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Yesterday at 08:00 I had soaked white Chickpeas in water and left the container in the kitchen. Daytime temperature here is 44C.

At 20:00 the same day I saw the container covered by white froth. Is it normal for the Chickpeas to develop white froth or was it caused by the heat?

Not sure if that's edible.

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44 centigrade is about 111 Fahrenheit. (Posting this for reference, so that not every single Fahrenheit user has to look it up (or compute it).) –  msh210 May 25 '12 at 8:53
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Thanks for the effort @msh210. –  TheIndependentAquarius May 25 '12 at 8:54
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44 degrees and it is only spring? Bloody hell! –  Doug May 27 '12 at 5:42
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@Doug The month is May and it is NOT spring, it is "summer". The News Weather Forecast says that in June the temperature may get to 50C. That's BTW not the problem, the problem is that average people here do not have AC at home. One Cooler for the whole family - that too if the family is a middle class one. –  TheIndependentAquarius May 27 '12 at 6:12
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Good gravy, Anisha. I am NEVER visiting you at home. Why do you even bother with a stove? Just leave the food on the counter, it'll cook itself. –  FuzzyChef May 31 '12 at 4:32
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up vote 13 down vote accepted

Yes, it is normal for pulses to develop froth when soaked. I've seen it at lower temperatures and shorter soaking times. They can feel slimy too. This isn't a sign of bacteria development in itself. Chickpeas, as well as other legumes, contain lots of saponins. Saponins are a type of detergent, and they form a foam when dissolved in water. An example is found in Saponin content of food plants and some prepared foods by D. Fenwick and D. Oakenfull, published in Journal of the science of food and agriculture, vol. 34-2 (no free version available). Chickpeas, soy, lucerne, and other legumes all had significant amounts of saponin, 56 g/kg in the case of chickpeas.

Note that soaking dissolves also lots of other molecules contained in the beans. Some recommend to soak and throw out the soaking water in order to remove the oligosaccharides contained in most legumes, because bacteria breaking down these indigestible sugars produce gases as a side product, which is felt as bloating. McGee reminds us that this soaking also dissolves many of the micronutrients contained in the beans, and advices against the practice. If the beans are soaked (for shortening of cooking times), the soaked water should be used for cooking. If the eaters experience bloating, the beans should be cooked for a longer time, to give oligosaccharides time to break down under temperature.

This was about the general case, but now a note on your current situation. The conditions of your chickpea soaking were risky. Your chickpeas can have developed bacteria independently of the froth. In temperate regions, soakers aren't a problem, because bacteria growth in them is not especially quick (the 2 hours rule is made tight enough to cover things like meat, and a soaker doesn't even have enough hydrated bacteria food initially). But I have noticed that food I would have had no problem with at 22°C goes bad in short time at 28°C. The relationship between bacteria growth and temperature is not linear, and with growing heat, bacteria growth can speed up a lot. So I don't know if I would eat the peas - not because of the froth, but because of the conditions you had them in. I would recommend that you soak in the fridge next time - you don't need any fermentation to take place, so the low temperatures aren't a problem.

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Thanks for the confirmation, rumtscho. I thought the coldness of fridge may not allow the beans to get tender, that's why kept them out side? Besides, "I think it is caused by the oligosaccharides slowly dissolving in water " Is this good for health or harmful? –  TheIndependentAquarius May 25 '12 at 9:44
    
    
@AnishaKaul depends on your definition of "good for health". If you want to remove the oligosaccharides (because you get bloated), it is good that they get washed out of the chickpeas. But they are not harmful. As for tender, it is the length of soaking which helps, not the temperature. You need a minimal temperature while cooking of course, but you always reach it at a simmer. (Soaking is good for letting the water penetrate into the bean, cooking then gelatinizes starches and explodes cellulose cell walls - they work differently). –  rumtscho May 25 '12 at 10:08
    
Actually, after typing that comment I found that article and pointed it out. It answered my question. Thanks. –  TheIndependentAquarius May 25 '12 at 10:13
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@Laura good that you urged me to check, I was wrong. Oligosaccharides can feel a bit slimy, but they don't foam. Turns out that it was saponins - another class of chemicals which is rare in edible plants, but abundant in legumes. I updated the answer. –  rumtscho May 26 '12 at 21:53
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