What is the role of fat in the manufacture of puff pastry

In the manufacture of puff pastry, fat may added to the paste in two ways: as part of the base dough formulation and as fat layers formed between two adjacent dough layers. The latter is by far the more important of the two uses and contributes most to the formation of the characteristic layered structure and flaky eating character.

It is not common to add aerating agents to puff pastry yet considerable expansion of the structure occurs as the dough layers are forced apart during baking. The pressure for the expansion comes from the water present in the dough layers as it turns to steam. As the steam tries to escape to the atmosphere, the melting fat acts as a barrier to its progress and the dough layers move apart (Cauvain and Young, 2000).

In order to obtain maximum pastry lift it is important that the fat layers remain separate and discrete from the dough layers for as long as possible, so careful attention should be paid to the processing temperature for the paste. For example, butter has a low solid fat index at 20 °C and pastes made with all butter benefit from processing at temperatures around 12-14 °C, which gives workable fat layers but ones that will not be so brittle as to break during sheeting.

Since the aeration mechanism involves the fat it is reasonable to assume that the characteristics of the fat play a part in the degree of lift during baking. Telloke (1991) showed that the pastry lift depended on the following fat characters:

• The level of added fat, with higher fat levels giving greater lift.

• The solid fat index, with higher SFI giving greater lift.

• The firmness of the fat at point of use, with greater firmness giving greater lift.

• The crystalline form, with smaller crystal size giving greater lift.

While pastry lift benefits from a higher solid fat index there may be some loss of eating qualities as fats with very high melting points tend to give a greasy mouth-feel and 'palette cling'. The addition of fat to the base dough has a small adverse effect on pastry lift and gives a more tender eating quality to the final product.

The impedance of steam by the fat layers also plays a part in the aeration of Danish pastries and croissant, though in these cases lift is affected by the activity of the yeast which contributes to the expansion of the dough layers (Cauvain and Telloke, 1993).

Continue reading here: What is the optimum level of fat to use in the production of puff pastry

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