Transcript Glucose or Ethanol

BAKER’S YEAST PRODUCTION
AN OVERVIEW
A SCHEMATIC FLOW DIAGRAM FOR THE
PRODUCTION OF BAKER’S YEAST
Chemicals
Beet
PC
Culture
Ammonia
F1
Pasteur
flask
Cane
F2
H3PO4
Aeration
Minerals
De
Vitamins
former
Mixer
Clarifier
Air blower
Wort
storage
F3
Cooler
Wash &
Storage
F4
Separator
For
compressed
Filter press
Mixer &
extruder
Packaging
Storage
3-5C
Consumer
For ADY
Filter press
Extruder
Dryer
Packaging
Bulk
Cool
storage
CELL DIVISION BY BUDDING
BUD INNITIATION
DAUGHTER CELL
(NUCLEUS)
DNA
BUD SCAR
MOTHER
CELL
DNA
DUPLICATION
BUD
ENLARGEMENT,
NUCLEAR
MIGRATION
MOTHER CELL
BASIC REQUIREMENTS FOR CELL DIVISION
‡ Carbon matrix to build the structure (glucose
or ethanol)
‡ Nutrients to produce bio-molecules (O2, P, N,
micro nutrients, Trace elements, etc)
‡ Energy source to drive the biological systems
(Glucose or Ethanol)
PREREQUISITS FOR BUDDING OR CELL
DIVISION
Bud scar
OXYGEN
CARBON
SOURCE
PHOSPHATE
SOURCE
Mother cell
NITROGEN
SOURCE
Daughter cell
MICRO
NUTRIENTS
CHROMOSOME DOUBLING
BEFORE CELL DIVISION
POWER BEHIND LIFE
 LIFE NEEDS ENERGY TO CARRY OUT ITS TASKS
 ATP - LIFE’S BATTERY
 IT’S THE ENERGY CURRENCY MOLECULE OF CELL
 GLUCOSE OR ETHANOL AT HIGH OXYGEN
TENSION PROVIDES THE NECESSARY ATP TO
DRIVE ALL REACTIONS INCLUDING CELL
DIVISION
HOW YEAST BEHAVES UNDER AEROBIC VS
ANAEROBIC CONDITIONS
 ANAEROBIC (No Oxygen):
Alcoholic fermentations, Example: wine or beer
fermentations
 AEROBIC (In the presence of Oxygen)
Yeast propagation
CRITICAL DIFFERENCE IN ATP GENERATION
 Alcohol production via anaerobic conditions
utilize one pathway
 ATP produced by anaerobic pathway is low
(2ATPs)
 Biomass production via aerobic conditions utilize
another pathway
 ATP production via aerobic pathway is high
(38ATP)
METABOLIC FATE OF GLUCOSE UNDER ANAEROBIC VS AEROBIC
CONDITIONS
ANAEROBIC
AEROBIC
GLUCOSE
Glycolysis
2ATP
PYRUVATE
At high O2
and/or low
glucose
AS WITH CELL PROPAGATION
36ATP
Acetaldehyde
ETHANOL
At low O2 or
high glucose
AS IN A WINE FERMENTATION
A decision point for carbon flow
depending on oxygen tension
and sugar in the medium
METABOLIC FATE OF GLUCOSE AS DICTATED BY FEED RATE AND
OXYGEN (AIR)
GLUCOSE
Glycolysis
At high O2
and/or low
glucose
PYRUVATE
Acetaldehyde
ETHANOL
TCA
CYCLE
At low O2 or
high glucose
BIOMASS
PROPOSED PATHWAY FOR THE PRODUCTION OF
BIOMASS FROM CORN SYRUP
Glucose + O2 + N + P + Nutrients
Biomass + CO2 + 38ATP
GLUCOSE
Feed-back
control
O2
Citrate
Ethanol
3ATP
CO2
TCA CYCLE
CO2
Pyruvate
 - ketoglutarate
3ATP
8ATP
Acetyl CoA
3ATP
O2
CO2
Succinate
3ATP
Oxaloacetate
Fumarate
Precursors
BIOMASS
Energy
3ATP
ATP
Malate
Conditions that favor formation of volatiles
during propagation of Torula Yeast
Ethanol
Acetaldehyde
Low O2
Low Fe
ADH
Ethanol
Acetaldehyde
TCA
Low O2
Ethyl acetate
CYCLE
Acetate
Low O2
Low Fe
CoA
O2
Fe
Acetyl CoA
Acetate
Excessive contaminants also contribute to higher level of volatiles
thereby affecting yields
Low Fe
Ethyl acetate
TYPICAL COMPOSITION OF CREAM OR
COMPRESSED YEAST (ON SOLIDS BASIS)
PROTEIN (N X 6.25)
52%
CARBOHYDRATES
30%
MINERALS
8%
NUCLEIC ACID
5%
LIPIDS
4%
OTHERS
1%
ACTIVE DRY YEAST
CHARACTERISTICS OF ACTIVE DRY YEAST
 SPECIAL STRAINS WITH HIGH TREHALOSE ACCUMULATION USED
