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vol. 7, nr. 1 (2006)
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Effects of convective roasting conditions on microbial safety of cocoa beans
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Helena Stoińska 1, Wiesława Krysiak2, Ewa Nebesny2, Elżbieta Kozanecka1
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vol. 7 (2006), nr. 1,
pp. 239-248
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abstract:
Cocoa beans (the Ivory Coast variety) were subjected to convective roasting at air temperatures of 135, 140 and 150°C, relative humidity (RH) of 0.35-0.45% or 2, 5 and 10%, and air constant flow rate (v) of 1 m s-1. Microbial contamination (total numbers of aerobic bacteria, numbers of spores) was estimated in raw and roasted cocoa beans. Results of the assays demonstrate that the most effective bactericidal temperature, independently from the relative humidity of air, appeared to be 150°C. However, the air humidity influenced the time of roasting at 150°C, providing sufficient reduction of microflora. To achieve satisfactory microbial safety as a result of roasting at 140°C, the beans required processing with so called “dry air” (RH of 0.4%) for 45 min. Roasting for 45 min at 135°C andRH of 2% reduced indigenous microflora of cocoa beans to 104 cfu per g.
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keywords:
cocoa beans, roasting, relative humidity of air, quality, microbiological safety
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original in:
Polish
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