Ah, that first cup of coffee. The rich aroma of brewing beans rouses millions of Americans every morning.

But not if you're a kid. Most children don't appreciate the fine arom terminate composition a of hot java. Like many foods -- from beer to zucchini -- coffee seems to be a taste acquired later in life.

Now a group of Australian researchers has documented the changing preferences of kids. They find that the senses of taste and smell are intertwined, and kids' dietary likes and dislikes often change at a very certain time: puberty.

The researchers asked 300 Australian schoolboys in three age groups -- pre-puberty (ages 8 and 9), puberty (14) and postpuberty (16) -- to rate unmarked vials containing food odors.

Not surprisingly, everyone loved spearmint and chocolate. And few at any age could stomach odors of onion or boiled fish. But a few foods changed in appeal as the boys got older.

The smell of peanut butter, for example, rose steadily in popularity until age 14, the midpoint of puberty, then declined. And coffee turned into a veritable puberty test. It doubled in popularity between ages 8 and 16, perking to favor with two-thirds of the 16-year-olds from one-third of the 8-year-olds.

What is it about puberty that makes coffee smell better? Part of it could be a desire to be more adult. But the researchers suspect hormones are another cause of the change in scent perception. It's known, for example, that women's sensitivities to odors change as the level of the estrogen hormone shift during the menstrual cycle.