Apple Delights Past And Future

exploring the secrets of old apple varieties

Have you ever tasted an apple and thought how dull it tasted or how little aroma it contained? Or how every apple available in the supermarket somehow looks, smells and tastes alike? Maybe you have never given a second thought to a specific type of apple on your shopping list. After reading on, you might be surprised by the diversity these little fruits have in offer! Reinette, Golden Pearmain, Berlepsch and Cox Orange are no exotic pet names. Those are apple varieties that have somehow been forgotten in recent times.

This article tells the old story of the apple’s ancestry and its long way to Europe. It recounts some of its turbulent changes in taste and nutritional value, and gives an outlook into some recent breeding developments.

A short history of apple cultivation

Presumed to have been the famous ‘forbidden fruit’ of the Garden of Eden, the apple has been depicted on many paintings illustrating the account of Adam and Eve from the Bible. Botanically, apples belong to the family of Rosacea, just the same as roses, pears, cherries and strawberries.

Malus domestica, Latin for the domesticated apple, has got several wild relatives occurring in nature, like Malus pumila or Malus communis. Plant scientists hold that the genetic ancestor of all the apples we eat today, Malus sieversii, grows in central Asia somewhere between China and Kazakhstan. There, it evolved for several million years within its mountain homeland, before it spread to other parts of the world. The history of apple cultivation presumably goes back 6000 years, when traders carried the apple from central Asia to Europe. (1)

Today, its general availability, affordable price and flavour make it the most often consumed fruit in the world. (2)

There are more than 70 000 varieties of apples, with over 20 000 cultivated varieties! So, if you’ve ever tasted anything different from Pink Lady, Gala or Elstar, you might have caught a glimpse of the exploding variety that exists among apples. While our modern apple cultivars are usually quite big, red, sweet and of round shape, their wild relatives are nothing alike. They can sometimes be found in the woods, bearing tiny, green, and extremely sour fruit.

Henry David Thoreau, an American poet and naturalist, insisted that he much preferred the wild apple (“of spirited flavour”) to the civilized versions. But even he admitted that the occasional bite was “sour enough to set a squirrel’s teeth on edge and make a jay scream.” (3)

From sour to sweet – why the acidity matters

Why were apples intended to be sour in nature? The answer lies in the chemical composition of apples. The substances responsible for their acidity are malic acid, phosphoric acid and ascorbic acid. Even the cultivated fruits are of an unpleasant acidity when they are not fully ripe. During the ripening process, the acidity steadily decreases, while the sweetness of the fruit increases. This acidity in the early stages of growth prevents wild animals from eating it, thus preventing the releasing of yet unripe seeds. (4)

The ratio between the acids and sugars contained in the growing fruit mainly determines the time of harvest. But even at the point of harvest, apples still contain a certain amount of acids. This time, they have another benefit. Acids are responsible for the conservation of the fruit during storage and transportation. Good storage quality was especially relevant during wintertime in the past, for a lack of other fresh fruits or refrigerators. Transportability is more important in nowadays’ globalized world. You can observe the same phenomenon of conservation through acids in the food industry. Many canned products, for instance, contain acids to maintain durability.

Why are today’s apples sweeter?

Though apple cultivars of the past were of course never as sour as their wild relatives, they still contained a healthy acidity to improve their storing traits. In times before fridges and storehouses, this was ever more important. It helped secure stocks of healthy fruits even during winter. While the sweetness of a fruit used to signal “edibility” to our ancestors, we have developed an overly sweet tooth in recent times. This was also helped by the emergence of cheap sugar production technologies in the 20th century, and so a change in “taste” occurred in the western societies. These developments called for sweeter fruit varieties as well.

Since plant breeders breed varieties that are consumed and accepted by the population, our supermarkets are now filled with sugary tasting apple varieties, depleted of much of their former taste and features. Along with this loss of taste diversity comes a loss of precious, healthy substances. Among these lost substances is the above-mentioned ascorbic acid. This acid is also known as vitamin C – an essential nutrient to humans that helps maintain the immune system, functions as an antioxidant and is involved in the repair of tissue, among others. Older apple varieties generally contain larger concentrations of vitamin C compared to modern breeds. (5)

Multi-talent Flavonoid

Another “lost” substance in modern apple cultivars are flavonoids. For humans, flavonoids have anti-inflammatory and anti-bacterial effects and help reduce the risk of cancer (6) and cardiovascular diseases. (7) In plants, flavonoids have the role of protecting plants from stresses, like drought, frost and UV-light, and are responsible for the colour and aroma of many fruits. (8) On the other hand, flavonoids also cause apples to turn brown after being cut and exposed to oxygen. (9) This is not much of a pleasant sight, is it? Since brown apple-juice, for instance, wouldn’t be quite as saleable and accepted by customers, plant-breeders have been breeding apple varieties with a lower flavonoid content. But that inevitably goes along with the compromise of apples being less healthy nowadays.

