Table l-Theobromine and caffeine levels in chocolate liquor Commercial chocolate products were analyzed for theobromine and caffeine content by High Performance Liquid Chromatography. Levels in 22 samples of chocolate liquor averaged 1.22% theobromine and 0.21% caffeine. Commercial cocoas contained, on the average, 1.89% theobromine and 0.21% caffeine. Sweet chocolate averaged 0.46% theobromine and 0.07% caffeine, while milk chocolate averaged 0.15% theobromine and 0.02% caffeine. Hot cocoa (chocolate) beverages averaged 65 mg of theobromine and 4 mg of caffeine per 5 ounce serving and chocolate milk prepared from a variety of cocoa-sugar mixes averaged 58 mg of theobromine and 5 mg of caffeine per 8 ounce serving. Theobromine and caffeine levels varied widely in individual samples within the product categories examined. Also, the ratio of theobromine to caffeine varied widely among different chocolate liquors ranging from a low of 2.5:1 to a high of 23.0: 1.
A method was developed for determining theobromine and caffeine in cocoa and chocolate products by high pressure liquid chromatography. After a simple hot water extraction, both theobromine and caffeine were separated by using a reverse phase Cl s column and a mobile phase of methanol-water-acetic acid (20+ 79+1). Theobromine and caffeine were quantitated at 280 nm; average recoveries were 98.7 and 95.0%; and coefficients of variation were 2.31 and 3.91%, respectively.
Samples of grated milk chocolate were equilibrated with moisture at increased humidity levels. In the first part of the study, the moisture content of the samples was determined by using the alternative OICC method, manual Karl Fischer titration, and azeotropic distillation. In the second part of the study, the AOAC official method (13.002), azeotropic distillation, and an automated Karl Fischer titration were used for the moisture determination. The results show that the Karl Fischer titration method is more accurate, more precise, and much faster than either of the official methods tested. The azeotropic distillation method gives results that are comparable with those obtained using the Karl Fischer titration method but it requires much more time.
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