# Antimicrobial and Odour Qualities of Alkylpyrazines Occurring in Chocolate and Cocoa Products
## 1 Introduction  
The Maya people, who were the first to produce and use the cacao plant, are credited with the invention of chocolate around 400 AD. The dried cocoa beans were then combined with water, cinnamon and pepper to make a drink [1]. It is assumed that the Spanish were the first ones to bring cocoa beans to Europe from their trip to South America in the 16 th century as a present to Prince [PERSON]. In the 17 th century, it gained popularity in Spain and was drunk as a beverage just as the Maya people did [2]. Until the 19 th century, when the manufacturing of pulverized chocolate and defatted cocoa was developed and they were widely distributed around Europe as a food commodity, cocoa was regarded as a luxury good [3]. _Thebroma cacao_ L, a member of the _Malvacae_ family, is the cacao tree which produces the cocoa beans used to make chocolate in modern times [4]. For thousands of years, people have valued chocolate for its rich flavour. The process of turning raw cocoa seeds into cocoa powder produces the distinctive aroma of chocolate. Fermentation, drying, roasting, grinding cocoa beans, combining all components, conching and tempering are the phases of cocoa manufacturing [5]. The largest per capita consumption of chocolate in 2016 was found in Western Europe: 11 kg per person in Great Britain, 9.6 kg in Ireland, 9.5 kg in Switzerland and around 7.5 kg each in Austria and Germany. In the United States of America, about 4.6 kg per person has been eaten annually [6]. In 2006, the annual yield of cocoa beans was approximately 3 million metric tons [7], 4 million tons in 2011-2012 [8] and 4.8 million tons in 2018 [9]. Cocoa's trade value increased by roughly 7% every year between 2014 and 2018 and between 2019 and 2025, and the average annual increase inthe value of cocoa beans is estimated to be 7% as well, amounting to a USD 16 billion commodity circulation [9], which points at the increase in the demand for cocoa and chocolate. Chocolate has gained in popularity also due to its physiological and possible health benefits, including blood pressure management, insulin levels, vascular functions, oxidation processes, prebiotic effects, glucose homeostasis and lipid metabolism [4]. The fermentation, drying and roasting of cocoa beans, and the conching of chocolate masses all involve significant chemical reactions that produce flavour and odour [5]. Those qualities are brought on by a variety of chemical compounds, including alcohols, phenols, pyrazines, esters, aldehydes and ketones. We chose to concentrate on pyrazine derivatives, which were abundant in great quantities in cocoa and goods made from cocoa, including chocolate, in this paper. Pyrazines belong to the group of heterocyclic diazines. They consist of an aromatic ring with two atoms of nitrogen situated in a 1,4-orientation [10]. The relevance of pyrazines in the food business is predicted to expand in the next years due to an increased demand for convenience goods, as well as rising public knowledge about the components and origins of their daily meals. Depending on the substitution and concentration of the roasty, nutty and earthy aroma is characteristic of pyrazine use, and as a result, they have attracted attention from the food sector as key components in raw and roasted meals. Pyrazines are also used as an ingredient in herbicides, insecticides, cosmetics and medicinal substances [11]. The most intriguing feature of pyrazine as a potential therapeutic molecule is the ease with which the hydrogen atoms in its aromatic rings can be substituted to produce various derivatives. While such structures exhibit a wide variety of characteristics and biological functions, we focused on the odour and antimicrobial capabilities of alkylpyrazines.