You’ll need to do a little prep work first: Cut the base and top flat, then carefully cut off the membrane (skin) and all pith (the white parts). Decide whether you’d like to freeze it whole or in segments; if whole, pop into a resealable freezer bag and freeze. If segments, divide by cutting between the membrane sections, then arrange the segments single layer on a tray lined with silicone or parchment and place in the freezer; when frozen, transfer segments to resealable freezer bags and immediately put back into the freezer. Always date and label frozen foods, grapefruit should keep frozen for up to 12 months, after which it won’t be as good in quality. It can be eaten frozen or thawed, but its texture won’t be as firm as when fresh.