Sediment at the bottom of a bottle worries people more often than it should. In some liquid products, the producer expects it, and this is why the label says to shake before use. But sometimes a change in how a product looks is a sign that you should not take it. Below we explain where sediment comes from, how to shake a bottle and when a change should worry you.
Solution, suspension, emulsion – three different things
Liquid products differ in the form in which their components are present. This decides whether the product needs shaking.
| Form | What it is | Does it usually need shaking |
|---|---|---|
| Solution | Components dissolved in a liquid, the same all the way through | Usually not, unless the producer says otherwise |
| Suspension | Solid particles spread through a liquid, not dissolved | Yes, the particles can sink |
| Emulsion | Two liquids that do not mix, one spread through the other | Yes, the layers can separate |
| Mixed system | Some components dissolved, some spread through the liquid | Depends on the product, the instructions decide |
A solution is the same all the way through: every portion has the same composition, no matter which part of the bottle you measure it from. A suspension or an emulsion is different, because the components are not permanently bound to the liquid.
The practical conclusion: whether you need to shake a product does not depend on how it looks, but on what the label of the specific product says.
More: How to use liquid supplements without losing their properties
What sedimentation is and why it happens
Sedimentation means that particles spread through a liquid sink because of gravity. The opposite process, when a lighter part collects near the surface, is called creaming.
Both processes come from the physics of the system. The producer designs the product so that shaking can reverse these changes, and puts this information in the instructions.
The role of density and particle size
How fast the particles sink depends on the difference in density between the particle and the liquid, and on the size of the particles. The bigger the difference and the bigger the particles, the faster they separate.
The thickness of the liquid also matters: in thicker products, particles sink more slowly. This is why producers sometimes make the liquid thicker.
The role of time and temperature
The longer a bottle stands without being moved, the clearer the layers can become. A product you use every day usually looks different from one that has stood for a week.
Temperature affects the thickness of the liquid and how easily the particles move, so it also affects how fast these changes happen. The producer gives the storage conditions, and you should follow them.
More: Storing supplements – temperature, light, moisture and the fridge after opening
What happens if you do not shake the bottle
If the components have sunk, the liquid is not the same all the way through: there is more of them at the bottom and less near the surface. A measured portion then has the composition of the layer you took it from.
So the first portions from a bottle may contain less of a component than the label states, and the last ones more, even though the volume is the same each time.
So shaking evens out the composition before you measure, which means the portion matches the label. It does not make the product work better. It is a condition for measuring correctly.
More: Liquid supplement, capsule or powder – how the forms differ
How to shake correctly
How many seconds and why
The producer says how long to shake. For example, the information about THESYBIN food supplement says: “Shake before use.”
A few seconds are enough, because the aim is to mix the contents. Shorter shaking may not be enough if the bottle has stood for a longer time and the sediment has become packed.
It is worth checking the result with your eyes: the liquid should have an even colour and texture, with no visible layers and no sediment stuck to the bottom.
Why very strong shaking is sometimes not needed
Very strong shaking puts air into the liquid and makes foam, which makes it hard to read the level in the measuring cup. In this case, it is better to wait 10 seconds or more until the bubbles go down.
Keep the bottle closed while you shake it, after checking that the cap is tight. Calm, even movements for the time given in the instructions are enough.
When sediment should worry you
Not every sediment is something the producer expects, and you should not assume that it is. In the situations below, stop using the product and contact the producer or seller.
- A change in colour compared with the product when you opened the package or with the description on the label.
- A change in smell, including a sour, rotten, alcoholic or other unusual smell.
- A change in texture, for example thickening, layers that do not disappear after shaking, or flakes and lumps.
- Sediment that does not spread after shaking as the instructions say, even after longer mixing.
- A swollen package, a lid that bulges or gas escaping when you open it.
- Visible dirt or deposits on the surface of the liquid or on the sides of the bottle.
- A leaking package, a broken seal or signs of leaking.
In each of these situations, the same rule applies: do not take the product and contact the producer. Keep the package with the batch number and the best before date, because this makes it easier to deal with your report.
The same applies if the product was not stored as recommended, for example if it was kept outside the fridge although the label says to keep it in the fridge.
Summary
The instruction to shake before use comes from the form of the product. In suspensions and emulsions, the components are not permanently bound to the liquid, so they sink or collect near the surface.
Shaking evens out the composition before you measure a portion, so that the portion matches the label. It does not make the product work better.
But not every sediment is expected. A change in colour, smell or texture, sediment that does not spread after shaking and a swollen package are situations in which you should not take the product and should contact the producer.
FAQ
Does sediment at the bottom mean that the product has gone off?
Not necessarily, because in products that are suspensions, the instructions sometimes say that the components can separate. But this is not a general rule: if the smell, colour or texture has changed, or the sediment does not spread after shaking, do not take the product and contact the producer.
Can I stir the product with a teaspoon instead of shaking it?
The instructions say to shake the closed bottle, and you should follow them. Stirring with a teaspoon means putting an object from outside into the package, which the instructions do not cover.
What should I do if foam remains after shaking?
Just wait 10 seconds or more until the bubbles go down, and only then measure the portion. Foam makes it hard to read the level in the measuring cup exactly. Next time, shake more gently.
Sources
This article is based on general knowledge of liquid product technology and on typical instructions from producers of liquid products. For the information that must appear on the package, it refers to the laws listed below. The producer of the specific product always sets the detailed recommendations for it.
- Regulation (EU) No 1169/2011 of the European Parliament and of the Council of 25 October 2011 on the provision of food information to consumers.
- Directive 2002/46/EC of the European Parliament and of the Council of 10 June 2002 on the approximation of the laws of the Member States relating to food supplements.