Antioxidants in Apples

Apples are a significant dietary source of antioxidants and have been associated with a reduced risk of chronic disease. Most of this protective quality in fruits and vegetables has been attributed to phytochemicals, which protect against oxidation. Oxidative damage plays a role in cancer and heart disease, and as oxidative damage accumulates it plays a role in the overall aging process. Flavonoids are a major class of phytochemicals found commonly in fresh fruits and vegetables.

Boyer and Liu (2003/04) found apple to have the second highest level of antioxidant activity, compared to other commonly consumed fruits. Cranberry had the highest level of antioxidant activity, while apple was followed by red grape, strawberry, peach, lemon, pear, banana, orange, grapefruit, and pineapple in decreasing order.

A wide range in antioxidant content among different apple cultivars has also been found (Boyer and Liu, 2003/04). Fuji had the highest level of flavonoids, followed by Delicious, Northern Spy, Fortune, Gala, Liberty, Rome Beauty, Golden Delicious, Jonagold, Idared, Cortland, and Empire in decreasing order. Fuji also had the highest level of phenolics, followed by Delicious, Gala, Liberty, Northern Spy, Golden Delicious, Rome Beauty, Fortune, Jonagold, Idared, Cortland, and Empire in decreasing order. Similarly, MacLean, Murr, and DeEll (2003) showed that the antioxidant capacity of Empire was half that of Delicious apples.

Lee, Rupasinghe, and Jackson (2004) investigated the major phenolic profiles of eight Ontario-grown apple cultivars and found that the total antioxidant capacity, total phenols content, and flavonoids levels were the highest in Honeycrisp and Delicious, moderate in Idared, Spartan, Granny Smith, and Cortland, and the lowest in Crispin and Empire. Furthermore, apple peel contained 2 to 10-fold higher levels than the core and flesh tissue.

In general, the phytochemical content of fresh apples is not significantly affected by storage (Boyer and Liu, 2003/04). However, 1‑MCP treatment improves the retention of antioxidant levels during storage (MacLean, Murr, and DeEll, 2003). On the other hand, processing can reduce the phytochemical content. Apple juice obtained from Jonagold apples had only 3-10% of the antioxidant activity of fresh apples.

References

Boyer, J., and R.H. Liu. 2003/04. Antioxidants of apples. New York Fruit Quarterly 11(4):11-15.

Lee, V.W., H.P. Rupasinghe, and C-J. Jackson. 2004. Bioflavonoids of Apples: Effects of Genetic Variability, Fruit Parts and Processing. HortScience 39:829.

MacLean, D.D., D.P. Murr, and J.R. DeEll. 2003. A modified total oxyradical scavenging capacity assay for antioxidants in plant tissues. Postharvest Biol. Technol. 29:183-194