Cocoa analysis

This experiment describes a quantitative analysis for caffeine, theobromine, and theophylline in tea, pain killers, and cocoa. Separations are accomplished by MEKC using a pH 8.25 borate-phosphate buffer with added SDS. A UV detector set to 214 nm is used to record the electropherogram. An internal standard of phenobarbital is included for quantitative work. 

The analysis of cocoa shell (7) is given in Table 4. In the United States, shells are often used as mulch or fertilizer for ornamental and edible plants, as animal feed, and as fuel for boilers. 

McLean, Virginia) completed a nutritional analysis from 1973 to 1976 of a wide variety of chocolate and cocoa products representative of those generally ... 

The analysis of the methylxanthines (caffeine, theobromine, and theophylline) is important in the areas of nutrition and clinical chemistry. These three compounds compose the majority of the alkaloids present in coffee, tea, cocoa, cola nuts, and guarana. 

Theobromine was determined by GC in various foods (bitter chocolate, milk chocolate, chocolate cake, cocoa powder, chocolate milk), and results are given in graphs and tables.27 Homogenized samples were boiled in alkaline aqueous media, then fat was extracted with n-hexane. The aqueous layer was acidified with diluted HC1 and NaCl was added. Theobromine was extracted from this treated aqueous solution with dichloromethane and the extract was evaporated to dryness. The residue was redissolved in dichloromethane containing an internal standard. GC analysis was performed on a column packed with 1% cyclohexane dimethanol succinate on Gaschrom Q, with FID. Average recoveries were 99 to 101%, coefficient of variation was less than 3% and the limit of detection for theobromine in foods was about 0.005%. 

HPLC allows a quantitative determination with relatively simple extractions. In many cases, extraction only involves a heating of the commodity with water, followed by filtration and injection onto an HPLC column. In the determination of caffeine, theobromine, and theophylline in cocoa, coffee, or tea, as well as in other foods, there is scarcely a month that passes without a new paper on this assay. Kreiser and Martin provide typical conditions for analysis.28 In their studies, samples were extracted in boiling water and filtered prior to injection onto the HPLC column. The HPLC conditions used a Bondapak reversed phase column and a mobile phase of water methanol acetic acid (74 25 1) with detection at 280 nm. This method is accurate, precise, and conserves time. It has also been adopted by the AOAC as an official method for the determination of theobromine and caffeine in cocoa beans and chocolate products.29... 

Horwitz, W., Ed., Cocoa bean and its products, HPLC method, in Official Methods of Analysis of AOAC, 13th ed., AOAC, Washington, D.C., 1980, p 382. 

Chocolate milk samples prepared from sweetened cocoa powders averaged 58 mg per serving of theobromine and 5 mg per serving of caffeine.28 Analysis of a "home-style" recipe resulted in higher methylxanthine values — 94 mg theobromine and 10 mg caffeine per serving. However, the authors noted that this recipe also had a stronger chocolate flavor. The lower values reported by Zoumas et al. and Blauch and Tarka compared to others was attributed to the inability of older methods to separate theobromine and caffeine, and the lack of precision and accuracy of the older methods. A compendium of theobromine and caffeine values reported for chocolate beverages from both published and unpublished studies has been compiled in Table 8. 

Meyers, E., Graham, A., Finnegan, E., Kreiser, W., Chocolate and cocoa products, in Encyclopedia of Industrial Chemical Analysis, vol 9, John Wiley Sons, New York, 1970, 534. 

Cocoa shell, analysis of roasted beans, 6 357t... 

AUTOMATIC ANALYSIS OF NMR SPECTRA 241 7.5. ASSEMBLE/CASE/SESAMI/COCOA... 

Whitacre, E. et al., Predictive analysis of cocoa procyanidins using near-infrared spectroscopy techniques, J. Food Scl, 68, 2618, 2003. 

KI Tomlins, DM Baker, IJ McDowell. HPLC method for the analysis of organic acids, sugars, and alcohol in extracts of fermenting cocoa beans. Chromatographia 29(11/12) 557-561, 1990. 

Hernandez and Rutledge (1994) investigated, by low resolution pulse NMR, the evolution of solid fat content (SFC) at 27.5 °C of cocoa masses of various geographical origin. The ANOVA analysis of a few quantitative parameters correlated with solid content and the speed of its transition from decomposition of fusion curves which indicated that the... 

Analysis and Sampling and the International Office of Cocoa and Chocolate were involved. The Protocol gives a series of 11 recommendations dealing with ... 

Quantitative data ranges for DKPs found in four cocoas are expressed in mg of DKP/Kg of fat free-cocoa as follovs c(Gly-Leu), 0-25 c(Gly-Pro), 2-7 c(Gly-Phe), 0-11 c(Ala-Gly), 0-12 c(Ala-Val), 56-143, c(Ala-Leu), 22-69 c(Ala-Pro), 19—44 c(Ala-Phe), 2-19 c(Leu-Pro), 39-115 and c(Phe-Pro), 0-26. Tovard the end of the study an eleventh DKP vas qualitatively identified in cocoa and shoved to be c(Val-Phe). Our results confirmed the DKPs found by previous authors (4, 17) except for c(Asp-Pro) and c(Asp-Phe) which were apparently not amenable to direct GC analysis. Tvo nev DKPs, c(Gly-Leu) and c(Ala-Leu) vere observed for the first time in cocoa. Cocoas contained similar kinds of DKPs, however quantitative differences suggested that DKP profiles obtained by HRGC might serve as a sensitive fingerprint technique. Also, dutched cocoas typically had lover levels of DKPs compared to ordinary processed cocoas. 

Linssen, J. P. H., Janssens, J. L. G. M., Reitsma, J. C. E., and Roozen, J. P. (1991). Sensory analysis of polystyrene packaging material taint in cocoa powder for drinks and chocolate flakes. Food Addit. Contam. 8(1), 1-7. 

All of the classical analytical techniques applied to oils analysis have been applied to studying the authenticity of cocoa butter and considerable attention has been paid to the issue of detecting and quantifying non-cocoa fats in mixtures with cocoa butter and as incorporated into chocolate. A substantial review of these methods has been published (Lipp and Anklam, 1998b). 

Much of the sterol component of shea butter is present as esters of cinnamic acid, which are less readily saponified than esters with glycerol (Peers, 1977) published data for this fat might therefore underestimate the hue value. Surprisingly measurement of cinnamic acid has not been used to test for the presence of shea butter in mixtures. Triterpene alcohols similar to those found in shea also occur in sal fat. Homberg and Bielefeld (1982) showed the presence of triterpene alcohols in illipe and sal fats and in commercial CBEs, and their analysis was proposed as a qualitative measure to detect cocoa butter adulteration. 

Reaction of shea triterpene alcohols with acetic anhydride and sulphuric acid to produce coloured products (Fitelson s reaction) was the basis of a sensitive early test for the presence of shea butter in cocoa butter (Fincke, 1975). Analysis of the triterpene fraction of a commercial cocoa butter by TLC fractionation followed by GC (Fincke, 1976), or argentation TLC followed by GC (Gegiou and Staphylakis, 1985), have been shown to have potential for detecting CBEs in chocolate based on the difference in levels of P-amyrin, butyrospermol and... 

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