Being lactose intolerant and going to the gym I looked for lactose free protein powder. Soy protein isolate seemed like a good option until I read something about the protein Trypsin Inhibitor (TI). Which soybeans have the highest content of of all legume. When reading up on this I discovered it isn't something that you want to be eating. Now I am far from an expert on this kind of topics and 2 days of reading papers has given me some information but I cannot get to a proper conclusion because I do not understand the half of it.
In this article https://onlinelibrary.wiley.com/doi/full/10.1111/1750-3841.13985 they test different methods on how to remove TI. Where cooking removes most of the TI. However, they also state that cooking above 80 degrees Celsius damages important nutrients.
https://link.springer.com/chapter/10.1007/978-1-4757-0022-0_20 In this article they say "In the processing of defatted soy flour to prepare a soy protein isolate, generally no heat treatment is used. Instead, a high percentage of the trypsin inhibitors (TI) is physically removed in the whey fraction. However, depending on their mode of preparation, soy isolates may contain trypsin inhibitor activity as high as 40% of that found in raw soybeans"
What do they mean with "whey fraction"? Does the commercial available soy protein isolate still contain trypsin inhibitor activity even if they have treated it in some way?
This article they show in the first diagram a simplified version of how soy protein is made and one of the last steps is cooking the product. This process also occurs for protein isolate as far as I understand. Horan, Frank E. “Soy Protein Products and Their Production.” Journal of the American Oil Chemists' Society, vol. 51, no. 1part1, 1974, p. 67., doi:10.1007/BF02542094. (This was available through my university online library tool)
To summaries: Does the process of making protein isolate contain any of the treatments needed to remove Trypsin Inhibitor mentioned in the first article? If yes, then did that not damage other nutrients within the product? How much of the TI is removed from the soy protein isolate in the process of making it?
Thanks for anyone that reads this and trying to figure this out as well. I also don't know if this is more a biology or chemistry topic...