Green and roasted arabica coffees differentiated by ripeness, process and cup quality via electrospray ionization mass spectrometry fingerprinting

Abstract

A habilidade da técnica de espectrometria de massas com infusão direta e ionização por eletronebulização (IES-EM), nos modos de íons positivos e negativos, foi avaliada na diferenciação de cafés Arábica verdes e torrados e com diferentes estágios de amadurecimento (verde, maduro e passado), processo pós-colheita (seco, úmido e semi-úmido) e cafés classificados por prova de xícara. No modo negativo, a análise dos cafés verdes mostrou que os íons correspondentes aos ácidos graxos e ácidos clorogênicos desprotonados são os mais importantes para a discriminação da maturidade. No modo positivo, a maturidade é diferenciada através de íons correspondentes a cafeína, ácidos clorogênicos protonados e adutos de K + de ácidos graxos. Na diferenciação da pós-colheita, em ambos os modos de ionização, são mais importantes os íons correspondentes aos ácidos graxos, ácidos clorogênicos, açúcares e ácidos carboxílicos formados da fermentação. Cafés Arábica torrados também são discriminados com eficiência. No modo negativo, são importantes os íons correspondentes aos ácidos clorogênicos e ácidos orgânicos de cadeia curta, derivados de açúcares. No modo positivo, a discriminação é realizada por íons de baixa m/z tais como piridina e alquil piridinas protonadas, formadas através da degradação da trigonelina. Ambos os IES(+)-EM e IES(-)-EM são capazes de discriminar diferentes cafés Arábica torrados classificados por prova de xícara e os íons que permitem esta diferenciação são os mesmos descritos para a maturidade e processos pós-colheita.Direct infusion electrospray ionization mass spectrometry in both the negative ESI(-)-MS and positive ESI(+)-MS ion modes are investigated to differentiate green and roasted Arabica coffees with different stages of ripeness (green, ripe and overripe), post-harvesting process (dry, wet and semi-wet) and coffees with different cup qualities. In the ESI(-)-MS of green coffees, ions from deprotonated fatty acids and chlorogenic acids are the most important for ripeness discrimination. In the ESI(+)-MS, maturity is differentiated by ions from protonated caffeine, chlorogenic acids and K + adducts of fatty acids. To differentiate between post-harvesting process in both ionization modes, ions from fatty acids, chlorogenic acids, sugars and carboxylic acids generated in the fermentation process are the most representative. Roasted Arabica coffees are also well discriminated: in the ESI(-)-MS, ions from chlorogenic acids and short-chain organic acids derived from sugars are important. In the ESI(+)-MS, discrimination are mainly performed by low m/z ions such as protonated pyridine and alkylpiridines formed via trigonelline degradation. Both ESI(+)-MS and ESI(-)-MS are able to differentiate cup quality for Arabica roasted coffees and the ions used to perform discrimination are the same ones described in ripeness and post-harvesting processes.Keywords: Arabica coffee, ripeness, post-harvest, cup quality, ESI-MS fingerprinting IntroductionCoffee is the most popular beverage in the world and a commodity of ext...

Discrimination of arabica coffee cultivars by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry and chemometrics

“…Identification of the ions was done comparing the m/z values and MS/MS data obtained by ESI FT-ICR MS in the negative-ion mode with a homemade library of coffee compounds based on literature search (Alonso-Salces, Guillou, & Berrueta, 2009;Amorim et al, 2009;Clarke & Vitzthum, 2001;Clifford, Johnston, Knight, & Kuhnert, 2003;Jaiswal & Kuhnert, 2010) and standards. We considered a match between the experimental m/z value and the theoretical m/z value from our library when the mass error was <3 ppm.…”

“…Coffee quality is a demanding analytical task because the genetic background of the plants, associated with agronomic practices and environmental conditions e such as climate, soil type, and altitude e can affect the final chemical composition of the grain (Amorim et al, 2009;Leroy et al, 2006;Vaast, Bertrand, Perriot, Guyot, & Génard, 2006). Furthermore, the genetic variability has been reported to contribute to coffee acidity, sugars, chlorogenic acids, lipids, and caffeine (Guerrero, Suárez, & Moreno, 2001;Kitzberger et al, 2010;Ky et al, 2001).…”

Analytical chemistry in Brazil: healthy and growing

“…An electrospray ionization mass spectrometry fingerprinting was developed for green and roasted coffees for differentiating them by different stages of ripeness (green, ripe, and overripe), post-harvesting process (dry, wet, and semi-wet) and cup quality. 51 The quality of coffee was also investigated by the determination of fatty acid profile 52 and by evaluating the prediction of sensory properties by solid phase microextraction-gas chromatography and partial least squares. 53 In the first work it was shown that the fatty acid methyl ester composition could not be used to detect corn adulteration in commercial coffees.…”

Extra virgin (EV) and ordinary (ON) olive oils: distinction and detection of adulteration (EV with ON) as determined by direct infusion electrospray ionization mass spectrometry and chemometric approaches

“…Direct infusion ESI‐MS requires no or little sample preparation yielding almost instantaneous information about the composition of a given sample 13. Some recent studies have reported the employment of direct infusion ESI‐MS to obtain fingerprints of samples as diverse as rum and Brazilian artisan cachaça,14 essential oils,13 whisky,15 beer,16 vegetable oils,11, 17 coffee,18 wine,19 biodiesel,20 media used for in vitro production of bovine embryos,21 grape juices,22 perfume,23 genetically modified soybeans,24 and snake venoms 25. In conjunction with chemometric methods, such as principal component analysis (PCA) and hierarchical clustering analysis (HCA) used to treat the MS data, ESI‐MS has been successfully applied to classify, for instance, samples of vegetable oils10 and Brazilian artisan cachaça aged in different wood casks 26…”