Agar gels, can they be heated?

As we already know, agar-agar is a natural product extracted from red seaweed. In the food industry, it is used as a gelling agent, emulsifier, and thickener, and consumers can obtain it in the form of powder, flakes, or transparent sheets. 

This versatile ingredient has wide uses in the kitchen and allows us to modify the texture of our recipes without changing their smell, taste, or color. 

One of the most important properties of agar is its high hysteresis, the highest of all hydrocolloids. As we have mentioned before, hysteresis is the difference between the gelling temperature and the melting temperature of a gel. 

To dissolve agar, it is necessary to reach the boiling temperature, and once dissolved, the gel will form when the temperature drops below 40 degrees. Agar gels are thermoreversible, and this, combined with the significant advantage of agar’s high hysteresis, means that this gel can be heated while maintaining its solid consistency, melting again if it reaches 85-90°C, but not before. 

Therefore, unlike gelatin gels, agar gels can be plated hot. Thanks to this property, agar became part of high cuisine with Ferrán Adrià. The menu at El Bulli included for the first time in the late 90s one of its legendary dishes, “roquefort sorbet with hot apple gelatin,” taking advantage of this advantageous property.