## 3 Results
### Non-Specific Markers of Maillard Reaction
#### 3.1.2 Assessment of the Maillard Reaction Evolution by Ultraviolet-Visible
At 100 \({}^{\circ}\)C the same terpenoid compounds showed inhibitory capacity at 2 h and 3 h of incubation (Supplementary Table S2), but only in low glucose concentrations (for aniseed median--13.35% and for thymol median--9.3%) (Figure 4B). Aniseed oil (median 18.75%)  
Figure 2: The effect of terpenoid compounds on early glycation products formation (280 nm) in heated glucose/lysine solutions at 0.1 M and 1 M glucose at pH 7.2 and **(A)** 80 \({}^{\circ}\)C and **(B)** 100 \({}^{\circ}\)C. Symbols (\({}^{\star}\), \({}^{\star\ast}\), \({}^{\circ}\)) outside the boxplots indicate outliers. and thymol (median 24.55%) promoted the production of intermediate glycation products at 100 \({}^{\circ}\)C and high glucose concentration (Figure 4B). Linalool (median--13.85%) successfully inhibited the production of intermediate glycation products at higher glucose concentrations and that only for the 2 h and 3 h timepoints (Supplementary Table S2). According to the RSM analysis, all factors were associated with differences in absorbance at 360 nm (\(p<0.02\)). Significant effects were also seen for the interactions between time and temperature (\(p=0.03\)), glucose concentration and terpenoid compound concentration (\(p=0.03\)), terpenoid compound and its concentration (\(p=0.02\)), glucose concentration and temperature (\(p=0.007\)), glucose concentration and terpenoid compound (\(p=0.02\)) as well as terpenoid compound and temperature (\(p=0.02\)). Figure 3: The effect of terpenoid compound concentration and glucose concentration on early glycation products formation (280 nm) expressed as percentage difference from control (no terpenoid compound added) at pH 7.2 and 80 \({}^{\circ}\)C and 100 \({}^{\circ}\)C. Figures indicate average values of all three terpenoid compounds (linalool, aniseed oil and thymol). At both temperatures, there was inhibition of the formation of intermediate glycation products at 0.1 M glucose at all time points, however there was stronger inhibitory effects with increasing time at higher glucose levels (1 M) (Figure 5). At 1 M glucose, increasing terpenoid concentration was associated with lower inhibitory effect (Figure 5). The later was seen in all terpenoid compounds tested. Interestingly, at 0.1 M glucose aniseed oil and linalool showed a positive association between terpenoid concentration and inhibitory effect (data not shown). The relationship between thymol concentration and its inhibitory effect remained negative at 0.1 M glucose as well. At 420 nm, at 80 \({}^{\circ}\)C thymol showed no inhibition (at 1 M glucose median--0.5%, at 0.1 M glucose median--0.95%) compared to the other two terpenoid compounds in both glucose systems (for aniseed oil at 0.1 M median--4.25%, at 1 M glucose median--11.55% and for linalool \(-\)3.65 and \(-\)14.25, respectively). At 100 \({}^{\circ}\)C, linalool showed higher inhibitory effect in both glucose systems (at 0.1 M glucose median--17.5% and at 1 M glucose median--21.2%) (Figure 6B) compared to the other two terpenoids compounds tested. In the higher glucose concentration thymol promoted the production of advanced glycation products in high temperature (median 26.8%) throughout the heating time. Similar effects were seen for aniseed oil at higher glucose concentration (median 11.1%) (Supplementary Table S3). Once again, larger variability in absorbance measurements at 420 nm was seen at higher temperatures (Figure 6). According to the RSM model, absorbance at 420 nm was influenced by glucose concentration, incubation temperature, the choice of terpenoid compound and its concentration (\(p<0.003\) for all). Interactions between terpenoid compound choice and its concentration, terpenoid compound and glucose concentration and terpenoid compound and temperature also significantly impacted absorbance at 420 nm (\(p<0.003\)). More specifically, linalool showed the greatest inhibitory capacity followed by aniseed oil, while thymol did not show any inhibitory capacity (data not shown).