According to Ad Age magazine, there has been a "melting away" of the middle market of food buyers. Food has become "a mark of our social status and it really has divided people more than ever," brand planner Nusara Chinnaphasaen told the magazine.

At one end are what SAI Marketing has defined as "food elites," who earn more than $100,000 and demand natural and handmade foods: artisan products with organic, ethical ingredients. At the other end are "food realists" who like familiar brands and who put price and convenience above all.

Of the fastest-growing food categories over the past decade, only two (pizza and pasta) even needed heating, according to NPD Group which follows food trends. The rest can simply be opened and eaten.

Food manufacturers are catering to this trend with new products such as Kellogg's "Eggo Wafflers" - flavored waffle bars that are marketed with the tag line "No fork, plate or syrup needed!"

And J&J Snack Foods have created "Tater Stuffers" which roll together hash brown potatoes, eggs, green peppers and onions into a hand-held fast food.

To try and cope with the fragmenting market, manufacturers are also creating different versions of the same food.

Campbell Soup, for example, sells its microwaveable Go Soup brand in exotic flavours such as Moroccan Style Chicken with Chickpeas.

Other companies are trying to hedge their bets, describing food as "natural" - but not organic, which consumers associate with being expensive, and brewing giant MillerCoors has launched a division to focus on craft beers, which now make up almost a tenth of the beer market.

Top foods in 1959:
1. Baked goods and baking supplies 16%
2. Prepared beverages (coffee, tea etc) 13%
3. Cereals, flour, macaroni 13%
4. Dairy 9%
5. Confectionery 6%
6. Spreads, relishes, jams and preserves 4%

Top foods in 2011:
1. Confectionery 14%
2. Dairy 11%
3. Cereal 10%
4. Carbonated beverages 8%
5. Bakery goods 7%
6. Chips, nuts, popcorn and snacks 6%

Source: Ad Age (note: does not include alcohol)