Golfer, Marmite gave birth to the saying in English culture ‘It’s Marmite. You either love it or hate it’. I do think it doesn’t have many fans in the CR, but for those who may have tasted it, they likely made the cardinal error of spreading it thick. Marmite, as a byproduct of the process of producing beer is real bona fide chometz.
Anyway, for many years in England, marmite made locally was not kosher and had to be imported from South Africa. That’s why one would have sold it, rather than burn it with the rest of the chometz.
Winnie, you’re absolutely right and thank you for clarifying the shaaloh. It should also be pointed out that some people sell any chometz, even a loaf of bread. Many people sell cosmetics which may contain chometz, as their status is doubtful.
LB, I hope we have clarified this subject which, as you can see, absolutely must be presented to a Rav who knows you.