Post Tagged with: "food"

What links self-heating drinks and the D-day landings?


The imposing cliffs of Pointe de Hoc overlook the Normandy beaches where Allied troops landed on June 6 1944. The assaults marked the beginning of the liberation of German-occupied Europe. And the cliff tops were the perfect spot for artillery pieces capable of devastating any troops who tried to attack the Omaha and Utah beachheads.

The Allied command knew this and so, to shore up the attack, the navy bombarded Pointe de Hoc. Afraid this might not be enough, they also had a backup plan. A team of US Rangers scaled the 30-metre cliffs and, after locating the weaponry, deployed grenades, destroying the guns. The key to success was the choice of thermite-based charges. Yup, just good old iron oxide and aluminium.

 

 

Ok, so what this got to do with self-heating cans?

Link number 1:  Some of the same troops who were landing on the Normandy beaches that day had self-heating soap cans.

These were essentially a stove and can rolled into one, with a tube of cordite (more typically used as the propellant in small arms ammunition) running through the centre of the can to act as fuel. The cans were quick and easy to use and could be lit with a cigarette, allowing troops to prepare a hot meal in under five minutes. Unfortunately, they also had a tendency to explode, showering the assembled squaddies with piping hot soup.

Self-heating cocoa. University of Cambridge

Since then, there have been numerous attempts to make self-heating cans into a mainstream product. Most relied on a rather less volatile reaction to provide the heat, although some have still struggled with explosive issues.  Calcium oxide heats up rapidly when mixed with water. But it’s not particularly efficient, producing about 60 calories of energy per gram of reactant.

The upshot is that, to heat the drink by 40℃, you need a heating element that takes up nearly half the packaging. That’s just about OK if you want a small drink on a warm day, but in the depths of winter, when you might really want a hot drink, you only end up with a tepid coffee.

More powerful cans

What’s needed is a much more efficient reaction. Something, like thermite perhaps? As crazy as packing a can with a reaction capable of disabling an artillery gun may seem, that’s just what HeatGenie is planning. Over the last ten years, the firm has filed numerous patents describing the use of thermite within self-heating cans. It turns out the reaction used by the US Rangers is still too hot to handle, so they’ve dialled things back a bit by replacing the rust with a less reactive but no less familiar material, silicon dioxide. So the latest generation of heated cans is fuelled on aluminium and ground-up glass.

When this reaction is triggered it still kicks out a whopping 200 calories per gram of reactant and can achieve 1,600℃. Given the troubled history of self-heating packaging, releasing this much energy from the can in your hand might be a bit of a concern, so several of HeatGenie’s patents cover safety issues.

These include a complex arrangement of “firewalls” that can block the so-called “flamefront” should things get too hot, and energy-absorbing “heatsinks” to ensure the heat is efficiently transmitted around the drink, as well as vents to let off any steam. With all that is place, the company claims just 10% of the packaging is taken up by the heating elements, which can still produce a warm coffee in two minutes (although the exact temperature hasn’t been revealed).

A US technology firm is hoping to make a very old idea finally work by launching self-heating drinks cans. HeatGenie recently received US$6m to bring its can design to market in 2018, . Yet the principles behind the technology go back much further – to 1897, when invented the first self-heating can. So how do these cans work, why has no one has managed to make them a success, and what’s HeatGenie’s new approach? To answer that, we have to go back to World War II.

The ConversationSo, well over a century on fromRussian engineer Yevgeny Fedorov first attempts to make self-heating cans and more than 15 years after Nestle abandoned a similar idea, has HeatGenie final cracked it? Judging from the patents and investments, the firm might have sorted out the technical side, but whether it really has a hot product on its hands is another thing entirely.

This article was originally published on The Conversation. Read the original article.

By June 22, 2018 2 comments general chemistry, science news

Halloween Chemistry: Cinder Toffee!



How about a spot of halloween chemistry? With nice simple explanations for the trick or treaters.

Cinder toffee!!

You’ll need:

  • Sugar
  • Golden syrup
  • A jam/jelly thermometer
  • Bicarbonate of soda
  • Grease proof paper
  • A baking tray
  • A saucepan

Safety:

The toffee mix gets very hot, be careful when handling in and make sure there’s an adult helping.


What to do:

1. Weigh out 100grams (3.5 oz) of sugar into the saucepan.
2. Add 3 tablespoons of syrup
3. Heat the mixture on a stove whilst stirring it.
4. Check the temperature of the mixture.
5. Carry on heating until it reaches 145-150oC (293-302).
6. Quickly stir in 1 teaspoon of bicarb. It will suddenly bubble up.
7. Now pour it into the baking tray, lined with grease proof paper.
8. Leave it to cool.

9. Break it all up (best done with a hammer) and enjoy!

What’s going on?
So that’s a nice simple recipe for a tasty treat but where is the science?

