Is this really a problem? Well, yes, as there is no sugar in the pastry – it is just flour, water and butter – so it does not naturally brown well during baking. We need to understand that, even if it is fully cooked, pale and colourless pastry looks pretty unappetising.
To overcome this, pastry chefs/bakers/cooks use a glaze made from
beaten egg. They brush the pastry with this before baking.
During cooking, this glaze turns golden brown – the attractive colour that makes puff pastry items so appealing:
vol-au-vent,
rolls,
pasties, etc.
It is very easy to glaze a piece of pastry with a brush, but it is also easy to make the mistake which can ruin everything: glazing down the cut edges of the pastry as well. This prevents the pastry rising, as it effectively "welds" the edges shut and stops the pastry puffing up into flaky layers.
Simply put, we should only brush the glaze over
the top surface of puff pastry, and avoid getting on the sides. This will allow the pastry to puff up as much as possible.
This diagram represents a piece of puff pastry on a baking sheet: brown indicates
where to brush the glaze, and red indicates
where to avoid glazing (yes, I know, I know – you can see that my drawing skills are somewhat limited).
This is why on a
vol-au-vent, for example, the top is always nicely browned, but the sides are still pale – and that is just how it needs to be.
To sum up: For nicely browned puff pastry, brush the glaze over the top, but avoid glazing the sides.
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