Grapefruit seed extract, not to be confused with grape seed oil, is a by-product of the citrus industry. It is an all vegetable antioxidant used in the soap making process to extend the shelf life of lotions, creams, and superfatted soaps (made with more oil than can be converted to soap, to replace skin oil lost in the cleansing process with the nourishing oils selected for soap making).

Containing vitamin C and glycerin, grapefruit seed extract has proven to be antibacterial, antifungal, antimicrobial, antiparasitic, deodorizing, astringent, and antiseptic.

Hummingbird uses grapefruit seed extract as a natural preservative in all of its products.