Mechanistic insights into the degradation and cis-trans transformation of the new tasty analogs of hydroxy-γ-sanshool pungent dietary components: A DFT study

Sanshool tasty dietary components in Sichuan peppers are structurally unstable and their conformers structurally in series have different oral pungency. To explore the structural change rules behind their possible pungency, the degradation and <i>cis-trans</i> transformation mechanism of hydroxy-coco-sanshool conformers as the new tasty analogs of pungent hydroxy-γ-sanshool have been investigated in this paper. Our results have showed that the conjugated combinations of six <i>trans/cis</i>-C=C bonds lead to variations of C[bond, double bond]C bond strength, max<i>.</i> 57.31 kJ/mol energetic difference among 64 conformers and <i>max.</i> 0.229 ev difference of their photochemical stability. Besides, these conformers could be structurally activated by the light radiation especially in polar environment, which may largely accelerate their mutual isomerization or degradation. Furthermore, their structural activation to form excited states is found to be easier than that of hydroxy-γ-sanshool or hydroxy-α-sanshool conformers. Additionally, eight conformers are found to be dominantly distributed and may be feasibly detected experimentally.