17 May, 2011

Insulated cooking : hot bag me.

Today I received three HotBags from South Africa.
The HotBag Project promotes cooking with retained heat, with particular relevance to all food cooked with water (rice, porridge, potatoes, vegetables, soups, stews, dried beans, and even a whole chicken). Once brought to the boil on any stove, food actually continues to cook in this neat, insulated bag, thereby saving  time, trouble and electricity/gas.
The point being that in Africa where fuel for cooking is at a premium , the archaic haybox cooker is back.
Hay boxes are so called because hay or straw were the commonly used insulators. Pots of food would be brought to a boil and then placed in a box filled with hay or straw. Additional hay or straw would be added around and on top of the pot. Campers and hikers have used variations of hay boxes for years, heating their food in the morning and then storing the heated pot in a sleeping bag or backpack. In this way a hot meal is available for eating at the end of the day.
It seemed to me that this was a fascinating prospect because here at home we were seeking ways to reduce our electricity consumption (being poor)  despite my penchant to cook food -- curries, tagines and stews -- long and slow  in the oven at temperatures less than 160 degrees celsius.

I like cooking slow but cooking slow on top of a stove-top panders to burnt bottoms, or fretting about the prospect of one. But cooking slow in an oven will burn up a lot more electricity --and may still lead to burnt food.  Nor is it  very efficient to cook one dish -- such as  a casserole --  in a  cavernous oven.

In your cooking angst every time you open the oven to check on the cooking you let out a lot of heat. 

I looked at slow cookers -- and compared them with oven cooking -- and  the ruling isn't necessarily in their favour. They may be very useful for the worker coming home to a cooked meal after 8 hours away, but they are drawing from the mains every one of those hours.

Hot bags sell for under $20 and while retaining heat generated through an initial heat up, the meal will cook itself  over a space of  time not much longer  than you'd demand on the stove.

This means that the HotBag:
-  may save up to 75% of cooking fuel cost
-  but cooks in normal time
- food remains hot for 3-5 hours without burning or drying out
- food will not burn, boil dry or dry out in a HotBag
- food can be safely left cooking without supervision (avoid fire hazard)
- food tastes better and has a better texture (more moist)
- less nutrients are lost with HotBag cooking
- transportation is possible during the cooking process and afterwards (keeps food hot)
Some of my cooking preferences have required seemingly very low temperatures in pursuit of  a succulent repas. But it hasn't been easy to cook with confidence at these temperatures because few recipes cook that slow.

I use one cast iron Dutch Oven at home on top of and in the stove . It is my primary piece of hardware for most of what I cook. 

I'm de one pot man. That and one fry pan...My tools.I rarely boil up anything in water and I use a rice cooker for plain rice. So the supplementary option offered by these bags jells with what I'm after. 

My HotBags arrived with a few recipes  and tips but I suspect that HotBaggery has yet to register culinary significance and what is lacking is the HotBag/Retained Heat Cook Book . 

The much more expensive thermal vacuum pot  cookers (they're metal and high tech and overpriced -- eg: Thermos -- nothing under $AUD280) nonetheless have generated a cuisine presence  with adapted recipes (more recipes here) often developed within the caravanning and camping milieu. 

So that's the quest -- to HotBag my tucker where hotbaggery seems to fit.

Today's exercise (my first experiment) -- a crude ab hoc pork stew --  cooked  over three hours -- was an interesting mix of succulent meat and tender but not mushy or overcooked vegetables. The  texture of the vegetables  did not go to mush at all. I was very surprized. I did some finishing off on the stove top but I could have eaten the meal straight from the bag. 

Straight from the bag?  Generally, I gather, temperature falls inside the bag gradually after an initial sharp drop but the heat retention figures sponsor confidence:
 In one sample, using boiling water, after 5 hours in the HotBag, the temperature of the water had dropped from 93.3°C (simmering) to 54.4°C. The water was still scolding hot. After 12 hours (overnight) the temperature of the water had dropped to 38.4°C, which is luke- warm.
60 °C throughout the dish for 10 minutes is sufficient to kill most pathogens that may cause food poisoning or infection. It is then safe to continue to cook at lower temperature. Since the process begins with an initial cook up followed by significant retention of near those beginner temperatures the HotBag offers a lot of leeway -- so long as you follow a few simple protocols.
PostScript: Previously I had experimented with cob ovens and built one for domestic use. An Earth Oven or Cob Oven is a fairly primitive cooking device. It is a wood fired oven made from a mixture of mud or clay, sand and straw, which is what "cob" is. It is built to retain the heat from a fire built inside of it.An earth oven can be used to bake bread, cook pizzas, or slow cook stews, roasts, or anything you would cook in a conventional oven.(ref) But while cob ovens may have cult status among bread bakers, they are not the most efficient way to oven up as you first need to heat up the oven, then remove the fire  so that you can cook with the retained heat. Same principle as the HotBag but on a bigger scale and much more demanding of fuel/energy inputs.