Consumers and food makers looking to pack an antioxidant punch should plump for specific varieties of apples, say scientists, reports Lindsey Partos.
Apples, and especially apple peels, have been found to have a potent antioxidant activity (scavenges free radicals) that can inhibit the growth of cancer cells, with the antioxidant activity of one apple equivalent to about 1500 mg of vitamin C.
And recent animal and cell culture studies suggest there is an association between polyphenolic compounds found in apples and a wide variety of effects that may help prevent chronic disease. This supports the hypothesis that it is the phytochemicals found in fruits, especially apples, that impart healthy benefits.
Red Delicious, Northern Spy and Ida Red have more potent disease-fighting antioxidants reflected in higher levels of polyphenol activity, claim researchers at Agriculture and Agri-Food Canada that tested a variety of different species.
Polyphenols - phytochemicals that act like astringents - are major sources of antioxidants in apples, but which polyphenols are most active in the fruit has perplexed scientists.
Study leader Rong Tsao and colleagues used three different laboratory measures to evaluate polyphenol activity in apples that are popular in Canada: Red Delicious, McIntosh, Cortland, Northern Spy, Ida Red, Golden Delicious, Mutsu and Empire apples.
All of the apples used in the study were grown on the same farm under similar conditions.
They found that polyphenols were five times more prevalent in the skin than the flesh of the apples and that two polyphenols, epicatechin and procyanidin B2, were the greatest contributors to total antioxidant activity of the apples.
Procyanidins accounted for about 60 per cent of the antioxidant activity in the peel and 56 per cent in the flesh.
Red Delicious apples had two times more antioxidant activity than Empire apples, which had the least activity of any of the apples studied.
"When taste and texture do not matter, choosing an apple with a high proportion of polyphenols in the flesh and skin can potentially produce more health benefits," Tsao said, publishing the findings in the 29 June issue of the Journal of Agricultural and Food Chemistry.
This latest research joins a growing body of evidence to suggest populations looking to improve health should consume more apples.
Researchers at Cornell University in New York, for example, recently suggested apples could fight the neurodegenerative disease Alzheimer's disease.
In rats, quercetin - another potent antioxidant abundant in apples - appears to protect brain cells against oxidative stress, a tissue-damaging process associated with Alzheimer's.
Apples still remain one of the most popular fruits for European consumers that crunch their way through about 20 kilos of apples a year, about 1.5 apples a day, compared to the US counterpart who eats about 9 kilos a year, one every four days.
In terms of production, China has emerged in the last few years as the single largest processor of apples in the world.
Industry observers attribute the success of the Chinese sector to a huge apple crop that now exists there, which at some 20 million tonnes per annum dwarfs all other producers, and makes the Chinese apple sector around five times the size of the US industry and ten times bigger than the largest EU based producers, such as France and Italy.