2. What part does each play in the
making of bread?
GLUTEN – provides dough with elasticity
and strength.
YEAST – makes dough rise and gives it it’s
porous texture
Under
developed
gluten
Developed
gluten
5. Hydration of dry active yeast
Dry active yeast must
be hydrated with
warm water, not too
hot.
The proper
temperature helps the
yeast give off the
correct amount of
carbon dioxide.
Too
Cold
85°
If the water is too hot,
the balloon doesn’t
inflate at all!
6. In order to grow yeast needs:
Moisture -- Milk or water
Warmth -- @ 110° F
Food -- sugar
OR
7. How does each affect the growth
of yeast?
Sugar
– Provides food for the
yeast to grow.
Salt
– Controls the growth of
the yeast.
8. Four main processes for making
yeast dough:
1. MIXING
2. KNEADING & RISING
3. SHAPING & RISING
4. BAKING
mixing
Kneading
and rising
10. Yeast Growth
As yeast grows CARBON DIOXIDE
develops causing the dough to rise.
Once multiplying begins
11. How do you know the bread has
risen enough?
Should double in size
Push two fingers into the dough, if the holes
remain but the top stays smooth and satiny.
12. Why is the milk scalded then
cooled?
To destroy enzymes that make dough sticky
To allow yeast to grow at optimum temp.
– Too hot of temperature will kill the yeast!
13. What does kneading do?
Develops the gluten so the dough will
stretch and expand.
1
2 3
4
How to knead
14. When judging bread look for:
Appearance
– Uniform golden brown
– Smooth rounded top
– Creamy white inside
Crumb
– Cut surface is moist
and springy to touch
18. Yeast is used for making alcohol.
Yeast is a single-celled fungus
Yeast cells feed saprophytically. This means they
secrete enzymes from their cells. The enzymes
digest the food on which the yeast is living, breaking
down large molecules into small ones. The small
molecules then diffuse into the yeast cell.
19. 'Wild' yeast grows in many different places. It
usually grows on foods which contain sugar,
such as fruit. When we grow yeast, we need to
provide it with the types of food which it needs. It
is usually grown in a solution containing
carbohydrate - usually in the form of sugar and
minerals, including ammonium ions. Each yeast
cell absorbs the sugar and minerals, and uses
some of them to grow. When the cell gets to a
certain size, it produces a new cell by budding.
Yeast cells reproduce fastest when the tem-
perature is quite warm, around 40 °C.
20. People have been using yeast for thousands of years to
make alcohol. If yeast is added to a sugar solution, it
absorbs some of the sugar into its cells. It then uses this
sugar in respiration.
Usually, the yeast respires anaerobically. When it does this,
it converts the sugar to ethanol (a type of alcohol) and
carbon dioxide. This process is called alcoholic
fermentation. 'Fermentation' is a name for any type of
respiration which makes a product other than carbon dioxide
and water. The equation for alcoholic fermentation is:
Glucose → alcohol + carbon dioxide + energy
21. Many different alcoholic drinks are made in
this way Beer is made by providing the
yeast with the sugar maltose, obtained from
germinating barley seeds. Usually, hops
are added as well, to give a bitter flavour to
the beer. Wine is made by providing the
yeast with sugar from grapes.
22. Yeast is used for making bread.
When yeast respires, it produces carbon dioxide. If this
happens inside a dough made from flour and water, the
bubbles of carbon dioxide get trapped in the dough, and
make it rise. This is how bread is made. The dough is
made using flour made from cereal grains, usually
wheat. The flour contains starch, amy- lase and protein.
23. The starch is the energy source for the yeast.
The amylase digests the starch to sugar, so that
the yeast can absorb it and use it in respiration.
Some bread flours have extra amylase added to
them to speed up this process. The amylase
does not begin acting on the starch until water is
mixed with the flour.
The protein is important for the texture of the
bread. The most important protein in bread flour
(apart from the amylase!) is called gluten. This
forms sticky, threads as the yeast works on the
dough.
24. This helps to trap the bubbles of carbon dioxide, and
makes the dough rise well. Farmers who want to sell
their wheat for bread making choose varieties which are
known to produce grains containing a lot of gluten.
To make bread, yeast, sugar, flour and water are mixed
together to make a dough, which is then left in a warm
place to rise. The dough is then mixed again, and made
into the shapes of the loaves to be made. It is left to rise
again, and then baked. The high tempera- tures kill the
yeast, break down the alcohol which it has made, and
alter the remaining starch and gluten to make a firm
textured bread.
25.
26.
27.
28.
29.
30. Use of enzyme in biological washing powders
Biological washing powders contain protease and lipase to remove protein
stains
and fat/grease from clothes. The enzymes break down proteins or fats on
the fabric,
forming water-soluble substances that can be washed away.
31. Example: Blood contain the red protein Haemoglobin (Hb). The
Proteases in biological washing powder break Hb molecules into
smaller molecules, which are not coloured and which dissolve in water
and can be washed away.
This makes the washing powder more effective than detergent alone,
especially at lower temperatures.
This save energy (no need to boil water), but if the temperature is
too high, the enzyme will be denatured.
32.
33.
34.
35.
36. Fermenter or bioreactor refers to a device that
provides all the basic necessities important for
biological product extraction. A fermenter
contains different devices that help to maintain
the environmental factor inside it which in turn
leads to the production of biological products.
Therefore the main objective of a fermenter is
to maintain a controlled environment that
supports the growth of the bacteria or any
other organism.
37. here are several important factors that need to be accurate
to design a fermenter. Those factors are following
•The vessel should be well equipped to maintain aseptic
conditions inside it for a number of days.
•Aeration and agitation are important for the production of
biological metabolites. However, controlled agitation is
required to prevent any damage to the cells.
•It should be less expensive in terms of power consumption.
•Temperature is an important environmental factor required
for microbial growth. Therefore, a temperature control
system is required.
38. •Optimum pH is important for the growth of the organism;
therefore, the fermenter must be equipped with a pH
controller.
•The fermentation of a huge culture is a time-consuming
process. It needs to be contamination-free until the
process is complete. Apart from that, it is also important
to monitor the growth rate of the organism. Therefore, an
aseptic sampling system is needed to design a fermenter.
39. •The fermenter vessel should be designed properly to
minimize the labor involved in cleaning, harvesting, etc.
•It should be designed in such a way that it reduces
evaporation.
•The vessel needs to be equipped with a smooth
internal surface to support adequate mixing.
