Process engineering

Question 1

Glucose has a molecular weight of 180g/mol. what is the Mw in Cmol?

Answer 1

30g/Cmol. (180/6)

Question 2

What is meant for Cmol?

Answer 2

Converting a molecule like glucose to have C expressed as 1. So glucose is C6H12O6 then it become CH2O.

Question 3

In a graph Mx over time an exponential growth is observed. In the first section we see almost no increase in growth? is this considered a lag phase?

Answer 3

No, lag phase can be only be observed only if Mx is expressed in log.

Question 4

What are the four stage of bacterial growth?

Answer 4

1. Lag phase -> cell dividing cannot still occur. RNA synthesis and other components are playing occuring
2. Exponential of Log phase -> cell number doubles
3. Stationary phase -> Growth rate equals death rate due to limiting nutrients
4. Death phase -> bacteria die as a result of no available nutrients.

Question 5

What are the three assumptions made for bacteria growth?

Answer 5

1. All cells stay in the flask
2. Constant td (doubling time) and u (growth constant)
3. Constant average cell size

Question 6

If oxygen is consume is the production rate positive or negative?

Answer 6

Negative

Question 7

rs= (rx/Yxs + msMx) -> what does ms stand for and what does msMx indicate

Answer 7

ms = maintenance coefficient
ms*Mx = cell maintainance, not for growth

Question 8

When can maintenance be neglected?

Answer 8

When cells grow as fast as they can

Question 9

Why is buckwheat seeds used in combination with P. roqueforti?

Answer 9

Because buckwheat have specific mechanical properties and high sporulation yields.

Question 10

How is cooling conducted in liquid and solid fermentation?

Answer 10

Liquid:
1. Convection due to stirring
2. Conduction through wall

Solid
1. Conduction via medium and wall
2. Evaporation cooling