Many are cordon bleu, a few are cordon blah, but the new comestibles coming to a grocery near you are all wonders of marketing, chemistry or overnight airfreight:

•Technicolor Taters: The beige age is over. The Yellow Finn potato tastes prebuttered, while certain purple and blue-skinned varieties—a few are lavender inside—pack intense flavor. Potato Madness, by esteemed cooking teacher Lydie Marshall, should stir interest in '91.

•Yes, We Have No Kiwanos: A New Zealand native, this homely, cantaloupe-size horned melon gets no raves for its lemon-cucumber taste but makes for amusing table conversation.

•Do the Jerk: The 300-year-old art of Jamaican jerk cooking—wrap marinated meat in foil (or fronds) and barbecue slowly—may catch fire in the U.S. Concocted from Scotch bonnet peppers, onions, garlic, cinnamon, thyme and tomato, jerk marinade is liquid reveille. Jamaica-born Atlantan Helen Willinsky will try to fan the flames with a Caribbean cookbook this summer.

•Nonfat Fats: Snack cakes have gone lite of late, but mayo, ice cream and cheese are chemically tougher to slenderìze. Nutra-Sweet's Simplesse, made of egg white or milk protein, and Olestra from Procter & Gamble, made of sugar and fatty acids, claim to mimic the texture of cream but await FDA approval. Olestra has become a carcinogen suspect, so don't hold your breath.

•Gourmet Water: By 1992, we'll each double our annual bottled water consumption to 12.4 gallons. Edison, N. J.'s Water Centre stocks over 100 kinds and runs a sensible, if not sensual, Water-of-the-Month Club ($349.95 per year for a six-pack).