There's an idea in publishing of "reasonable usage". If you are writing a mystery novel and your gum-shoe detective loves to drive a 1969 Ford Mustang, you don't have to say FordTM MustangTM every time you mention it, and you don't have to write the Ford Corporation to get their permission to have their car in your story. It's accepted that a Ford Mustang is a common car and that mentioning it in a story is simply describing a normal type of life for that character.
The area you want to be careful is if you're focusing on a particular product and saying nasty things about it. If your entire story is about the Oprah show and you decide to cast the Oprah management in a very nasty light, describing all sorts of shady deals they do, you might get a call from the Oprah team's lawyers complaining about it. It's better, if you want to write a story that involves a very negative situation, to use fictional names. That way you are not maligning a real organization.
If you are writing a cookbook, there are many times that you have personal recommendations about what brand you feel works best for a recipe. It might be that a particular brand of soup, for example, has just the right combination of vegetables that other brands do not provide. What is best to do here is to have the recipe listed with a generic description - like "8oz can vegetable soup" - and then mention that you personally like the Campbell Light Soup. It's fine to make your own recommendations as you go - after all, your take on the recipe is why people are buying the book. It's generally wise not to mandate that they must buy "that one brand".
You want to avoid all impressions that you are somehow associated with the company you mention. You don't want to name your recipe "Hershey's Syrup Cookies" for example. You don't want to include the brand names in any of your promotions. They need to be incidental to the recipe, not the main focus.
If you include photos with brand names, it's good to include a line in your copyright page to indicate that the logos and designs shown in the image have a recognized copyright / trademark on them. You can do so by adding a line something like this -
"All trademarks and copyrighted items mentioned and shown in photos are the property of their respective owners. All photos were taken by Lisa Shea."
You might think this would be fairly obvious, but it's always good to cover all bases.
Here, for example, are the instructions from the "Ten Speed Press Cookbook Stylesheet" -
In general, brand names for ingredients and equipment should be avoided except in cases where no substitute exists. It's fine if an author wishes to occasionally tout one product that they find works particularly well in a dish (a certain kind of goat cheese they like), but the plug should be put in the headnote rather than the ingredients list. An exception to rule on brands: if the book is intended to be a beginner's guide to a topic (e.g., Bread Made Easy), it is acceptable to discuss brands and give modest endorsements. Capitalize trade names, but do not use the registered trademark or trademark symbols.
If you are heavily dealing with copyrighted content in your material, it would not hurt to touch base with a lawyer and get some assistance with your project, just to be sure.
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