## 4 Discussion
One possible mechanism could be that the molecules antioxidant activity is linked with its antiglycative capacity at high terpenoid concentrations, whereas for the low terpenoid concentrations, mechanisms like hydrophobic binding on glycation sites should be further tested in the future [33]. Inhibition of the formation of fluorescent AGEs was only seen at 80 \({}^{\circ}\)C. This temperature is representative of a gentle cooking procedure as that obtained in traditional earthenware pots, consisting integral part of the Mediterranean culinary tradition [34], and it is concluded that it facilitates the action of terpenoid compounds towards inhibition of AGEs formation. On the contrary, cooking at 100 \({}^{\circ}\)C, representative of boiling procedure, promoted the formation of AGEs in both glucose levels. Thymol and aniseed oil seems to have a uniform behavior toward the formation of the Amadori products during the early stage of the glycation in the equimolar system perhaps through their antioxidant and antiradical properties. Such a behavior was not observed in the higher glucose concentration suggesting that the compounds under investigation were not involved in glucose autoxidation. Previous research has showed that molecules with more than one phenolic rings such as hydroxytyrosol, and flavonoids possess the ability to act during the intermediate stages of glycation by trapping glyoxal and methylglyoxal and inhibiting AGEs formation [6; 13; 23]. Based on the later, thymol and aniseed oil molecules with one and none phenolic rings, respectively, are not expected to exhibit dicarbonyl trapping activities and hence would have limited impact on glucose autoxidation driven reactions. As with many in vitro trials, this study possesses a series of questions for future research. This initial screening showed that the terpenoid compounds have both antiglycative and proglycative capacity depending on the glycation conditions and that these compounds may be modulating glycation in more than one mechanism. Although these findings are interesting, the study of mechanisms of action as well as the translation of the current findings to actual foods would require the experiments to be repeated in model systems using intact protein molecules like albumin. Especially the possibility of terpenoid-amino acid interactions that allow for binding and the creation of a physical barrier around glycation sites could only be tested in systems involving intact protein molecules. Furthermore, if dose-response is a factor of interest, then future research should focus either on larger terpenoid concentrations than the ones tested herein, or even more to study terpenoid concentrations potentially smaller than 2 uM and understand their impact on protein glycation. As essential oils are rarely added in foods, small dose of these terpenoid compounds have a larger relevance to the conditions of thermal processing of foods. As terpenoid rich herbs and spices are often added during the thermal processing of foods, the final food is enriched in the terpenoid compounds of the herb/spice but during cooking the transfer of lipophilic compounds from the herb/spice to the food system is likely to be small. The addition of more objective markers of glycation like the measurement of dicarbonyl compounds and cross-link agents, even the production of reactive oxygen species would be an important addition to better describe the chemical transformations taking place in these systems. Despite those limitations, this study is still valuable as it is to our knowledge the first study to simultaneously study the impact of five experimental conditions (glucose, temperature, time, terpenoid compounds and terpenoid compound dose) on lysine glycation. It is this design that allowed the detection of the opposing behavior of terpenoid compounds on glycation markers based on the experimental conditions and to pose novel research questions that could further explore the potential of terpenoid compounds to be used as antiglycative agents during thermal processing.