Proteins
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what is the most important role of protein in food?
acts as an emulsifier
what are plant sources of protein?
pulses (more) and cereal grains (less)
what is the dimer of cysteine called?
cystine (dimerize under oxidizing conditions)
food source with highest protein?
meat, fish
what is an example of a basic amino acid important in food science?
Lysine
what is an example of a polar, uncharged amino acid important in food science?
cysteine
Milk protein rich in ____ tend to brown more quickly because of the _____ reaction
lysine; Maillard Browning
What are the essential amino acids?
histidine, leucine, isoleusine, lysine, methionine, phenylalanine, threonine, tryptophan, valine
in acidic pH, the AA has a ___ charge; in basic pH, the AA has ____ charge
positive; negative
what is a zwitterion?
a neutral AA (when pH = pI)
the pH at which the charge on AA becomes neutral
isoelectric point
Why is the isoelectric point important in food?
at this point, protein can’t stay in solution so will form aggregates and precipitate out
what is casein’s isoelectric point?
pH 4.5-4.6
how is yogurt formed?
action of lactobacillus or addition of lemon juice brings the pH to pI
casein derived phosphorylated peptides that enhance vit D absorption?
caseinophosphopeptides 3 Ser, 2 Glu
34 AA residues, with antimicrobial properties that is produced during certain bacterial fermentation
Nisin
Aspartame is about _____sweeter than sucrose; it is made up of ___ and aspartate
200 times; phenylalanine, methanol
sucralose is ___ times sweeter than sucrose, and is made through selective ___ which makes a product we can’t digest
600; chlorination
what is the primary driving force behind tertiary structure formation?
thermodynamic stability in aqueous solution
what interactions stabilize protein structure?
H bond, electrostatic, disulide, and especially hydrophobic
what are the three types of tertiary structure?
globular (insoluble AA), disordered (interact well with water), fibrous (strong secondary structure)
an example of globular protein
whey
an example of disordered protein
casein
example of fibrous protein
muscle protein collagen