What is Agar agar?
Agar agar is a mixture of several different carbohydrates extracted from seaweed where as gelatine is a substance produced from animal protein.
The unusual and complex agar carbohydrates that form agar agar are extracted from gelidium species of Red Sea algae. Agar agar is also known by its Japanese name Kanten. In Indian cuisine agar agar is also known as “China grass” however this could be made from a combination of various other carbohydrates and not seaweed. Please read the ingredients list to ensure that you have purchased the correct product i.e. agar agar made from Red Sea algae.
Agar agar is suitable for vegans, vegetarians and is suitable for most religious diets where as gelatine is not as it’s made from animal protein, mainly pigs.
Agar agar is available in different forms: bars, flaked and powdered, and in the UK you are most likely to find it in the flaked or powdered forms. Natural agar agar is unflavoured, producing a firm clear jelly and is rich in iodine and trace minerals and has a mildly laxative properties as it’s consists of approximately 80% fibre.
The flakes are produced by a traditional method of cooking and pressing the sea algae and then freeze-drying the residue to form bars which are then flaked for easier packing and transport.
How does it work?
Agar agar has stronger setting properties than gelatine which requires refrigeration to set. A jelly made with agar agar will set at room temperature after about an hour. It is advisable to store agar jellies in the fridge as it is a high protein food.
Agar jellies will collapse if stirred, shaken or disturbed before they have set completely. My advice is to prepare the container for setting the jelly in advance. The container must be oil free and for some bizare reason agar agar does not set in the liquid form if it comes in contact with clingfilm. Therefore do not line the moulds with clingfilm and ensure it’s grease free.
Agar forms a gel at a lower concentration than gelatine. In practice you need less agar to set the same volume of liquid than gelatine.
Agar is opaque in colour and once dissolved sets into a jelly, it also has a more crumbly or flaky texture than gelatine jellies.
Just like gelatine the gelling ability of agar agar is affected by the acidity or alkalinity of the ingredients it is mixed with. More acidic foods, such as citrus fruits and strawberries, may require higher amounts of agar agar. Some ingredients will not set with it at all unless the enzymes in those fruits are broken down by cooking. The fruits are kiwi fruit, which are too acidic, pineapple, fresh figs, papaya, mango and peaches, which contain enzymes which break down the gelling ability. Chocolate and spinach also prevent agar agar from setting.
How to use agar agar
Like gelatine you must soak agar in cold water but then unlike gelatine you must boil the agar solution for 5 minutes to activate and completely dissolve the carbohydrates. Agar sets at around 38-40°C where as gelatine dissolves completely at 35°C. Agar jellies will become liquid again at 80°C – 90°C.
Ratios of Use:
- Use the ratio of 100ml of neutral liquid to 0.9g of powdered agar agar
- Use 1.3g of agar agar to 100ml of acidic liquid solutions
- You will need very accurate specialist scales to weigh agar correctly
Unlike gelatine, agar agar can be boiled and can even be re-melted if necessary. If you are unsure of the setting ability of your gel, test a small amount in a cold bowl it should set in 20-30 seconds, if not you may need more agar agar, if too firm add some more liquid.
Agar v Gelatine
Agar has a few advantages over gelatine. Many bacteria can digest and destroy gelatine and turn it into a liquid. Agar is more difficult to digest and only a very few bacteria can destroy agar carbohydrates.
The ideal temperature for bacteria growth is at 35 °C hence gelatine completely dissolves, agar only melts when it reaches 85°C.
So in short gelatine jellies melt in the mouth where as agar jellies do not and will remain chewy.