Why Does Bread Become Hard and Biscuits Go Soft Over Time?
There has been such a phenomenon in life: if we don't finish the opened bread that day, it will harden the next day; on the contrary, the opened biscuits will go soft. Both of them contain starch and are exposed to the air, so why are these two foods in different states?
First of all, we need to know about the raw materials and technologies for making bread and biscuits.
The main ingredients of bread are rye flour or wheat flour, as well as buckwheat flour, ground brown rice and cornflour. It needs to undergo a second yeast fermentation and be quickly baked at high temperature for 10-20 minutes, with the product having relatively high water content and being fluffy and soft.
Biscuits are made of wheat flour, sugar, starch, oil, dairy products and other ingredients. They will be baked in an oven for about 20-30 minutes after being shaped, and cooled to become the finished products that are crisp and contain less water and more oil. Different processing techniques of bread and biscuits lead to different water contents. And it is for this reason that they are in different states.
Bread needs to be fermented in the process of making. After fermentation, there is more moisture in the bread so that it will evaporate water instead of absorbing the moisture in the air and become dry over time. Actually, except for bread, products like rice and steamed buns will harden after being left in the air for some time, either. The hydrogen bonds among starch molecules will be destroyed by high temperatures. However, when the temperature falls below 30℃ or is near that number, the hydrogen bonds will return to a stable state, and the molecules will gradually be in a compact arrangement. Meanwhile, the original moisture will be squeezed out and reduced. At this time, the soft and delicious bread becomes hard to eat.
Although biscuits contain much starch, they have low water content because they are baked at high temperatures in the manufacturing process. And biscuits contain much more salt and sugar than bread. The particles of sugar and salt dispersed in biscuits can absorb moisture, with the osmotic pressure in biscuits becoming very high. Hence, biscuits will be moist and soft after being opened for a long time.
What are the correct ways to preserve bread and biscuits?
· Freeze Your Bread
Low temperatures will accelerate the aging of starch. Nevertheless, the aging effect will be greatly slowed down when the temperature falls below 0℃. Therefore, put the bread in the freezer after storing it in a fresh-keeping bag, which can prolong the shelf life of the bread to 2 weeks. But it must be noted that only bread without stuffing, such as toast, croissants and baguettes, is suitable for freezing. Other stuffed bread ought to be preserved at room temperature or refrigerated, and be eaten as quickly as possible.
· Keep Your Biscuits Sealed
All kinds of biscuits need to be sealed for preservation. The heavier the humidity, the shorter the shelf life. And being isolated from the air is the simplest and most effective method of storage. It's all acceptable to preserve biscuits in containers or sealed bags. If there are too many biscuits to eat up at once, we can put them in an airtight container and add desiccant or some cube sugar that can absorb moisture, alleviating the softening of biscuits. Or if they don't be eaten within a long time, it's better to freeze them directly after sealing so that they can be stored for 2-3 months. However, it is best not to freeze them again and again.
First of all, we need to know about the raw materials and technologies for making bread and biscuits.
The main ingredients of bread are rye flour or wheat flour, as well as buckwheat flour, ground brown rice and cornflour. It needs to undergo a second yeast fermentation and be quickly baked at high temperature for 10-20 minutes, with the product having relatively high water content and being fluffy and soft.
Biscuits are made of wheat flour, sugar, starch, oil, dairy products and other ingredients. They will be baked in an oven for about 20-30 minutes after being shaped, and cooled to become the finished products that are crisp and contain less water and more oil. Different processing techniques of bread and biscuits lead to different water contents. And it is for this reason that they are in different states.
Bread needs to be fermented in the process of making. After fermentation, there is more moisture in the bread so that it will evaporate water instead of absorbing the moisture in the air and become dry over time. Actually, except for bread, products like rice and steamed buns will harden after being left in the air for some time, either. The hydrogen bonds among starch molecules will be destroyed by high temperatures. However, when the temperature falls below 30℃ or is near that number, the hydrogen bonds will return to a stable state, and the molecules will gradually be in a compact arrangement. Meanwhile, the original moisture will be squeezed out and reduced. At this time, the soft and delicious bread becomes hard to eat.
Although biscuits contain much starch, they have low water content because they are baked at high temperatures in the manufacturing process. And biscuits contain much more salt and sugar than bread. The particles of sugar and salt dispersed in biscuits can absorb moisture, with the osmotic pressure in biscuits becoming very high. Hence, biscuits will be moist and soft after being opened for a long time.
What are the correct ways to preserve bread and biscuits?
· Freeze Your Bread
Low temperatures will accelerate the aging of starch. Nevertheless, the aging effect will be greatly slowed down when the temperature falls below 0℃. Therefore, put the bread in the freezer after storing it in a fresh-keeping bag, which can prolong the shelf life of the bread to 2 weeks. But it must be noted that only bread without stuffing, such as toast, croissants and baguettes, is suitable for freezing. Other stuffed bread ought to be preserved at room temperature or refrigerated, and be eaten as quickly as possible.
· Keep Your Biscuits Sealed
All kinds of biscuits need to be sealed for preservation. The heavier the humidity, the shorter the shelf life. And being isolated from the air is the simplest and most effective method of storage. It's all acceptable to preserve biscuits in containers or sealed bags. If there are too many biscuits to eat up at once, we can put them in an airtight container and add desiccant or some cube sugar that can absorb moisture, alleviating the softening of biscuits. Or if they don't be eaten within a long time, it's better to freeze them directly after sealing so that they can be stored for 2-3 months. However, it is best not to freeze them again and again.