Minerals in food have nutritional and functional importance. Because of that, their concentrations should be measured and controlled. In many countries all over the world, enrichment law is mandatory. Fortification of some types of food has allowed addition of some minerals and their levels will be higher than levels expected naturally. Breakfast cereals are often fortified with calcium, iron and zinc. Fortification of salt with iodine has almost eliminated goiter in Europe and USA. In some other cases, minerals may be added for funcionality. Salt is mostly added for flavor, but it can modify ionic strenght that affects solubilization of protein. Phosphorus can be added as phosphates to increase water-holdin capacity in meats and to change the texture of processed cheese. Calcium may be added to promote gelation of proteins and gums.
In measuring mineral content sample preparation is important. Doing that we will ensure a wellmixed and representative sample. A major concern in mineral anaysis is contamination during sample preparation. Comminution and mixing using metallic instruments can contribute to mineral concentration. You should use nonmetallic instruments or instruments not composed of the sample mineral. Solvents, including water, can contain significant quantities of minerals. Because of that, all procedures involving mineral analysis require the use of the purest reagents available.
Measuring mineral content with ISE
Many electrodes have been developed for the selective measurement of various cations and anions, such as bromide, calcium, chloride, fluoride, potassium, sodium, and sulfide.
The principle for using ISE to measure specific mineral is similar as for measuring pH, but the composition of glass in the sensing electrode is made to be specific for the element of interest.
Applications
Some examples of applications of ISEs are measurements of:
- salt and nitrate
in processed meats
- salt content
of butter and cheese
- calcium
in milk
- sodium
in low-sodium ice cream
- carbon dioxide
in soft drinks and wine
- potassium and sodium
levels in wine
- nitrate
in canned vegetables and etc
- ammonia
can be measured in wine and beer
An ISE method applicable to foods containing <100 mg sodium/100 g is an official method of AOAC International (Method 976.25). Some heavy metals, such as cadmium and lead can be measured in food too.
List of ISE that Hanna can offer you:
HI4101
Ammonia
Ammonia
Type:HI4002 Solid state; Half cell
HI4102 Solid state; Combination
Possible applications: Detremination of free bromide ions in emulsified food products, beverages, plants, soils and as indicator for titration
HI4105
Carbon dioxed
Type: HI4105 Gas sensing; Combination
Possible applications: Determination of carbonates as CO2 in water, soft drinks and wine samples
HI5315
Reference
Type: HI5315
Possible applications: To complete the electrical circuit and to provide a stable reference voltage for ISE half-cells
Author:
Tajana Mokrović, mag.nutr.
Tajana Mokrović, mag.nutr.
Source:
Ward, R. E., & Legako, J. F. (2017). Traditional Methods for Mineral Analysis. Food Analysis, 371–386. doi:10.1007/978-3-319-45776-5_21
