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Biochemical characterisation
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NIZO food research can source from a broad range of analytical techniques available for use in your research projects, among others protein and peptides, carbohydrates, fats, vitamins and minerals and other compounds :
Protein and peptides
- Proteins and peptides can be analyzed using an array of analytical techniques, resulting in measurement of the concentration, the molecular mass or molecular mass distribution in case of aggregated proteins, identification by generation of tryptic maps (in case of proteins), LC-MS-MS analysis of peptides and amino acid composition. Techniques available include Capillary zone electrophoresis (CZE), Reversed-phase HPLC coupled to on-line mass spectrometric detection (LC-MS), enzymatic hydrolysis in combination with reversed-phase HPLC using pulsed electrochemical detection (PED).
- Confirmation of the presence of caseinomacropeptide by Capillary zone electrophoresis (CZE), Reversed-phase HPLC coupled to on-line mass spectrometric detection (LC-MS), and enzymatic hydrolysis in combination with reversed-phase HPLC using pulsed electrochemical detection (PED).
- Gelatins can be analyzed by Size Exclusion Chromatography in combination with Multi Angle Laser Light Scattering (MALLS) and on-line viscosity detection. Moreover, quite often these natural products contain material having sizes >100 nm, which cannot be analysed by SEC-MALLS, but which can be analysed by Field Flow Fractionation (FFF).
- Estimation of the tertiary structure: e.g. compact sphere, extended random coil or rod.
- Formation and characterization of protein aggregates.
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Carbohydrates
- Sugar composition, by HPLC using cation-exchange columns in combination with refractive index detection or anion-exchange columns in combination with highly sensitive pulsed amperometric detection (PED).
- Lactulose, which is formed upon heating of milk products, can be estimated at low levels using a specially developed column switching technique.
- Polysaccharides can be analyzed by Size Exclusion Chromatography in combination with Multi Angle Laser Light Scattering (MALLS) and on-line viscosity detection. Moreover, quite often these natural products contain material having sizes >100 nm, which cannot be analysed by SEC-MALLS, but which can be analysed by Field Flow Fractionation (FFF).
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Fats
- The fatty acid composition of monoglycerides, diglycerides and triglycerides is measured by gas chromatography (GLC, FAME method).
- Intact triglycerides are analysed by GLC for carbon number and degree on unsaturation.
- Highly specific analyses of (un)saturated triglycerides, including the position of the fatty acid residue can be performed by LC-MS in combination with reversed-phase or argentation chromatography.
- Phospholipids, like phosphatidylserine, phosphatidylinositol, phosphatidylethanolamine, phosphatidylcholine and sphingomyeline, are measured by HPLC in combination with evaporative light scattering detection (ELSD).
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Vitamins and minerals
- Vitamins are important nutrients for humans and can be essential for certain microorganisms: e.g. the analysis of riboflavin in milk and of folate and vitamin K down to ppb level by LC-MS-MS in fermented products.
- The contents of a large number of metals and of sulfur and phosphor can be determined by Inductively Coupled Plasma (ICP)
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Other
- Nucleosides and nucleotides are important ingredients of infant feeding, they can be analyzed by LC-MS.
- The nitrogen content can be determined by classical Kjeldahl analysis or by the method according to Dumas.
- Polar organic acids
- Inorganic anions and cations can be analysed by capillary zone electrophoresis (quick, ppm range) or by highly sensitive ion chromatography (down to ppb range).
- Chloroform in products is a result of disinfection using active chlorine containing agents (e.g. hypochlorite, chloramine T). Measurement of chloroform is possible down to ppb level by a fast head-space analysis using direct MS (Food-sense) or down to sub ppb level using GLC in combination with Electron Capture Detection (ECD).
- Carbon dioxide can be formed in fermentations, the amount can be easily measured in the head-space by using direct MS (Food-sense).
- Volatile metabolites formed in fermentations can be directly measured in the head-space by using direct MS (Food-sense) or by (ultra fast) GLC-MS for high sensitivity, high resolution analysis.
- Sulfur containing components like hydrogensulfide and dimethylsulfide, which can be present in flavours (e.g. onion, garlic) and in off-flavours (e.g. decomposing products, bad breath) can be measured down to ppb level using direct MS (Food-sense).
- Optical enantiomers of e.g. lactic acid using chiral detection.
- Determination of intrinsic viscosity and Mark Houwink constants using a single analysis (classical analysis requires one day of labour).
- Dry matter, ash, acidity, water content, etc.
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