Hello Iqbal, Apple is great source of anti oxidants but you need to extract bioactives from it which acts as a antioxidant. There are various methods of bioactive extraction such as solvents, microwave assisted extraction, Liquid pressurized extraction and natural methods such as Enzyme assisted extraction. Once u get those bioactive then check for anti oxidant assays such as DPPH radical scavenging, estimation of flavonoid content by aluminum chloride colorimetric assay and even it's reducing power assays. It's a huge and interesting topic. You will enjoy working on it. 

Read attached article. for detail insight!

I think the review mentioned by Ajay will give you all the information you need.

Please check out this article.

Regards

Article Antioxidant Activity of Apple Peels

Excellent question Ali . Lets wait for some revealing answers.

Check these publications for any usefulness to you

As you know there are different type of apple

https://plus.google.com/app/basic/stream/z13yzx5hbrirebpwk04chry40lmnin4geco?cbp=toc0oso2lou1

Particularly strong is the ability of apples to decrease oxidation of cell membrane fats. This benefit is especially important in our cardiovascular system since oxidation of fat (called lipid peroxidation) in the membranes of cells that line our blood vessels is a primary risk factor for clogging of the arteries (atherosclerosis) and other cardiovascular problems. Apples' strong antioxidant benefits are also related to their ability to lower risk of asthma in numerous studies, and their ability to lower risk of lung cancer. In addition to their unusual polyphenol composition, apples also provides us with about 8 milligrams of vitamin C. While that amount is not a lot, it's still important, especially since the recycling of vitamin C in our body depends on the presence of flavonoids and apples do an amazing job of providing us with those flavonoids.

http://www.whfoods.com/genpage.php?tname=foodspice&dbid=15

Hello Igbal,

Although I am not an expert in antioxidant activity and assay, I have benefited from the string of responses.

Regards.

thank you for the answer, its give me more knowledge about Apple peels..

The high content of phenolic compounds and antioxidant activity of apple peels indicates that they are valuable source of antioxidants and can impart health benefits when consumed.

The result showed total phenolic and flavonoid contents were quantitatively more in the peels, followed by the flesh-peel combination and then flesh.

http://www.phytojournal.com/vol3Issue1/Issue_may_2014/23.1.pdf