I would suggest getting some help from somebody that has experience with the AC mains, they can quickly become fatal. You can hold off on this until you get things operating. You can experiment and run everything for debugging on 12V AC and be safe but use a 12V lamp for the food dehydrator, it won't run on 12V but you can see what is happening. This will allow you to learn all about zero cross and how to fire the triac in whatever quadrant you want. This response is to help you get started in solving your problem, not solve it for you.
Good Luck & Have Fun!
Gil