For a casual picnic in the city park, more or less any food can be brought. For wilderness backpacking and long outdoor life expeditions far from restaurants and supermarkets, and limited carrying space, travellers need to be more selective.
Packed food is either ready to eat, or prepared through outdoor cooking.
Outdoor shops offer food prepared and packaged for use on hikes and expeditions, at high markups. While food in supermarkets is usually cheaper, the preparation and packaging is rarely good for outdoor expeditions. They may also have some of the products found in outdoor shops, and some of their ordinary food is suitable on the trail as well.
Another option is to buy regular food for re-packaging and/or cooking at home, to make rations for individual need, size, and taste.
Some traditional preserved foods may also be seasonally available at farmer's markets or roadside stands directly from producers.
- Fresh food such as fruits and vegetables provide the best taste and nutrition but are bulky and perishable.
- Canned food is usually cheap, durable, and easy to prepare and serve. Metal and glass containers make up lot of dead weight, and should not be discarded in the wild. Good for driving expeditions, when baggage weight is less of an issue, and trash can be carried on.
- Dried food has been used since ancient times. Dried fruit is high in sugar and fibre. There are special drying equipment, suitable for those often drying food for the trail or for the winter, but an ordinary oven (low temperature, possibly half-open door) or drying lines (for thin enough pieces) can be used.
- Smoke treated food is another traditional option. Warm smoking makes the food just somewhat less perishable, while cold smoking can help quite a bit, but is more difficult at home.
- Fermented food, by various types of fermentation. Particularly lactic and acidic fermentation have millennia of tradition behind them, and produce foods that can be tasty in their own right and store better than their origin products. Unlike most other types of preservation, some types of fermentation actually increase the amount of certain vitamins. Sauerkraut, for instance, has a history of preventing scurvy on long seafaring expeditions.
- Freeze-dried food is a high-technology option for minimizing weight, associated with space flights and professional expeditions. A "low-tech" version of freeze drying has been practiced with potatoes in the Andean Highlands since before the first Europeans got there. The resulting product is usually lightweight and has a large or almost indefinite shelf life
- Military food rations are mass-produced for durability, light weight and nutrition. They may or may not be commonly or legally available to civilians.
- Biscuits and cookies contain fats and carbohydrates. Regular cookies might be brittle.
- Chocolate is high in calories and easy to consume, but melts and deteriorates in high temperatures (and taste is diminished by low temperatures).
- Nutrition bars are usually costly, but convenient, and with longer shelf life and more micronutrients than biscuits and chocolate.
- Pemmican is a high-energy dish invented by the indigenous people of North America, including meat, grease, and berries. It has been popular in polar expeditions.
- Powder milk is useful for cooking, baking, and for tea and coffee.
- Trail mix can contain granola, raisins, nuts, dried fruit and/or chocolate.
- Pasta (noodles) can be stored for years in dry conditions and needs nothing but saltwater and heat to be prepared into a high carbohydrate meal.
- Oatmeal can be stored for 2–3 years. It contains plenty of micronutrients, and can easily be boiled to porridge.
Water is needed for drinking, as well as making beverages such as coffee and tea. On foot, you can only carry a limited amount of water. There are various methods to make water drinkable, but they all have some drawbacks, be they the need for fuel, taste and health concerns or simply the time it takes to get water drinkable – and none will be 100 % safe to get rid of all possible contaminants.
Packing a few plastic bottles can spare you from buying bottled water, if you can get safe water from other sources (tap water, good wells, water boiled or filtered by yourself, what have you). And a bottle of your choosing is handy if you buy water or other drinkables in packages that cannot be closed once opened.
While alcoholic beverages can provide an experience of relaxation, community and celebration, they drain the body of heat and water, not to mention the impairment of being drunk.
Shelf life varies greatly between different foodstuffs. Properly stored industrial food generally remains good some time past the "best before" time that's stamped on the product, at least for products with a shelf life of several months – but their nutritional and culinary values do hardly increase with age.
Anything protected from air will become perishable once the protection is broken. Tins and other products that depend on a sealed envelope should not be consumed if they might be defective. Most products with a metal lid are packed hot, which means there should be negative pressure and a click when they are opened – if not, there has probably been microbiological activity. Bloated cans are a dead giveaway for Clostridium botulinum contamination, which produces one of the most lethal toxins known to man.
Many of the preservation methods rely critically on being performed the right way, such as drying a product fast enough, using absolutely clean cans, having the right amount of preservatives or keeping a product under the level of the preservation liquid. It is easy to invite Clostridium botulinum or other nastiness. Do not improvise unless you are sure about what you are doing. Also storing the product in the right way afterwards is important.
Some food prepared to store well does so only at cool or moderate temperatures (10–20°C, 40–50°F). While some signs of food being spoiled are immediately apparent to the unaided human eye or nose, there are some types of microbiological or other contamination that are not apparent to the naked eye. The best way to avoid those is to never store food for much longer or under vastly different conditions than it was intended to.
Most preservation methods, but particularly heating, destroy vitamins and other nutrients. Others greatly increase the sodium and/or sugar content. In short, fresh food is almost always preferable to food designed for large shelf lives.