# Antimicrobial and Odour Qualities of Alkylpyrazines Occurring in Chocolate and Cocoa Products
## 5 Relationship between Odour and Antimicrobial Activities of Pyrazines  
In scientific debates on the sense of smell, it has become common knowledge that olfaction and emotion are tightly related. Because they excite olfactory receptors and relate to emotionally intense events, alkylpyrazines have powerful odour-beneficial effects. Human sensitivities to chemosensory and olfactory effects can become constitutional through neuroplastic changes in the olfactory pathways to the limbic system and other parts of the brain related to hedonic feeling. Such situations can increase the intake of pyrazine-containing foods and pharmaceuticals through associative learning. According to certain theories, smells may affect mood: arouse strong feelings of pleasure or repulsion, lead to relaxation or bring back emotional memories [71,72]. That is why we decided to focus on pyrazines, which are known for having distinctive fragrance properties. These structures have also lately been discovered to possess potential antibacterial properties. The issue of patients disliking drugs due to their unpleasant flavour may one day be resolved by combining those two features of pyrazines. We made the decision to investigate the correlation between aroma and the antibacterial capabilities of alkylpyrazines. It was chosen to use the odour threshold (OT) and probability (Pa) values of the antibacterial activity generated by AntiBac-Pred as a comparison value. The decision to count the arithmetic medium of the OT measured in water was made in light of the fact that the values of OT vary considerably among the literature sources we examined. A statistical hypothesis test, or as it is called, a \(t\)-test, was conducted with PQStat software. Because testing the association between raw OT value and Pa yielded insufficient data, it was decided to use log10 of the OT as a correlation value. The data that were analysed are presented in Table 6. The relationship between the odour activity values (OAVs) and Pa was not statistically significant and is not included in the paper. The results of the independent groups' \(t\)-test showed that the p-value was 0.000371 at significance level \(\alpha\) = 0.05. This number indicates evidence of a strong correlation between the OT and antibacterial activity probability. The [PERSON]'s rank-order correlation test showed a \(p\)-value of 0.224445, which points at some predisposition of correlation as well. The results of the tests are presented in Table 7 and Figure 4.  
The fact that pyrazines are potent antibacterial agents with pleasant odour effects on the items they are employed on cannot be disregarded and should be investigated on a deeper level. A great example of this combined proficiency application of pyrazines was demonstrated by [PERSON] et al. (2019). 2-Isobutyl-3-methylpyrazine showed itself as a promising preservative for chicken meat strips and added roasted undertones to the flavour and scent of the food. The textile business is another industry that integrates the antibacterial and aroma properties of chemicals. [PERSON] et al. (2019) looked into the connection between the scent intensity and antibacterial properties of encapsulated thyme essential oil on cotton fabrics in their study. The correlation coefficient r = 0.988 between the odour intensity and antibacterial activity of samples was found to be strong. The success of this initiative may benefit textile and clothing consumers tremendously because the antibacterial activity of materials can be simply determined by analysing the scent assessment via the e-nose system. This also demonstrates the importance of research into the links between odour and the antibacterial capabilities of odourants, such as pyrazines.