I remembered my auntie saying she never wanted eating patani that were slightly past its harvest maturity. Those with skin developing a brown to red map. She never wanted it because it tasted like poison. It made me wonder if she indeed tasted a real poison before.
Lima beans are harvested when pods are already plumb but still spongy soft when pressed. Those passing harvest maturity develops map like marking, color brown to red. The skin taste awful. However the beans could still be cooked by peeling off the skin.
It turned out the patani is really poisonous. It contains linamarin, a cyanogenic glucoside. There has been reports regarding lima bean poisoning. The beans should be cooked well to deactivate the poison. Half cooking is discouraged.
In addition, lima bean contains other anti-nutrient compounds. cyanide (the one I mentioned above), trypsin inhibitor, lectin, phytin and tannin. Soaking, autoclaving and toasting completely eliminated trypsin inhibitor and lectin, while significantly reduced the levels of phytin, tannin and cyanide. Autoclaving for 20 minutes was found to eliminate all the other anti-nutrients, but tannin. It has at least 23 proteins that may have allergenic potential.