On average we each eat 43 loaves of bread each year. But a lot of that goes in the bin, with UK households throwing away 24 million slices of bread each day.

So, what’s the best way to store bread? A member of the public asked food scientist Dr Marina Corrado this question during a public engagement event. The question sparked a research project on the effect of storage on bread characteristics.

Research suggests the best way to store bread is at room temperature in an airtight container or in the freezer, if you want to delay bread staling. It can depend on the type of bread too.

Stopping bread turning stale

As well as turning mouldy, bread shelf life is determined by bread ageing or staling. Mouldy bread can be unsafe to eat and should be discarded. Even when we can prevent molds from growing, storing bread for a long time can result in staling.

Staling is a complex process where bread becomes harder over time. This change is due to bread losing water and the crumb firming up. A third factor in the staling process is a change in the characteristics of starch. Starch is a complex carbohydrate found in cereals like wheat.

To study the impact of storage on bread characteristics, Marina produced several bread rolls in the Quadram Institute Bioscience experimental kitchen. The kitchen is a controlled lab environment.

Marina analysed freshly baked rolls and after 24 hours, 48 hours, and 72 hours of storage at:

• room temperature (19 to 21 °C)
• fridge temperature (3 to 5 °C)
• freezer temperature (−18 to −20 °C)

In Marina’s experiment, bread rolls were stored packed in sealed plastic bags. So the results of this research may not reflect bread behaviour when left unpacked.

Room temperature

At room temperature, bread is a victim of its environment. If you are leaving freshly baked bread for a few days, moisture loss will be significant and lead to stale, and dry, bread.

A plastic bag or container can buffer the effect of the environment and prevent excessive moisture loss, at first.

Over time, the bread will become chewier, harder and less resilient to touch which means that if you are preparing sandwiches, it will crumble easily and will be difficult to pack and transport.

The fridge

A household fridge temperature and humidity are very variable, depending on the amount of food you have stored in it and the number of times you open it in a day.

At 3 to 5 °C, bread stales faster than in the freezer or at room temperature. The fridge will prevent moulds growth and spoilage, and lower moisture loss than when at ambient conditions (without plastic bag) but starch properties change a lot faster here, leading to faster staling.

The freezer

Freezer storage prolongs bread shelf life because it prevents moulds growing and stops excessive water loss from the bread. This means that we can freeze bread for quite some time and then use it by warming or toasting it.

The sub-zero temperature (−18 to −20 °C) stops water from evaporating but also causes the starch to have a more rigid structure which over time can lead to staling, even though at a slower rate than when in the fridge.

While freezing traps water, this is only a temporary solution. If you notice your bread, or any foods in the freezer, getting a “freezer burn” (going whitish and opaque) that means you have waited too long, and your bread is now stale.

How is textured measured?

The Texture Analyser

Researchers at the Quadram Institute study bread texture using a piece of equipment called a Texture Analyser. By compressing a cube of bread crumb, researchers can measure texture parameters such as hardness, resilience, and chewiness.

The equipment mimics compression between your fingers or teeth. Try it yourself. Is the crumb hard? Does it spring back quickly after compressing it? Does it crumble as you touch it?

Do all breads stale the same?

Breads storage characteristics strongly depends on the flour used.

Wheat flour is mostly made of starch, a nutrient made of glucose chains in linear form (amylose) and rigid highly branched chains (amylopectin). The proportion of linear versus branched chains confers distinct characteristics to the starch that can affect bread making, storage and digestion of starchy foods.

Along with looking at regular white bread, Marina and the team studied bread made from a new type of wheat flour which is high in amylose (or “sbeII”). Researchers in the Brittany Hazard group have developed this bread wheat, with the aim to develop new foods with that are digested to a slower rate and reduce the sharp blood sugar rise caused by conventional white bread.

Starch has a direct effect on glycaemia, also known as blood sugar levels. The amount of glucose released and absorbed during digestion is proportional to the amount of starch eaten. However, starch digestibility strongly depends on its characteristics which can change during storage.

To understand the effect of storage on different types of bread, Marina tested two types of wheat bread over three days storage in different conditions. She used strong white bread flour from a high amylose wheat and conventional wheat to make bread and stored it at room temperature, in the fridge and in the freezer. The two types of flour have different starch characteristics that lead to different starch digestibility.

When sbeII bread is freshly baked, it has a similar texture to regular white bread. However, unlike regular bread, the overall crumb structure of sbeII bread is less affected by storage. This is more pronounced when it is stored in the fridge or at room temperature.

On a microscopic level, the sbeII bread shows a lower starch digestibility compared to conventional bread, when freshly baked and after even storage too. This suggests sbeII flour could be used in convenience foods such as chilled sandwiches, fridge or freezer ready meals as well as everyday bread.