Tuesday, 23 December 2014

Vacuum Flask Cooking

People use vacuum flasks because they are a highly versatile product.  The first person to use one, Sir James Dewar, wanted to keep oxygen and other gases in their liquid state, so he invented the vacuum flask.  The 20th century English train spotter wanted one to keep his hot tea in.  The 21st century East Asian cook wants one large enough to contain a cooking pan of freshly boiled stew in.  They all want something different.  But they all want a product that does the same thing: That maintains a fluid at a given temperature, be it freezing cold or piping hot, over a long period of time (12-24 hours).  The vacuum flask (or thermos bottle) is the product that meets those needs.  That element of versatility is something that we can all take advantage of whether we are scientists like Sir Dewar or not, because we all need to eat, and we all enjoy eating hot food. 

While the vacuum flask is useful to many people for many purposes, vacuum flask cooking is equally as useful to a wide variety of people, such as those who:
- Work in an office with no cooking facilities.
- Want to save money and not waste it on expensive lunches, snacks, coffee breaks etc (
UK lunch & snack budget = £7.81, USA lunch & snack budget = $18).
- Spend long periods of time commuting (e.g. 40 minute train journey) where food is prohibitively expensive.
- Live in accomodation with little-no cooking facilities (e.g. university student accomodation).
- Live off-grid (little or no electricity or gas, ergo energy used efficiently).
- Staying in a hotel room with little or no access to cooking facilities (i.e. just an electric kettle).
- Is hiking, or biking for the day and want to have a hot meal but doesn't have cooking equipment.
- Is camping and wants a container to keep hot water in (e.g. to boil up in the evening and use the following morning).

This article will cover a few areas on the topic of vacuum flask cooking, and the related topic of cooking rehydrated or 'just add hot water' foods that hope to show to the reader that his lunches may be warm, pleasant and cheap instead of cold, dreary and expensive.

Now we can get down to the proverbial meat and potatoes of this blog post, and explore some of the multitude of meals that can be cooked with the aide of hot water and a simple vacuum flask.  We'll start with savoury meals, then move on to desserts, and then to the drinks.
All of the meals given below require three items: A vacuum flask (350ml or larger); A bowl (~500ml capacity, to prepare & eat out of); A fork or spoon (to mix the food together and eat with).

Porridge is a generic term used for any cereal grain which has been soaked and cooked in water and/or milk.  Un-surprisingly different cultures use different cereals to make their porridge with, because cereals thrive in particular climates.  Oatmeal porridge predominates in Northern Europe, Buckwheat porridge (grechnevaya kasha) predominates in Eastern Europe, Maize/cornmeal porridge predominates in Central America, Rice porridge predominates in South East Asia, Millet porridge predominates in East Africa, Rye porridge predominates in Scandinavia, potato porridge predominates in Scandinavia & Russia, and so on.  The advantage of this for modern consumers, like thee and me, is that he has a plethora of porridges to pick from. 
Instant 'Just add hot water' versions are easy to find.
Homemade porridge is easy enough to make.  And as with most things in life, you can alter them to suit your fancy, i.e. add any kind of topping that you can think of: spices, sugars, syrups, sauces, chopped fruits, chopped nuts, jams, preserves etc; or combinations of the above.
Here are some online recipes:
Make your own homemade oatmeal packets 
http://www.theyummylife.com/Instant_Oatmeal_Packets (Lots of graphics, lots of bags, lots of charts, great for someone with OCD!)

An invention from our gastronomic friends in the Far East. 
China can lay claim to the oldest known noodles yet discovered (2000 BC), while Momofuku Ando recently (1958) invented Ramen noodles and instant noodles.  Both of which added to the global culinary cornucopia.
Instant noodles like Pot Noodle often come in their own container and just require hot water.
Bog-standard noodles cook easily inside a vacuum flask or a bowl with hot water.
Here are some online recipe ideas: 
Batchelors: Cup a Noodles (instant meal)

The Italians may have not been the first in the world to invent the noodle/pasta concept, but they certainly made it popular in the West.  There are plenty of pasta dishes knocking around to attest to it's perennial popularity with the public.

Instant pasta meals are like instant noodle meals: cheap and cheerful non-gormet food, often with a bad PR image.
Run-of-the-mill pasta cooks easily in a vacuum flask within 20 minutes.  Treat it the same way you would if you were cooking it in a pan on a hob.  As for ingredients, if you want to add vegetables then make sure they are finely chopped so that they cook quicker, or add some dry soy mince as suggested by this individual.
Here are some online recipe ideas: 
Batchelors: Cup a Pasta (instant meal)

Rice is to the East what Wheat is to the West: a key stone on which civilisation is built.  So why not make it a key stone on which your diet is built?

