At first thought, it would be simple to keep foods cold in camp. However, the most obvious solutions are not always the ones used, and even those aren’t always used properly, so it is a good thing to give them some thought.
The idea that often comes to mind for most people is to use an ice chest or cooler. This is really a great idea, but they should be used properly and should be of the right kind. That is to say, those Styrofoam coolers may be great for a day out, but they aren't suitable for a camping trip. The coolers need to be the insulated sort, with a tight fitting or locking lid to keep the cold in.
It is also a good idea to have two ice chests, or more. One is used for the items that need to be kept the coldest, such as meats, while the other can be used for condiments and drinks. The second is more likely to be opened more often, so the temperature inside will usually be higher than in the other. Block ice is better for use than crushed ice, too, for either chest. The surface area is greater so it takes longer to melt.
A helpful tip is to uncap bottled water, pouring some of it out or drinking it, then freezing the rest, a few days before the camp trip. These can then be added to the secondary chest for additional cooling, and as the water melts, it gives ice-cold water that can be wonderful on hot days.
It is also helpful if the meat and similar foods put into the primary chest are frozen before they are put into the ice chest, as this helps keep the food cold longer. If everything in the ice chest is frozen, it all helps keep everything else frozen.
The ice chests should also be kept in the shade rather than in the sun, to keep them cold longer. It is also helpful to put blankets around them, when the blankets aren't being used for sleeping, as this adds additional insulation. This slows down the process of the interior heating up. Nighttime is cooler, so it doesn’t hurt a great deal to remove the blankets to use for sleeping.
In addition, light colored coolers are better than darker shades. The lighter colored ice chests don't pull quite as much heat. A red or green ice chest will heat up much faster than a white or silver colored one.
Note, though, that if the ice chests are kept in a sealed car, the interior of the vehicle can get very hot. If you are trying to keep food cold, it isn't a good idea to put the chests in a sealed car.
Another great idea is to have one or two water containers of the sort that have a spout, and to freeze the contents of these prior to the trip. This will work with tea and juice, as well as water, and the idea is that as the ice melts, it allows for cold refreshing drinks without the need to open the ice chests repeatedly.
Mentioned at the beginning, there are solutions that are often sadly ignored. Granted, the opportunities won't always exist, however it is surprising how many people who camp on the banks of mountain streams that don't even think about the icy cold water for keeping things cold. Milk, pop, and beer can be kept quite cold if tied off and put into the stream, and again, this lessens the number of time the ice chests are opened.
Some people even use the cloth drawstring bags sold for collecting dirty clothing when camping, for this purpose. Food, drinks, and condiments that should be kept cool but which don't necessarily need to be kept cold, can be put in the bag and the bag can be placed in the cold water.
A slightly less effective method involves dipping towels in water, and laying them over the ice chests, sopping wet. As the water evaporates, it cools the chests from the outside in. This is the general idea behind swamp coolers, in fact.
It isn't hard to keep food cold in camp, and the trick is to keep it as cold as possible, for as long as possible. Don't forget to use the opportunities presented by nature. The last is what most people most often miss.