Ah, the Brussels Sprout.
I always think that this poor tiny defenceless vegetable gets too much hate. True, it's not the most visually appealing vegetable, and it is not perhaps the best tasting. But it does seem to me that in this season of peace and goodwill, we should perhaps extend a small bit of kindness to this humble accompaniment to the Christmas dinner table.
I, like many others reading this blog, have probably eaten
and drunk far too much over the last few days and currently have no idea what
day it actually is. Food hasn't been too far from my mind and whilst hunting in
the fridge for some Christmas leftovers, I was surprised to see that for once,
Brussels Sprouts were not included in the remains of our Christmas feast. The
brain fog caused by food and drink means I'm currently incapable of proper
scientific thought and I found myself thinking about the Brussels Sprout. Where
did it come from? When -and why did we start eating it? Does it have much
nutritional value and why the hate?
So, a simple article this week: The story of the Brussels
Sprout!
The Brussels Sprout, as the name gives away, first were
cultivated in the 13th century near Brussels. They grow best at a
moderate temperature of 15 - 18 celsius, and during the 16th century, their
cultivation spread throughout cooler parts of Northern Europe. They eventually
made their way to Britain by the 17th century. It's unclear when they
made their way to the Americas, but it is known that they were grown in
Louisiana by French Settlers around the 1920s. One theory is that Thomas
Jefferson brought Brussel sprouts to America from France where he grew them in
his experimental garden.
They eventually made their way to Mexico; where the climate
allows for almost year round production. Mexico currently has the second
highest in export of Brussels Sprouts - second only to the Netherlands.
But the Brussels Sprout didn't always look how it does now. Brussels Sprout are only descendants of a type of plant called Brassica Oleracea. When uncultivated, Brassica oleracea is known as wild cabbage. This species originated from populations of plants in the Eastern Mediterranean. Its early days are still a bit of a mystery, but we do know that references to the plant date back to about the sixth century B.C.
Eventually, it was cultivated and gradually became an
important crop plant - giving us many vegetables we now know and eat. Cousins
of the Brussels sprout include Broccoli, cabbage, and kale. They are all
part of the Brassicaceae family, and all share the name Brassica
oleracea.
These vegetables are part of what we call 'cultivar groups'.
What these means is that seeds of the wild plant were taken up and grown in
cultivation - i.e. a garden or tended field giving us a cultivar. Over time,
those cultivating the plants noticed useful characteristics that some of the
plants had. For example, larger leaves or thick stems. Plants with these
characteristics would be selected and allowed to propagate - i.e. produce
offspring (Side note: it always used to confuse me how plants actually 'breed'
-I mean, it’s not exactly 'mobile'. So quick lesson in plant sex ed: plants are
able to produce clones of each other, but they do have sexual organs that have
gametes - or half of their genetic information. Pollen is basically plant sperm
whilst flowers are the ovary - I'm not making this up. So anyway, if a
mummy plant and a daddy plant are in love, a person comes along, takes the
pollen from one plant and deposits it on the flower of another plant, and a
beautiful new baby seedling comes along. Obviously, there's a bit more to it
than that but I'm not a botanist. Lesson over). These offspring would hopefully
have the useful characteristics and also be selected for breeding purposes.
Eventually, these characteristics would become overlarge and emphasized.
Each cultivar group would have originated from a different characteristic of
the original plant being selected and bred for.
One of these cultivar groups is the Gemmifera group- or the
bud producing groups. This is where sprouts and Brussels sprouts belong. It's
actually only the buds of the plant that we eat- the name Brussels Sprouts
refers to the entire plant. This group would have come along when botanists
selected plants that produced large buds along their thick upright stem. At
some point, someone realised that you could eat the buds, and in a move that
would be judged as controversial based on the amount of hate the sprouts get,
declared that it was actually pretty tasty.
Whether a sprout is tasty or not is a very contentious
point, with their taste profile being described as anything from bitter to
sweet to nutty to salty to disgusting to wonderful.
In the 1990s, it was discovered by Hans van Doorn that the
bitterness of the sprouts was caused by two chemicals: sinigrin and progoitrin.
Sinigrin is also found in mustard and is part of the Brussels sprouts defence
system. When the growing sprout is attacked by a hungry herbivore, Sinigrin is
broken down into allyl isothiocyanate - a pungent awful-tasting compound,
deterring the hungry herbivore. This effect is known as the mustard oil bomb.
