protein 3
No description yet. This curated deck is ready for daily study.
Card preview (15)
Proteins in wheat flour are extracted using H2O, NaCl and ethanol as solvent. What is the mode of action of these solvents?
• H2O: protein with a polar surface are extracted • NaCl: salting in –> at low ionic strength ions increase the solvation of charged groups at the protein surface • Ethanol: organic solvent –> more apolar solvent, increased solubility of hydophobic groups
how do globular proteins occur?
as soluable, monomeric or multimeric proteins combination of alpha&beta- sheet
what are fibrous proteins?
muscle protein –> are tipically associated into larges complexes
what are random coil protein
these are neither globular or fibrillar and do not have a fixed secondairy or tertiary structure
what does the solubility of protein influence?
• appearance • teture • digestibility • foam/ emulsion properties
what happens to the solubility if you add salt ions around the pI?
normally the proteins wil aggregate; so not solubule but by adding salt, they neutralize; increased solubility
what are chemical reactions that can happend?
• hydrolysis of peptide bonds • formation of lysino-alanyl derivatives • formation or reshuffling of S-S bridges • deamidation of decarboxylation • maillard reaction
what is the sweetening power of aspartame?
• 180 times that of sucrose
peptides are often bitter; what is the rule of thumb:
• Amino acids in a peptide are more bitter than free amino acids • Non-terminal amino acids are more bitter than terminal amino acids • A peptide is bitter when the average hydrophobicity >1400 Cal/mole • Peptides > 6000 Da are not bitte
what is the advantage and disadvantage of total N content of protein?
• fast • also insoluble materials • measures all nitrogen, also non protein
that is the advantage and disadvantage of spectrophotometric?
• fast • cheap • only for soluble protein • influenced by other compounds
how does SDS work?
• Unfolding of protein and dissociate complexes • Separation of proteins on a gel under influence of an electric field • Separation distance on gel relates with molecular weight • Calculate molecular weight by comparison with marker (contains protein of known Mw)
what is strecker degration ?
• Combination of decarboxylation and deamination • Removal of alpha-carboxylic acid and alpha-amino group: Results in: • Formation of aldehydes (aroma compounds)
In big apolar group is L or D bitter or sweet?
L: bitter; D: sweet
in polar/ small apolar group is L or D bitter or sweet?
L: sweet natural, D: neutral