If by "early modern" you're thinking of say the 1500s through 1800s, there were various methods of preserving food to eat on board ship. Salting and smoking meat (or just salting and drying it) is the obvious one, with salt cod being an enormous business in the late Middle Ages into the early modern period. English ships such as the one Raleigh took on his trip around the world would have been victualed with salt meat, flour or bread baked as hardtack, and dried vegetables, as well as beer (both for the alcohol and as a source of calories) and water. They would have re-victualed and re-watered several times along the journey, of course, knowing that fresh meat and vegetables would mitigate scurvy.

If you're interested in the end of the early modern period, I wrote this answer a few years ago that links to some other answers about victualing in the RN.

Salting, drying, smoking (which usually also involved drying and/or salting), pickling (with vinegar), fermentation (both alcohol -- beer and wine -- and anaerobic (sauerkraut)) storing fruit and vegetables on shelves places not touching until they rotted and were unusable, covering with a layer of fat (like confit), clamping (storing certain vegetables like potatoes, cabbage, carrots, turnips in pits underground or partly subterranean), sugaring (fruit "preserves").