Pre-blending the small components

A useful technique in supplement blending, and the one most often skipped because it looks like an extra step.

The problem with a gram in a kilogram

A high-intensity sweetener at 0.1 percent, or a vitamin premix at half a percent, cannot be distributed evenly through a bulk powder by adding it to the top and mixing harder.

It will form pockets, it will cling to the vessel, and whatever does disperse will segregate again on handling because it differs from the bulk in size and density.

Mixing longer does not fix it and makes segregation worse by generating fines.

Geometric dilution

The technique is to double the diluent at each step. Blend the small component with an equal weight of the bulk, then with an equal weight of that mixture, and so on, until it is dispersed enough to add to the remainder.

Each step is mixing two quantities of roughly comparable size, which is a problem a mixer can actually solve. It takes a few minutes and it is the difference between a uniform blend and an approximately uniform one.

Which components need it

Anything below roughly one percent of the batch. In a typical formula that means sweeteners, vitamin and mineral premixes, flavor components where usage is low, color, and any active present in milligrams against a bulk in grams.

It also helps anything whose particle size differs sharply from the bulk, even at higher percentages.

Getting it right

Use bulk material from the same batch as the diluent, not a different lot. Record the pre-blend as part of the batch record, because it is a manufacturing step and the rule expects steps to be documented.

And remember what it buys beyond uniformity: dispersing a sensitive ingredient evenly with a protective carrier is part of what maintains its potency across shelf life. Pre-blending protects the active as well as distributing it.

References