Why titration is an outmoded salt measurement method

Salt is a common additive to food products as both a flavour enhancer and preservative.

It is a component of sodium, which occurs naturally, as well as being used as an additive.

While sodium is valuable as an additive, it can have a detrimental - as well as positive – impact on human health.

For that reason, it is important that food manufacturers test salt levels in food products.

An established method for doing so has been titration but, increasingly, it is becoming outmoded for several reasons.

Principally it isn’t fast enough to keep up with the high-volume production of certain groups, especially snack foods.

There are now faster alternative methods for measuring salt and NIR (Near Infrared) spectroscopy can do so in real time.

How salt titration works

Titration is a procedure that uses a solution of a known concentration, or titrant, to determine the concentrate of an unknown one – an analyte.

It is used for salt analysis by manufacturers with in-house food testing facilities.

Testing involves calculating the amount of titrant used to reach a specified endpoint.

There are two methods, manual and automated. Both are widely used, but have inherent disadvantages.

Manual titration

Manual titration uses the Mohr method to determine salt content. It involves manually adding silver nitrate to a sample using a burette.

A reaction then occurs between the silver ions in the titrant and chloride present in the sample.

It happens between each dose, producing a silver chloride precipitate that is insoluble.

The process continues until there is no chloride present. It shows up as a red colour, which is then the endpoint.

Calculating the chloride content allows the operator doing the testing to infer how much sodium chloride content there is.

It is a cost-effective testing method because it does not involve any specialist kit beyond the burette and other glassware containers, plus a colour indicator and the titrant.

However, manual titration has its drawbacks.

It involves a high degree of subjectivity which impacts on accuracy when working out the titration endpoint via a colour change.

Automated titration

Automated titration is the potentiometric method, detecting titration levels and endpoints automatically.

Instead of relying on a visible colour change, this method measures changes in mV, or membrane, potential.

The automated system dispenses more precise, smaller doses of titrant, and many devices can also provide dynamic dosing where the amounts get progressively smaller when approaching an endpoint.

It is a time-saving approach that reduces the likelihood of human error during the titration process along with helping to prevent any overshooting of the endpoint.

The automated titrator will complete the necessary calculations, displaying the required number of concentration units.

Unlike manual titration, however, the automated method does require a considerable investment - higher than alternative salt testing methods.

Production line issues

If a snack producer uses titration to test a production line sample, the whole procedure can take up to 10 minutes.

The problem is that’s not a real-time reading.

Meanwhile, the line will have moved on.

Therefore if the testing reveals poor results for salt content, then anything produced during that time will either become waste or have to be put in quarantine.

Food manufacturers could benefit from a real-time measurement of salt content which will not end up incurring losses.

That real-time solution is NIR.

Online salt measurement with NIR

Real-time measurement of seasoning while making snack food gives production line staff the opportunity to intervene and make adjustments without losing whole runs of a product.

When there are issues with seasoning, they can cause blockages in the line.

NIR testing helps avoid that happening, making it an extremely cost-effective salt-testing solution.

Sophisticated NIR methods

Just as production lines for food have become more sophisticated, so testing methods need to keep up.

That’s not just a question of technology, but efficiency too.

Cutting edge NIR equipment can analyse food samples in as low as 30 milliseconds, determining salt content accurately and in real time.

Contact us

For more information about advanced food quality testing equipment, including NIR, call us on +44 (0) 1925 860 401, email info@calibrecontrol.com or fill in our online contact form