Knut Franke and Katrin Heinzelmann from the German Institute of Food Technology report that a mechanical-thermal treatment led to milk powder particles possessing a higher density, and the particles had less fat on their surfaces.
The powders also possessed better flow properties, said Franke and Heinzelmann, “indicating that chocolate manufacturers can save energy and time for chocolate manufacture.”
Their findings are published in the International Dairy Journal.
While offering milk processors a potentially new ‘grade’ of milk powder, the new study also has significant implications for chocolate manufacturers. Milk chocolate formulations typically contain about 20 per cent milk powder. The ingredient plays a key role in the taste and texture of the finished product, and also influences the behaviour of the molten chocolate during processing.
“The latter is important for chocolate manufacturers with respect to moulding and coating,” explained Franke and Heinzelmann.
The researchers applied the new process to skimmed and whole milk powders. Both were treated in a twin-screw extruder at 75 degrees Celsius. The researchers removed the die from the extruder in order to avoid increases in pressure and to produce a “flowable” powder.
Results of sorption tests confirmed that the amorphous lactose in the powders was re-crystallized due to this treatment.
When subsequently used for processing into milk chocolate, the researchers found that the processing behaviour of both powders was improved by subjecting them to the mechanical-thermal treatment.
Proof in the tasting
Sensory tests indicated that there were no significant differences between chocolates made with untreated and treated skimmed milk powders. On the other hand, chocolates made with treated whole milk powders were rated as slightly better than milk chocolates formulated with untreated whole milk powders.
The study was financed by the German Ministry of Economics and Technology (via AiF) and the FEI (Forschungskreis der Ernahrungsindustrie).
Source: International Dairy JournalVolume 18, Issue 9, Pages 928-931“Structure improvement of milk powder for chocolate processing”Authors: K. Franke, K. Heinzelmann