The composition of the tomato is affected by the variety, state of ripeness, year, climactic growing conditions, light, temperature, soil, fertilization, and irrigation. Tomato total solids vary from 5 to 10%(Davies and Hobson 1981), with 6% being average. Approximately half of the solids are reducing sugars, with slightly more fructose than glucose. Sucrose concentration is unimportant in tomatoes and rarely exceeds 0.1%. A quarter of the total solids consist of citric, malic and dicarboxylic amino acids, lipids, and minerals. The remaining quarter, which can be separated as alcohol-insoluble solids, contains proteins, pectic substances, cellulose, and hemicellulose.

Tomatoes are mostly water (94%), a disadvantage when condensing the product to paste. They are a reasonably good source of vitamin C and A. In 1972 tomatoes provided 12.2% of the recommended daily allowance of vitamin C, and only oranges and potatoes contribute more to the American diet (Senti and Rizek 1975). Tomatoes provided 9.5% of the vitamin A, second only to carrots. When major fruit and vegetable crops were ranked on the basis of their content of 10 vitamins and minerals, the tomato occupied sixteenth place (Rick 1978). However, when the amount that is consumed is taken into consideration, the tomato places first in its nutritional contribution to the American diet. This is because the tomato is a popular food, added to a wide variety of soup, meat, and pasta dishes. The red carotenoid in tomatoes, lycopene, does not have any vitamin activity, but it may act as an antioxidant when consumed (Stahl and Sies 1992). A review of epidemiological studies found that evidence for tomato products was strongest for the prevention of prostate, lung, and stomach cancer, with