While the amount of solanine in tomatoes is relatively low, it is still enough to cause problems for cats. Even small amounts of solanine can be harmful to cats, so it is best to avoid feeding them any tomato products.
In addition to solanine, tomatoes also contain other compounds that can be harmful to cats, such as tomatine and lycopene. Tomatine is a toxic glycoalkaloid that can cause gastrointestinal problems in cats. Lycopene is a carotenoid that can give cats orange-colored urine.
For all of these reasons, it is best to avoid feeding cats any tomato products, even those that are labeled as "premium human grade." If you are not sure whether a cat food contains tomato products, you should always check the ingredient list before feeding it to your cat.