Stabilization of curcumin against photodegradation by encapsulation in gamma-cyclodextrin: A study based on chromatographic and spectroscopic (Raman and UV–visible) data

Application of curcumin in foods is limited because of its low bioavailability and its high sensitivity to light. The effect of light irradiation, temperature and time stabilization of both free and encapsulated curcumin in γ-cyclodextrin was studied by chromatography, UV–vis absorption, and vibrational spectroscopy (Raman). Curcumin is degraded drastically in the presence of light, but it is highly stable with the temperature. From this work it was deduced that the exposure of curcumin to light induces two possible effects (i) demethoxylation and (ii) isomerization of keto-enol to diketo form in curcumin and the formation of small sub-products such as methanol or acetate. UV–vis and Raman spectroscopy were important to determine the nature of the structural modifications. The complexation of curcumin with γ-cyclodextrin was demonstrated to protect this molecule from the photodegradation.