Recipes and copyrights

Can recipes be copyrighted? If yes, at which point can a recipe be considered sufficiently changed, so that the original author can't sue? How does it work between the celebrity chefs? For example, I've seen comments in Delia Smith's Comlete Cookery Course, where she mentions that she has taken some recipes from other people.

Do you need to ask written permission? What if you take a recipe from the book of a chef, but change some ingredients, or even only some of the proportions of the ingredients, would that be OK to publish it in My Cook Book? And believe me, I've cooked some recipes from food "gurus" and boy were they crap. But sometimes, they are OK, just need something extra. Which I work out and make the dishes nice. So would that count as a different recipe?

I need to investigate this further. It's one thing to publish my Mum's and my own recipes, but if it'a my own personal take on someone elses recipe? Some are just happy with an acknowledge, but from a legal point of view, it's not that simple. Though I guess, the likelihood of getting sued would become a reality if I were actually making money on the recipes and at this point in time, I'm not.

Same goes if I've noted down a recipe from a TV show, particularly if it wasn't on the webpage of the show in question due to copyright reasons.

I have a recipe like that and I'm planning on trying it out tonight and I'd like to put it in My Cook Book. I'll change two ingredients - one because I don't what to buy it, since I think I have a good replacement for it already - the other because I couldn't find the actual ingredient in the supermarkets that I frequent.

That would be mainly Sainsbury's. I'm not trying to advertise for them, they certainly aren't paying me. But after 6 years in the UK, I've tried Waitrose (OK, but pricey), ASDA (feels a bit creepy, not sure why), Tesco (don't have many of the things I buy). Sainsbury's have the items I use in my everyday cooking. So there.