W. Jeffrey Hurst

Survey of Commercially Available Chocolate- and Cocoa-Containing Products in the United States. 2. Comparison of Flavan-3-ol Content with Nonfat Cocoa Solids, Total Polyphenols, and Percent Cacao

A survey of a broad range of chocolate- and cocoa-containing products marketed in the United States was conducted to provide a more detailed analysis of flavan-3-ol monomers, oligomers, and polymers, which can be grouped into a class of compounds called procyanidins. Samples consisted of the three or four top-selling products within the following six categories: natural cocoa powder, unsweetened baking chocolate, dark chocolate, semisweet baking chips, milk chocolate, and chocolate syrup. Composite samples were characterized for percent fat (% fat), percent nonfat cocoa solids (% NFCS), antioxidant level by ORAC, total polyphenols, epicatechin, catechin, total monomers, and flavan-3-ol oligomers and polymers (procyanidins). On a gram weight basis epicatechin and catechin content of the products follow in decreasing order: cocoa powder > baking chocolate > dark chocolate = baking chips > milk chocolate > chocolate syrup. Analysis of the monomer and oligomer profiles within product categories shows there are two types of profiles: (1) products that have high monomers with decreasing levels of oligomers and (2) products in which the level of dimers is equal to or greater than the monomers. Results show a strong correlation (R(2) = 0.834) of epicatechin to the level of % NFCS and also very good correlations for N = 2-5 oligomers to % NFCS. A weaker correlation was observed for catechin to % NFCS (R(2) = 0.680). Other analyses show a similar high degree of correlation with epicatechin and N = 2-5 oligomers to total polyphenols, with catechin being less well correlated to total polyphenols. A lesser but still good correlation exists between the calculated percent cacao (calcd % cacao) content, a proxy for percent cacao, and these same flavanol measures, with catechin again showing a lesser degree of correlation to calcd % cacao. Principal component analysis (PCA) shows that the products group discretely into five classes: (1) cocoa powder, (2) baking chocolate, (3) dark chocolate and semisweet chips, (4) milk chocolates, and (5) syrup. PCA also shows that most factors group closely together including the antioxidant activity, total polyphenols, and the flavan-3-ol measures with the exception of catechin and % fat in the product, which group separately. Because catechin distribution appears to be different from the other flavan-3-ol measures, an analysis of the epicatechin to catechin ratio was done, indicating there is a >5-fold variation in this measure across the products studied. The cocoa-containing products tested range from cocoa powder with 227.34 +/- 17.23 mg of procyanidins per serving to 25.75 +/- 9.91 mg of procyanidins per serving for chocolate syrup. These results are discussed with respect to other studies on commercial products, the bioavailability of the flavanols, and the possible role of processing on the amount of catechin in products.

Impact of fermentation, drying, roasting and Dutch processing on flavan-3-ol stereochemistry in cacao beans and cocoa ingredients

This paper reports a systematic study of the level of flavan-3-ol monomers during typical processing steps as cacao beans are dried, fermented and roasted and the results of Dutch-processing. Methods have been used that resolve the stereoisomers of epicatechin and catechin. In beans harvested from unripe and ripe cacao pods, we find only (-)-epicatechin and (+)-catechin with (-)-epicatechin being by far the predominant isomer. When beans are fermented there is a large loss of both (-)-epicatechin and (+)-catechin, but also the formation of (-)-catechin. We hypothesize that the heat of fermentation may, in part, be responsible for the formation of this enantiomer. When beans are progressively roasted at conditions described as low, medium and high roast conditions, there is a progressive loss of (-)-epicatechin and (+)-catechin and an increase in (-)-catechin with the higher roast levels. When natural and Dutch-processed cacao powders are analyzed, there is progressive loss of both (-)-epicatechin and (+)-catechin with lesser losses of (-)-catechin. We thus observe that in even lightly Dutch-processed powder, the level of (-)-catechin exceeds the level of (-)-epicatechin. The results indicate that much of the increase in the level of (-)-catechin observed during various processing steps may be the result of heat-related epimerization from (-)-epicatechin. These results are discussed with reference to the reported preferred order of absorption of (-)-epicatechin > (+)-catechin > (-)-catechin. These results are also discussed with respect to the balance that must be struck between the beneficial impact of fermentation and roasting on chocolate flavor and the healthful benefits of chocolate and cocoa powder that result in part from the flavan-3-ol monomers.

Screening Antioxidants Using LC-MS: Case Study with Cocoa

Oxidative stress enhances pathological processes contributing to cancer, cardiovascular disease, and neurodegenerative diseases, and dietary antioxidants may counteract these deleterious processes. Because rapid methods to evaluate and compare food products for antioxidant benefits are needed, a new assay based on liquid chromatography-mass spectrometry (LC-MS) was developed for the identification and quantitative analysis of antioxidants in complex natural product samples such as food extracts. This assay is based on the comparison of electrospray LC-MS profiles of sample extracts before and after treatment with reactive oxygen species such as hydrogen peroxide or 2,2-diphenyl-1-picrylhydrazyl radical (DPPH). Using this assay, methanolic extracts of cocoa powder were analyzed, and procyanidins were found to be the most potent antioxidant species. These species were identified using LC-MS, LC-MS/MS, accurate mass measurement, and comparison with reference standards. Furthermore, LC-MS was used to determine the levels of these species in cocoa samples. Catechin and epicatechin were the most abundant antioxidants followed by their dimers and trimers. The most potent antioxidants in cocoa were trimers and dimers of catechin and epicatechin, such as procyanidin B2, followed by catechin and epicatechin. This new LC-MS assay facilitates the rapid identification and then the determination of the relative antioxidant activities of individual antioxidant species in complex natural product samples and food products such as cocoa.

Cocoa Polyphenols and Cardiovascular Health

Cocoa is derived from the seeds of the fruit of the Theobroma cacao tree and has a complex chemical composition. A number of compounds found in cocoa have documented physiological effects. In particular, a significant body of literature supports the role of cocoa polyphenols in maintaining cardiovascular health. Future studies on cocoa should be aimed at elucidating the mechanisms whereby cocoa polyphenols modulate cardiovascular function and at identifying individual polyphenolic compounds within cocoa that are efficacious.

Genetically Modified Crops

When man evolved from a hunter gatherer they began to grow crops for food. They found that selection of crops improved the quality and yield of foods for food production. The selection of seeds led to the evolution of new crops that are more productive and nutritious crops.

Automation in Food and Agricultural Laboratories

Developments in analytical technology are making today’s food and agricultural laboratories the center of exciting new achievements and promising new challenges. The catalyst for much of this change is the continued advancement of laboratory automation, which initially focused on flow injection (FI)-based assays and eventually migrated to laboratory robotics. To quote Sean Connery from the movie The Hunt for Red October, ‘‘those were heady times.’’ With respect to the food industry, laboratory automation has evolved from moving samples through robotics to miniaturization, where the automation is internal. This issue of JALA provides a snapshot of laboratory automation in the food and agricultural segments in 2009. We are delighted to be able to include articles that show automation in use from the farm to the fork. DNA fingerprinting of grain seeds showcases the importance of ingredient quality. Manufacturing efficiencies ethanol production and the cheese industry are highlighted. Continued advancements in microbiological testing are key components to the safety of the entire food supply. All of these contributions provide important perspectives on how innovative automation solutions are driving progress in this unique segment of the ALA membership. These contributions also illustrate how automation technologies and procedures harnessed by a particular industry (such as food and agriculture) can be familiar to laboratories that serve other industries (such as drug discovery and development, forensic and security science, or