Grapefruit seed extract (GSE), also known as citrus seed extract, is a liquid extract derived from the seeds, pulp, and white membranes of grapefruit.[1] Self-made natural GSE processed in the laboratory without synthetic agents is prepared by grinding the grapefruit seed and juiceless pulp, then mixing with glycerin. Commercially available GSE sold to consumers are made from the seed, pulp, glycerin all blended together