TO WITHSTAND DRYING CONDITIONS
 MOISTURE CONTENT IN THE 3-7% RANGE
 YEAST LESS ACITVE THAN COMPRESSED ON EQUAL SOLIDS BASIS
HENCE, HIGHER AMOUNTS NEEDED
 BETTER STORAGE STABILITY AT ROOM TEMPERATURE
 SIGNIFICANT SAVING ON TRANSPORTATION COSTS
 SPECIAL REHYDRATION PROCEDURES NEEDED
EFFECT OF TREHALOSE DURING DRYING
YEAST
CELL
1
2
3
Proteins
Shrunken Protein
Lipids
OUT
DRYING
DRYING
Trehalose
effect
INSIDE
Membrane
Cell wall
of compressed
yeast
Dry cell wall
Leaky
membrane
A more stable
membrane
CRITICAL CONTROL POINTS IN THE
PRODUCTION OF ACTIVE DRY YEAST
 LOWER % NITROGEN AIMED IN THE YEAST
- GENERALLY IN THE 6.5 - 7% RANGE
 LESS PHOSPHERIC ACID TO COMPENSATE REDUCED AMMONIA
 END BUD INDEX TO BE LESS THAN 2%
- CONTROL FEED AT END TO LIMIT BUDDING(MATURATION)
 EXTRUDE COMPRESSED YEAST TO 0.2 - 0.3 CM
 DRY IN TRAY DRYER (P & S DRYER)
INSTANT ACTIVE DRY YEAST
CHARACTERISTICS OF INSTANT ACTIVE DRY
YEAST
 PRODUCTION PROCEDURE PARALLELS ADY PROCEDURE
 SPECIAL STRAINS USED FOR HIGHER ACTIVITY AND DRYABILITY
 LOW NITROGEN AIMED IN YEAST
 NO SPECIAL REHYDRATION PROCEDURE NECESSARY
 NOODLES MADE THINNER TO IMPROVE REHYDRATION
 GENERALLY VACUUM PACKED TO RETAIN STABILITY
CRITICAL CONTROL POINTS IN THE
PRODUCTION OF INSTANT ADY
 UP STREAM PROCESSING PARALLELS ADY PROCESS UP TO POINT
OF CAKE PRODUCTION
 THINNER NOODLES TO INCREASE SURFACE AREA OF PELLETS
 EMULSIFIER TO IMPROVE EXTRUSION
 DRY BY A MORE GENTLE AIR LIFT DRYING PROCESS
 USE VACUUM PACK TO MAINTAIN STABILITY FOR LONGER
PERIODS
MECHANISM OF ACID TOLERANCE IN THE
MICROBIAL WORLD
H+
H+
pH gets
lowered
H+
ACID INTOLERANCE
Example: Bacteria
Proton Pump
pH
remains
steady
H+
ACID TOLERANCE
Example: Yeast
BACTERIA VS YEAST - MAJOR DIFFERENCES
 Yeast produces ethanol at low oxygen and biomass at high
oxygen. Bacteria does not follow this rule. Hence, bacteria
can proliferate more easily.
 Aerobic bacteria grow fast and anaerobic bacteria grow
slower under high O2 tension. The opposite occurs at low
O2 tension
 Growth rate of bacteria is 5 - 8 times faster than yeast
 Under conditions where yeast growth is suppressed,
bacteria can gain dominance, instantaneously
PROBABLE WAY THE CELLS INCREASE AFTER pH
TREATMENT
Yeast
Generation time for yeast:
100 minutes
Generation time for bacteria:
20 minutes
40
80
Bacteria
3
6
12
24
48
96
192
Time
0
20
40
60
80
100
120
(Minutes)
PROBABLE MECHANISM IN THE INDUCTION OF
ENZYMES TO UTILIZE A NEW SUBSTRATE
EXAMPLE: A CHANGE
FROM GLUCOSE TO
ETHANOL
ETHANOL
Transcription
ATP
translation
ATP
Coiling
ATP
Enzyme
DNA
Gene
Template
Messenger
RNA
Polypeptide
chain
PYRUVATE
[> 30 MINUTES]
TCA
cycle
Tilak 11.4.04
BREAKDOWN OF SUGAR DURING WINE
FERMENTATION
Wine
Fermentation
C6H12O6
2[C2H5OH] + 2[CO2] + 57 kcal (2ATP)
180
92
88
C
O
O
CH2OH
H
OH
O
H
H
OH
OH
H
OH
Glucose
H
H
C
C
H
H
Carbon dioxide
CO2; MW =44
OH
Ethanol
C2H5OH; MW=46
H
O
H
(Corn Syrup)
C6H12O6 ; MW=180
Water
H2O; MW =18
BREAKDOWN OF SUGAR DURING YEAST
PROPAGATION
Baker’s
propagation
C6H12O6 + 6[O2]
180
BIOMASS + 6[H2O] + 6[CO2] + 686 kcal
192
108
(38ATP)
264
C
O
O
CH2OH
H
OH
O
H
H
OH
OH
H
OH
Glucose
H
H
C
C
H
H
Carbon dioxide
CO2; MW =44
OH
Ethanol
C2H5OH; MW=46
H
O
H
(Corn Syrup)
C6H12O6 ; MW=180
Water
H2O; MW =18