using the generic entries that spark provides will be your best bet. if a company manages your cafeteria, check out their website [www.balancemindbodysoul.com/balance/campus
is sodexho's, they managed my college cafeteria] for info. do be mindful that these might be for more adult sized portions, so if you are being served children's portions you might want to enter it as 1/2 to 3/4 of a full sized portion depending. every place that serves kids that i have ever been has had a ton of charts on the walls with what a serving of food is and what should be served at each snack/meal and all you need to do is compare that to regular usda guidelines to see if they differ so that you can adjust the portion that you track it if they do.
so you might search
and use the generic entry. search
chicken noodle casserole
and use the generic entry.
and use the generic entry. or whatever it was that you were actually served.
so for the apple versus cocktail question you would have to find the portion size of fruit cocktail [likely half a cup], find the generic info for it [or better you find out what brand they use and get the actual info] the compare it to the info for the size of apple you have.
-google first. ask questions later.