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

To evaluate the effect of roasting and Dutching processes on the stability of B-aflatoxins (AFB۱+AFB۲), experimental units of cocoa beans contaminated with aflatoxin at a concentration of ۲۲۰.۷ ng g-۱ were roasted at ۲۵۰ºC for ۱۵ minutes. Roasting conditions caused a notable reduction in the aflatoxin content (up to ۷۱%). The resulting cocoa liquors contaminated with ۶۳.۹ ng g-۱ were thermal-alkaline treated with sodium, potassium, and calcium hydroxide at three different concentrations (۱۰, ۲۰, and ۳۰ g kg-۱). The effects of the two variables (alkali type and concentration) were analyzed as a completely randomized factorial ۳´۳ design. At a concentration of ۱۰ g kg-۱, the aflatoxin reduction was more effective when using NaOH and Ca(OH)۲ (up to ۹۴%) than when using KOH (up to ۸۸%); however, at concentrations of ۲۰ and ۳۰ g kg-۱, all of the three chemicals were almost equally effective for aflatoxin degradation (up to ۹۸%). 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:

Alkalization , Aspergillus flavus , Cocoa beans , Mycotoxins , Sanitary quality