(FORTUNE Magazine) – Batten down the breakfast table, there's an orange juice war brewing. Tropicana Products, owned by Seagram Co., and Coca-Cola Co.'s Minute Maid are digging in for a major battle. At stake: brand-bragging rights to the hotly competitive chilled orange juice market. Americans drink about a billion gallons of o.j. every year, but retail sales of frozen concentrate, which held 61% of the market in 1980, have been declining in favor of ready-to-serve chilled juice, which now has a 52% share and is growing. Tropicana, which Seagram bought from Beatrice Cos. last month for $1.2 billion, is the leader in chilled juice, while Minute Maid holds sway in frozen. Tropicana's Pure Premium is the only nationally marketed orange juice that is actually squeezed from oranges. (Alas, most orange juice is made not from oranges but from concentrate.) Pure Premium was introduced on the West Coast in January. It sells in California for around $3.40 a half gallon vs. about $2.40 for the stuff made from concentrate. Minute Maid is also working on a fresh-squeezed juice to be available later this year. Says Tom Pirko of Bevmark Inc., a Los Angeles-based management consulting firm: ''The temperature is going to turn to the boiling point, and then they're just going to bang away at each other.'' Into that caldron throw rising costs due to drought conditions in Brazil and stiff competition from groves of store and regional brands that sell at lower prices. Moreover, Procter & Gamble's Citrus Hill, though a distant third with 9% of the market, will hold down prices enough to vie for additional share. Tropicana, despite its momentum, may be vulnerable. Seagram paid an astronomical price for the juicer, and as a relative newcomer to the dairy section of the supermarket, the liquor company is still feeling its way around. But until Minute Maid does introduce its new juice, Tropicana has the field to itself. Meanwhile, price cutting has already started in some areas. In Los Angeles in early April, the price of Citrus Hill dropped to $1.49 a half gallon from $2.39, while Minute Maid went to $1.69 from $2.49; Tropicana held fast at $3.29.- W.E.S.