The only way to keep products fresh when travelling or going for a walk is to store them in a special thermobag. What is a thermobag and how do you choose one?
How does a cooler bag sustain temperature?
Do you know how a flask of a regular thermos works? There is a thermo isolating frame, and inside there is a flask made of reflecting material. Cooler bags use the same principle.
It consists of thick walls that are filled with thermo isolating foam. The products stored inside are separated from the outside environment with a layer that doesn’t transport heat well, so the heat exchange takes a long time. And because of that the initial temperature is preserved much longer.
You can wrap hot food as an extra step; to keep low temperatures in the cooler, they place special cold accumulators inside, which help to preserve products longer.
But the speed of temperature changes is not stable. It depends on several factors. Those factors must be taken into consideration when you choose a cooler bag in the store.
The main criteria
A detailed overview of the best 10 bags can be found here. Let’s go over the main criteria.
The bigger the cooler bag, the longer it takes to change the temperature. But its dimension is defined by your personal needs.
If you are going to the picnic with a big company of friends, you can choose spacious cooler bags, while to preserve freshness of a few sandwiches, a mini sandwich holder or a lunch box will be sufficient for a student. The smallest cooler bag weighs just 300-400 grams and it can fit 2-3 sandwiches.
The number of cold accumulators depends on the amount of products. They usually come in a set with the bag but you can also purchase them separately.
Materials and design
As written on DiligentChef.com, you can find many kinds of thermo bags and thermo containers. It is easy to distinguish between them: the container is made of hard plastic while the bag is made of softer materials.
Container also preserves its shape; you can even sit on top of a thermo container. Cooler bags are softer; their shape is defined by the thickness of its walls and presence or absence of the frame.
The walls of containers are usually thicker and they help to preserve the temperature better. Thermo isolating properties of the bag depend on the thickness of the walls and the quality of a thermo isolating material.
Don’t waste your time buying bags with less than 0.8 cm walls. The preserve cold for only 2-3 hours, and that’s when the weather outside is not even that hot.
If you live in a hot region, your best option is to buy a cooler bag with thicker walls.
They believe that a thermal container with a nominal load and a recommended number of cold accumulators can maintain a temperature of 25 ° below that of the environment. The refrigerator bag provides a temperature of only 15 ° below that of the environment.
The outer layer of the bag is made of a strong synthetic fabric or film that is easy to wash and quick to dry. It is better if the material is water-repellent.
Interior layer must be made of foil paper material with reflective properties. Cooler bags with simple plastic or waterproof cloth doesn’t preserve cold as well even if there are cold accumulators. Interior layer must be waterproof. Places of joints – hermetic.
Pay attention to the presence or absence of fixtures on cold accumulators. It defines the easiness of use of a cooler bag.
Smaller bags must have convenient handles for carrying and a broad strap for a shoulder.
Bigger cooler bags may be made in a form of a backpack, which is very convenient during walking or hiking. The biggest and the most spacious cooler bags and thermo containers have a telescopic handle and they are placed on a frame with wheels – just like a modern suitcase.