Forskningsapparatur

Electron Spin Resonance (ESR)

Differential Scanning Calorimetry (DSC)

High Pressure Food Processing Press (HP)

High Pressure Spectrophotometer

Stopped-Flow spectroscopy

 

 

Electron Spin Resonance (ESR)

 

Electron spin resonance spectroscopy (ESR) or electron paramagnetic resonance spectroscopy (EPR) as the technique is often also called, can be used to study a number of food related phenomena:

· Oxidative changes in foods

· Testing stability of foods towards oxidation

· Mobility of molecules in foods

· Measurement of oxygen levels in microscopic domains of foods (oximetry)

 

ESR spectroscopy detects radicals which are molecules with unpaired electrons. Radicals often appear in foods and other types of biological materials as short-lived intermediates during the oxidative reactions that result in oxidation of lipids, proteins, vitamins, and other important food components.

The line shapes of ESR-signals are sensitive to the physical molecular environment of the radicals. Analysis of ESR line shapes can give information about physical properties at a molecular level such as molecular mobility, polarity, or the presence of paramagnetic molecules (e.g. oxygen).

 

ESR-Instruments:

Ø Bruker ECS-106 (low-temperature and light induced reactions)

Ø JEOL JES FR-30 Free Radical Monitor

Ø Magnettech Miniscope MS200 (low-temperature and light induced reactions)

 

 

 

Differential scanning calorimetry (DSC)

 

Thermal analysis techniques are those that dynamically follow physicochemical changes that a substance undergoes during heating or cooling.

 

As temperature is raised heat is generated or consumed as the material undergoes chemical or physical reactions/processes. Examples of transformations of food components that involve heat, and can be used to study a number of food related phenomena:

· Crystallization /melting

· Glass transition

· Protein denaturation, aggregation, (starch) gelation

· Lipids; melting point, degree of crystallinity, polymorphs, and oxidative stability

 

DSC-Instruments:

Ø DSC heat flux, 820Mettler-Toledo

Ø Microcalorimeter, MicroDSC III SETARAM

 

High Pressure Food Processing Press (HP)

 

High pressure processing relies on the application of hydraulic pressures between 100 to 1000 MPa (1000 to 10000 atm).

Pressure is an important thermodynamic variable and can affect a wide range of biochemical reactions and processes.

 

HP-Instruments:

Ø Quintus Food Processor 6 high pressure press from Avure with a pressure chamber of 0.9 L and a maximum operating pressure of 900 MPa.

Ø Psika high pressure press with a pressure chamber of 0.25 L and a maximum operating pressure of 1000 Mpa.

 

High Pressure Spectrophotometer

 

High pressure spectrometer is tailor-made with a hand-operated pressure generator and an optical cell.

 

With the high pressure spectrometer absorptions spectra (from 350 to 700 nm) of aqueous solutions can be measured in situ at pressures up to 700 MPa. The sapphire windows in the optical cell can be changed from 14 mm for transparent solutions to 2 mm for turbid samples like milk or reconstituted solutions of milk powder.

 

Stopped-Flow spectroscopy

 

Stopped flow spectroscopy is used for rapid kinetics and can measure 1^st order reaction constants higher than 0.1 s^-1.