Scientific research offers different perspectives to the fruit – here’s how experts of biology, nutrition, history and theology approach the essence of an apple.
Plant biologist Harri Kokko studying the harvest in the Pellesmäki orchard. Photo: Raija Törrönen
Researcher Harri Kokko, Department of Environmental and Biological Sciences
What is the essence of an apple from a biologist’s point of view?
“From a biologist’s perspective, apples are like bred dogs: selections made by humans have steered them in a certain direction and to please their owners. Similarly, apple trees come in thousands of varieties that have been selected to please humans with the composition of their pulp – its sweetness, acidity and aromas –, as well as with their many different colours.
Thanks to evolution and selection, fruit in the Malus genus have evolved into apples that store not only carbohydrates and energy, but also seeds, which carry new life in their genes, and they are also capable of spreading. The purpose of apples is to spread their seeds to new sites where the surrounding conditions, nature or humans choose individuals that will grow up to become apple trees that will further spread their diverse genes.”
Why are apples of interest to a biologist?
“Researchers are presented with the challenge of cultivating and growing bigger and better varieties that give greater harvests and are more resistant to diseases and the climate. Much research has been conducted into the properties and genes of apples; after all, the global apple market is an over 100-billion-dollar industry. For a biologist, however, apples are just a product organism among many, and we study their growth while also considering the interaction of genes, diseases, pests and the environment.”
What kind of plant biology research addressing apples is conducted at the University of Eastern Finland?
“We have a broad range of expertise in plant biology, biotechnology and plant production. As an effort between us researchers and gardening enthusiasts, we maintain one of the world’s northernmost apple and pear orchards in Pellesmäki, Kuopio. This gene bank enables research, plant cultivation and experimentation in the changing climate of eastern Finland also in the future.”
An apple is a good addition to a meal, and a good snack. Photo: Raija Törrönen
Professor Marjukka Kolehmainen, Institute of Public Health and Clinical Nutrition
What is the essence of an apple from the viewpoint of a professor focusing on food and health?
“That is an interesting question because the viewpoints offered by nutrition are also broad, ranging from societal-level perspectives to the tiniest elements of human physiology. When thinking about nutrition, the first thing that comes to mind is the nutrient content of apples and its effects on humans. Apples belong to a food group that contains vegetables, fruit and berries, the daily intake of which should be at least 500 grams per day, according to the latest Finnish nutrition recommendations. We Finns could eat more foods from this category, as findings from the FINDIET study show that very few Finns meet this guideline.”
Why are apples an important source of human nutrition – and an interesting topic of research?
“Apples are nutrient-dense food, i.e., they contain very little energy and plenty of different nutrients and vitamins. They are also a good and tasty source of fibre, when eaten as part of diet. Compared to most berries, however, apples contain considerably less fibre and vitamin C. In addition to the ‘traditional’ nutrients, apples also contain bioactive compounds, the health effects of which are of great interest to researchers. Apples are especially rich in flavanols and flavonols, both of which are polyphenols. Some of these compounds may be absorbed from the small intestine and they make use of the transport mechanisms of glucose, thus possibly also contributing to post-prandial glucose metabolism.
Often, bioactive compounds are transported in the dietary fibre fraction of fruit – apples in our case – and they are attached to the apple fibre, i.e., the plant cell structure. Fibre is not absorbed from the small intestine but carried further to the large intestine where it is subjected to fermentation by microbes. Gut microbes use undigested components of food, that is, mainly fibre and compounds attached to fibre, in their own metabolism. Nowadays, gut microbiome-mediated health effects of food are a topic of huge research interest in nutrition.
Over the past few decades, we’ve come to understand the significance of the gut microbiome in mediating health effects, and it seems that these effects keep on extending to broader health effects and disease prevention. We’ve known for quite some time that vegetables, fruit and berries, thanks to being nutrient-dense and fibre-rich, are associated with a lower risk of cardiovascular disease, type 2 diabetes and some types of cancer, for example. Nowadays, we also know that some of this effect is mediated via gut microbial function both through effects on the microbial composition and through microbial metabolites. The fermentation of fibre in the gut produces short-chained fatty acids that can, for example, enhance glucose and lipid metabolism in people who have problems in them. Microbial quality and metabolites continue to affect the well-being of the gut wall, which is also of great importance in maintaining balanced metabolism and preventing problems in it.”
