Influence of growing area, year, season, and cultivar on the composition of myrtle leaves and infusions

Leaves of five myrtle cultivars were analyzed for chlorophyll a and b, polyphenol, and tannin contents in two years (2000 and 2001), two seasons (spring and winter), and two growing areas (Alghero and Oristano, Sardinia, Italy). The hydroalcoholic leaf infusions obtained from the same cultivars were analyzed for the above-mentioned compounds and for their chromatic values as well. L* chromatic component ranged from 44.22 to 49.94, a* values ranged between −5.82 and −2.50, and b* values ranged between 10.74 and 18.40. The relationships between leaf and infusion characteristics were evaluated. Chlorophyll a content ranged from 1.9 to 4.7 mg·g−1 of dry weight in leaves and from 14.8 to 35.2 mg·L−1 in infusions. Chlorophyll b ranged between 0.3 and 2.9 mg·g−1 of dry weight in leaves and between 3.4 to 12.1 mg·L−1 in infusions. Polyphenols ranged between 6.8 and 15.3 g/100 g of dry weight in leaves and between 2.6 and 13.9 g·L−1 in hydroalcoholic infusions. Tannins ranged from 140 to 516 mg·g−1 of dry weight in leaves and from 57 to 291 mg·L−1 in infusions. Significant interactions among year, growing area, season, and cultivar effects occurred for all leaf and infusion parameters, except for leaf chlorophyll a. Strong correlations between leaf and infusion composition were not found. Because infusion quality was little influenced by the studied variables, to the best of our knowledge, winter harvest of myrtle leaves for white myrtle liqueur is feasible.