MANY of us must have, at certain points in our lives, wondered why our fruits and vegetables have various colours.
Amongst the key reasons are to distinguish the quality, and also for some discerning consumers to really know what to look for.
Recently, a friend complained to me about the wrong colour of a ‘cempedak’ (sodt jackfruit, or Artocarpus integer) that was sold to him – the flesh was not yellow!
Normally, the sweet flesh of cempedak can be in colours other than yellow like red, white, orange and even a mild yellow tone, but we cannot determine this until we have cut the fruit open.
In the case of my friend, he said his grandson would only eat the yellow-flesh cempedak, just like the one that I had once given to him.
Well, colours can be the ‘make-it-or-break-it’ point for some people.
There was this lady customer who had specifically asked for a red dragonfruit with the pigment so intense that it could stain the lips.
Bananas are not always yellow – there are red and blue Java varieties.
Passionfruit occasionally comes with purple pulps and let us not forget, there are purple and red potatoes, too.
Watermelons with yellow flesh are also available in the market nowadays, and the same goes for rock melons.
Recently, I came across a pomelo with red pulps – different from the usual pink or white ones.
Truly, we have a colourful world of fruits and vegetables, just as vibrant as the colourful world of flowers.
Aspect of nutritional value
Have we ever wondered what nutritional value is attached to the colours of the external and internal content of a fruit?
According to many dietitians, the colour green is usually associated with ‘life, nature, growth, earth and energy’. The greens have antioxidant properties that can lower the risk of cancer. Today, it is very popular to consume a variety of fruits and vegetables that are green in colour. Some of the best vegetables are the dark green ones; avocado, as a fruit, has plenty of nutrients including vitamins B, C and E.
The red and yellow fruits and vegetables can protect us against excess sodium and cholesterol. These red natural foods protect our hearts through the antioxidants, which can reduce the risk of developing atherosclerosis, hypertension and high cholesterol level.
Examples of red vegetables are tomatoes, radishes and red chillies, while the red fruits include grapes, strawberries, watermelons and red apples.
The blue and purple-coloured ones help prevent heart disease, stroke and cancer. They are important for memory-reinforcement and they promote healthy ageing too.
The orange and yellow fruits and vegetables are able to protect the nervous system and also the eyes i.e. our sight. They help maintain skin health, boost our immune system and keep our bones strong.
White fruits and vegetables are known to be able to reduce the number of bad cholesterols and lower the risks of developing colon, prostate and breast cancers.
In short, we need and can benefit from these colourful foods, which contain many vitamins and antioxidants, but have very low calories.
The nutrients in these fruits and vegetables work together to protect us against developing cancer, heart diseases, vision loss, hypertension and other diseases.
The ‘appealing’ factor
Fresh fruits and vegetables come in an array of appealing colours from every section of the colour wheel. These colours – from red to green, purple to yellow – make the food more palatable and everything on the table brighter and more vibrant.
These different colours derive from varying plant pigments – each with its own nutritive value and specific health benefits. The deeper the colour, the more effective the nutrients are documented.
Many red tomatoes and berries are such because of the red pigments, either lycopene or anthocyanins. Lycopene is touted for its cancer-fighting properties, such as those fighting prostate cancer, while anthocyanins provide antioxidants that can guard us against heart damage and also colon cancer.
The orange and yellow-toned fruits and vegetables are coloured by plant pigments called carotenoids. Orange-coloured fruits and vegetables like carrots contain beta-carotene, which is converted to Vitamin A and known for maintaining visual health and mucous membranes.
Yellow fruits like most citrus varieties contain more vitamin C, with antioxidants and Vitamin B folate, while blue and purple fruits and vegetables have anthocyanins, which reduce free radicals.
Apart from having anti-inflammatory, anti-oxidising and anti-viral properties, anthocyanins can prevent age-related chronic diseases, cardiovascular diseases, cancers, as well as neuro-degenerative and eye-related diseases.
Chlorophyll colours the vegetables and fruits green, with lutein and folate; others contain cancer-fighting phytochemicals, namely sulforaphane and indoles.
Anthoxanthin, which is present in white-coloured fruits and vegetables, is known for the chemical ‘allicin’, which can lower cholesterol and blood pressure levels, as well as having anti-fungal, anti-bacterial and anti-viral properties. The white-coloured fruits and vegetables also contain high level of potassium.
Rhodophyta, found in sea vegetables, contains antioxidant and carrageenan for interferon in the immune system, which fights against shingles and cold sores.
The basic question of ‘what are colours’, has its answer in physics. Light – and thus, colour – is a type of electromagnetic radiation that is described by its wavelength, and the resulting frequency.
The visible spectrum is between the very long wavelength of the radio or microwave, and the very short wavelength of X-rays. The visible light has a wavelength of 380-750 nanometres (nm) in length, which we can see with our eyes. It is the wavelength that determine the colour.
The wavelength of 600nm is orange, 450nm is blue and 550nm, green. The sunlight is white as contains all wavelengths of all colours.
The secret of colour on and inside the fruits and vegetables – or anything else, for that matter – lies in reflection of the wavelengths not absorbed by the molecules of the materials.
The specific groups of molecules that give colour are the pigments. There are four families of plant pigments:
- Chlorophyll (green)
- Carotenoids (yellow, red, orange)
- Flavonoids, anthocyanins and canthaxanthins (red, blue, purple)
- Betalains (red, yellow, purple)
It seems that here, we are getting too scientific for the gardeners, but this is necessary to understand the colours of our fruits and vegetables.