Microwave Total Fat Determination in Milk and Milk Products
The traditional fat extraction methods are very labour intensive and time-consuming. Large amounts of solvents are required to remove fat from the sample matrix, resulting in very high running costs. As an example, conventional fat extraction of pretreated cheese usually requires 3 hours and over 100 mL of solvent per sample. Therefore, the standard fat extraction methods are not time- and cost efficient. Furthermore they expose laboratory technicians to dangerous solvents.
To overcome these limitations, Milestone has developed a fast yet accurate microwave-based technology which allows the chemist to carry out the simultaneous total fat determination in 12 milk and milk products samples in just 90 minutes, with equivalent results of those obtained with reference methods. The main advantages of this technology include:
- One basis method for most milk and milk products
- Hydrolysis and extraction in one step
- High sample throughput, 12 total fat determinations in 90 minutes
- Large sample amount, up to 10 gram
- Green method, just 25 mL of solvent required
- The fat obtained can be used for fatty acid analysis
- Reproducible and fully documented
- Safe working conditions
A new method
The ETHOS X determines total fat in milk and milk products as a result of two working steps. In the first step sample hydrolysis and extraction take place simultaneously at relatively elevated temperature and pressure conditions. In the second step a known aliquot of the solvent with the extracted fat is evaporated allowing the chemist to weigh and measure the fat content.
HYDROLYSIS AND EXTRACTION
Up to 12 samples can be analyzed simultaneously, with a typical sample amount up to 10 gram. 10 mL of diluted acid and 25 mL of solvent are used for most matrices. The combined hydrolysis and extraction process takes place at 125°C and requires approximately 50 minutes or less. Temperature is monitored and controlled in each and every vessel by using a unique combination of fi ber optic and infrared temperature sensors. The ETHOS X built-in magnetic stirrer assures an even heating and temperature uniformity in all vessels, as well as intensive mixing between the aqueous and the solvent phases.
In the picture a typical combined hydrolysis and extraction temperature profile. Acid: diluted sulfuric acid or diluted hydrochloric acid. Solvent: cycle-hexane or petroleum ether.
A measured aliquot of the solvent with the extracted fat is evaporated in disposable cups, located in a dedicated rotor, in just 15 minutes.
The evaporation process takes place under controlled temperature and vacuum conditions, to avoid the thermal degradation of the fat content. At the completion of the evaporation, the fat content is immediately weighed on a balance which is directly interfaced with the ETHOS X, taking advantage of the extremely short cooling time of the disposable cups. The instrument operating software automatically calculates the fat content and all the statistics associated with the analysis of the 12 samples analyzed.
In the picture a typical evaporation temperature profile.
The new Milestone ETHOS X is equipped with the most advanced yet easy to use reaction temperature and pressure sensors for complete quality control of the extraction conditions. It is controlled via a compact terminal with an easy-to-read, bright, full-color, touchscreen display. The terminal runs a completely new user-friendly, icon-driven, multi-language software to provide easy control of the microwave run. All extraction parameters can be modifi ed “on-the-fly”, thus assuring the highest fl exibility of operation.