Most commonly seen on ingredient lists as kelp or carageenan, seaweed helps bind a variety of ingredients together in addition to adding a boost of nutrients. Whether adding seaweed extract to a homemade ice cream recipe or for cosmetic or even outdoor uses, making your own extract offers an inexpensive alternative to buying it. Grab a few common kitchen items and some seaweed and cook up a pot of extract.

Things You'll Need

Fill the pot with water and bring to a rolling boil. Turn off the heat and let the water sit.

Cut the seaweed into ice cube sized pieces. Place one to two pieces in each zipper-sealed bag. Porphyra, used in sushi, or the green sea lettuce, ulva, are two of the more common types available. Seaweed classifications fall into red, brown or green types based on color. All of these groups have seaweeds used in commercial food production.

Add 2 tablespoons of hot water per piece of seaweed in each bag. For example, a bag with 2 pieces of seaweed would need 4 tablespoons of the hot water. If possible, have a helper hold the bag open to make it easier to spoon the water in. Squeeze out excess air and seal the bag tightly.

Place the bags in the pot of hot water. Remove excess water as necessary to ensure the bags are covered. Anchor them under water with a drinking glass, mug, or other object. Set a timer for 20 minutes.

Remove one bag from the pot and check to see if the seaweed has dissolved. If the water has changed color and rice-sized or smaller solid particles remain, remove the bags.

Line the wire mesh strainer with a double layer of cheesecloth. Place the strainer over the container for storing the extract. Carefully empty a bag into the strainer. Squeeze out as much of the dissolved seaweed as possible. Continue with the remaining bags without overfilling the strainer.

Allow the strainer to sit for the first 20 minutes. Then gently press with the back of a spoon. Do not force the solids through the cheesecloth. Only press to squeeze any remaining liquid out.

Seal the container and refrigerate until use.


  • Purchase seaweed from a grocery or health food store to make food grade extracts for use in homemade ice cream recipes, toothpastes and more.

  • Collect seaweed from beaches for garden use. Rinse gently with cold water to remove sand, salts and other debris. Once extracted, dilute with 5 parts water to one part extract and feed to vegetable plants and flowers.