How is the University of Eastern Finland’s nutrition research related to berries and fruit?
“The University of Eastern Finland has a long history of research into the health effects of berries. In particular, this line of research deals with the positive effect of berries on post-prandial glucose metabolism, and with the effect of longer-term consumption of berries on low-grade inflammation. We have also studied, for example, how side streams of juice production, which are particularly rich in bioactive compounds, affect the composition and function of the gut microbiome. However, nutrition is not just about studying food, food components or physiological effects of nutrients. As I mentioned, we Finns could eat much more vegetables, fruit and berries, and only a small proportion of us eat the recommended amount. These perspectives are also important in research addressing eating behaviours: how could we nudge people towards eating more vegetables, fruit and berries as part of their diet, and how could we make it easier for people to choose these foods in the grocery store or at lunch, for example.”
The cultivation of apple trees gained wider popularity in Finland over the course of the 19th century. In the photo, an apple tree blooms in a park in Oulu. Photo: Wikimedia Commons
Professor Kimmo Katajala, Department of Geographical and Historical Studies
When and how did apples begin to be grown in Finland?
“Humans started to cultivate and use apples some 4,000 years ago by favouring wild apple trees that gave the biggest harvests. We know for sure that apples were cultivated and eaten as a delicacy in Ancient Greece. As the Roman Empire expanded, the cultivation of apple trees spread further north.
Scattered mentions of apples in Finland can be found in some sources from the 15th century, but by the 17th century at the latest, apples were grown in the gardens of clergy houses and official residencies. However, Finland’s cold winters posed a problem because apple trees, which were grown from seedlings imported from abroad, often did not survive many seasons before freezing to death in the harsh winter. During the Enlightenment in the 18th century, the cultivation of apple trees was promoted by selecting varieties that were better resistant to cold. Another way was to grow apple trees from seed: that way, they were thought to become more resistant to the Finnish climate. Stems grown from seed could then be grafted with varieties that produced better fruit. Clergy houses and mansions served as model orchards of sort, from where the cultivation of useful plants was sought to be spread among peasants in the surrounding rural areas.
However, it wasn’t until in the 19th and early 20th century that the cultivation of apple trees gained wider popularity among people. One institution to spread the word about growing berries and fruit was the primary school. Gardens were established in the yards of rural schools and schoolchildren would tend to the gardens, which were also used for teaching purposes. Fruit and berries from these gardens were also a healthy addition to school meals. Back then, apple tree seedlings were imported to Finland mainly from Germany and Russia. Many varieties that currently thrive in the Finnish climate can be traced back to the genome of these apple varieties. One of the oldest and probably the most famous is the variety Huvitus, which was cultivated already in the 19th century.”
Adam, Eve and the forbidden fruit are common themes in art history. The photo shows part of a Hendrik Goltzius painting from 1616. Photo: Wikimedia Commons
Professor Lauri Thurén, School of Theology
In the Christian tradition, an apple is often referred to as the forbidden fruit. Where does this symbolism come from?
“The most famous apple of the Bible isn't actually there. According to urban legend, evil entered the world when Adam and Eve took a bite of the forbidden apple (First Book of Moses, 3). The original text in Hebrew, however, only talks about a fruit. The legend was born when the text was translated into Latin, where the word malum means both evil and an apple. The letter a, however, is short in the former and long in the latter. The Bible only has seven mentions of an apple, especially in the Song of Songs where it is used as a metaphor of sexuality. If the vine is dried up, and the apple tree, surely the people’s joy is withered away (Joel 1:12).
According to another Christian urban legend, Martin Luther would have said:
‘If I knew that tomorrow was the end of the world, I would plant an apple tree today.’
In reality, the reformist precedes the idea by hundreds of years.”
Why is symbolism an interesting topic of theological research?
“Metaphors emerging from nature have always been central to Christian thinking, as well as to its original form, early Judaism. After man, a tree is the most mentioned living organism in the Bible.”
