What happened in the show: As I explained just before, Walter prepares ricin twice in the show, the first batch intended for Tuco but the attempt failed, and the second is used to kill Lydia Rodarte-Quayle. What we didnt mention though was that Walt made this deadly poison from beans. Yes, beans. Maybe not your average baked beans, but a seemingly harmless food stuff nonetheless. Could it really happen? It's very unlikely. Its true that ricin can be extracted from castor beans, but its by no means an easy process. Theres tonnes of ricin recipes online, detailing the stages from softening the outer coat of castor beans, through cooking, mashing, filtering and adding solvents to ultimately synthesise your very own ricin. It looks easy; you can do the entire process in your kitchen using glass jars and coffee filters they say, but its really not that simple. Pure ricin is highly dangerous, but the home-brewed form is not so pure as the methods to make it are crude. Its also likely that home brewing will degrade the activity of the ricin protein so even if you do manage to find a technique thatll increase your purity levels, its pretty likely that the protein will probably decay as youre making it anyway.
