It separated in the jar

What is actually happening

The solids and the water in a sauce are held together by starch, pectin, gums or simply by particle size. When that structure is not strong enough to hold the water, gravity does the rest over weeks on a shelf. It does not make the product unsafe and it does make it unsellable.

The formulation causes

• Not enough thickening for the water present.
• A thickener that does not hold up to the acid, the heat, or both.
• Too much thinning from the acid: vinegar brings water with it.
• Over-processing, which can break down the structure you built.

Why acid makes this harder than it looks

Many thickeners lose strength in acid, and this is an acidified product by definition. A sauce that held together beautifully before acidification can separate afterwards, which sends makers looking at the wrong step. Test the acidified product over time rather than the pot.

Finding out before a customer does

This is the clearest case on the property for keeping a retain from every batch and opening it on a schedule. Separation is a month-three failure and no amount of inspection at packing time will show it to you. One jar per batch, stored the way a customer stores it, answers a question nothing else can.

If a jar is meant to be shaken, say so on the label. A product that separates by design is fine; a customer who was not told is not.

Over-processing is the cause people miss

Makers looking at separation almost always look at the thickener first, and the process is the one that does not occur to them. Extra time at temperature can break down exactly the structure the formulation built, so a batch that separates may be one that was processed longer rather than formulated worse. Another reason the filed time is a figure to hit rather than a minimum to exceed.

References