Instant rice meals that require hot water take ~90 seconds to cook and are available in supermarkets.
Ordinary rice (e.g. easy-cook rice) can also be cooked in a vacuum flask, but it doesn't seem to be worth it because: a) it takes ~120 minutes; b) you have the hassle of scraping it all out of the vacuum flask once it's cooked; c) because the vacuum flask is only part full with hot water it loses it's temperature quicker meaning that the rice is only luke warm when it's finally cooked.
Nevertheless other people have had success cooking rice in vacuum flasks where I have not, and you might have success aswell, so here are their recipes:
A youtube video of someone cooking rice in a thermos. 
Batchelors: Super Rice (instant meal)

Mashed Potato
Smash was a popular instant mashed potato brand back in the 1970s (in the UK) due in part to THIS quirky set of TV adverts.  While the strange aliens may have moved on to another part of the solar system the instant mashed potato has remained firmly on planet Earth.  (Wow... There's a sentence I think no one could ever conceive of.)
Instant mashed potato just requires hot water and a little butter/margarine.  It can be mixed with other ingredients, e.g. cooked meats, hotdog sausages, cheese, butter, mustard, spices, sauces etc, inside a bowl.
Here are some online recipes:
BBQ Chicken and instant mash' (campers instant meal)

Dehydrated soups have been in use since the Lewis & Clark expedition
back in 1804 (they were called 'portable soups'), and they're still popular today.  Although todays soups are packed out with MSG, sacharine and other not-so-goodies that Lewis & Clark didn't have to experience.  Nevertheless hunt around until you find some you like. 

Instant soups are ten-a-penny at any supermarket, and there's plenty of variety aswell.
Home-made soup can of course be cooked at home, poured and stored in a vacuum flask, and then eaten later that day.
Here are some online recipes for soups that cook in the vacuum flask:
Batchelors: Cup a Soup (instant meal)
Leek and Potato Soup (Recipe)

From modern day Eire to ancient Scythia, stews have been a popular dish.  Vacuum flask cooking is particularly compatable with the concept of stews, because stews require a low level of heat over a long period of time, and vacuum flasks contain heat over a long period of time.  It's a perfect match.  The only problem is that you'll need to cook the stew on a hob before transferring in it to a vacuum flask.  But that shouldn't take more than 15-20 minutes.

Instant stew meals can be purchased from hiking/outdoors shops, though they are somewhat expensive.
Home-made stews can easily be transported in vacuum flasks.  But go easy on the dumplings!  It's a right 'mare getting the stew out otherwise with those dumplings acting like a plug.

Rice and Vegetable Stew.

Instant Polenta
Like the label says, instant polenta!  THIS biker has it in his larder.

Other Meals
Anything that doesn't fit into the above categories (which is a lot!).  Just browse online using terms like 'just add hot water' or 'dehydrated meals' or 'vacuum flask cooking' and you'll find plenty of foods to satiate your every hunger, be it Santa Fe Breakfast Corn Pudding or Potato Somosas with Mango Chutney.

Dehydrated camping food from the UK and dehydrated camping food from the USA(quite expensive but a good variety, no idea on the quality).  As are MRE's (Meals Ready to Eat).  Rumour has it they can give you constipation.

There's a bunch of Youtube videos on Thermal cooking, albeit with a larger vacuum container, that you can find HERE.  It also has links to lost of other related videos on thermal/vacuum cooking.

HERE is a page to a graphic that has ten recipes on it.

If you thought that vacuum flask cooking was only about savoury foods then think again.  There are plenty of sweet hot treats lined up here to get your taste buds going.  Below are just two that spring to mind.

Instant Custard
The first batch of eggless custard powder was invented by scientist, inventor, family man and all round good egg (was that a bad pun or was that a bad pun?!) Alfred Bird back in 1837 for his wife who suffered from yeast and egg allergies.  While custard powder is cooked using a sugar & milk in a pan on a hob, instant custard powder can be made by just adding hot water.  If you've got hot custard then you can eat it with an otherwise cold muffin, sponge cake, brownie, mince pie, or other cake, not to mention sliced banana or other fruit, and that way make yourself a half-decent dessert.  Granted it's not gormet food but at least it's halfway warm and that's better than nout.

Rice Pudding
Porridge for pudding - that's basically what rice pudding is, porridge for dessert.

Rice Pudding Flakes are cheap and cheerful can be bought in many stores.  Just add hot water, powdered milk, mix it together for a few minutes and it's done.  Finally top it off with a dollop of jam, chocolate-fudge sauce, chopped dates or whatever floats your boat.

Use a vacuum flask instead of giving mega bucks to to Starbucks.  Use a vacuum flask instead of being a mug and paying for your cup of coffee.  Use a vacuum flask instead of saying "This coffee costa lotta" every time you visit Costa Coffee.  Use a vacuum flask instead of... well... you get the idea: Use a vacuum flask because it saves you money.

