Comparison of the bioactive chemical components and antioxidant activities in three tissues of six varieties of Citrus grandis ‘Tomentosa’ fruits

The total phenolic, flavonoid, coumarin, and volatile contents and antioxidant activities in three tissues of six Citrus grandis ‘Tomentosa’ (CGT) fruit varieties were investigated. Two flavones, 3 coumarins and 147 volatiles were identified. The exocarp contained 3 coumarins, however, no coumarins were identified in the mesocarp, and only isoimperatorin was found in the pulp. In the exocarp, mesocarp and pulp, 104, 79 and 71 volatiles were identified, respectively. FuMao (FM) contained the highest total phenolic, naringin and rhoifolin amounts; HouYeZhengMao (HY-ZM) contained the highest meranzin hydrate and bergapten amounts; and XiYangZhengMao (XY-ZM) contained the highest isoimperatorin amount. The ABTS radical scavenging power of HuangLongZhengMao (HL-ZM) was the strongest, and FM had the strongest DPPH radical scavenging effect and ferric ion reducing antioxidant power. According to overall performance, FM and HY-ZM are the top two varieties with the highest total phenolic, flavonoid, and coumarin contents and antioxidant capacities.