This thesis addresses the production of coffee extracts and their subsequent incorporation into unconventional food product – meads with the addition of coffee grounds and extracts. The samples produced were then chracterized using chemical and sensory analyses.
The thesis is divided into two main sections: theoritical section, which discusses coffee in general, its current status, and its uses; and a practical section, which focuses on the preparation of extracts themselfes, their incorporation into a food product and the subsequent analysis of said product. The experimental work adresses the incorporation of coffee extracts and coffee itself into mead, in which coffee grounds were added during the preparation of the wort prior to fermentation. It also adresses the analysis of the resulting samples using methods of sensory analysis and the quantitative identification of substances via HPLC/RI and HPLC/PDA. HPLC/RI was used to monitor the kinetics of the fermentation process in terms of sugar consumptions and ethanol production. The results showed that the addition of coffee and its extracts influences yeast metabolism, with higher concentration of additives exhibiting a mild inhibitory effects, especially extracts, at the begging of fermentation, but in later stages, the supoorted the yeast’s ability to melabolize sugars even at a higher concentration of ethanol.
A key component of the thesis was the sensory analysis of the produced samples and their comparison with commercially available mead sample. The sensory profile of each variant was defined using principal components analysis. The highest-rated samples were meads with added coffee extracts, which exhibited a harmonious blend of coffee notes, sweetness, and alcohol. In contrast, samples with coffee added during fermentation stages were perceived as having a sensory profile that was too distinctive and, in some cases, less acceptable.
The analytical section further focused on determining caffeine levels in the final samples and during samplening using HPLC/PDA. An increase in caffeine was observed in samples containing ground coffee, followed by a decrease in its concentration during maturation and filtration, likely due to adsorption onto yeast biomass and clarifying agents (bentonite). This study confirms that coffee extract is a suitable means of enriching mead with new sensory and antioxidant properties while maintaining the quality of the final product.