3. Results
3.1. Total flavonoid contents of different citrus peels
A summary of the total flavonoid content of different citrus
peels is shown in Table 1. The flavonoid content of the citrus peel
extracts varied greatly. Lemon peel extract contained 11.9 mg/g of
rutin equivalents, which was the highest value among the tested
citrus peels. In contrast, Hutoukan peel extract had the lowest level,
containing only 4.43 mg/g rutin equivalents, which was less
than half of the content for lemon peel. For convenience of comparison
between findings found in this study and those reported in
other studies, the flavonoid contents were also expressed on a
weight basis of the dried peels. Ponkan had the greatest level of
flavonoids, at 478 mg/100 g of dried peels. By contrast, the level
of flavonoids in Liucheng (151 mg/100 g of dried peels) was only
one-third of that found in Ponkan.