Carrageenan is one of the smaller marine algaes. It ranges in colour from purple, brown to yellow and grows in clusters on rocks or in pools on the lower shore, where foragers can pick it at low tide. Subtidal plants tend to be larger with thicker blades. Carrageenan has colloquial names and the spelling of these vary, so for safety, stick to the Latin Chrondus crispus. Carrageenan is the EU regulation spelling.If you buy it in a shop you have a choice between: Iota, Kappa and Lambda. A vendor selling plainly labelled "Carrageenan" or "Irish Moss Powder" is likely not to be the Iota variety because Chrodus crispus is said to be made up of kappa and lambda.Natural carrageenans occurring in iota, kappa and lambda are very difficult to separate and so, I have to suggest raising a question mark over standardisation, which will vary from mixture to mixture, depending on what the carrageenan is to be used for.
Fortunately I forage carrageenan and so, my life as a home cook should be much more straightforward, or is it? I often find that I need to use more carrageenan to encourage a dish to 'set' than on previous occasion and I can only think that this is down to variation within the species or perhaps, the time of year that I've gather the carrageenan. Who knows, I am not a scientist but I do cook with it on a regular basis.I live on an Outer Hebridean so carrageenan is readily available and definitely more accessible to me than leaf gelatine.My amateur advice is not to measure the dried grams, as cookery books direct didactically but to measure the cooked gel in tablespoons: Rehydrate foraged and dried carrageenan, put it in a pan, cover with water and then simmer for about 15 minutes. Strain the resulting thick, gelatinous gruel and have a good look at the gloop (which is rather clever and will, unlike gelatine, set at room temperature). The experienced cook will soon learn to work out the quantity of strained brown gel that is need to obtain a wobbly or solid set.
When dried, carrageenan shrinks to nothing and is extremely light.When a recipe calls for 25grams, it will make a large dent in your store cupboard supply.On occasions when I've cooked with fresh carrageenan, I've found that I needed to use significantly more to ensure a decent set.
Food scientists use carrageenan to thicken : e.g. in ice-cream and marshmallows, to emulsify i.e. to stop liquids separating in cheeses, to change food texture that is to make something chewy or to prevent sugar crystallising.Carrageenan used commercially has not one but two E numbers.
The home cook can use carrageenan in puddings, savoury mousses and as a thickener in stews, soups and gravies. In confectionery it has the benefit that unlike gelatine it is not of animal origin.I've made rather good fudge with it and something similar to Turkish Delight, which I flavoured with Rosa rugosa. Although deemed to be an invasive species the birds, butterflies and bees seem to like Rosa rugosa.
If the scented petals are picked on a sunny summer's day, brushed to free visiting insects and then, tightly packed in zipped freezer bags, they can be used in the kitchen at a later date. Opening the bag unleashes colourful, scented summer memories but a word of caution, less is often more from a culinary point of view.