A change of perspective

Plant-breeders are constantly in a tug-of-war of interests: higher nutritional value of the plants and fruits they are breeding, or higher yield? Good storage qualities and transportability or appealing sweetness and colour of fruits? One has to bear in mind that breeding new varieties is a costly undertaking. The whole process until a new variety can be put on the market takes 10-15 years and is connected with many uncertainties. Ultimately, the varieties produced will have to be accepted by the wider public and the farmers.

From the perspective of the farmer setting up an apple plantation, he has to make sure that his produce can be sold throughout the whole 20-30 years his trees will bear fruit. In his decision on which varieties to choose for his plantation, he will have to consider the trees’ resistance to pests, their yield, their performance under stresses like drought or frost, the timing of the harvest, the quality of the fruits (whether destined for the juicing industry, baby foods or consumption) and their acceptance by those who will ultimately buy and consume them. For instance, fruits from older apple cultivars are often not of standard size (too small, too big…). What’s the use of fruits that nobody will buy in the end?

Flavour, Scent and Genetic Diversity

These are some reasons for which older apple cultivars have been pushed from the market. The modern varieties that have replaced them are regrettably of less nutritional and aromaleptic value. Along with this comes that many locally adapted cultivars have disappeared not only from the shelves in our supermarkets, but from our landscape as well. This narrowing variety deprives us of some excellent aroma and extraordinary beauty hidden in some of these gems! Can you tell how Reinette, Golden Pearmain, Berlepsch and Cox Orange taste, look and smell like?

But genetic diversity (i.e. the diversity of plant varieties cultivated, and the genes contained in them) is also important for breeding in general. Its basis is and remains the naturally occurring diversity of species and varieties. Plant-breeders of the future will want to breed cultivars that are robust and resistant to plant diseases (as many older cultivars still are), well-adapted to their local environment, as well as to a changing global climate. For this, they will have to use the existing genetic diversity.

Of the existing 20 000 apple varieties, only 4 cover 70% of the European market! (10) And most modern apple varieties have their genetic ancestry in just three cultivars (Golden Delicious, Cox Orange and Jonathan). This narrowing genetic diversity is a problem. To do something about it, we will need to look into the past, as well as into the future. Rediscover some old apple varieties, and you will realize that they are necessary for maintaining future breeding work, too. Only recently, Nature (one of the most prominent scientific journals) published an interesting paper on that topic. The research discusses the role of Malus sieversii, the domestic apple’s ancestor from Asia, in breeding apple varieties with a higher flavonoid content. (11) Australia’s agricultural department is also currently leading research into breeding flavonoid-rich apples again. (12)

Your part

But what can you do? Here are just some ideas. Visit the farmers market and try out some apple varieties you haven’t tasted, or even known they existed, before. (Note: you might have to get accustomed to the new, unfamiliar flavours you’ll encounter. Persevere until you find “your” variety! The richness and diversity of flavour won’t disappoint you.) Ask your local farmer which apple varieties he’s growing and what’s special about them. Look up some farms or associations that are dedicated to preserving old, local varieties. If you have a garden yourself, follow Martin Luther’s advice, who supposedly once said:

“If I knew that tomorrow was the end of the world, I would plant an apple tree today.”

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Sources:

(1) https://nmfruitgrowers.wordpress.com/2015/11/01/the-origins-of-the-apple/
(2) https://applesfromeurope.eu/apples/history-of-cultivation
(3) https://www.nationalgeographic.com/people-and-culture/food/the-plate/2014/07/22/history-of-apples/
(4) Chemie Oberstufe – Organische Chemie. 1. Auflage, Cornelsen-Verlag, Berlin 2010, ISBN 978-3-06-011177-0
(5) https://www.ph-heidelberg.de/fileadmin/ms-faecher/biologie/dokumente/apfel2016.pdf
(6) González CA et al. (2012). Dietary flavonoid and lignan intake and gastric adenocarcinoma risk in the European Prospective Investigation into Cancer and Nutrition (EPIC) study. American Journal of Clinical Nutrition. 96 (6): 1398–1408
(7) Higdon, J; Drake, V; Frei, B (March 2009). Non-Antioxidant Roles for Dietary Flavonoids: Reviewing the relevance to cancer and cardiovascular diseases. Nutraceuticals World. Rodman Media.
(8) Samanta, Das et al. Roles of flavonoids in Plants. International Journal of pharmaceutical science and technology 6 (2011)
(9) https://www.tagesspiegel.de/wissen/aha-warum-werden-angeschnittene-aepfel-braun/1164738.html
(10) https://www.vitamine.com/lebensmittel/apfel/
(11) Wang, N., Jiang, S., Zhang, Z. et al.Malus sieversii: the origin, flavonoid synthesis mechanism, and breeding of red-skinned and red-fleshed apples. Hortic Res5, 70 (2018) doi:10.1038/s41438-018-0084-4
(12) https://www.agric.wa.gov.au/pome-fruit/apples-and-flavonoids