Chocolate evaluation

Jordan, Stroud, assisted by K. E. Langwell, Chocolate Evaluation, New York, Applied Sugar... 

Cocoa beans are sometimes evaluated in the laboratory to distinguish and characterize flavors. Beans are roasted at a standardized temperature for a specific period of time, shelled, usually by hand, and ground or heated slightly to obtain chocolate Hquor. The Hquor s taste is evaluated by a panel of... 

This chapter has compiled and evaluated information on the methylxanthine composition of cocoa and various chocolate foods and beverages, as well as the consumption pattern for these commodities. Cacao is the major natural source of the xanthine base theobromine. Small amounts of caffeine are present in the bean along with trace amounts of theophylline. Numerous factors, including varietal type and fermentation process, influence the methylxanthine content of beans. 

Roozen, J.R and Legger-Huysman, A. 1994. Sensory analysis and oral vapour gas chromatography of chocolate flakes. In Aroma. Perception, Formation, Evaluation (M. Rothe and H.-P. Kruse, eds) pp.627-632. Eigenverlag Deutsches Institut fur Ernaehrungsforschung, Potsdam-Rehbruecke. 

Evaluating odor and flavor taints is frequently done with water, fatty food simulants (oil, chocolate, unsalted butter), hydrophilic powders (sugar, cornflour), or combined hydrophilic-hydrophobic matrices (milk or cream, biscuits) (Kilcast, 2003). The Robinson test often is used to evaluate materials for tainting potential. This test places the test material in a sealed container separated from the food simulant or test food at a relative humidity between 53% and 75%. After about 48 h, the test food is evaluated for taint compared to a control, using a discrimination method (Lord, 2003). Chocolate is frequently used as the food simulant for this test. Intensity of the taint may be evaluated using a... 

Fincke, A. (1982) Possibilities and limits of gas chromatographic triglyceride analyses for detection of extraneous fats in cocoa butter and chocolate fats. IV. Evaluation of gas chromatographic triglyceride analyses of milk chocolate fats. Deut. Lebensm.-Rundsch., 78(11), 389-396. 

A. Sepe, S. Constantini, L. Ciaralli, M. Ciprotti, R. Giordano, Evaluation of aluminium concentrations in samples of chocolate and beverages by electrothermal atomic absorption spectrometry, Food Addit. Contam., 18 (2001), 788-796. 

In cases that do not resolve or become worse, in the absence of overt signs of orbital involvement, laboratory evaluation should include a complete blood coimt with differential as well as blood cultures. Cultmes often show positive growth in children under the age of 4 years (usually streptococci) but are rarely positive in older children or adults. In patients with skin lesions, specimens should be obtained for culture onto blood, chocolate, and... 

Sophisticated analytical methodologies play a major role in unfolding the mysteries of speciality fats in chocolate. Recent harmonization of European Union law for speciality fats in chocolates will demand newer sources of exotics to be evaluated to fulfill future requirements. 

Figure 4. Antioxidant capacity and lipid oxidation in plasma of volunteers consuming different amounts of procyanidin-rich dark chocolate (6.9 mg of procyanidins per g of chocolate). Antioxidant capacity was evaluated by the ability of plasma to inhibit luminol-dependent chemiluminescence and lipid oxidation by plasma TEARS. Plasma epicatechin concentrations are the average amount of epicatechin determined two hours after chocolate consumption. Ordinate values indicate increases over basal levels of plasma antioxidant capacity (white bars), or decrease over basal values for TEARS (gray bars).

The new European Chocolate Directive [14] allows the addition of up to 5% of vegetable fats other than cocoa butter (CB), the so-called cocoa butter equivalents (CBEs), in chocolate. CBEs resemble the chemical composition and physical properties of CB very closely, making them therefore extremely difficult to quantify and even in some cases to detect (especially at very low levels). There is a perceived need within official control laboratories for reliable analytical methods for the quantification (around the 5% level) of CBEs in chocolate, as Member States laws and administrative provisions need to comply with the new Chocolate Directive before August 2003. All proposed analytical methods have been evaluated by the JRC in collaboration with EU expert laboratories [15]. The performance of several methods has been compared and a final method based on the analysis of the main components, triglycerides, has been proposed for further validation. 

Schnermann, P, Schieberle, P. Evaluation of key odorants in milk chocolate and cocoa mass by aroma extract dilution analysis. J. Agric. Food Chem. 1997,45, 867-872. 

Depending on the food matrix, multiplex DNA can show some discrepancies in the detection of different allergenic targets, due to differential efficiency of the amplification process. This issue has been shown in the case of the determination of the hazelnut allergen isoforms Cor a 1.03 and Cor a 1.04 in some matrices, including dark chocolate, soy milk, lecithin supplement, and snack muesli (Bettazzi et al., 2008). For this reason, multiplex assays must be evaluated carefully during and after development, to reduce inconsistent results. 

In 1993, two external interlaboratory studies were conducted using commercially available peanutkits. In North America, three kits (BIOKITS, Ridascreen, and Veratox) were evaluated in three laboratories and the data submitted to the AOAC Research Institute (RI), and Performance Tested Method stams was awarded to all three kits by May of that year (Park et al, 2005). In Europe, Poms et al. (2005) evaluated the performance of five test kits (BIOKITS, ELISA Systems, Prolisa, Ridascreen, and Veratox) to detect and quantify peanut residues in biscuit and dark chocolate at four concentrations (0, 2, 5, and 10 mg peanut/kg) using 31 laboratories in 14 countries. 

Of the tree nuts, only the almond and hazelnut kits have been evaluated in independent studies. In December 2004 the Veratox Almond kit completed a full evaluation in seven laboratories that met the criteria for it to be added to Health Canada s Compendium of Food Allergen Methodologies (Health Canada, 2004). Although this evaluation does not confer endorsement of the method, the consistent approach adopted means that the methods can be used for enforcement in Canada should it be required. The study required 630 samples to be analyzed by the laboratories 10 replicates at each of three levels (0, 6.25, and 15.63 ppm) in cookies and in milk and plain chocolate. The kit produced satisfactory results for the matrices and at the levels tested. Analysis of plain chocolate produced the lowest recoveries, as expected, due to the presence of tannins and other phenolic compounds that interfere with the extraction of proteins. 

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