Why does the chocolate coating on our marshmallow teacakes crack during storage How can the problem be solved

The cause of this problem is easy to explain but rather more difficult to eradicate. A marshmallow is a composite product made up of biscuit, marshmallow topping and chocolate coating. Each of these components has a different ERH or water activity. Moisture will move from one component to another, driven mainly by the relative differences in water activity between components.

Biscuits have a low ERH and will readily absorb moisture from the atmosphere and become soft. When marshmallow is deposited on the biscuit it will absorb moisture from the mallow (higher ERH) more easily than from the atmosphere and as a result it expands or swells (Cauvain and Young, 2000). This occurs in a period of time after the chocolate coating has dried and the overall effect is to crack the chocolate coating which is not extensible enough to take up the increase in size.

To overcome this cracking:

• The biscuit must not be allowed to absorb moisture from the mallow. You could try spraying the surface of the biscuit when cool with melted hydrogenated fat which places a moisture barrier between the biscuit and the mallow.

• The biscuit, before the mallow is added, must have absorbed enough moisture to have an ERH similar to that of the mallow. This can be achieved by increasing the ERH of the biscuit or by decreasing the ERH of the mallow through modifications to the formulations. Spraying the biscuit shortly after baking with water, using a fine nozzle, or storage in a moist atmosphere for about 12 h before depositing and enrobing should increase the ERH of the biscuit. For the marshmallow, replacing some of the sugar by glucose will decrease its ERH and enable it to hold on to its moisture. Using one of these remedies or a combination the moisture migration from mallow to biscuit should be reduced.


CAUVAIN, S.P. and YOUNG, L.S. (2000) Bakery Food Manufacture and Quality: Water control and effects, Blackwell Science, Oxford, UK.

Continue reading here: What causes the white bloom that sometimes occurs on chocolate coatings

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