is not yet available, especially when roasted beans are considered (12-16).Therefore, the approach presented in this paper is (i) a new attempt to verify the utility of FA profiles in the discrimination between arabica and robusta coffee varieties, both in the green and roasted stage, (ii) a study of the possible role played by trans isomers of unsaturated FA in the discrimination of the roasted coffees, and (iii) an attempt to develop a statistical model for green and roasted arabica and robusta coffee varieties for use as a starting point for the development of a database. EXPERIMENTAL PROCEDURES Samples.A total of 16 samples of coffee beans from C. canephora Pierre ex Froehner var. robusta and 8 samples of C. arabica Linn., before and after roasting, were studied. The 16 C. robusta samples in the green stage were identified as RG01-RG16, and the same 16 samples after roasting were identified as RR01-RR16. These samples had several geographical origins (India, Vietnam, Uganda, Amboim/Angola, Angola, Cameroon, and the Ivory Coast). Like the C. robusta samples, the 8 C. arabica samples were prepared in green and roasted st...

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“…Casal et al (1997) and then Alves et al (2003) reported that in Arabica and Robusta coffee the roasting process increased the trans-fatty acid levels, specifically the contents of C 18:2ct and C 18:2tc .…”

A Review of Technologies for Detection and Measurement of Adulterants in Cereals and Cereal Products

“…It is also used to quantify and classify metabolites in cereal plants such as maize, rice, wheat, barley, rye, and oats (Khakimov et al, 2014). Chemometric analysis is necessary for extraction of the molecular signatures of adulterants present in the sample (Alves et al, 2003;Reid et al, 2004). This adds to the labor, expertise, and time required for analysis and is the most common drawback for this technique (Cao et al, 2013).…”

Fatty Acids Profile of Coffea arabica L. Resistant to Leaf Rust Grown in Two Environments of Minas Gerais, Brazil

“…The profile of fatty acids can be used as tracer of a cultivar and can inform about the main qualities of the coffee (Alves et al, 2003). The fatty acids play a role in a series of catabolic reactions that lead to the production of compounds of flavor and aroma typical in food (Collins et al, 2003), and have capacity to cover the tongue during the digestion, providing an fatty and creamy buccal sensation, typical of the body of the drink.…”