How to Clean Strawberries Properly: Bicarbonate of Soda Against Residues

The evidence is clear: this reflex does very little to remove the real risk.

During strawberry season, the red fruit finds its way into almost every home. It looks fresh, smells sweet and seems harmless after a quick rinse. Yet modern residue testing shows that strawberries are among the fruits most heavily affected by residues – and that a few seconds under tap water leave the key substances largely untouched.

Why strawberries so often contain residues

For years, strawberries have featured in international rankings of fruit with the highest number of detectable residues. Studies by authorities such as the US Department of Agriculture (USDA), alongside assessments by organisations including the Environmental Working Group (EWG), paint a consistent picture: a large proportion of conventionally grown strawberries carry several different molecules on their surface.

In test series, for instance, laboratories found at least one residue in 99 per cent of the samples examined. Around one third of the fruit contained ten or more different substances, with individual samples containing up to 23. Altogether, the analyses identified more than 80 different substances in varying combinations.

Substances commonly detected include:

• Carbendazim – an active ingredient from the fungicide group, frequently found as a residue on part of the samples
• Bifenthrin – an insecticide detected in a notable share of the fruit in numerous analyses

For consumers, this means that the glossy exterior may conceal a chemical mixture that cannot be seen with the naked eye.

“Strawberries can look visually perfect – and still carry an entire range of residues that are barely removed by simple rinsing.”

Why plain water alone has little effect

Many people rely on the quick method: put strawberries in a colander, hold them briefly beneath the tap, turn them for a few seconds – done. While this does remove loose soil and dust, it misses what causes the greatest concern: residues that cling to the fruit.

The explanation lies in the chemistry of modern treatments. Many are specifically designed not to be simply washed away by rain. Some are lipophilic, meaning they are attracted to fats, and adhere to the waxy layer of the fruit's skin. Tap water is more likely to run off that layer than carry the molecules away.

Studies, including work by a US university, indicate that plain tap water removes only around 10 to 20 per cent of detected residues on average – mainly those that are already readily water-soluble. Even leaving the fruit under running water for longer therefore offers no thorough protection.

A common mistake: removing the hull before washing

Another widespread habit can make matters worse: cutting off the green hull first and washing the fruit afterwards. This opens the top of the strawberry, leaving its interior unprotected.

If water and any substances attached to it then enter the soft flesh through this opening, they can scarcely be removed afterwards. Specialists therefore recommend cleaning strawberries whole and removing the hull only after washing.

The more effective option: a bicarbonate of soda bath for strawberries

A soak in a solution containing bicarbonate of soda, also known as baking soda, has proved particularly effective. Its pH is mildly alkaline, usually around 8 to 9. In this environment, certain molecules can partly break down or detach more easily from the surface.

Experiments involving fruit show that a properly prepared bicarbonate of soda solution removes considerably more residues from the surface than water alone. In measurement series involving other fruits, soaking for up to 15 minutes reduced residues on the skin by around 90 per cent in some cases.

Step-by-step guide: how to clean strawberries properly

For everyday use, a straightforward but consistently followed method is sufficient:

1. Prepare a large bowl
   Pour about 1 litre of cold water into a sufficiently large bowl or pan.
2. Stir in bicarbonate of soda
   Dissolve 1 heaped tablespoon of bicarbonate of soda completely in the water.
3. Soak intact strawberries
   Place the untrimmed fruit, with the hulls still attached, in the solution. Add only enough at a time to avoid crushing them.
4. Move them gently
   Carefully turn the strawberries in the water using your hand or a spoon, ensuring that every side is wetted.
5. Leave for 10 to 15 minutes
   Let the fruit sit undisturbed in the solution. This time period is crucial to the cleaning effect.
6. Drain and rinse briefly
   Transfer the strawberries to a colander, discard the solution and rinse the fruit under cold water for about 30 seconds.
7. Dry thoroughly
   Spread them on a clean tea towel and gently pat them dry, or allow them to air-dry.

“A quick splash from the tap can leave up to 80 per cent of the residues clinging to the surface – a bicarbonate of soda bath reduces them far more effectively.”

How do vinegar, salt and other home remedies compare?

Alongside bicarbonate of soda, numerous other suggestions circulate: vinegar water, salt water and specialist sprays. Comparative tests reveal clear differences.

Method	Estimated reduction of residues on the surface
Plain tap water	about 10–20%
Salt water (lukewarm)	around 40–60%
Water with white vinegar (mixture of about 1:5)	approximately 60–70%
Water with bicarbonate of soda	up to around 90% with sufficient contact time

Products such as washing-up liquid, multi-purpose cleaner or other household cleaning products do not belong on food. They may leave residues of their own, which are equally unwanted on the plate.

Moisture is the enemy of freshness

Shelf life is another important consideration. Anyone who washes strawberries immediately after buying them and puts them back in the fridge while damp risks them going mouldy much more quickly. The combination of moisture and sweetness creates ideal conditions for microorganisms.

A better approach is to wash strawberries only shortly before eating or using them. To store them in the fridge, keep the fruit as dry as possible and loosely arranged, for example in a bowl lined with kitchen paper.

Is this also necessary for organic strawberries?

Many shoppers choose organic strawberries hoping that this solves the residue issue. Certified growers do use different products and are subject to stricter requirements. Nevertheless, analyses repeatedly detect residues on organic produce too – either permitted substances or traces caused by spray drift from neighbouring fields.

The core cleaning routine therefore remains the same, regardless of the growing system. A bicarbonate of soda bath followed by rinsing and drying also reduces unwanted substances on the surface of organic strawberries, while removing dust, soil and germs at the same time.

How significant is the risk really?

Considered individually, many recorded values remain within legal limits. Specialists nevertheless identify two critical factors: mixtures of many substances at once and regular consumption over a long period. Children in particular often eat large quantities of strawberries during the season.

A consistent cleaning routine acts as an additional safety filter. It reduces the intake of avoidable substances without requiring anyone to give up the fruit itself. Once incorporated into daily life, it is not difficult or time-consuming.

Practical everyday tips

• Where possible, buy strawberries that are in season and locally grown, as transport distances are shorter.
• Sort out fruit with visible damage or mould immediately.
• Use the bicarbonate of soda bath consistently for children's portions, especially where plenty of strawberry yoghurt, quark or smoothies are eaten.
• The same rule applies when baking cakes or freezing fruit: clean it thoroughly first, then process it further.

Anyone wishing to explore the underlying chemistry will come across terms such as lipophilic active ingredients, contact poisons and systemic treatments. In everyday life, a practical approach is enough: a substantial proportion of residues sits on, or directly within, the outer layer. The more effectively that layer is loosened from the surface and rinsed away, the lower the level of contamination on the plate.

It is also worth considering other delicate fruits, such as grapes, cherries or apples with very smooth skins. Many of the effects described can be applied to them: a brief rinse removes only surface dirt, whereas a structured cleaning bath reduces a much larger share of adhering substances. Those who invest the extra few minutes get not only greater peace of mind, but simply cleaner fruit.