enzymes 3

Question 1

in a natural setting apple juice is cloudy: how can a clear juice be obtained?

Answer 1

adding exogenous pectinases

Question 2

extra effects of adding pectinase:

Answer 2

• increase juice yield
• intense colour and increased flavour

Question 3

which enzymes are added to the pulp for total liquification?

Answer 3

pectinases and cellulases

Question 4

how does the enzyme pectinases and cellulases cause extreme high juice yield?

Answer 4

cell walls are almost completely degraded by cellulase

Question 5

problem 1:
you have a highly esterified pectin, and you want to make a strong Ca2+ gel with it

Answer 5

solution:
vegetable PME
This hydrolyzes the methanol group in the blocks; is necessary for gel formation

Question 6

problem 2:
you have a pectin that makes strong Ca2+ gel, you want a less strong gell

Answer 6

endo-PG;
cuts in the middle of the pectin chain so shorter chains are produced

Question 7

problem 3:
you have got a highly esterified pectin, which you use to make a sugar/ acid gel. you would like it less strong. you do not want to split off methanol

Answer 7

Pectin lyase; cuts in the middle of the chain next to the methylated group

Question 8

problem 4:
you have got a highly esterified pectin, which you want to degrade completely into galacturonic acid. which combination fits this purpose?

Answer 8

PME + PG + exo-PG;
PME + PG produce galacturonic acid

Question 9

what does invertase do?

Answer 9

makes from saccharose –> glucose + fructose

Question 10

what does lactase do?

Answer 10

makes from lactose –> galactose + glucose

Question 11

what does beta amylase do?

Answer 11

hydrolyses 1,4-bond from non-reduced end. Produces maltose.

Question 12

what does alpha amylase do?

Answer 12

only hydrolyses 1,4 bond: produces glucose and a rest.

Question 13

what does glucoamylase do?

Answer 13

hydrolyses all 1,4-bonds and 1,6-bonds: finally produces glucose.

Question 14

what does isoamylase do?

Answer 14

hydrolyses only 1,6-bonds.