First off there’s the sugar and syrup. There are actually loads of different types of sugars, the stuff you put in your coffee and the granulated sugar used here is sucrose. It looks like this:

Sucrose
Golden syrup is a mixture of water, sucrose and two other sugars called fructose and glucose. They look like this:
Fructose
Glucose
Sucrose is actually made up of a fructose and glucose molecule that have been joined together.
So why do we need these three sugars to make the toffee? Well, when they are mixed all together they interfere with crystal formation. To explain how this works let’s represent each of the sugars with a different shape.
If we have one type of sugar then the molecules can pack together nice and neatly, like in the diagram. And that is exactly what happens in a crystal. But if you mix them all together they can’t form ordered patterns and so you don’t get crystals forming.
So if we tried to make the toffee with just one type of sugar then we’d end up with crystals forming which make for hard dense toffee (more like a boiled sweet). But by using 3 different sugars the crystals don’t form and instead you end up with a brittle, crunchy, glass like toffee.
Then there’s the bicarbonate of soda. You normally put this in cakes to make them rise. That’s because when you heat up the bicarb it turns to carbon dioxide gas (hence the bubbles in your cakes). The same thing happens here. When you spoon the bicarb into the hot sugar it almost instantly gets converted to carbon dioxide and causes the mixture to foam up.

Hope you enjoy the toffee and whilst you do you can find out more about the science of cinder toffer here.

By October 31, 2015 4 comments chemical education, entertainment, fun

It’s time science reclaimed health food from the quacks


 

IMG_0189I’m not quite sure what came over me, I’d set out in search of a beer and a burger. But somehow ended up in a juice bar wolfing down falafel, quaffing a cucumber, celery, ginger smoothie and sprinkling sweet potato chips with some strange pink salt.

And it was good. Really, really good. Tasty, satisfying and altogether wholesome.

Whilst I mopped up the last of the beetroot ketchup with my rye bread and slurped the dregs of the green juice, I flicked through the menu, idly wondering why the salt was pink. Tucked away on the back page I found the info I’d been looking for.

Apparently it was Himalayan pink salt.

What I read next pretty much ruined the whole dining experience.

Himalayan Pink Salt

This is a natural salt not like white table salt, which is a drug. Pink salt is extracted from the Himalayan mountains. It is negatively charged helping to draw positive ions out the body.

I sat paralysed. And wondered if this was due to my dinner having been laced with this strange substance that had removed all the ions essential for nerve impulses.

I regained enough movement to flick on my phone and Google the credentials of Himalayan salt. My panicked state subsided. For it is 98%, good old, sodium chloride, 2% polyhalite and a smidgen of rust (hence the pink tinge).

Once my composure had returned, I continued to flick through the menu. It was laced with plenty more pseudo-scientific claptrap.

IMG_5084IMG_5083

 

At this point I was starting to wonder if the place was run by Food babe. I rapidly made my exit and went in search of a stiff drink.

In the pub down the road, over a nice glass of single malt I got to thinking. The food, service and atmosphere in the juice bar had been great. Their products really were healthy. There was no need for the pseudo-science. Especially since genuine science about their ingredients is actually really interesting.

So I say to you Juice bar (and I will write to them) “Why not redraft your material with real science? I’ll even help you do it.”.

And if that doesn’t work, how about someone out there starts a health food cafe which doesn’t shy away from hard science, where real evidence prevails, where they tell you why the salt is pink, what chlorophyll actually does and how to eat a healthily diet. Wouldn’t such a place be more credible?

By April 18, 2015 7 comments opinion

Garlic Challenge, the results show!

Back in October I posed a question: Is there any truth in the old wives tale that rubbing your hands on stainless steel gets rid of garlic smells? Various theories as to how steel may achieve this were posited. But I wanted to know if there was a real effect in the first place. Kitchen chemists everywhere helped answer this by taking part in a stinky citizen science challenge. And the results are, well, interesting.

Garlic

I asked people to conduct a quick experiment whilst prepping dinner. The task was simply to rub the palms of their hands with garlic. Then treat one hand with a wipe from a stainless steel spoon and the other with a wooden spoon. Finally participants asked some other poor soul to take a sniff of their hands and report on whether there was a discernible difference.

Thanks to everyone who took up the garlic challenge (especially the person who did their experimenting whilst cooking Christmas dinner).

And so to the results.

These were collected via surveymonkey, with the question “Which hand smelt more of garlic?” and the answer choices a) The hand rubbed with the wooden spoon, b) The hand rubbed with the stainless steel spoon, c) Couldn’t tell the difference.

44 allium lovers responded. Of those 17 thought the hand treated with the wooden spoon smelt more garlicky, 6 said the stainless steel treated hand was the stinkier. So far, so good. Looks like the stainless steel effect might be real. But here’s the rub, there’s still the other 21 responses, none of whom could tell the difference between the smelly hands.

 

Screen Shot 2013-12-31 at 10.48.37

 

So we’ve got results that are significantly different from an even distribution between the options (the two-tailed P value equals 0.0163 ,according to a chi squared test) . However, the stainless steel treatment seems to be only about 38% effective, assuming the wooden spoon is a good negative control. But maybe the abrasive, absorbent wooden spoon is also quite good at removing garlic smells? In which case the effectiveness of the stainless steel is an underestimate.

Oh well, sorry people, but it looks like I can’t really offer a definitive answer. In hind sight I think the experimental design could have been better. A before and after spoon treatment sniff test would have been a good idea. And maybe a better negative control was in order.

Looks like another round of experiments  could be in order. Or can anyone offer a better way of analysing the data (I suspect sensitivity vs specificity analysis might be more appropriate)?

By December 31, 2013 5 comments fun