MoLife Research Seminar by:
Ms. Diana Sirbu (PhD student - cacao project COMETA), Jacobs University Bremen, Workgroup N. Kuhnert, Bremen, Germany
Title of the talk:
A Perspective from a PhD student in Analytical Chemistry. Towards Lipidomics of Cocoa and chocolate related products.
My passion for analytical chemistry began when I ran my first TLC plate. It was my first experiment. The separation of the colored spots sparked my fundamental interest in chromatography. Separation, identification or quantification of compounds or matter constitute the core of analytical chemistry. What has impressed me about this branch of chemistry is the very broad list of possible areas of research: includes areas of spectroscopy, spectrometry, electrochemistry, and atomic-level imaging, with applications to innovative problems, including genomics, proteomics and metabolomics. Lipidomics is a subdivision of metabolomics, committed to a comprehensive exploration of lipids. Our research work has its focus on lipidomics of cocoa lipid extract, cocoa butter and other chocolate related products. Due to the high economic value of cocoa butter, there is an increased desire to understand and acquire more knowledge on its composition, which is directly responsible for its physical properties. It is well known for decades that more than 95% of cocoa butter is represented by triacylglycerols (TAGs) with palmitic (P), oleic (O) and stearic (S) acids being the most abundant [1-3]. However, comparative data on the composition of cocoa butter from different stages of the technological processing are scarce. Our recent HPLC-MS study on unfermented fresh cocoa beans lead to the identification of unusual TAGs present in cocoa. At least three main homologous series of these compounds could be observed in different origin samples, which have the same structural pattern of the main cocoa TAGs (POP, POS, SOS). Application of high resolution mass data, as well as tandem MS data, indicated the presence of additional hydroxyl moieties on the second position of fatty acid chains that have more than 2 double bonds. This type of hydroxylated polyunsaturated fatty acids is rarely found in plant material and they are known to have beneficial health effects . Fresh cocoa samples of different origins show minor differences in the relative amount of this TAG subclass. However, these components were not present in any of the fermented samples analyzed. Upon fermentation, these hydroxylated polyunsaturated fatty acids might undergo chemical transformations, where they are converted into other fatty acids or molecular precursors, which can influence the formation of flavor components. Having a better understanding of the TAGs composition of raw cocoa beans is of crucial importance as unfermented fresh beans are the starting point of the industrial processing from bean to chocolate bar.
 Lipp, M. & Anklam, E. Review of cocoa butter and alternative fats for use in chocolate—Part A. Compositional data. Food Chem. 62, 73–97 (1998).
 Lipp, M. et al. Composition of Genuine Cocoa Butter and Cocoa Butter Equivalents. J. Food Compos. Anal. 14, 399–408 (2001).
 Podlaha, O., Toregard, B. & Puschl, B. TG-type composition of 28 cocoa butters and correlation between some TG-type components. Lebensm. - Wiss. Technol. Food Sci. Technol. (1984).
 Vieira, C. et al. Effect of ricinoleic acid in acute and subchronic experimental models of inflammation. Mediators Inflamm. 9, 223–228 (2000).M. Salwiczek, et al. Chem.Soc.Rev. 2012, 41, 2135.
Further information by:
Prof. Dr. Nikolai Kuhnert, Professor of Chemistry (Focus Area: Health - Life Sciences & Chemistry) Email: n.kuhnert [at] jacobs-university.de - Link to Homepage: http://www.jacobs-university.de/directory/nkuhnert