I was surprised, recently, to find that beans could be Sous Vide cooked… So I looked into it and found that they are possibly best Sous Vide cooked. Here are some of my notes. I hope they are useful to someone. It would be good to hear other views.
A lot of this information is from “McGee on Food and Cooking” pp 486 – 488.
Flatulence is caused by two different indigestible carbohydrate groups which make it into the large intestine where the biom produces CO2 and Hydrogen.
Soy, Harricot and Lima are particularly high in these carbs. (I expect their close relatives Canellini and Flageolet may be similar in this).
The carbohydrate group found as cell wall cements produce the same amount of gas in the gut, but they exist in much higher quantities.
The first group of carbohydrates, is found in lesser quantities, is water soluble. So soaking beans and throwing away the water will reduce them to a degree. However this is at the cost of: soluble vitamins; minerals; simple sugars; seed coat pigments; flavour and antioxidants. (“High price”.) So beans are best cooked in just enough water for them to absorb and cook. This means the cook does not use vigorously boiling water as they might with vegetables. Putting beans into water on a rolling boil can damage seed coats and caust the bean to break down into a mush. So too does stirring the pot.
Slow cooking breaks both of these carbohydrate groups down into simple sugars. 180–200 deg. F / 80–93 deg. C works well.
Beans will absorb water more slowly at first if it is salted, but the bean is then seasoned throughout. It makes little difference to the overall cooking time. The beans will absorb the water. It is a myth that salting the water makes beans tough.
Cooking Water / Medium:
Hard water with high levels of Calcium and Magnesium soften the cell walls and can make the beans mushy, Whereas an acidic cooking medium reinforces the cell walls. Acidic mediums can slow or even prevent the beans from softening fully. Sugar re-enforces the cell walls and it slows the swelling of the starch granules. So tomatoes which have sugars and are acidic can actually preserve the bean structure during prolonged cooking – baked beans.
Soaking beans reduces the cooking time by 25% because the beans have re-hydrated and a lot of the cooking time is waiting for the beans to re-hydrate. Additionally the long cooking times can lead to the outer bean being overcooked and breaking down. Though soaking depends on temperature and pressure a rough guide at sea level is that beans absorb about ‘more than half of their total water capacity’ in the first two hours and they reach their original weight in 10 – 12 hours. Blanching the beans for 90 seconds in boiling water and then soaking them in cool water reduces the soaking time to 2-3 hours because the blanching rapidly hydrates the seed coat which controls the water absorption of the bean.
Salt and Baking Soda:
Both shorten cooking time when they are added to the soaking water. Salt at 1% reduced cooking time greatly. Baking Soda at 0.5% reduces the cooking time by 75%.
The alkalinity of the baking soda imparts a slippery mouthfeel and a soapy taste to the bean.
Salt reduces the swelling and gelation of the starch granules and this lesds to a mealy texture rather than a creamy one without the salt.
Persistently Hard Beans:
Some batches take much longer than usual to soften, or never do quite soften. This can be caused by high growing temperatures or low waterfall during growth. Thr coat on these beans becomes unusually water resistant. These beans a generally smaller than the usual ones and so they can be avoided. These are called ‘Hard Seed’.
‘Hard to cook beans’ might become so by long storage or storage in overly warm or humid conditions.
Douglas Baldwin gives the following times
1 Cup 250ml Beans
3 Cups 750ml Water
1 Tsp Salt (!)
Cook at 195 deg F / 90 deg C
Black Beans 3.5 – 4.5 Hr
Cranbery Beans 2.5 – 3.5 Hr
Chickpeas 5 – 6 Hr
Great Northern Beans 3 – 4 Hr
Navy Beans (Haricot) 3 – 4 Hr
Pinto Beans 4 – 5 Hr
Kate Williams recommended using canning jars instead of bags – This seems like a really good idea – Thanks Kate!
Be great to hear others views on this topic.