Some outbreaks of Salmonella have been linked to chocolate consumption. As the p

Question

Some outbreaks of Salmonella have been linked to chocolate consumption. As the processing of cocoa beans requires heating steps, it was assumed that Salmonella contaminants would be killed during processing. Calculating the D-values of Salmonella at 70°C gave these data:

Glucose solution 0.03

Milk 0.35

Milk chocolate 813

Which of the following can be validly concluded from these data?

Multiple Choice

(a) Milk is not the source of Salmonella in milk chocolate-related outbreaks.

(b) Components of milk chocolate exert a protective effect on Salmonella cells.

(c) Temperatures lower than 70°C should be used for bacterial control.

(d) Milk chocolate should not be consumed by individuals with compromised immune systems.

Explanation / Answer

Choice B is correct.

Reason: The D-value of a microbe referes to the decimal reduction time of the microbe under specific conditions of temperature/treatment. Numerically, a value of 1 D-value represents that 90% of the bacteria have been killed. Thus, qualitatively, higher the D-value, lower the number of living microbes and lower the D-value, higher the number of living microbes.

According to the question, the D value for Salmonells is highest in milk chocolate and lowest in sugar solution. This clearly represents that the Salmonella number is very high in the sugar solution and a very few or negligeble amount of pathogen resides in the milk chocolate itself. This suggsts that sugar being one of the main ingredient of milk chocolate, preserves the Salmonella microbes in the product and thus might be the reason for this infectious outbreak. Milk as such does not seem to be a source because heating the milk at more than 70 degree celcius kills virtually all bacteria. Further, lactose intolerance also has not significant role in this outbreak since indigestion of milk is not related with Ssalmonella outbreak. This explanation suggests that choice B is most correct answer.

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