**2.2 Concentrations of polyphenols, flavonoids, and anthocyanins and antioxid ant activity in apple fruits**

Many studies have shown that polyphenol, flavonoid, and anthocyanin concentrations and antioxidant activity in apples differ between the edible parts of the fruit. In a study of four cultivars, "Rome Beauty," "Idared," and "Cortland" (all three red-skinned), and "Golden Delicious" (golden-skinned), total phenolic and flavonoid concentrations were highest in the peel, followed by the whole fruit and then the flesh [9]. The peels of these apple cultivars also had significantly higher total antioxidant activities than the whole fruit or the flesh. In a study of ten different cultivars in New Zealand, on average, 46% of polyphenols in whole apples were in the peel, and essentially all of the flavonols (quercetin derivatives) were found to be present in the peel [15]. In a more recent study of "Fuji" (bright red skin with green patches) and "Epagri COOP24" and "Epagri F5P283" (both deep red skin) cultivars, the total phenolic and total flavanol concentrations and total antioxidant activity were also highest in the peel, followed by the whole fruit and then the flesh [16]. The peel and whole fruit possessed 1.1–4.1 times the total phenolic concentration, 1.2–4.9 times the total flavanol concentration, and 1.1–3.9 times the total antioxidant activity of the flesh. The total phenolic concentrations of the flesh, the whole fruit, and the peel were all positively associated with total antioxidant activity [16]. From a nutritional point of view, the above findings suggest that regular consumption of apples with peel is recommended to enhance the dietary intake of antioxidant compounds.
