I love the Internet! I begin with a research idea and frequently end up going in an entirely different direction. This morning, for instance, I was going to do some more research on the bioavailability of curcumin but came across a fascinating study (http://tinyurl.com/2fh26z) titled Effect of heat processing of spices on the concentrations of their bioactive principles: Turmeric (Curcuma longa), red pepper (Capsicum annuum) and black pepper (Piper nigrum). Researchers tested these spices using three different home cooking methods: in boiling water for 10 and 20 minutes, and in a pressure cooker for 10 minutes. The greatest loss of curcumin occurred in the pressure cooking process: 53 %. Good thing I don’t own a pressure cooker, I guess!
The spices were heated separately and also with tamarind powder, an acidulant, and red gram, a legume also known as pigeon pea. The losses were still significant, although the combination turmeric-tamarind reduced the pressure cooker loss to 34 %. I have been cooking with turmeric and red pepper for a long time. (Since taking curcumin with piperine capsules, though, I no longer add black pepper to my food.) I will now make sure that I don’t overcook these spices, but add them at the last minute. I certainly don’t want to lose too many of their beneficial properties.