Direct measurement of mineral content in food with ISE

Category: Food | Tags: #  #  
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
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
HI4002 and HI4102
Bromide

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

HI4003 and HI4103 Cadmium
Type: HI4003 Solid state; Half cell HI4103 Solid state; Combination Possible applications: Used as an indicator for titrations using chelates

HI4004 and HI4104
Calcium

Type: HI4004 Polymer Membrane; Half-cell HI4104 Polymer Membrane; Combination Possible applications: Determination of free calcium in beverages, milk, water, and seawater

HI4105
Carbon dioxed

Type: HI4105 Gas sensing; Combination Possible applications: Determination of carbonates as CO2 in water, soft drinks and wine samples

HI4007 and HI4107
Chloride

Type: HI4007 Solid state; Half-cell HI4107 Solid state; Combination Possible applications: Determination of free chloride ions in emulsified food products, beverages, plants, soils and as an indicator for titration

HI4008 and HI4108
Cupric

Type: HI4008 Solid state; Half-cell HI4108 Solid state; Combination Possible applications: Used as an indicator for titrations using chelates

HI4009 and HI4109
Cyanide

Type: HI4009 Solid state; Half-cell HI4109 Solid state; Combination Possible applications: Determination of free cyanide ions in plating baths, waste waters and in plant and soil samples

HI4010 and HI4110
Fluoride

Type: HI4010 Solid state; Half-cell HI4110 Solid state; Combination Possible applications: Determination of free fluoride in potable water, soft drinks, wine, plants, emulsified food products, planting and pickling acids

HI4011 and HI4111
Iodide

Type: HI4011 Solid state; Half-cell HI4111 Solid state; Combination Possible applications: Determination of free iodide ions in emulsified food samples (iodized table salt), plants adn for titration

HI4012 and HI4112
Lead/sulfate

Type: HI4012 Solid state; Half-cell HI4112 Solid state; Combination Possible applications: Determination for lead ions in plating baths and as an indicator for titrations

HI4013 and HI4113
Nitrate

Type: HI4013 Polymer Membrane; Half-cell HI4113 Polymer Membrane; Combination Possible applications: Determination of free nitrate in natural waters (fresh and sea), and in emulsified food and plant samples

HI4014 and HI4114
Potassium

Type: HI4014 Polymer Membrane; Half-cell HI4114 Polymer Membrane; Combination Possible applications: Determination of potassium ions in wine, water soils and biological samples

HI4015 and HI4115
Silver/Sulfide

Type: HI4015 Solid state; Half-cell
HI4115 Solid state; Combination
Possible applications: As an indicator for titrations using silver nitrate. For the determination of sulfide ions in water, paper liquors, natural waters and soils

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.
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 

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