Physical and Chemical Degradation of B-aflatoxins during the Roasting and Dutching of Cocoa Liquor

Authors
A. Mendez-Albores 1
A. Z. Campos-Agular 1
E. Moreno-Martinez 1
A. Vazquez-Duran 2
1 UNAM-FESC., Campus 4, UNIGRAS, Multidisciplinary Research Unit., Cuautitlan Izcalli, Mexico.
2 UANL-FA, Agropecuary Sciences Campus., Francisco Villa s/n, Escobedo, Nuevo Leon, Mexico.
Abstract
To evaluate the effect of roasting and Dutching processes on the stability of B-aflatoxins (AFB1+AFB2), experimental units of cocoa beans contaminated with aflatoxin at a concentration of 220.7 ng g-1 were roasted at 250ºC for 15 minutes. Roasting conditions caused a notable reduction in the aflatoxin content (up to 71%). The resulting cocoa liquors contaminated with 63.9 ng g-1 were thermal-alkaline treated with sodium, potassium, and calcium hydroxide at three different concentrations (10, 20, and 30 g kg-1). The effects of the two variables (alkali type and concentration) were analyzed as a completely randomized factorial 3´3 design. At a concentration of 10 g kg-1, the aflatoxin reduction was more effective when using NaOH and Ca(OH)2 (up to 94%) than when using KOH (up to 88%); however, at concentrations of 20 and 30 g kg-1, all of the three chemicals were almost equally effective for aflatoxin degradation (up to 98%). According to these results, higher reductions in aflatoxin levels were achieved during the roasting and an effective extra-reduction occurred during the Dutching process. Treatment of cocoa liquors with these alkalizing agents not only improved their physicochemical properties, but also enhanced their sanitary quality through the reduction in the aflatoxin content.

Keywords

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Journal of Agricultural Science and Technology
Volume 15, Issue 3
May and June 2013
Pages 557-567