Demographic, economic and life-style changes in the U.S. during the past 20 years have significantly affected the structure of food distribution and marketing costs. The principal trend is a sharp increase in the consumption of convenience foods. This is reflected in rising expenditures for meals eaten away from home, frozen foods in supermarkets, and convenience stores that operate long hours in residential areas. Rising incomes enable consumers to pay the higher costs of convenience foods and ancillary appliances such as microwave ovens