Changes in phenolic compounds, colour and antioxidant activity in industrial red myrtle liqueurs during storage.

The results of a study on the evolution of phenolic compounds, colour and antioxidant activity in two industrial red myrtle liqueurs during storage in bottles under different bottle headspace (constant or increasing) and exposure to light are reported. In the year of the study, the phenolic compounds showed considerable changes even in the liqueurs stored with constant headspace. The anthocyanins in particular, both free and combined, tended to decrease. As expected, the same phenomena were observed in an accelerated form in the product stored in bottles with increasing headspace. The colour, evaluated according to the classic spectrophotometric parameters of intensity and hue, showed marked variability, especially in samples in which headspace was progressively increased. The two liqueurs showed antioxidant capacity values, expressed as mM of Trolox, comparable to those of red wine. They significantly decreased during storage in the bottles with increasing headspace, while values remained almost constant in the others.