Scribd
Upload
356 views1 page

Yeast Production Process Explained

Yeast production takes approximately five days and involves four stages: 1) Preparing molasses and other raw materials for fermentation. 2) Growing a pure culture of yeast which is then transferred to progressively larger seed and semi-seed fermenters. 3) Conducting large-scale fermentation in commercial fermenters up to 50,000 gallons in size, where the yeast population increases 5-8 times over 15-20 hours. 4) Filtering and packaging the finished yeast by centrifuging, filtering, and packaging in bags for distribution.

Uploaded by

Oluwaseun Godson
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
356 views1 page

Yeast Production Process Explained

Yeast production takes approximately five days and involves four stages: 1) Preparing molasses and other raw materials for fermentation. 2) Growing a pure culture of yeast which is then transferred to progressively larger seed and semi-seed fermenters. 3) Conducting large-scale fermentation in commercial fermenters up to 50,000 gallons in size, where the yeast population increases 5-8 times over 15-20 hours. 4) Filtering and packaging the finished yeast by centrifuging, filtering, and packaging in bags for distribution.

Uploaded by

Oluwaseun Godson
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
You are on page 1/ 1

Operating review

Explaining the business

The magic ingredient:


The yeast production process

The essential ingredient in the production of so many of our


day-to-day products. But how is it made?
stage one

stage two

stage three

seed
fermenter

frozen
vial

stage four

semi-seed
fermenter

filter
press
yeast
storage

beet
molasses

growth
tube

commercial
fermenter

semi-seed
fermenter

pa
l

pa
ck

le

ag

semi-seed
yeast
storage

tis

in
g

er

pre-pure
culture
tank

cane
molasses

as

tc

washing

stage one molasses and


raw material preparation
Yeast production takes approximately
five days from start to finish and
begins with the energy source for
yeast growth sugar. Beet and cane
molasses are commonly used
because the sugars present in
molasses are readily fermentable.
Yeast also needs minerals, vitamins
and salts for growth, which are often
added to the molasses prior to flash
sterilisation which produces the
mash or wort used to feed the yeast
as it grows.

stage two culture or


seed yeast preparation
Yeast production starts with a pure
culture tube or frozen vial of the
appropriate yeast strain. This yeast
serves as the inoculum for the

pre-pure culture tank where seed


is grown under sterile conditions
before being transferred to a larger
pure culture fermenter. From the
pure culture vessel, the grown
cells are transferred to a series
of progressively larger seed and
semi-seed fermenters. These later
stages are conducted as fed-batch
fermentations where the yeast
is fed molasses, phosphoric acid,
ammonia and minerals.

stage three fermentation


and harvesting
At the end of the semi-seed
fermentation, the spent molasses
are removed and the yeast is washed
with cold water and held in a storage
tank at 34 degrees Fahrenheit
(1 degree Celsius) before it inoculates
the commercial fermentation tanks.

14 // Associated British Foods Annual Report and Accounts 2008

yeast
cooler

st

sterile
mash tank

di

flash
steriliser

rib

ut

io

ye

pure culture
fermenter

oo

le

separation

These commercial fermenters are up


to 50,000 gallons in size and are the
final step in the fermentation process.

is kept at approximately 86 degrees


Fahrenheit (30 degrees Celsius) and
the pH in the range of 4.55.5.

Following addition of the seed


yeast, aeration, cooling and nutrient
additions are started to begin a
1520 hour fermentation. At the
beginning of the fermentation, the
liquid seed yeast and additional
water may occupy only about one
third to one half of the fermenter
volume. Constant additions of
nutrients during the course of
fermentation bring the fermenter to
its final volume. The rate of nutrient
addition increases throughout the
fermentation and by the end of the
process the number of yeast cells
will have increased by between
five and eight times. During
fermentation the temperature

stage four filtration


and packaging
At the end of fermentation, the
resultant broth is separated, washed
with water and re-centrifuged to
yield a yeast cream, which is then
cooled to about 45 degrees
Fahrenheit (7 degrees Celsius).
Cream yeast can be loaded directly
into tankers for delivery direct to
customers or can be pumped to a
plate and frame filter press and
dewatered to a cake-like consistency,
which is crumbled into pieces and
refrigerated. Bags of yeast can then
be distributed to customers in
refrigerated trucks.

You might also like