Science Snippets!

Cocoa (Theobroma cacao L.) is an important plant product used in the beverage and food industry. It’s grown mainly in West Africa and South America. Cocoa processing involves cleaning, separating from its pods by shelling, roasting, milling and pressing. Cocoa is often alkalinized. Typically this processing work is done in manufacturing countries. The shells, still containing antioxidants (flavonoids), are often used as dietary fiber.

Ochratoxin A (OTA) is a toxin produced by fungi (Aspergillus and Penicillium) and can be found in coffee, cocoa, grapes, figs, and cereals. Prevalence of ochratoxin A depends on the growing conditions (presence of fungi, humidity, number of spores, sanitation procedures). Cocoa beans and chocolate can be contaminated with ochratoxin A (beans up to 15 µg/kg and chocolate 4.3 µg/kg, Amézqueta et. al, 2008). However, efficient shelling can reduce ochratoxin contamination significantly.

Amézqueta et al (2008) were interested in decreasing ochratoxin A content in cocoa shells by chemical- and physical means. The authors obtained naturally contaminated cocoa shells (8.4 µg/kg or 8.4 ppb) and exposed them to either sodium bicarbonate (NaHCO3) or potassium carbonate (K2CO3) in a solvent extractor. They experimented with different concentrations: 2.0, 1.0, and 0.5% of above solutions. The authors also investigated the effect of pressure: 1,000 or 1,500 lb/in2, and four different temperature settings: 40, 65, 90, and 115ºC. Cocoa shells were left in the extractor for 5 or 10 minutes. Ochratoxin A was quantified by HPLC using a fluorescence detector.

Amézqueta et al (2008) found K2CO3 to the most efficient solvent: it reduced 84% of the OTA vs. 27% with NaHCO3). The 2.0% concentration seemed to work best in reducing OTA: e.g. 1.0% achieved 71% reduction. The highest reduction (95%) in OTA content was obtained with a pressure of 1,000 lb/in2 at 90ºC for 10 minutes (Amézqueta et al 2008).

The authors conclude that cocoa shells decontamination of OTA by 2.0% K2CO3 is economically feasible and effective. After rinsing the treated cocoa shells with water, the decontamination procedure shouldn’t pose a problem to human health.

Reference:
Amézqueta, S., E. Gonzáles-Peñas, T. Lizarraga, M. Murillo-Arbizu and A. López de Cerain. 2008. A simple chemical method reduces ochratoxin A in contaminated cocoa shells. J. Food Protection. 71:1422-1426.

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