Properties of hydrolysates

Question 1

Protein hydrolysates in food products, for which purposes?

Answer 1

1. Nutritional properties: easier digestibility and loss of allergenicity.
2. Techno-functional properties: they change solubility, foam, emulsion and taste
3. Bio-functional properties: NOT IMPORTANT

Question 2

Protein hydrolysis: which two components will made?

Answer 2

Alpha carboxyl group and alpha amino group on the released ends. The charged groups in each peptide is going to be different. (+/- , +/+, -/-, neutro)

Question 3

Degree of hydrolysis (DH):

It can be analysed by determining ….?

Answer 3

How many bonds in the protein have been split. Number of hydrolysed peptide bonds/ g protein
/total number of peptide bonds/ g protein * 100%

Determining the amount of free amino groups (-NH2) in the sample

Question 4

FIGURE 22: The amount of intact protein as function of the DH of B-lactoglobulin by V8 protease and BLP protease.

Answer 4

For the BLP at a degree of hydrolysis of 3% almost all the intact protein has been degraded, while for V8, still intact protein is present and this will affect the properties. In addition, intact proteins we get many peptides this results in changed properties. CONCLUSION: the DH does not contain any information on the amount of intact protein that may still be present, or on the size distribution of the peptides in the hydrolysate.

EXERCISE: Equal number of peptide bonds are broken down in hydrolysate V8 as in hydrolysate BLP AT 3%DH. Hydrolysate BLP contains relatively many larger peptides compared to hydrolysate V8 at 3 %DH.

Question 5

Gel properties: Effect of hydrolysis.

Answer 5

Acid induced gelation of soy glycinin hydrolysates: if you take native soy glycinin so a degree of hydrolysis of 0%. the intact protein only makes a gel at pH 5.4 (close to pI). If we take hydrolyzates you see that the pH where we get gelation is increasing (5.4, 6.8, 2.7,) and a certain pH the type of the gel is changing. It appears black holes–> syneresis, changed electrostatic and hydrophobic interactions result in changed aggregation and gel properties.

Question 6

Foam and emulsions: Effect of hydrolysis, two enzymes are use what is the different in some properties ( for example the foam capacity)?

Answer 6

Depends on the exact composition, this depends on the degree of hydrolysis.

Question 7

The foam properties of two protein hydrolysates made by different enzymes are compared. Why would the foam stability (at same DH ) be much higher for the protamex than for the alcalase hydrolysate ?

Answer 7

Difficult to predict only with this data, even at one DH you may have different peptides, as well as different amount of intact protein.