BAKER’S YEAST PRODUCTION AN OVERVIEW
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Transcript of BAKER’S YEAST PRODUCTION AN OVERVIEW
BAKER’S YEAST PRODUCTION
AN OVERVIEW
A SCHEMATIC FLOW DIAGRAM FOR THE PRODUCTION OF BAKER’S YEAST
For compresse
d
For ADY
Filter press
Filter press
Mixer & extruder
Extruder
Packaging
Dryer
Storage
3-5C
Cool storage
Consumer
Packaging
Bulk
Ammonia
H3PO4Mineral
s
Vitamins
De
former
F 3
F 4
Wort storage
Beet CaneChemicals
Mixer Clarifier
F 1F 2
PC
Pasteur flask
Aeration
Air blower
Culture
Wash & Storage
Cooler
Separator
CELL DIVISION BY BUDDING
MOTHER MOTHER CELLCELL
BUD INNITIATIONBUD INNITIATION
DNADNA
DNA DNA DUPLICATIODUPLICATIONN
BUD BUD ENLARGEMENT, ENLARGEMENT, NUCLEAR NUCLEAR MIGRATIONMIGRATION
DAUGHTER CELLDAUGHTER CELL
MOTHER MOTHER CELLCELL
(NUCLEUS)(NUCLEUS)
BUD SCARBUD SCAR
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
OXYGENCARBON SOURCE
NITROGEN SOURCE
CHROMOSOME DOUBLING BEFORE
CELL DIVISIONMICRO
NUTRIENTS
PHOSPHATE SOURCE
Daughter cell
Mother cell
Bud scar
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
GLUCOSE
PYRUVATE
ETHANOL
AcetaldehydeAt low O2 or
high glucose
At high O2
and/or low glucose
Glycolysis
AS IN A WINE FERMENTATION
2ATP
A decision point for carbon flow depending on oxygen tension and sugar in the
medium
AS WITH CELL PROPAGATION36ATP
ANAEROBIC AEROBIC
METABOLIC FATE OF GLUCOSE AS DICTATED BY FEED RATE AND OXYGEN (AIR)
GLUCOSE
PYRUVATE
ETHANOL
Acetaldehyde At low O2 or
high glucose
TCA
CYCLE
At high O2
and/or low glucose
BIOMASS
Glycolysis
PROPOSED PATHWAY FOR THE PROPOSED PATHWAY FOR THE PRODUCTION OF BIOMASS FROM CORN PRODUCTION OF BIOMASS FROM CORN
SYRUPSYRUP
- ketoglutarate
Succinate
Fumarate
Malate
Oxaloacetate
3ATP
3ATP
3ATP
3ATP
Acetyl CoA
Pyruvate
GLUCOSE
TCA CYCLE
ATPEnergyBIOMASS
CO2
O2
8ATP CO2
CO2
Precursors
Citrate
Glucose + O2 + N + P + Nutrients Biomass + CO2 + 38ATP
Ethanol
Feed-back
control O2
3ATP
Conditions that favor formation of volatiles during propagation of Torula
Yeast
Ethanol
Acetaldehyde
Acetate
Acetyl CoA
Ethyl acetate
Ethanol
CoA
FeO2
Low O2
Low Fe
Low O2
Low Fe
Low O2
Low Fe ADH
Acetaldehyde
Acetate
Ethyl acetate
TCA
CYCLE
Excessive contaminants also contribute to higher level of volatiles thereby affecting yields
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 BASISHENCE, HIGHER AMOUNTS NEEDED
BETTER STORAGE STABILITY AT ROOM TEMPERATURE
SIGNIFICANT SAVING ON TRANSPORTATION COSTS
SPECIAL REHYDRATION PROCEDURES NEEDED
EFFECT OF TREHALOSE DURING DRYING
Cell wall
of compressed yeast
DRYING
Membrane
Dry cell wall
Leaky membrane
Trehalose effect
A more stable
membrane
DRYING
Lipids
Proteins
Shrunken Protein
1 2 3
OUT
INSIDE
YEAST
CELL
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+
H+
H+
pH remains steady
pH gets lowered
ACID INTOLERANCE
Example: BacteriaACID TOLERANCE
Example: Yeast
Proton Pump
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
Bacteria 3 6 12 24 48 96 192
Time 0 20 40 60 80 100 120
(Minutes)
Yeast 40 80
Generation time for yeast: 100 minutes
Generation time for bacteria: 20 minutes
PROBABLE MECHANISM IN THE INDUCTION OF ENZYMES TO UTILIZE A NEW SUBSTRATE
Gene
Transcription
translation
DNAMessenger
RNA
Polypeptide chain
Coiling
ETHANOL
PYRUVATE
Enzyme
ATP ATP
ATP
TCA
cycle
EXAMPLE: A CHANGE FROM GLUCOSE TO
ETHANOL
Tilak 11.4.04
[> 30 MINUTES]
Template
BREAKDOWN OF SUGAR DURING WINE FERMENTATION
O
CH2OH
H
OH
OH
OHOH
H
H
C C OH
H
H
H H
H
CO
O
H
HOGlucose
(Corn Syrup)
Ethanol
Carbon dioxide
WaterC6H12O6 ; MW=180
C2H5OH; MW=46
CO2; MW =44
H2O; MW =18
C6H12O6 2[C2H5OH] + 2[CO2] + 57 kcal (2ATP)
Wine Fermentatio
n 180 92 88
BREAKDOWN OF SUGAR DURING YEAST PROPAGATION
O
CH2OH
H
OH
OH
OHOH
H
H
C C OH
H
H
H H
H
CO
O
H
HOGlucose
(Corn Syrup)
Ethanol
Carbon dioxide
WaterC6H12O6 ; MW=180
C2H5OH; MW=46
CO2; MW =44
H2O; MW =18
C6H12O6 + 6[O2] BIOMASS + 6[H2O] + 6[CO2] + 686 kcal
Baker’s propagation
180 192 108 264 (38ATP)