Interestingly, sinigrin may also have anti-cancer and antibacterial properties
and is being investigated for use in tumor prevention. Progoitrin is also
involved in the Brussels sprout defence system and releases the bitter tasting
goitrin.
This discovery allowed for cross-breeding (back to mummy
plant and daddy plant) allowing for the production of Brussel sprouts with
lower levels of sinigrin and progoitrin, arguably improving the flavour.
Still, some people will still insist that Brussel sprouts
taste absolutely revolting even with the lower levels of these chemicals. The
answer to why this is the case may lie in human genetics. It possible that a
certain human gene TAS2R38 may be part of the reason some people really
hate Brussel Sprouts.
This gene, discovered in 2003, is involved in making a
protein involved in producing a taste receptor. These are different proteins
that are found on the surface of your tongue. How taste works is that some
molecules in food have shapes that are designed to lock into certain taste
receptors, sending off signals that tell you what you are tasting- for example,
something sweet, or something salty. In the case of TAS2R38, it's
involved in producing bitter taste receptors. TAS2R38 is not the only gene for
bitter taste receptors, but specific bitter taste receptor is produces is
designed to lock with a chemical called Phenylthiocarbamide. Bit of a mouthful
so it's usually just called PTC. PTC, as expected, tastes extremely bitter.
It's not usually in the human diet - but chemicals of a very similar structure
are found in Brussels sprouts.
Thing is, not everyone has a gene variant of TAS2R38 that
codes for a functioning version of this specific taste receptor. Some people
have a variant that doesn't work at all. This means that those lucky
people can't detect the taste of PTC, and can eat as many Brussel sprouts as
they want without them tasting bitter at al So if you don't like Brussel
sprouts, it may not be your fault -it may be your genetics!
Interesting fact. PTC was once used for paternity testing.
If a father can taste the PTC and his child could not, odds are that he wasn't
the biological father. This was all before genetic testing was actually
possible.
Also affecting the taste of a Brussels Sprout is whether
it's been exposed to a frost- they actually taste better if they have. Brussel
Sprouts produce their own antifreeze to prevent them freezing to death. They
release enzymes that break down their energy store-made up of starch, into
sugars. These sugars spread out within the plant tissue and lower the freezing
point- this means the frost isn't enough to freeze them. It's a bit like
scattering salt on a road. The sugars released make the buds taste sweeter and
balance out the sour or bitter chemicals. So, it makes scientific sense
that a sprout is better after a touch of frost. A bit of frostiness makes the
whole thing sweeter- could be a rule of life!
So now we have established why Brussel sprouts taste the way
they do, but we have to ask what benefit is there to actually eating them? I
mean, surely you would have to eat a whole plate of them to have much
nutritional benefit. And considering a load of us probably roast them into
caramelized oblivion with a load of butter and oil before we eat them, do they
give us any nutritional benefit at all and just become bad for us?
Well, Brussels sprouts are actually 'superfoods'. I'm not a
massive fan of that label but they are very good for you. They are low in
calories but high in fibre which is great for digestion - especially after the
fun of Christmas food and drinking. They also have high levels of Vitamin
C, which is needed for immune function and tissue repair, and Vitamin K which
is needed for bone health. Vitamins aside, they are high in antioxidants which
is really great for preventing damage to cells
They also have sulforaphane. This is a type of chemical that is the subject of anti-cancer research and has been for years. It may have some use in stopping tumours from proliferating and may also trigger apoptosis - or cell death. There's not much good clinical evidence at the moment suggesting eating Brussel sprouts reduces your cancer risk- but the research is ongoing. It has also been linked to antidiabetic and anti-obesity effects and therefore may be a good dietary supplement. So, we should definitely be eating them a bit more! They deserve a place at the dinner plate beyond Christmas day. A Brussels sprout should be for life and not just Christmas!
I hope that this article helps reduce the amount of hate that Brussel Sprouts receive and extends a little bit more appreciation towards these vegetables! In short, these are wonderful little veggies with a great story, a great nutritional profile. and a genetics-dependant great taste. In my house, Brussels sprouts are shredded and then fried with chestnuts and bacon until caramelized. Absolutely gorgeous!
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