Andreas Degenhardt

Quantification of Important Flavor Compounds in Beef Stocks and Correlation to Sensory Results by “Reverse Metabolomics”

The meaningful correlation of sensory data with analytical data is one of the most challenging tasks in flavor research. In beef stocks in particular, due to the presence of low levels of aroma-active compounds and the taste contribution of non-volatile molecules to the typical “juiciness” character, the consumer encounters a complex matrix situation. The goal of our study was to carry out a comprehensive analysis of all relevant flavor molecules and the correlation to human sensory data. A technique recently developed at the IPB and termed “reverse metabolomics” was used to link biological activity (i.e., sensory data) with variations in the metabolic profile (i.e., analytical data). We used this methodology for the first time to correlate sensorial attributes and GC-MS, LC-MS, and NMR data in culinary beef stocks. Reverse metabolomics was applied to study the link between sensory and chemical composition in a series of freshly prepared culinary beef stocks. A set of 10 different beef stocks was prepared. The degree of liking of the samples was recorded on a hedonic 1–9 scale. Analysis of the stocks was performed by LC-MS, GC-MS, and NMR. 1H-NMR data directly obtained from the meat stock were very complex. Analysis of this dataset by reverse metabolomics revealed some basic structural elements of the key taste compounds, such as carnosine or anserine. The reverse metabolomics correlation of quantitative data with partiality revealed the importance of a set of compounds. This relevance of these compounds has been confirmed by additional sensory experiments which showed an increase in perceived juiciness.

Chapter 45 – Studies on Stability of Citrus Flavors and Insights into Degradation Pathways of Key Aroma Compounds

Model studies have been performed with individual citrus related aroma compounds such as citral, α-terpineol, α-terpinene, and others, in order to de-couple the complexity of citrus flavors. Degradation pathways and transformation rates have been determined for the most relevant compounds leading to the most prominent off-note compound p-methyl acetophenone. Citral is one of the main precursors. Catechins (flavan-3-ols) are often used as antioxidants for stabilization of flavor mixtures. The reactivity of catechins towards aldehydes is underestimated. In our study, we demonstrate the formation of covalent catechin–citral adducts – a reaction that might influence the aroma stability of citrus flavors in the presence of catechins. As a result, the freshness of citrus flavors and stability of key aroma-active substances can be improved, on the result of this study.