Finally, safe and simple acid hydrolysis for determining the total fat of nearly any sample. Automatic, standardised, internationally comparable…
HYDROTHERM - Automatic acid hydrolysis for total fat determination.
In many sample types, the fat is not freely accessible to the solvent and it cannot be extracted in full. In milk, for example, the majority of the fat is surrounded by membrane and in oil seeds it is surrounded by cell walls. The bonding of fats in starch-lipid complexes or to lipoproteins or phospholipids, as in mixed products such as baked goods, also prevents direct extraction of the fat.
To break open the membranes in milk products, official methods now tend to treat the sample with an alkaline ammonia solution or a hydrochloric solution. Once the sample is digested, the fat is separated out using various extraction methods.
In a wide variety of other sample types, the Weibull-Stoldt or Weibull-Berntrop chemical method for total fat determination is used. Here, before the fat is extracted with petroleum ether, the sample is first hydrolysed with hydrochloric acid to digest the proteins and release the bonded lipids.
Classic acid hydrolysis is time-consuming and dangerous, due to the acid. C. Gerhardt developed the HYDROTHERM automatic hydrolysis system to solve this problem; it automatically performs acid hydrolysis for 6 samples simultaneously and safely in an enclosed system. Laboratory personnel no longer come into contact with hot liquids and acid fumes and each cycle now takes just 3 minutes, rather than 40. Costs per sample are reduced by up to 80% compared to the manual process.
HCl hydrolysis to prepare samples for fat determination is prescribed by law in a range of national and international methods. In Germany, the LFGB requires this form of sample preparation in the context of fat determination using the Weibull-Stoldt method, e.g. for total fat determination in bread and fine baked goods, in meat and meat products, in chocolate and cocoa products, and for milk and milk products that have been mixed with other foodstuffs and additives, e.g. yoghurt with fruit or processed cheese. HCl digestion also has to be performed before extraction when determining the crude oil or crude fat content in feedstuffs.
The American standard AOAC prescribes HCl hydrolysis for total fat determination in flour, bread and baked goods, for example, and for crude fat determination in fish and seafood. ISO Standard 1443 and British Standard BS 4401 require HCl hydrolysis for total fat determination in meat and meat products. ISO Standards 8262-1(E) and IDF 124-1(E) (International Dairy Federation) require HCl digestion in the context of the Weibull-Berntrop reference method for total fat determination of infant food containing milk, ice cream and ice-cream mixtures, and for liquid, concentrated or dried milk products for which the Röse-Gottlieb method or the Schmid-Bondzynski method cannot be used due to the composition.
HYDROTHERM operates in accordance with these standards and regulations and it provides precise, completely documented and exactly reproducible HCl digestion. Regular participation in various ring tests has repeatedly proven the excellent quality of analysis. HYDROTHERM can process almost all sample types and sizes. Sample weights of 1 to 20 g enable reliable analysis of even very inhomogeneous matrices and samples with a very small fat content. Using the preset standard method, 95% of all sample types can be validly analysed.
Thanks to its high degree of reliability and the major potential for saving, HYDROTHERM is already in use in all important contract laboratories around the world.
Combined with the automatic rapid extraction system SOXTHERM®, which has proven its worth over decades of use, HYDROTHERM is a very efficient and reliable means to determine total fat.