Two people can put the same fruit into the same jug and end up with a drink you chew and a drink you gulp. Thickness is the most controllable variable in blending and the one most recipes ignore, because they give quantities in cups rather than telling you what each ingredient does to the texture. Once you know which lever moves which way, you stop guessing.

The three levers

Texture comes down to how much free water there is, how much solid is suspended in it, and how cold the mixture is. Add liquid and it thins; add frozen solids and it thickens twice over, once through bulk and once through chill. Everything else is a variation on those three.

Start thick and let it down

Always blend with less liquid than you think you need and add more through the lid opening. Going the other way is miserable: thinning is a splash, thickening means finding another banana and running the motor again. A thick start also blends better, because the vortex has something to grip. Cups sold for single servings, such as the range at KOIOS, carry a fill line that assumes a pourable mixture rather than a paste.

Ingredients that thicken without shouting

Frozen banana is the standard for a reason, but it brings a strong flavour with it. Rolled oats, cooked and cooled white beans, silken tofu, avocado and a spoonful of chia all add body with far less taste. Nut butters thicken and enrich at once, though they also make the drink heavier than most people expect at eight in the morning.

Where the machine sets the ceiling

A personal blender with a tall narrow cup handles thick mixtures better than a wide jug, because the walls keep pushing the contents back into the blades. Even so, every machine has a viscosity at which the vortex collapses and the motor howls at a stationary lump. Overfilling makes that happen sooner, because the mixture at the top never reaches the blades at all.

The tamper problem

Full-size jugs often come with a tamper so you can push food down whilst the blades run. Personal cups do not, and you must never poke a spoon or spatula into a running jug of any kind. Stop, unplug or unlock, scrape the sides, reassemble and run again; the ten seconds you lose are cheaper than a bent blade or a cut hand.

Matching thickness to the job

Different uses want different consistencies, and it is worth being deliberate about it.

• Drink from a cup on the move: pourable, holds a slow ribbon off a spoon.
• Bowl with toppings: thick enough that the toppings sit rather than sink.
• Soup base: loose, because it will thicken again as it cools in the pan.
• Batter: just thin enough to spread on its own within a couple of seconds.
• Sauce for freezing: thicker than you want it, since ice crystals dilute on thawing.

Cold does the work sugar used to

A very cold, thick drink tastes fuller and reads as sweeter than the same mixture at room temperature. If a smoothie tastes thin and sharp, chilling and thickening it will often help more than adding honey. This is the same trick ice cream makers rely on, and it costs nothing.

When thick goes wrong

Past a certain point the mixture stops circulating, the motor draws hard current and the jug warms quickly. Listen for the sound going from a busy churn to a strained hum with no movement in the middle. Stop immediately, add liquid, and remember that roughly a minute of continuous work is all most domestic motors are rated for before a rest.