Rode Bonheider

Beneficial nutrients, such as vitamin C,  in apples vary from variety to variety and this also applies to their phenol content as shown by a Belgium study reported in Pomologia, the magazine of the Nationale Boomgaardenstichting  Oct-Dec 2007. Howard Stringer has kindly translated the article, which we print below with the permission of the editor of Pomologia.

Phenols protect plants against diseases and predators. In humans they protect against cancer, heart and artery problems. The apple skin contains noticeably more of these secondary plant chemicals than the flesh. The phenol content also varies greatly with the variety. In the main it is higher in old varieties than modern ones.

A high phenol content can be detected by its flavour -  tannin compounds give an astringent bitter flavour. Varieties with high phenol content usually go brown rapidly when sliced open. The selection process in commercial breeding mostly gives rise to varieties low in phenols, because they have a sweeter taste and do not brown rapidly. Apples with a  high phenol content are especially health-giving, but  they are not released, because as judged by our modern sense of taste, they are rather astringent. In the long run it is the total amount of fruit eaten rather than the phenol content of 100 grams of  fruit which is important. For example,Gala contains a third the amount of phenols than the same weight of Belle de Boskoop, but for many children and adults it is more pleasant to eat Gala than the sour Belle de Boskoop.

About 10 different compounds are grouped under the name ‘secondary plant substances’ which comprise tannins, pigments, bitter tasting compounds, and acids. They act as the language of the plant, in that they control the plant’s defence mechanism:  tannins and  bitterness inducers regulate a plant's consumption or they control colouration of  fruit. In the case of humans, they remove body poisons  and protect from infection, cancer, furring up of the arteries, thrombosis and heart disease.

The most effective of these phenols are the flavonoids, which are red in colour. These are found in greatest abundance in red coloured vegetation, either in the flesh or skin: for example, black grapes,  red lettuce and red onions. Most plants show their phenolic content by their outward appearance. Apples have the highest content in the skin, it being 5-10 times that of the flesh. Red-fleshed apples contain more than 10 times that of the  non pigmented varieties. The old variety Belle de Boskoop has three times that of Gala, which shows that one must eat 3 Gala apples to 1 of Boskoop to gain the same amount of phenolic compounds.

The highest phenolic content was shown to be in the older varieties: the red Calville Rouge d'Automne, and the red flushed  Winter Calville, for example, and those listed in the table below.  Red Bonheider, pictured above,  with its bright red skin and transparent red flesh is reckoned to be one of the apples with the highest phenol content, as also is the Reinette Rouge Etoilé, another well known Belgium variety.


Total phenol content in 100g. fresh apples in mg. (Ljubljana 1998)