Why do biscuits become softer and bread become harder as time goes by?

Friends who like to stock up on snacks, have you ever thought about this question: Why do biscuits become soft and not crispy after being opened for a few days, while fluffy bread becomes hard after being opened for a few days? Today, let's take a look at the reasons behind this phenomenon!

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01Why do cookies become soft after being stored for a long time?

Biscuits will become soft after being stored for a long time, and bread will become hard after being stored for a long time, which is mainly caused by the difference in their ingredients and storage environment. During the production process of biscuits, they are baked at high temperature, and the moisture is almost completely evaporated , which makes the biscuits have a crispy taste. Biscuits themselves are very dry, and dry substances easily absorb moisture from the surrounding environment , so when biscuits are exposed to the air, they absorb moisture and become soft.

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Not only that, biscuits usually contain more sugar and salt . These two substances are highly hygroscopic , which makes biscuits more likely to absorb moisture and become soft.

02Why does bread become hard after being stored for a long time?

The moisture content in fresh bread is usually high , accounting for 35% to 45% of the total weight of the bread. Of course, this ratio also varies according to the type of bread, recipe and production process. For example, baguettes have a low moisture content, while soft white bread, cream bread, etc. may contain higher moisture, close to 50% or even more. During the storage of fresh bread, the internal moisture will slowly be lost , causing the bread to become hard. In addition, the starch in the bread will undergo " starch aging " during the cooling and water loss process. In fact, starch aging is a process in which starch molecules become more stable. When we heat foods containing starch such as bread, rice, and steamed buns, the starch molecules will become loose and disordered. This is the process of starch "gelatinization", which makes the food softer and tastes better. But as the food cools, the starch molecules will slowly rearrange themselves, becoming orderly and tight . This change will gradually make the food lose its softness and fresh taste.

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Simply put, the starch molecules in freshly baked bread are disordered and loose. After a period of time, they will rearrange to form an ordered crystal structure. This process makes the bread hard and tastes woody. In addition, the moisture content also has a direct impact on the speed and degree of starch aging . A higher moisture content can delay starch aging and keep the bread soft for a longer time. On the contrary, if the moisture content is low, the starch will age faster, causing the bread to harden quickly.

03If the biscuits become soft and the bread becomes hard, can we still eat them?

The answer is yes . Biscuits absorb moisture and become soft, and bread loses water and becomes hard. These are all natural phenomena. It is just the taste that changes, and it does not affect food safety. If biscuits become soft, you can put them in the oven to heat them slightly, and they will regain their crispness after the water evaporates; if bread becomes hard, you can use a microwave or steam to heat it, which can restore the soft texture of the bread to a certain extent. However, if food is stored for too long, it may cause mold or other food safety problems, so be sure to eliminate signs of deterioration such as odor or color change before eating.

Image source: Photo Network 04 How to properly store biscuits and bread?

Choosing the right storage method can effectively prolong the crispness of biscuits and the softness of bread. The key to preserving biscuits and bread lies in "waterproofing" and "locking moisture" and maintaining ideal temperature conditions.

1) How to store cookies

Sealed storage : Cookies should be stored in airtight containers or sealed bags to prevent the intrusion of moisture from the air.

Add desiccant : Place food-grade desiccant, such as silica gel packets, in the cookie container. If you don't have any, you can put some rice grains, which are a natural desiccant.

Avoid high temperatures : Store cookies in a cool, dry place away from direct sunlight and high temperatures to prevent accelerated deterioration.

Frozen storage : If you need to store the cookies for a long time, you can freeze them. After taking them out and slightly warming them up, they will regain their crispy taste.

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2) How to store bread

Short-term storage at room temperature : Fresh bread can be stored at room temperature for 2-3 days, preferably in a sealed plastic bag or bread box to reduce moisture loss. If it is sliced ​​bread, you can use a clip to clamp the seal tightly to keep the bread soft.

Avoid refrigeration : Although many people are used to putting bread in the refrigerator, the refrigeration temperature of the refrigerator can easily accelerate the aging of the starch in the bread and make it hard. Therefore, unless it is a special variety such as cream bread, it is not recommended to put bread in the refrigerator.

Freezing : If you need to store the bread for a longer time, you can freeze it after slicing it. Freezing can slow down the aging process of starch, and it will become soft again after being taken out and slightly heated.

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References

[1] Zhang Xiaojuan, Wang Qiang, Qian Ping. Study on hardening of bread during long-term storage[J]. Chinese Agricultural Science Bulletin, 2010, 26(6):54-59.

[2] Wang Zuoqin. The relationship between amylase and saccharifying enzyme and baking industry[J]. China Food Industry, 1996, (5): 32-35.

[3] Feng W, Ma S, Wang X. Recent advances in quality deterioration and improvement of starch in frozen dough[J]. Grain & Oil Science and Technology, 2020, 3(4): 154-163.

[4] Hallberg LM, Chinachoti P. A fresh perspective on staling: The significance of starch recrystallization on the firming of bread[J]. Journal of Food Science, 2002, 67(3): 1092-1096.

[5] Nivelle MA, Bosmans GM, Delcour J A. The impact of parbaking on the crumb firming mechanism of fully baked tin wheat bread[J]. Journal of agricultural and food chemistry, 2017, 65(46): 10074-10083.

Planning & Editing: Ding Dong

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