Effect of Treating Cocoa with Alkali: The Dutching Process

Cocoa is frequently dutched—treated with alkali in a 180 year old process — for several reasons. “The process darkens the cocoa ingredients, changes the taste by reducing bitterness, and increases the dispersability of cocoa powder for various applications such as beverages.”¹ In the U.S., food labeling regulations require that alkalized cocoa powder or liquor must be declared as “cocoa (liquor) treated with alkali.” Labeling requirement in other parts of the world differ, making it difficult for consumers to ascertain whether imported cocoa powder or cocoa liquor has been treated in this way.

Dutching makes a difference in the health value of cocoa. A 2008 paper¹ measured the ORAC (antioxidation efficacy), the TP (total polyphenol content) and content of flavanols (procyanidins) in natural cocoa (pH 5.39) and cocoa that was lightly alkalized (pH 6.5–7.2), medium alkalized (pH 7.21–7.60) and heavily alkalized (pH ≥ 7.61).

The results showed that natural cocoas tend to group with the highest total flavanols ranging from 22.86 to 40.25 mg/g. The lightly alkali processed cocoa powders ranged from 8.76 to 24.65 mg/g total flavanols, the medium alkali treated powders from 3.93 to 14.00 mg/g, and the heavily alkali treated powders from 1.33 to 6.05 mg/g total flavanols. The natural cocoas showed the highest levels of ORAC and TP. Both antioxidant capacity and TP were highly negatively correlated with pH.

The flavanol content of cocoa is importantly related to many of the most significant beneficial effects of cocoa ingestion.^2–6 (Note, much of cocoa research has been funded by Mars, Inc., which uses a process to retain flavanols in their flavanol-rich cocoa, so that their flavanol-rich cocoa, as used in papers #2, #3, #5, and #6 have higher levels of flavanols than ordinary natural cocoa. Their flavanol-enriched cocoa, Cocoapro™ is, after several years of published research, still not widely available or possibly not available commercially at all; we don’t know where to get it and we sure can’t understand what is holding up the release of this product. Possibly it would be relatively expensive as compared to ordinary natural cocoa and Mars, Inc. is not prepared (yet) to invest in a costly promotional campaign. Still, you have to imagine that they are spending money on research in preparation for marketing it, probably to substantiate health claims they want to make for it.)

The data in paper #1 show that the treatment of cocoa with alkali does have a detrimental impact on what you get from eating natural cocoa by reducing flavanols; about 40% of the natural level of flavanols is retained on average for lightly Dutched powders and an average of about 22% is retained in medium alkali treated powders.¹Since natural cocoa has a very high content of flavanols, even the losses seen in the light and medium alkali processing still leave the flavanol content in the top 10% of measured foods with detectable flavanols in the USDA database.¹ Nevertheless, as the authors note, compared to natural cocoa powder, alkali treatment or Dutching does substantially reduce the level of flavanols in cocoa powders and represents an important processing step during which losses can occur.”¹

The authors also point out that there can be a 20-fold difference between the lightest alkalized powder (24.56 mg/g) and the most heavily alkalized powder (1.33 mg/g), making the ingredient statement that tells you that the cocoa has been treated with alkali “almost meaningless as a tool to predict the total level of flavanols in the final product.”¹ We avoid alkalized cocoa entirely, purchasing natural cocoa in bulk and using it for any foods we want to contain cocoa, such as smoothies and baked goods.

References

1. Miller et al. Impact of alkalization on the antioxidant and flavanol content of commercial cocoa powders. J Agric Food Chem 56:8527-33 (2008).
2. Francis et al. The effect of flavanol-rich cocoa on the fMRI response to a cognitive task in healthy young people. J Cardiovasc Pharmaco 47(Suppl. 2):S215-20 (2006).
3. Schroeter et al. (-)-Epicatechin mediates beneficial effects of flavanol-rich cocoa on vascular function in humans. Proc Natl Acad Sci USA 103(4):1024-9 (2006).
4. Kang et al. Cocoa procyanidins suppress transformation by inhibiting mitogen-activated protein kinase kinase. J Biol Chem 283(30):20664-73 (2008).
5. Grassi et al. Cocoa reduces blood pressure and insulin resistance and improves endothelium-dependent vasodilation in hypertensives. Hypertension 46:398-405 (2005).
6. Rein et al. Cocoa inhibits platelet activation and function. Am J Clin Nutr 72:30-5 (2000).