This whole concept just doesn't make sense to me - this study included peanut butter and jelly as part of the "highly processed" meal and cheese as part of the "minimally processed" meal. I don't think that either peanut butter or jelly is more processed than cheese.

I suppose it's partly because it's the whole meal that is being represented and they match it for nutrients.

I'd guess they wanted to include store purchased bread, hence the pb&j.

The other thought i had was that most peanut butter includes (at least) palm oil (ultra processed) and sometimes other emulsifiers to prevent separation. Though you can buy pb that is just peanut and salt.

The jelly would contain quite a bit more in the way of preservatives, regulators and flavour enhancers etc than the jelly i'd make at home (if i did such a thing)

I'd guess it's just regular cheese which does require quite some processing to make but unless it's got extra additives to extend shelf life, change texture or taste it's just processed.