Oh, kull wahad, I have thought about food way too much. Let's see here...
There's Basic, of Dumarest origin - and various forms that it can be delivered in (the ubiquitous vat with a spigot on a ship, but also squeeze tubes, "survival cups" - these last two tend to be flavored in various ways.
There's Cracker (a Hardtack-esque survival food) and Cake (kind of very dense pound cake) that show up in survival/disaster stores and as government dole. Cake comes in Red, Yellow, Berry, Coco, and Pumpkin Spice varieties. Tubes of Frosting are occasionally included (Standard, Mint, and Rum flavorings)
Aidlyte is a either a pre-sold beverage or a water additive that has various vitamins, plus electrolytes, that help against dehydration. Comes in a wide varieties of colors and flavors - Black Ice, Blue Lightning, Red Thunder, Purple Bomb, Sport Extreme, with Misjump and Babycare being slightly more tuned for specific situations.
Fleather ("Fruit Leather") are a popular snack, and if there is a fruit, there's almost certainly a Fleather for it.
Meatsticks (aka a Slim Jim) also remain popular, and come in a crazy numbers of flavors.
Nutella (in various nut flavors) is easy to find.
Scout Brew is an alcoholic drink derived from Basic, "distilled and fermented" basically as moonshine. I have a whole Library Data entry on the customs.
SPAM is around of course, in Spiced Ham, Peppered Beef, Seafood Chowder, Smoked Salmon, Barbecue Chicken, Cheesesteak, and both Pumpkin Spice and Clove and Rum as special Holiday flavors. Stukan is the Solomani version, and much less processed (Soylent Green jokes abound).
Sylean Brandy (and the higher proof Imperial version) is a product of the Sylean Cultural Region.
The Twinkie has survived as traditional Terran-inspired wedding/betrothal gift indicating wishes for a happy marriage and quick and easy pregnancy.
Vargr Take-Out is a very common street food that is basically kebabs, traditionally only meat and very, very rare but for other species that various versions with many different ingredients. Basically the only requirement is that you can put it on a stick.
Vegamite remains a standard spacer and survival food.
And Vilani Beer is out there, an acquired taste for non-Vilani.
D.