Read the summary and the most important questions on Food chemistry | vincken

• 2 Proteins

• 2.5 Nomenclature

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• When is the extension -yl used in the nomenclature of amino acids / peptides?

  The extension -yl is used if the carboxyl group (-COOH) on an amino acid is involved in the peptide bond.

• 2.6 Examples of natural occurring peptides in foods

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• Which peptides form due to partial hydrolysis of proteins in fermented foods?

  Gluthathion, Carnosine/anserine/balenine, Nisin.

• 2.7 Taste of amino acids and peptides

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• 1: In which enantiomer can sweet amino acids be found? In which can bitter amino acids be found?

  Respectively in the D-group, and the L-group.

• 2.8 Proteins

• Why are cysteine and tryptophan the most used amino acids in proteins?

  Because of their bio-active functions.

• Which structural forces are present in proteins?

  Disuphide bonds (stabilise all conformations of a protein equally well), hydrogen bonds (extremely weak and not stable), ionic bonds (formed between positive and negative charged side groups), hydrophobic interactions (contribute to the stability of the protein), Van der Waals interactions (short distance, based on distribution of electronic charge around an atom that changes with time (so interaction of 2 atoms))

• 2.9 Protein classification

• To which three groups can proteins be divided based on their conformation?

  Globular or spherical proteins, fibrillar or fibrous proteins, neither globular nor fibrillar (caseins; random-coil like)

• Which classifications of proteins are there due to solubility of the molecules?

  *Water-soluble albumins * salt-soluble globulins * 70% aqueous ethanol-soluble prolamins * glutelins

• What are the consequences of denaturation of a protein?

  Decreased solubility (more hydrophobic groups exposed to water), increased accessibility of peptide bonds to proteolytic enzymes (increased degradability), loss of biological activity (precise conformation is changed. Also protease/amylase inhibitors are inactivated, so it is also important for nutritional properties), increased reactivity (reactive groups emerge and can react).

• 3 Lipids

• 3.1 Classification of lipids

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• How are lipids mostly classificated (definition given to the lipid)?

  This is done in solubility, in particular in organic solvents.

• 3.2 Fatty acids

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• Which two categories are fatty acids subdivided into?

  Saturated (single bond) and unsaturated (double bond) fatty acids.