Analysis of minor low molecular weight carbohydrates in cocoa beans by chromatographic techniques coupled to mass spectrometry.
J Chromatogr A
; 1584: 135-143, 2019 Jan 11.
Article
in En
| MEDLINE
| ID: mdl-30554780
ABSTRACT
The low molecular weight carbohydrate (LMWC) profile of cocoa beans has recently been studied using hydrophilic interaction liquid chromatography coupled to electrospray ionization-time of flight mass spectrometry (HILIC-ESI-TOF MS) and HILIC-ESI-tandem mass spectrometry (HILIC-ESI-MSn). However, different LMWC could not be unambiguously identified. Thus, as a first approach in this paper, gas chromatography coupled to mass spectrometry (GC-MS) was used as a complementary analytical technique to characterize LMWC of cocoa beans. Different mono-, di-, tri- and tetrasaccharides, as well as myo-inositol, galactinol and a diglycosil glycerol were detected. scyllo-Inositol, 1-kestose and 6-kestose were identified in unfermented cocoa beans for the first time. Moreover, other minor LMWC were tentatively assigned as fructosyl-fructose, fructosyl-glucose and glucosyl-sucrose. As a second step, in order to evaluate new possible indicators of cocoa bean origin or fermentation status, scyllo-inositol, 1-kestose and galactinol were selected as target compounds and a HILIC-ESI-TOF MS method was optimized for their analysis. The optimized conditions, using an acetonitrilewater gradient with 0.05% ammonium hydroxide at 40 °C showed narrow peaks (wh 0.3-0.5 min) with good resolution values (Rs 0.83-2.83). The validated HILIC-ESI-TOF MS method was applied to the analysis of 35 cocoa bean samples from different origins and fermentation status. The content of scyllo-inositol, 1-kestose and galactinol in unfermented beans (n = 21) was in the range of traces-504.9, 36.1-133.5 and traces-1970.4 µg g-1 cocoa DM respectively. In fermented beans (n = 14), the content of scyllo-inositol and 1-kestose was in the range of 15.5-491.9 and traces-115.5 µg g-1 cocoa DM respectively. Galactinol was absent in fermented beans, indicating that it could be a potential indicator of fermentation status. The methodology proposed could be used for quality control of natural products and other food ingredients containing inositols and oligosaccharides.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Cacao
/
Carbohydrates
/
Chromatography, Liquid
/
Spectrometry, Mass, Electrospray Ionization
/
Tandem Mass Spectrometry
/
Gas Chromatography-Mass Spectrometry
Language:
En
Journal:
J Chromatogr A
Year:
2019
Document type:
Article
Affiliation country:
Alemania