Apples are one of Australia’s most popular fruits and are a good source of vitamin C, potassium and dietary fibre. They also contain bioactive phytochemicals. These are defined as a native non-nutrient component of plants which have health promoting or beneficial effects when consumed. In simpler terms, they are naturally occurring in the diet and may improve health, but are not essential for life and reproduction as are nutrients and vitamins.
One of the major categories for phytochemicals is polyphenols which have a significant number of subcategories including flavonoids. Apples are particularly rich in flavonoids which includes the sub-classes flavonols, flavones and flavanols.
Flavonoids occur naturally in many plant foods. They are often referred to as antioxidants, this and other activities are most likely responsible for their health benefits. There are more than 3000 naturally-occurring plant flavonoids, which may have varied health effects.
There is increasing evidence for their role in preventing major chronic diseases such as cardiovascular disease, cancers and type II diabetes.
Flavonoids in apples
Apples are often one of the most important food sources of flavonoids, not only because the concentration of flavonoids in apples but also because the amount of apples that are consumed in the average diet.
Flavonoid content not only varies widely between different food types but also between apple varieties as well as between different parts of an apple. Flavonoids in apples are concentrated in the peel, with higher levels generally found in darker, redder and bluer coloured apples.
Flavonoid content is affected by a number of external factors which must be understood and manage in order for apples to reach and maintain flavonoid levels. These factors include:
- Fruit maturity
- Exposure of fruit to sunlight
- Length and type of storage
Breeding high-flavonoid apples
DAFWA and UWA are leading research into breeding flavonoid-rich apples – healthier apples for the consumers. The national project is focussing on aspects of the breeding process and the market knowledge required to deliver a healthier apple to the consumer.