 Hi students, welcome to HSC Year 12 Chemistry and Module 5 Equilibrium and Acid Reactions. This is video number 18 and we're going to be looking at detoxifying foods. In the Year 11 course we had a little bit of a look at the detoxifying of foods that was carried out by the Aboriginal and Torres Strait Islander people of Australia over thousands of years. They had developed some very important chemical techniques that allowed them to perform a number of different strategies in order to make foods more edible and certainly safe for consumption. One particular example of this is the cycads. Cycad seeds can provide a number of different types of foodstuffs for Aboriginal people but in order for that to happen some very important chemicals need to be removed from the seeds, particularly the psychosin. This is a quite complex chemical, it's actually an interesting one for us to come and revisit once we've had a look at organic chemistry later in the course because all of these things should make a little bit more sense when we do that. I won't go into the structure for now except to say that you can see from the type of molecule that we have as complex as it is that we still have ions that can be produced in solution. One of the important things about understanding about equilibrium and how to manipulate an equilibrium is that it also means that if we have an understanding of things like closed and open systems we can try and continually push particular reactions that may reach an equilibrium to continue to react in such a way that we don't necessarily push them to completion but seek to do so.