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use features of both the C3 and C4 pathways, spread throughout most of the
range of values found for C3 and C4 plants.
The possibility of characterizing a plant by its C/ C ratio has lead to
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some interesting applications in food regulation relevant to forensic sci-
ence. 48,49 Most of the plants used in agriculture are C3 plants with two major
exceptions; corn and cane are C4 plants. Cane sugar and high-fructose corn
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syrup derived from these two plants are lower-priced sweeteners and C/ C
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analysis allows the detection of the illicit addition of these sweeteners to food
items such as orange, grape, apple juices, maple syrup, and honey. The
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carbohydrates in honey are normally derived from flowering plants which
are almost exclusively C3 plants. The distributions of d C values in honey, 50
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maple syrup, 51 apple, 52 grape, 51 and orange juices have been thoroughly
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studied. The delta C values of related food items are listed in Table 4.1. This
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isotope ratio information is a basis for the detection of cane sugar and high-
fructose corn syrup in honey; apple, orange, and lemon juices; candied
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pineapple and papaya; and maple syrup. 51
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Table 4.1 Carbon Isotope
Composition of Common Sugars,
Syrups, and Juices
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Item dd d d C (‰)
Sugar and Syrup
High-fructose corn syrup –9.5 to –10.7
Beet sugar –24.2
Maple syrup –23.5 to –24.3
Maple sugar –23.4
Sorghum syrup –12.0
Cane sugar –11.5

Fruit juice
Apricot –24.1
Concord grape –26.2
Cranberry –25.0
Grapefruit –25.3
Pineapple –12.5
Plum –25.0
Prune –26.0
Strawberry –24.3
Lemon –24.2

Source: Parker, P.L., The chemical basis of the use
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of C/ C ratios to detect the addition of sweeteners
to fruit juice concentrates, in Proc. Symp. Technol.
Probl. Fruit Juice Concentrates, Oregon State Uni-
versity, Portland, OR, 1981, p. 50.

© 2004 by CRC Press LLC