Tea, Coffee
Why go to a coffee franchise and pay £2.50 a cup when you can bring your own coffee with you and pay mere pennies?  In the USA office bods spend more muller on coffee than on travel.  But increasing numbers of people are changing their expensive coffee habits, opting to make their coffee at home and store it in a vacuum flask.

Instant coffee mixes are cheap and plentiful.  Many of them have milk-powder in them already, which saves you the bother of lugging your own milk (powdered or fresh) around. (Or you could mix up your own batch at home using powdered milk and coffee granules).  Tea bags are also sold which contain milk powder in them.  The question is whether you add the coffee granules to the hot water in the vacuum flask, or carry them around in a separate container.

Malted Drinks
Malted drinks, like Ovaltine and Horlicks, when you want a 'put me down' rather than a 'pick me up'.  Just add hot water, sugar and powdered milk and your good to snooze.

Warm Milk.
Powdered milk plus hot water equals hot milk.  Simple enough.
Instant powdered milk is easy enough to find.  Add whatever flavourings you want to it: vanilla, sugar, nutmeg etc.

Fruit Squash
Warm fruit drinks like Ribena are always popular with the kids when it's cold and wet.

Mulled Wine.
It's Christmas time, and what Christmas wouldn't be complete without a little mulled wine during a get-together.  All you need are mulled wine recipes.  You can find these on the internet or by reading any old-fashioned (i.e. pre-1940s) housewives cookbook.  If you're hosting a dinner with friends, family, or whomever then you can prepare some mulled wine first thing in the morning before the guests have arrived, and then bottle it straight away in the vacuum flask.  That way it's ready and waiting for you when the evening comes around and time is a premium and you can't waste it heating wine over the hob.  For reference a 1 litre flask provides eight 125ml portions/glasses/cups.

There we have it, a small selection of links to recipes and foodstuffs to get your culinary juices flowing and your grey matter buzzing.  It's a simple enough process: find some tasty dehydrated foods, and just add hot water.  Experiment, Eat, and Enjoy!

There are plenty out there to choose from.  The cheapest, in the UK, start off at about ~£5 for a 1 litre flask (glass or steel).  Thermos brand or other brand name vacuum flasks are un-surprisingly more expensive.  Once you've decided to buy a vacuum flask then it's the questions like 'Glass or Steel?', and 'Small Capacity or Large Capacity?'.

Glass or Steel?
Steel bottles are, IF they are well manufactured, more robust than glass ones, ergo are more useful for hikers who need robust equipment.  However if the vacuum flask is poorly manufactured and the vacuum springs a leak, then it's impossible to tell until you fill it with hot water and touch the outside of the flask (warm = no vacuum/broken).  You don't have this problem with glass vacuum flasks.  You can tell if a glass vacuum flask is intact or broken simply by looking at it and seeing if it has cracks or not.

This means that if you want to buy a steel flask then buy one from a store you can return it to if it is faulty or the vacuum breaks.  Buy glass vacuum flasks from second hand places (like car boot sales, flea markets, charity shops etc), because you can determine if the vacuum flask is broken by simply looking at the glass for cracks, something that you can't do with a steel flask.  I've bought three steel flasks second-hand over the past year (350ml, 500ml 1000ml), and two of them were duff.  Thankfully the Emmaus store that I bought one from gave me another secondhand replacement (it's identical to the one link two paragraphs previously) free of charge; it's working perfectly.

Small Capacity or Large Capacity?
Smaller flasks (<500ml) are a more convenient size (if you want to carry weight, and/or volume) but also lose heat faster than larger flasks (>1000ml) - about 15C over an 8 hour period (based on the some internet reviews).  You can look at the figures for yourself in the chart below.  By the way 60 C is apparantly the ideal temperature for a cup of tea

All of the flasks were tested in ambient/room temperature unless otherwise stated.  This is to ensure that all data is comparable.  The reviews didn't mention whether the flasks were pre-heated or not.

(n.b. I'll post the source links when I've got some spare time).

Vacuum Flask Capacity Material (T) Temperature  after (H) Hours
Thermos Active 1000 vacuum flask 1000 ml Steel T = 80 C H = 8
Thermos Thermax Ultralite flask 1000 ml Steel T = 85 C H = 8
Thermos Thermax Light and Compact 500 ml Steel T = 70 C H = 8
Wynnster vacuum flask 500 ml Steel T = 65 C H = 8
Lifeventure TIV vacuum flask 750 ml Steel T = 70 C H = 8
Stanley Food Flask 480 ml Steel T = 68 C H = 8
Coleman Vacuum Flask 1000 ml Steel T = 84 C H = 6
Stanley Classic Legendary Vacuum Bottle 1000 ml Steel T = 60 C H = 12
Vango (unheated garage) 750 ml Steel T = 75 C H = 5
Vango (unheated garage) 750 ml Steel T = 55 C H = 15
Lifeventure (unheated garage) 750 ml Steel T = 79 C H = 5
Lifeventure (unheated garage) 750 ml Steel T = 62 C H = 15



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