Apple Research

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Mark Christensen was elected as recipient of the NZ Tree Crops Association annual prize for contribution to Tree Cropping for 2006, the Dr Don McKenzie Award. This honours Mark’s outstanding recent research relating apples and cancer prevention. Mark’s contribution is to have tested the old heritage apples using science’s most modern analytical tool. No apple industry group or medical research science unit did this: Tree Crops did this, and set the whole scientific community ablaze. Mark has been contributing Apple (anti-cancer) articles to the Tree Cropper for over 6 years. His articles are printed in national magazines, and attract international scientific cooperation, and give a high profile to NZTCA.

Mark’s search for “apples against cancer” on the internet threw up the Finnish study that established a link between flavonoid compounds, mostly found in apples and the reduced incidence of major human diseases. Finns who eat an apple a day have the lowest cancer incidence in the world. Dr Lieu at Cornell University, USA, was investigating procyanidins to fight cancer. He achieved 49% kill of cancer cells in bowel cancer in mice. In cooperation with Hort Research at Massey Mark supplied 59 varieties to be tested on their High Performance Liquid Chromatogram. The heritage apples had up to 4 times as much flavonoids and procyanidins as commercial apples. No two apple varieties are the same – all test with different levels of compounds. There is a strength in maintaining diversity of apple cultivars within the country.

New Zealand apple growers have been persuaded over many years to remove old varieties and replace them with supposedly superior modern varieties. From a health aspect, this advice has been wrong. The outstanding varieties identified by this research are all seedling or heritage varieties. This proves the vital importance of maintaining a diverse gene pool of material, in apples as with all plant material.

The latest analysis of 125 apples from apple collectors all over the country has shown up Fuero Rous, a French cider apple, with an even higher proportion of procyanidins, flavonoids, anthocyanins. The French medical research team at Straussbourg University are concentrating on anthocyanins (the red colour pigments). Mark has supplied Monty’s Surprise apples to Cornell University, to Straussbourg University and to the Finns. An unexpected outcome from the original research was identifying a unique substance in Russet apples which slows the body’s absorption of sugar. This makes them suitable for diabetics. Samples were supplied to Massey University for the Diabetic Unit to follow up. A little known French cider apple called Fuero Rous has tested with the highest levels of procyanidins in the skin and flesh. This specialist cider apple variety has tested even higher than Monty’s Surprise, although Monty’s Surprise still has the highest levels for an eating apple. Given the nature of cider making and the fact that these cider varieties are not palatable, it would be difficult to develop a better use of these apples than cider (or cider vinegar), where all the benefits of these nutritional and medicinal compounds can be captured in a liquid form that for all intents and purposes should have powerful anti-cancer properties.

Consistent findings on the very high levels of compounds in seedling apple varieties, appears to indicate that the rootstock may have a much greater effect on the phytochemical composition of apple fruit, than has previously been considered. The implication from this is that to grow a tree to achieve the maximum health benefits from its fruit, it should be grown on its own roots. (It is possible that budding or grafting low to the ground, onto a rootstock, and then moulding or replanting above the graft union, may achieve the desired result – once the roots are established from the grafted scion, but this will need to be confirmed with further research.) Another factor to consider is the age of the tree. As a tree gains great maturity, (for instance 80 to 100 years), it appears to exhibit greater levels of compounds. This may in fact be a gradual process as the tree ages. The research data indicates that specific trees that are very old, test with high levels of compounds. Thus apple trees should be allowed to grow to a great age – to realise their full potential – (having been planted on their own roots in the first place!) Mark’s budget this year for research is $54,000.00. There are another 500 apple varieties to test. Thanks to Mark’s enthusiasm, members all over NZ are keen to grow the heritage apples identified so far.

Comparison of Top New Zealand Apple Cultivars against Commercially Grown Cultivars

Total Phenolics (a large group of compounds that in apples include flavonoids and phenolic acids. Phenolics are known to have beneficial effects on human health, including protecting against heart disease.)

Chemical Analysis Data - New Zealand Apple Varieties