Tuesday's book: We Are What We Eat: ethnic food and the making of Americans

We Are What We Eat: ethnic food and the making of Americans by Donna R Gabaccia, Harvard University Press, pounds 16.5

One of the best bargains to be had in your local supermarket is the pack of four bagels from the New York Bagel Co, which come free with a tub of Kraft's Philadelphia Light Cheese. The reason for this largesse is that the latter spread on the former (sliced and toasted) is a mainstay of American cuisine. Obviously, it is Kraft's intention to develop a similar addiction over here.

In her blandly titled but fascinating guided tour of American foodstuffs, Donna Gabaccia admits that "no one knows who first slathered bagels with cream cheese - a product introduced by English Quakers in the Delaware Valley and Philadelphia in the 18th century". But the marriage has become so established that in 1984 Kraft purchased Lender's, a leading US bagel maker, as a "corporate companion" for its cheese.

Lender's has just been launched in the UK with a blast of advertising which stresses the product's authenticity and popularity. However, Gabaccia quotes the damning view of Nach Waxman, owner of a New York cookbook shop, that Lender's bagels have "no crust, no character, no nothing". Underlining this schism in the bagel biz, two Lender brothers refused to take the Kraft dollar and opened a suburban restaurant. It offers, according to Gabaccia, "a bagel of crust and character". She notes that the story of this Eastern European speciality highlights ways in which "the production, exchange, marketing and consumption of food have generated new identities for foods and eaters alike."

Gabaccia insists that food is one area where America has become, if not a melting pot, at least a communal salad bowl. After initial hesitation, colonial settlers avidly incorporated local ingredients in traditional dishes. Baking powder evolved from the Native American use of ash as a flavouring in cooking. Puritan housewives used local pumpkins for marmalade and pie-fillings.

She suggests that the spicy cuisine of the coastal Carolinas and Georgia, so sophisticated and complex compared to the stolid wholesomeness of New England and the Mid-West, originated with the African women who did almost all the cooking in elite southern households. And the lager-lout culture of contemporary Britain was paralleled in 19th-century New York where, one contemporary complained, "nothing was spoken of or drunk but LAGER".

Gabaccia pursues the oscillations of 20th-century taste from the bland mass-market fare of Middle America to the revived interest in ethnic cuisine, particularly in phosphorically powerful pepper sauces. Stressing the "extraordinary diversity" which runs in tandem with "homogeneous, processed, mass-produced foods," she insists that America is "not a multi- ethnic nation, but a nation of multi-ethnics".

It emerges that McDonald's euphonious "Fillet-o-Fish" was initially produced in response to ethnic demand in Cincinnati, where Catholic patrons headed for a fish outlet on Fridays. But a more cheering indication of ethnic influence on the American palate is salsa, which "dethroned ketchup as the king of American condiments in total sales in 1991".