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Food Chem

Title:		pH-Dependency of the proteolytic formation of cocoa- and nutty-specific aroma precursors
Author(s):		Voigt J; Textoris-Taube K; Wostemeyer J;
Address:		"Friedrich-Schiller-University Jena, Institute of Microbiology, Chair of General Microbiology and Microbial Genetics, Neugasse 24, D-07743 Jena, Germany. Electronic address: juergen.voigt@uni-jena.de. Charite - University Medicine Berlin, Institute of Biochemistry, Charite-Platz 1 / Virchowweg 6, D-10117 Berlin, Germany; Shared Facility Mass Spectrometry of the Charite, Charite-Platz 1 / Virchowweg 6, D-10177 Berlin, Germany. Friedrich-Schiller-University Jena, Institute of Microbiology, Chair of General Microbiology and Microbial Genetics, Neugasse 24, D-07743 Jena, Germany"
Journal Title:		Food Chem
Year:		2018
Volume:		20180210
Issue:
Page Number:		209 - 215
DOI:		10.1016/j.foodchem.2018.02.045
ISSN/ISBN:		1873-7072 (Electronic) 0308-8146 (Linking)
Abstract:		"Sensory evaluation of roasted cocoa not only revealed cocoa-specific but also more or less pronounced nutty-specific aroma notes. Essential precursors of the corresponding volatile compounds could be generated in vitro by proteolysis of the cocoa vicilin-class(7S) globulin using a mixture of cocoa aspartic protease and cocoa carboxypeptidase. Since both proteases have rather different pH optima (pH 3.5 and 5.5-6.0, respectively), we have investigated the pH-dependency of proteolysis of this protein substrate in the presence of both proteases, the liberation of free amino acids and the generated aroma potential. Our findings revealed that the precursors of the nutty aroma notes were generated at higher pH-values (pH 4.8-5.6) than the cocoa-specific precursor peptides (pH 4.4-5.2). Longer peptide fragments of the cocoa vicilin were formed by proteolysis at pH 5.2 than at pH 4.8. Furthermore, our findings indicated that cocoa-vicilin derived peptides are essential precursors of both the cocoa- and the nutty-specific aroma components"
Keywords:		Amino Acids/chemistry/metabolism Aspartic Acid Proteases/metabolism Cacao/*chemistry Carboxypeptidases/metabolism Food Handling/methods Hydrogen-Ion Concentration Nuts *Odorants Peptides Plant Proteins/*metabolism Proteolysis Seed Storage Proteins/chemist;
Notes:		"MedlineVoigt, Jurgen Textoris-Taube, Kathrin Wostemeyer, Johannes eng England 2018/03/25 Food Chem. 2018 Jul 30; 255:209-215. doi: 10.1016/j.foodchem.2018.02.045. Epub 2018 Feb 10"