  The natural variation of temperature at ambient conditions produces
spontaneous patterns on the surface of chocolate, which result from fat bloom.
These patterns are peculiar because of their shape and cannot be obtained by
controlled temperature conditions. The formation of these spontaneous grains on
the surface of chocolate is studied on experimental and theoretical
grounds.Three different kinds of experiments were conducted: observation of
formed patterns in time, atomic force microscopy of the initial events on the
grain formation and rheology of the melted chocolate. The patterns observed in
our experiments follow the trends described by the Avrami model, which
considers that is possible to define a characteristic time scale that governs
the growth of grains starting from germ nuclei. Through computer simulations,
in the NVT ensemble using a coarse-grained model of triacylglycerides
molecules, we studied the process of nucleation that starts the pattern growth
and that is consistent with the Avrami model.
