Solvents

Solvents are substances that dissolve other substances without chemically modifying them. Even with water being the most common solvent according to this definition, the generic term is generally applied to a large number of other industrially used substances, most of them organic (i.e. containing hydrocarbon), that belong to no particular group of substances.  Various alcohols and ethers, for instance, as well as aliphatic, aromatic or halogenated hydrocarbons, are used as solvents.

Solvents are used in the production of paints, varnishes and adhesives, in the rubber and textile industry as well as in cleaning agents and other household products. Since most solvents are volatile, they evaporate within a few hours or days. The use of solvents is therefore subject to regulations concerning their emission into the environment and occupational health and safety regulations (ventilation, protective clothing).

Solvents in foodstuffs

In the food manufacturing industry, the migratory ability of solvents used in food contact materials is a critical issue, i.e. when substances migrate from the packaging into the food itself. Solvents are frequently contained in the coatings of packaging material and other food contact materials, since they are used to make the components of binding agents flowable and processable.

Carrier solvents, by contrast, are added to food directly in order to facilitate blending with other additives.  These include 1,2-propanediol (propylene glycol) which has been approved for chewing gum and aromas only and is declared as E 1520, or triethyl citrate (E 1505) which has been approved for aromas and egg white powder.

Furthermore, so-called extraction solvents are required for extraction processes that aim to gain or remove certain substances from food, e.g. natural aromas. Declaration is not required, although residual concentrations may be contained in the product. Dichloromethane, for instance, is used to remove caffeine, bitters and irritants from coffee (permitted residual concentration 2 mg/kg) or tea (5 mg/kg). The permitted residual concentration in aromas is 0.02 mg/kg. Hexane is used as an extractant for cooking oils, cocoa butter and aromas and in the production of defatted protein products. All permitted extraction solvents and their maximum residual concentrations are specified in the German Regulations on Processing Aids (THV) that translate Directive 88/344/EEC into German law.

Benzene in soft drinks

Recently, reports about the carcinogenic solvent benzene in non-alcoholic soft drinks had come to light. In 2005 the German Federal Institute for Risk Assessment had published a statement pointing to the fact that the preservative benzoic acid (E 210) may turn into benzene in the presence of ascorbic acid (E 300, vitamin C). There is currently no limit value for benzene in beverages. The Drinking Water Ordinance specifies a permitted maximum value of 1 µg/l, which had been exceeded in some soft drinks, as detected in analyses commissioned by a TV magazine. When assessing the resulting hazard potential, unavoidable benzene concentrations from other sources must be taken into account. According to a counterstatement of the beverage industry, e.g., every person takes in several hundred micrograms of benzene via the air each day.

Analytics

ifp Institut für Produktqualität analyses solvents in foods and packaging material. Analysis is done by means of headspace gas chromatography with a mass-selective detector (MSD) and a deuterated internal calibration standard.

The range of analysis comprises:

• acetone
• benzene
• ethanol
• ethylbenzene
• hexane
• hexanal
• isopropanol
• methanol
• 1-propanol
• m/p-xylene
• o-xylene
• toluene
•  etc.

Melamine

Melamine (2,4,6-triamino-s-triazine) is a colourless substance and chemically a heterocyclic aromatic compound that contains nitrogen oxide. The term melamine is also commonly used for a plastic material from the group of duroplasts / aminoplasts.

In 2008 Chinese dairy factories and baby food manufacturers extended milk powder and other milk products with melamine. The raised nitrogen oxide content simulates a higher concentration of protein, since in food analytics the nitrogen oxide content is used to determine the protein content based on the Kjeldahl method. The toxic effect of melamine on the kidneys caused the death of six infants and around 294,000 cases of kidney stones in children in China. Melamine was also found in milk convenience foods and in ordinary milk.

ifp tests for melamine using HPLC coupled with double mass spectrometry (LC-MS/MS) after extraction from the sample materials.  

Other prohibited sources of nitrogen oxide are detected at the same time: dicyandiamid (DCD), cyanuric acid, uric acid, biuret, cyromazine and amidine urea.

Glycidol and glycidyl fatty acid esters

2,3-Epoxy-1-propanol fatty acid esters (glycidyl fatty acid esters) are process contaminants that form during the refinement of vegetable oils and fats, as is the case with 3-monochloro-1,2-propandiol fatty acid esters (3-MCPD fatty acid esters).

Which foods may contain glycidyl fatty acid esters?

Glycidyl fatty acid esters may be present in any foods that contain refined vegetable oils and fats. So far the highest levels were found in refined palm oil. It can be assumed that foods with a large share of palm oil also contain the highest levels of glycidyl esters.

What are the risks of glycidyl fatty acid esters to human health?

Glycidyl fatty acid esters may be broken down in the process of digestion and release glycidol. Glycidol has been classified as "probably carcinogenic to humans" by various scientific organisations such as the International Agency for Research on Cancer (IARC) and the German Commission of the Senate on Maximum Allowance Concentrations (MAK-Kommission).

The German Federal Institute for Risk Assessment (BfR) has shown in 2012 that glycicyl fatty acid esters are almost completely broken down by the human digestion system. A toxicological assessment is based on the MoE approach (Margin of Exposure).

Analytics

ifp Institut für Produktqualität performs the detection and quantification of glycidyl esters after alkaline hydrolysis and derivatisation using gas chromatography/mass spectrometer (GC-MS).

What are heavy metals?

The definition of heavy metals is not clearly stated in the literature. In public, all chemical elements grouped under the generic term "heavy metals" are often considered toxic substances. However, many of the elements so designated are, in small quantities, vital for humans and are therefore also called essential trace elements (e.g. iron, zinc and manganese). Lead, mercury and cadmium are not essential. They can be hazardous to health if they are ingested with food.¹

Legal requirements

For individual food or raw materials maximum levels for different metals are legally regulated in the following regulations:

• Regulation (EC) No 1881/2006 on maximum levels of contaminants: lead, cadmium, mercury, inorganic tin and inorganic arsenic
• maximum Pesticide Content Regulation (EC) No 396/2005: mercury, copper
• Drinking Water Ordinance

Cadmium in cocoa and chocolate products

Many fine flavoured cocoa varieties come from growing areas in Latin America whose volcanic soils naturally have high cadmium contents. The cocoa plant absorbs the cadmium through its roots and thus reaches the cocoa fruit. Chocolates with a high cocoa content in particular therefore have an increased cadmium content. ²

Since 1 January 2019, the maximum levels for certain cocoa and chocolate products have been regulated in the Contaminant Maximum Levels Regulation (EC) 1881/2006. Depending on the cocoa content, maximum levels for cadmium in chocolate are set at between 0.1-0.8 mg/kg and 0.6 mg/kg for cocoa powder.

Analytics

The ifp offers elemental analysis using ICP-MS (mass spectrometry with inductively coupled plasma) and AAS (atomic absorption spectrometry) for food, feed and water, among other things. In addition to heavy metals, minerals and other metals can also be determined analytically.

The following is an extract from our metal analysis:

Typical contaminants:

• cadmium
• lead
• mercury
• arsenic
• and others

Essential trace elements:

• cobalt
• iron
• copper
• nickel
• zinc
• molybdenum
• manganese
• tin
• and others

For arsenic we also offer the examination of the individual arsenic species.

Sources:
¹ Minerals A.Hahn/ J.-P. Schuchardt BEHR'S Verlag
² https://www.ua-bw.de/pub/beitrag.asp?subid=1&ID=1455