Fatty acids, tocopherols, phenolic and antioxidant properties of six citrus fruit species: a comparative study

Citrus fruit is a rich source of bioactive phytochemicals. Information on the fatty acid and tocopherol composition of locally grown citrus fruits in Korea is elusive. This work was aimed to study fatty acid, tocopherols, ascorbic acid, antioxidant potential, and selected phenolics from peel and pulp of six citrus species. The most dominant fatty acid was linoleic acid (15-45%), followed by linolenic, palmitic, and oleic acid. Stearic acid was highly abundant in yuzu peel (14.45%) and pulp (15.88%) compared to the other fruits. Unsaturated fatty acids (54-74%) contributed higher composition than saturated fatty acids (25-46%). Peel exhibited better antioxidant potential and contained higher phytochemicals than pulp. The concentrations of alpha-tocopherol and gamma-tocopherol were ranged from 22.96 (yuzu) to 86.93 (cheonhyeyang) and 38.59 (yuzu) similar to 83.03 (tangerine) mu g/g DW, respectively. J-Redhyeyang peel exhibited highest total flavonoids (4.17 +/- 0.10 mgQE/g DW) and DPPH radical scavenging activity (6.17 +/- 0.03 mgTE/g DW). FRAP values were highest (20.05 +/- 0.64 mgTE/g DW) in yuzu peel, while peel of cheonhyeyang was superior in total phenolic contents. Tangerine (3.02 +/- 0.05 mg/g DW) and yuzu (7.49 +/- 0.38 mg/g DW) had higher hesperidin concentrations in pulp and peel, respectively. Naringin was found in an appreciable amount in yuzu pulp (2.04 +/- 0.09 mg/g DW) and peel (6.30 +/- 0.19 mg/g DW) but not detected in all other fruit species. Our results indicate that citrus fruit peel is the rich source of antioxidant compounds, which can be used to prepare antioxidant rich food product.