For smaller, 100-200 ton ships, I have been assuming a RV-style kitchenette: cooktop, oven, sink, and enough storage (some of it refrigerated) to hold food for a small crew for a couple of jumps (in case one of their stops does not offer food resupply). Judging by models available online, this would take up about half of a 1.5x1.5 meter square on ship deckplans, possibly a quarter square if the oven and cooktop can fold away when not in use.
I went and measured the stove which is presently in use in our kitchen, and determined that it is 30 inches by about 30 inches by 38 inches high, so about .75 meters by .75 meters by 1 meter. Basically, in occupies about one-quarter of a 1.5 by 1.5 meter square. That gives 4 burners, an oven, and the option of a griddle between the burners. Do not forget that you also have about 2 to 2.5 meters of space above the stove to work with, so you put a microwave there. There is storage for cups and dishes beneath the over. Next to the stove, you have your sink and drainer area, with a cabinet above it for dishware and cooking utensils. Below the sink is the kitchen cleaning supplies. That takes up another quarter of a deck plan square. Add some counter space for food preparation, a drawer for silverware and serving pieces along with cooking utensils, and some more cabinet space for dishes, pans, and some non-perishable foods in air-tight containers, and about another one-half of a deck square is used up. You have a lot of volume in a 200 dTon ship, and still plenty of room in a 100 dTon ship. You also have to think about passengers who would like decent meals in a 200 dTon trading ship. With that set-up, you can feed about 20 to 25 people adequately, based on the US Navy Manual,
Feeding in Flight,
If one of the PCs has Steward, that's who cooks most of the time. The rest of the meals are either packaged or simple fare. Costs are included in life support, and describing the styles of food available at each port helps immerse the players in the setting: a dusty, fully automated, rarely visited starport where bland but long-shelf-life nutriwafers are available from poorly-lit vending machines, is quite different from one attached to an agricultural world where farmers prepare lunch for small merchant ship crews to ply them into purchasing large cargoes.
I would not assume that all you would get at a rarely visited star port is long shelf live tasteless rations. More likely the arrival of a ship is a time for celebration and having a party, such as occurred when whaling ships in the 1800s arrived at an island that did not have a lot of ships visit. You might do better at a D-class star port than you would at an A-class star port.
"You want buy my corn? Only 300 per ton; where you go, sell for 550, easily. Fill your hold? I throw in 32 packed lunches for your crew, all 4 for 8 days in case jump goes long."
On one of my early cruises on the Royal Caribbean, I spent some time talking with the maitre de in charge of the Windjammer Restaurant who also was the assistant maitre de at our table for dinner. Once he realized that I was serious about finding out how the ship was supplied, we spent a couple of hours talking. The first rule was that the ship also sailed on a cruise of one week with two weeks of food onboard to cover against weather delays, with food used on a first in-first out basis. At certain ports, they would take aboard more fresh fruits on a contract basis. Assuming that every possible berth was occupied also gave them a bit of a cushion, as not all cabins had 4 people in them. Kids also helped to add a cushion because of the lower food consumption that adults, which is what the planning was based on. The bottom line is that you need to carry at least enough food for 2 jumps as a minimum for your crew, plus an allowance for passengers as well.
As for the 32 box lunches, that will supply a crew of four one meal for eight days, assuming that the crew is going to want to eat a box lunch that is at least 3 days old. You need 12 meals a day plus snacks for a crew of 4, assuming no passengers. However, you need passengers to make a 200 dTon Trader work financially. So add 3 meals plus snacks for every passenger that you carry, and the high passengers are going to want excellent quality meals.