2015
Content of 4(5)-methylimidazole, caffeine and chlorogenic acid in commercial coffee brands
DIEU PHAN, Thi Thanh, Miroslava BITTOVÁ, Kamil MIKULÁŠEK, Vlastimil KUBÁŇ, Stanislav KRÁČMAR et. al.Základní údaje
Originální název
Content of 4(5)-methylimidazole, caffeine and chlorogenic acid in commercial coffee brands
Autoři
DIEU PHAN, Thi Thanh (203 Česká republika, garant), Miroslava BITTOVÁ (203 Česká republika, domácí), Kamil MIKULÁŠEK (203 Česká republika, domácí), Vlastimil KUBÁŇ (203 Česká republika), Stanislav KRÁČMAR (203 Česká republika), Pavel VALÁŠEK (203 Česká republika) a Blanka SVOBODOVÁ (203 Česká republika)
Vydání
Potravinárstvo, 2015, 1337-0960
Další údaje
Jazyk
angličtina
Typ výsledku
Článek v odborném periodiku
Obor
10406 Analytical chemistry
Stát vydavatele
Slovensko
Utajení
není předmětem státního či obchodního tajemství
Odkazy
Kód RIV
RIV/00216224:14310/15:00083015
Organizační jednotka
Přírodovědecká fakulta
Klíčová slova česky
káva, spektrofotometrické metody, HPLC, extrahovatelnost kofeinu
Klíčová slova anglicky
coffee; spectrophotometric methods; HPLC; caffeine extractability
Změněno: 1. 6. 2015 16:20, Mgr. Miroslava Bittová, Ph.D.
Anotace
V originále
Content of 4(5)-methylimidazole(4-MeI), caffeine and chlorogenic acid in commercial coffee brands were determined using high-performance liquid chromatography (HPLC) with UV DAD and MS detectors. Positive ion ESI mass spectra of the 4-MeI standard yielded intense signals corresponding to [M+H]+(83.0604) and [2M+H]+ions (165.1115). Also, adducts of 4-MeI with acetonitrile from mobile were detected –[M+ACN]+ions (124.0849). The LOD of 2.5 ng mL-1and LOQ of 8.4 ng.mL-1 were calculated according to the following formulas: LOD = 3.SD/S, and LOQ = 10.SD/S, where S is the slope of the calibration curve and SD is the standard deviation of the noise. The caffeine content was compared to the results of the standard addition, 1stderivative and liquid-liquid extraction spectrophotometry. 4-MeI was in tens mikrog g-1 in the Vietnamese coffees while in units mikrog.g-1in all Czech and Brazilian coffees (<2.4 mikrog.g-1 and <4.9 mikrog.g-1 , respectively). The results for caffeine were within the documented range (0.31 – 2.20%) in all coffee samples. The lower content of caffeine and chlorogenic acid was observed in Vietnamese coffees. All the methods used for determination of caffeine in the Czech and Brazilian coffees gave acceptable precision an d accuracy. However, there were significant differences in the results in Vietnamese coffees. The caffeine extractability (100 °C, 3 min brewing) almost reached 100% in Czech and Brazilian coffees, while it was less than 90% in Vietnamese coffees. The Czec h and Brazilian coffees tend to produce more caffeine in brews than the Vietnamese coffee because of the different composition of blends and the particle size degree.
Návaznosti
MUNI/A/1452/2014, interní kód MU |
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