Sodium Chloride and the Law of Healthy Eating

In June 2018, Supreme Decree No. 012-2018-SA was published in Peru approving the Advisories Advertising Manual in compliance with Law No. 30021 on Healthy Eating, in which it sets the limits of sodium content in products packaged for the labeling of " HIGH IN SODIUM" warnings inside a black octagon with white letters, when it is equal to or greater than: For solid foods 400 mg / 100 g of food and for 100 mg / 100 ml beverages drink.

The technical support

According to the World Health Organization recommends reducing sodium intake in order to reduce health problems by increasing blood pressure and cardiovascular disease risk to a daily intake of 2 grams of sodium (5 grams of sodium chloride) for adults and children must be reduced to be proportional to the child's energy needs.

 The sodium ion is part of the electrolyte in the blood and as a transmitter in nervous impulses through the nervous system. The excess consumption of sodium ion (Na +) or as sodium chloride (NaCl), has the effect of retaining water in the body because the body maintains a constant molar concentration of sodium. When increasing the sodium content (solute) the concentration of the solution also increases and therefore water is required to normalize the sodium concentration. Increasing the flow of water in the blood causes the increase in blood pressure.

Advertising regulations in America

 In Chile: The values established by Law 20,606 on food labeling and advertising (solids and beverages) and Law 20,869 on food advertising are the same as Peru. And the graphic warning on the packaging is mandatory similar to Peru.

 In Brazil: Resolution RDC n.360 / 2003 establishes 2.4 g of daily sodium consumption. This resolution establishes a nutritional table with a value less than 5 mg per gram or milliliter of food portion, to label it as "DO NOT CONTAIN SIGNIFICANT AMOUNTS" but when the value exceeds the value must be placed in the container.

 In Argentina: There is only regarding solid foods and not drinks, the corresponding law is 26.905 Law of Regulation of sodium consumption, here they make a list and values are established for each type of product in a range of 429 mg / 100 g of food. There is no graphic warning on the packaging.

 In the United States: The FDA in the law 21 CFR 101.9 establishes a daily consumption value of sodium in 2.4 g. but their solid products do not exceed 400/100 g of food and for beverages they do not exceed 50 mg / 100 ml of drink. Only a table of nutritional content is included in the package.

Analytical determination of sodium in solid foods and beverages:

There are basically 03 main methods for the determination of sodium concentration:

• Qualification by the Mohr method
• Analysis by flame photometer
• Analysis by Atomic Absorption Spectrophotometer

 Next, let's talk a little about each of these methodologies.

Analytical determination of the sodium: Titration by the method of Mohr

The titration by the Mohr method determines the sodium content in the form of sodium chloride and later by means of stoichiometric calculations it is possible to find the sodium concentration.

 The titration is based on titrating the sample in solution, which contains the chloride ions with silver nitrate, because it is more soluble, this in turn has red brick color, this coloration indicates the end point of the titration.

 NaCl + AgNO3 => AgCl + NaNO3

2AgNO3 + K2CrO3 => Ag2CrO3 + KNO3

Example: Titration System

Advantage => Very low cost method;

 Disadvantage => The margin of error and deviation in the results can be quite high, depending on the experience of the researcher.

Analytical determination of the sodium: flame photometer

Flame photometry or flame emission spectroscopy is a quantitative analytical technique based on atomic spectroscopy.

This analytical technique aims to determine the ions that will be excited by the radiation of the flame and is used on a large scale to determine the alkaline and earthy alkali metal ions, since this emits writing in the region of the visible.

Advantage

• Low equipment cost
• Simplicity and speed in the analysis
• It has good sensitivity for the atoms of sodium, potassium, lithium and calcium.

 

Disadvantages

• In the laboratory that possess Atomic Absorption Spectrophotometer (EAA), investing in a Flame Photometer would be an unnecessary investment, since the EAA makes this test with ease and greater precision.

But, how does the Flame Photometer work?

The Flame Photometer is made up of sample aspiration and gas inlet systems, nebulizer, mixing chamber, burner, light filter, detector, signal amplifier and result indicator.

 The nebulizer, burner and the gas mixing chamber constitute a set called atomizer assembly.

 The oxidizing gas that charges the sample to be analyzed is mixed with the fuel gas in the atomizer assembly, the nebulizer has the function of producing a mist of the solution and the burner is responsible for the supply of heat, necessary for the excitation of the ions elementary

 To reduce possible chemical or spectral interferences, light filters are used in the optic of the Flame Photometer.

 After the process of excitation of the elements of interest the luminous radiation is detected by the detector, amplified, coded and presented in the electronic panel of the equipment, with the indication of the concentration of the element of interest.

Determination of Sodium concentration by Atomic Absorption Spectrophotometer

Another technique for the determination of sodium concentration is the analytical technique called Atomic Absorption Spectrophotometry (EAA).

  

But, how does an Atomic Absorption Spectrophotometer work?

Consider, initially, an atom of any chemical element in the ground state (E = 0). When this atom absorbs a quantum of radiant energy, it passes from the state E = 0 to the state E = 1. This amount of energy can be determined and, through its variation, we can identify and quantify the element of interest.

 The technique of Atomic Absorption Spectrophotometry, uses this phenomenon for the qualitative and quantitative determination of elements (metals, semi-metals and some non-metals) in the most varied types of samples: environmental (water, soil, sediment, plants), materials biological (tissues and fluids), food, etc.

Components of an EAA:

• Peristaltic pump => Aspirates the sample into the system
• Nebulizer => Form an aerosol with the aspirated sample
• Atomizer => Stops the elements in the ground state
• Radiation source => Stops the elements in the excited state
• Monochromator => Defines spectral alignment of interest
• Detector => Process the received signal, when the element absorbs the radiation energy
• Software => It treats the obtained data, transforming them into qualitative and quantitative results.

Final discussions

There are other techniques for the determination of sodium in liquid and solid foods, but we believe we have addressed the main ones of this article.

 The important fact in this document, is not how to determine the concentration of sodium in food, but the importance of controlling the consumption of sodium daily, since excessive consumption can cause and / or intensify various problems to human and animal health.

 I hope you enjoyed this article and that you share it with your network of friends.

Regards,

Gilson Siqueira e Felipe Cieza

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References

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