Do you know why stone-baked potatoes are baked on stones?
Sweet potatoes become sweeter when heated. The sweetness increases by any heating method, such as boiling, steaming, or baking, but the sugar content (sweetness) of the finished sweet potato differs depending on the heating method. increase.
Sweet potatoes contain a lot of β-amylase, which is a saccharifying enzyme (an enzyme that converts starch into sugar), and when heated, it cuts starch into maltose (maltose) units, which are the source of sweetness, increasing the sweetness. .
The temperature range where this enzyme works most actively is 55-65°C, during which maltose (sweetness) especially increases.
(1) The reason why sweet potatoes are not so sweet when heated in a microwave oven is that the temperature rises rapidly and passes through the temperature range of 55-65°C, and the sweet potatoes are completed before amylase works.
(2) The reason why it is sweeter to leave the sweet potato whole or to take care of it is that the temperature does not rise easily, so the heat passes slowly and the amylase works well.
(3) The reason for using stones is that by indirectly heating high-temperature stones as a heat source, the temperature rises slowly and amylase works. In addition, the moisture on the surface evaporates, resulting in concentration of the taste.