Surprisingly it’s true, with test results published in Scientific American Magazine1. Blind tasting by 143 people confirmed that the skin of pigs with the head cut was crispier!
Why? Here is what researchers found.
“The underlying mechanism was easily discovered, as it was observed during cooking that in one pig a stream of vapour was escaping from a hole made during preparation.
Heat evaporates water from the surface of the meat during cooking, making the crust. Vapour formed inside the meat is not enough to compensate for the loss of surface water.
When the pigs are not heated any longer, the crust softens if vapour goes through. Cutting the head prevents vapour perfusion, as it escapes through the opening”2.
This is a good example of the open-minded approach needed to test such statements.
1 This, H., and N. Kurti, 1994. Physics and Chemistry in the Kitchen. Scientific American, 270, 44–50.
2 This, Hervé. 2005. Modelling dishes and exploring culinary ‘precisions’ – The two issues of molecular gastronomy. British Journal of Nutrition (2005), 93, Suppl. 1, S139–S146.