Effect of Alcohol in Starch-Thickened Fillings on the Storage Stability of Dark Chocolate Pralines

Commercial praline shells made from dark chocolate were filled with a mixture of invert sugar syrup, wine distillate and sucrose, which was adjusted to a viscosity of approximately 4 Pa·s by addition of pregelatinized starch. The pralines which also contained malt extract were subjected to storage at 20 and 24 °C. The liquefaction rate induced by enzymes of the malt extract depended on ethanol (0–15% w/w) and moisture content (approximately 30%) of the filling, and on storage temperature. The decay of apparent viscosity immediately after adding malt extract was delayed when ethanol was present in the filling, implying that viscosity stability after mixing and during subsequent processing is improved. Softening of the praline shells and fat bloom formation also depended on the ethanol concentration of the filling. A cross-comparison with praline shells which were filled with pure invert sugar syrup implies that the enzymes of the malt extract do not exhibit a negative influence on praline shell firmness. Electron micrographs give evidence that ethanol in contact with chocolate causes structural damage which results in a partial solubilization of praline shells.