Why does pastry go golden?

Pastry goes golden due to the Maillard reaction. This is a chemical reaction between amino acids and reducing sugars that occurs when food is heated. The reaction was first described by Louis-Camille Maillard in 1912.

The Maillard reaction is responsible for the browning of many foods, including bread, toast, and cookies. The reaction products of the Maillard reaction include melanoidins, which are dark brown pigments, and flavour compounds such as pyrazines and furans.

The rate of the Maillard reaction depends on several factors, including the temperature, pH, and water activity of the food. The reaction is accelerated by high temperatures and low pH levels. This is why pastry that is baked at a higher temperature or for a longer time will be darker than pastry that is baked at a lower temperature or for a shorter time.

The Maillard reaction is an important part of the baking process. It contributes to the flavour, colour, and aroma of baked goods.