Authors: R Pätzold H Brückner
Publish Date: 2006/05/29
Volume: 31, Issue: 1, Pages: 63-
Abstract
Fermented cocoa beans of various countries of origin Ivory Coast Ghana Sulawesi cocoa beans roasted under defined conditions 100–150 °C 30–120 min low and high fat cocoa powder various brands of chocolate and cocoa shells were analyzed for their contents of free Land Damino acidsAmino acids were isolated from defatted products using a cation exchanger and converted into volatile NOpentafluoropropionyl amino acid 2propyl esters which were analyzed by enantioselective gas chromatography mass spectrometry on a Chirasil®LVal capillary column Besides common protein Lamino acids low amounts of Damino acids were detected in fermented cocoa beans Quantities of Damino acids increased on heating On roasting cocoa beans of the Forastero type from the Ivory Coast at 150 °C for 2 h relative quantities of Damino acids approached 170 DAla 117 DIle 111 DAsx Asp + Asn 79 DTyr 58 DSer 48 DLeu 43 DPhe 370 DPro and 12 DVal In cocoa powder and chocolate relative quantities amounted to 145 DAla 106 DTyr 98 DPhe 81 LAsx and 72 DIle Lower quantities of other Damino acids were also detected In order to corroborate our hypothesis that Damino acids are generated from Amadori compounds fructose amino acids formed in the course of the Maillard reaction fructoseLphenylalanine and fructoseDphenylalanine were synthesized and heated at 200 °C for 5–60 min Already after 5 min release of 117 DPhe and 118 LPhe in the free form could be analyzed Based on the data a racemization mechanism is presented founded on the intermediate and reversible formation of an amino acid carbanion in the Amadori compounds
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