Testing for salt in food using titration

Why do I need to measure salt in food?

Salt plays a vital role in transporting water around the body, and in transmitting messages between the brain and the rest of the body. However, as with most things, too much salt in our diets can lead to problems such as water retention, raised blood pressure, and a higher risk of heart attack, kidney disease and stroke, so it’s worth keeping within safe limits.

Many everyday foods are not obviously salty, but they can contain high amounts of 'hidden salt' and with growing health concerns surrounding salt posing significant health risks, people are increasingly becoming more health conscious. Many manufacturers have recently made some positive changes to the amount of salt they add and government guidelines have made it mandatory to display salt content in all consumable products.

Current national health guidelines state the reference intake of salt for an adult should eat no more than 6g of salt a day (2.4g sodium) – that's around 1 teaspoon.

Introduction of a traffic light system on products has also been introduced to warn consumers High: more than 1.5g of salt per 100g (or 0.6g sodium, medium: 0.3g-1.5g Low: 0.3g of salt or less per 100g (or 0.1g sodium).

Testing salt content can allow you to be certain of the salt content of your product, ensure that you are adhering to government guidelines and presenting a safe measure of intake for the consumer.

How can I measure salt content?

Salt content can be measured via titration. In this procedure, NaCl concentration is determined by the combination of reagent and ion selective electrode that detects ionic activity which is directly measured to establish the concentration of the salt compound NaCl.

The Hanna Automatic Potentiometric Titration Systems

The use of the Hanna Automated titration system provides a quick and simple way to measure your acidity. This test can be simply programmed into the customisable system and saved for future use. Press ‘start’ and the Hanna titration system will automatically perform the reaction and calculate your result fast, accurately and reliably.

Which model is best suited for my needs?

*Please speak with a member of our sales team for further advice and assistance.*

SOP - Salt in Food

Theory

This application note details a simple procedure for determining the salt (NaCl) present in food/beverage using the Hanna automated titrator and a Hanna silver/sulphide ISE electrode.

The reaction below is performed through titration of a wine sample. The sample is titrated with silver nitrate in the presence of a silver ion selective electrode. The silver ions that are free in solution upon titration are determined and the calculation of NaCl present that must of formed with the Ag ions are calculated and directly proportional to the salt present in the sample as NaCl.

NaCl (aq) + AgNO^3 (aq) is the following: NaCl (aq) + AgNO3 (aq) → AgCl (s) + NaNO3 (aq).

Equipment:

• HI-4115 silver ISE electrode & HI-7072 Potassium Nitrate electrode filling solution
• Beaker

Reagents:

HI-70422 0.1M silver Nitrate

HI-70427 1.5M Nitric Acid

HI-4015-01 0.1M Silver standard Solution

De-ionised water

Procedure

Weigh 5g of sample and accurately record weight.

Add 100ml of de-ionised water to the sample and homogenise.

Filter the blended solution through a muslin cloth into a beaker to remove particles.

Add 2ml of 1.5M HNO3 Nitric Acid using a pipette to the sample solution.

Ensure the burette is full and containing titrant 0.1 Silver Nitrate

Place beaker into position, submerging the electrode and temperature sensor into the sample solution with the titrant dispensing tip just over the solution.

Press ‘Start’

*When the titration has finished the titrator will display your results on screen.*

*Homogenisation may be done using a hand blender.*