Military ration chocolate: the effect of simulated tropical storage on sensory quality, structure and bloom formation

A storage trial was conducted to observe the effect of typical northern Australia climatic conditions on a military ration chocolate (RC). The results indicate that sensory quality decreased during storage; after seven days the chocolate was no longer of acceptable appearance. Deterioration in RC sensory quality was strongly correlated with decreases in visual acceptance (appearance) and increases in degree of blooming. Instrumental colour measurements were also strongly correlated with sensory ratings. Visual and microscopic observations provide evidence for movement of fat to and across the surface of the RC, behaviour that may be explained in terms of the phase transition theory of fat blooming. DSC thermographs provide evidence of a shift from predominantly polymorph form V in a fresh RC sample to a greater proportion of form VI in bloomed storage samples. The study provides a baseline against which efforts to improve the quality of RC may be evaluated.