Salt Content Determination Guide
Salt is an essential ingredient in many processed foods and therefore the salt content of products often needs to be determined as accurately as possible.
"The Ultimate Salt Guide" covers the following topics:
- Methods of salt determination — Titration, Loss on drying
- UV/VIS Spectroscopy
- Application samples and results
- Tips & Tricks to simplify salt content measurements
Discover pros and cons of different methods of salt determination – from information about the right instruments, to the right measurement techniques for your application.
The Ultimate Salt Content Determination Guide
Proven Analytical Methods and Results
Salt and humans go a long way together. In earlier times, before mining of rock salt had started, salt was a high-priced and much sought after commodity. Nowadays, with cheaper salt prices, salt is a key ingredient in processed foods.
This Salt guide will:
• Give insights into methods of salt determination in food
• Provide a short overview of the history of salt
• Show and explain measurement in selected samples
• Present a few tips and hints to improve operator technique on titrators and balances.
Table of contents:
2. Solutions Overview
3. Argentometric Titration
4. Ion Selective Methods
5. Determination of Salt Content Based on Density
6. Ash Content
8. More Information
Determining Moisture and Water Content in the Food Industry
Moisture analysis, or water content determination, play an important role in all areas of the food industry, from incoming/outgoing goods inspections, production and storage, to the development of new versions of products. The industry is under high pressure to keep prices low while at the same time producing enormous volumes, and for this reason moisture analysis must be very fast, precise, and reliable. Furthermore, there are an increas- ing number of regulations which must be observed. Results and measurement procedures must therefore be reliably documented.
Technically there are several moisture analysis procedures available. Which option is right depends on very dif- ferent factors. The main features, advantages, and risks of these procedures are presented in the following.
1.1 Water Binds in Different Ways
Almost every natural substance contains water. In the simplest case, water is adsorbed from the air humidity on the surface of particles. It can also be stored deep in the pore systems of solid substances, or exist as chemi- cally bound water. Almost all forms exist in foods and ingredients. In addition to well defined products such as all-purpose sugar or alcoholic drinks, there are also complex cellular structures such as dried fruits or meats, in which water is bound both by sorption on the surface and by capillarity between particles. Water also exists deep in cells where it is very difficult to measure. For this reason, analysis and sample preparation methods must be selected based on the properties of the product being examined.
Salt – From White Gold to Commodity
Salt has a long standing culture and can be traced back to ancient times in most civilizations. Babylonians and Sumerians have used salt for conservation of food items. Salt was always in high demand and rare in many regions. Because of salt, many cities have become rich and influential, for instance Luneburg within the Hanse region.
No wonder that salt has been called 'the white gold'. Interestingly though, even the word salary originates from the original meaning of a 'soldier's allowance for salt'. Salt was especially high-priced in the Middle Ages and became affordable in the Germanophone regions only when harvesting the several 100 meters thick, about 250 million year old, salt layers of the Zechsteinmeer in Northern Germany, was made possible.
Table salt, consisting mainly of sodium chloride, is the most commonly used salt in our food. Even after the production process of customary table salt, either from rock salt or sea salt, 1-3% of other salts are remaining; unprocessed sea salt contains up to 5% of water. Table salt is a cleaned and refined salt. To improve attributes such as pourability and hygroscopy, small amounts of other substances are later on added to the salt. In table salt, sea salt and stone salt are often distinguished. Both are harvested in different processes
Rock salt is often a product that is mined from underground. Harvesting is assured either through digging the rock salt out or by solving out. Table salt is then separated from other substances in salines, through selected solving and concentrating and then condensation or boiling.
Different cultures around the globe have developed different techniques to harvest salt. Some South American Indian tribes gain a potassium chloride rich salt from leaching plant ash. In the area around the Chad Lake, earth containing salt is leached, filtered and then boiled down. In earlier times, in some areas of Northern Germany, peat which had been flooded by the sea was utilized to extract salt.
Harvesting salt from sea water is probably the oldest method of harvesting salt. Sea water is channeled into salt gardens, where the water slowly evaporates. All dissolved ions, depending on their solubilities, crystallize one after another in different layers. Sodium chloride is in the top layer that is harvested before the water entirely evaporates. Nowadays about 20% of the global consumption of salt is extracted from sea water.
Salt is an essential ingredient of processed food and the salt content of products often needs to be determined as accurately as possible. Considering the past glory of the 'white gold', salt nowadays often has something of a bad reputation. Too much of it – mainly sodium ion – has adverse effects on our health. Currently WHO and FAO have taken initiatives that aim at capping the salt consumption by defining maximum values for food products. It is expected that this trend will continue and maximum admissible values of salt content will come into place. Pressure on the food manufacturers to reduce the salt content in their products is likely to increase. Thus, many recipes have undergone reformulation or are still waiting to be reworked. Such tasks require quite a lot of testing including salt content determination.
The following sections will give insights into the different methods of salt determination, e.g. titration, loss on drying, then give insights into the determination of the salt content in selected food items and finally offer some tips and hints on how to improve measurement techniques – for easier working procedures and more accurate results.
2. Solutions Overview
Salt Content Determination in Solid and Liquid Samples
Several techniques for the determination of salt, chloride, sodium and potassium in almost any kind of samples are available at METTLER TOLEDO. Liquid samples may undergo direct determination. Solid samples however, may require a preparation step to release the salt and dissolve the ions.