1st mid term Flashcards
Increasing particle size in order to speed up beer clarification can be accomplished by
use of fining agent
Isinglass consists of 70 % of the protein gluten
false
Stokes law units
g
n
v
d
p
g= m/s2
n= kg/m/s
v= m/s
d= m
p= kg/m3
Auxiliary finings have ____ charge at beer pH.
negative
Which of the following is not an advantages of Hollow Fibre Membrane Filters over DE filters?
low capital investment
Silica gel has ___ influence on foam stability.
No influence
PVPP
-completely removed by filtration
-has no negative effect on beer foam and flavour
Sterile filtration is an alternative to
pasteurization
Absolute removal rating of a membrane indicates
the largest opening in the filter element
D value is the time needed at a given temperature to
inactivate 90% of all viable microbial population
beer spoilage organisms are not
pathogenic
Sterilization is an absolute heat treatment process and will produce
a fully stable product.
What are two practical options for speeding up beer clarification based on Stoke’s law?
-increase particle size
-increase force of gravity
Cellulose
DE
Perlite
Cellulose - obtained from wood
DE - fossilized skeletons from algae
Perlite - volcanic origin
Darcys equation
K
L
p
u
A
Q
K - filter bed permeability
L - Height of filter bed
p- differental pressure
u - viscosity
A - constant cross section area
Q - total liquid percolating in unit time
Bubble point test gives an indication as to
the size of the largest pores in the membrane.
Pasteurization was developed in the
19th century
The aim of beer stabilization is to prolong the product shelf life through
the deactivation of Microorganisms and
enzymes.
Hydrogels have ___ water content than Xerogels.
higher
Removal efficiency of sterile filter is defined as the titre reduction. Tr = (No of organisms at inlet/No of organisms at
outlet). If the number of bacteria at inlet is 100 billion, and the number of bacteria at outlet is 100, determine Tr
value of the filter.
10^9
The viscosity of a liquid ____ with increase in temperature.
increase
Nominal
- Gives no indication of the sizes of the particles which
have passed through the filter
Beta rating
measures the total particle count change across the filter at several different particle sizes
