Slow Cooking Pulses

Consumers should be aware that it is not safe to eat raw or undercooked kidney and soya beans as they contain harmful toxins. There is no need to avoid them as long as they are thoroughly cooked!

Red kidney beans: Incidents of food poisoning have been reported associated with the consumption of raw or undercooked red kidney beans. Symptoms may develop after eating only four raw beans and include nausea, vomiting and abdominal pain followed by diarrhoea. A naturally occurring haemaglutin is responsible for the illness, but can be destroyed by high temperature cooking, making the beans completely safe to eat. For this reason, kidney beans must not be sprouted. Kidney beans should be soaked for at least 8 hours in enough cold water to keep them covered. After soaking, drain and rinse the beans, discarding the soaking water. Put them into a pan with cold water to cover and bring to the boil. The beans must now boil for 10 minutes to destroy the toxin. After this the beans should be simmered until cooked (approximately 45-60 minutes) and they should have an even creamy texture throughout - if the centre is still hard and white, they require longer cooking.

Soya beans: Contain an anti-trypsin factor (or trypsin inhibitor) which prevents the assimilation of the amino acid methionine. Soya beans also require careful cooking to ensure destruction of this factor. They should be soaked for at least 12 hours, drained and rinsed then covered with fresh water and brought to the boil. Soya beans should be boiled for the first hour of cooking. They can then be simmered for the remaining 2-3 hours that it takes to cook them.

Soya flour should state heat treated on its packaging. Other soya products (e.g. tofu, tempeh, soya milk, soya sauces and miso) are quite safe to use. Soya beans can be sprouted, but the sprouts should be quickly blanched in boiling water to inactivate the trypsin inhibitor.

Pressure cooking: The temperatures achieved in pressure cooking are adequate to destroy both haemaglutins and the trypsin inhibitor. Pressure cooking also considerably reduces cooking times - kidney beans 10-20 minutes, soya beans 1 hour.

Canning: The temperature achieved in the canning process also renders pulses quite safe.

Slow cookers: Pulses must be soaked and boiled for 10 minutes before being added to a slow cooker, as they do not reach sufficiently high temperatures to destroy the toxins.

As beans and peas are all very similar nutritionally, with the exception of soya, they can be interchanged in most recipes if you want to experiment or have run out of one kind, as long as you take into account the different cooking times. If the beans are likely to need a lot longer to cook than the other ingredients, try pre-cooking them in a separate pan before adding to the other ingredients or using canned beans.

Article taken from http://www.vegsoc.org/info/pulses.html