For Hong Kong's mandarins the oranges are strictly US

Who consumes more oranges than anyone else in the world -- the people of California or Florida?

The answer is neither. The unchallenged champion orange-eaters are the Hong Kong Chinese, who annually put away some 60 pounds per person.

Hong Kong citrus habits bring a $49-million-a-year glow to the cheeks of United States orange growers. The tiny British-administered territory, its 5.1 million population 98 percent Chinese, is the world's biggest single customer for American oranges.

Hong Kong is also the biggest buyer of American eggs, apples, melons, table grapes, celery, lettuce, and prepared animal feeds. Far and away the leading import, however, is cotton, of which Hong Kong bought 490,000 bales in 1980, producing $151 million for the United States. The total value of Hong Kong as an American customer in 1980 was $436 million.

One reason Hong Kong is such a big importer is that the 400-square-mile territory has a severe shortage of land suitable for growing fruits and vegetables, let alone raising sufficient farm stock. Virtually all daily foodstuffs originate elsewhere.

Most of this daily produce is brought in from China, especially pigs, chickens, eggs, vegetables, and fruit. It arrives daily because Hong Kong Chinese have traditionally believed in freshness and will have little to do with frozen, dried, or packaged food.

But this desire for freshness has increased the sales of American goods. US apples are popular because they are big and red and stay that way for reasonable periods of time. Most fruit and vegetables from China look good the first day and then wilt, not having been bred for extended shelf life. Sales of US apples jumped from $4 million in 1976 to $10 million in 1980.

Similarly the Chinese prefer crisp lettuce from California to the small, soggy Chinese variety.

In the last five years, the big boom in supermarkets and top-quality hotels in Hong Kong has been largely responsible for a soaring market in American grapes and melons, a market valued at up to $10 million last year. Hotels are also leading contenders for American vegetables and beef.

The ago-old Chinese prejudice against packaged food weakens in the presence of creamed sweet corn. Each year the Chinese buy about $500,000 worth of this canned product, all of it destined to form part of a favorite Chinese dish, crab and sweetcorn soup.