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YEAST IN FOOD TECHNOLOGY:
Overview and Current Development
Lilis Nuraida
Southeast Asian Food and Agriculture Science & Technology Center
and
Departement of Food Science and Technology
Bogor Agricultural University - Indonesia
Yeast Technology in Food Industry
Jakarta September 4, 2007
YEAST
Unicellular Eukaryotes
Yeast Technology in Food Industry
Jakarta September 4, 2007
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Outline
• History, development and application of
yeast
• Technological function of yeast and yeast
preparation
• Yeast starter culture
• Production Process of Baker’s
Baker s Yeast
• Yeast Derived Products: Type, function
and production
Yeast Technology in Food Industry
Jakarta September 4, 2007
HISTORY AND DEVELOPMENT OF YEAST
First approved genetically engineered wine yeast,
brewer’s yeast, baker’s yeast
S. cerevisiae’s genome was the first eukaryote genome
fully sequenced
Improvement of industrial yeast strain
Yeast taxonomy study
Yeast observed in
malt, named
Saccharomyces
cerevisiae
Late 1600s
2000-6000
BC
Late 1800s
End 20th and 1st
ys 21st Century
Late 1900s
Isolation of single yeast and
employement of pure yeast
starter cultures for beer and wine
Early 1800s
Microscopic appearance of yeast (van Leeuwenhoek, 1685)
Fortuitous use of yeast in wine making (Caucasia), beer brewing
(Sumeria, Babylonia) and dough leavening (Egypt)
Verstrepen et al. 2006
Yeast Technology in Food Industry
Jakarta September 4, 2007
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Saccharomyces yeasts
• Mankind’s oldest domesticated
microorganism
• Considered to be the best studied and
most used yeast:
– 30 million tons of wine p.a.
– 60 million tons of beer p.a.
– 600,000 tons of baker yeast p.a.
– 800,000 tons of single cell protein p.a.
Verstrepen et al. 2006
Yeast Technology in Food Industry
Jakarta September 4, 2007
The road of discovery and application of yeast
Synthetic Biology
Systems
y
Biology
gy
Molecular Biology
Genetics
Biochemistry
•
•
•
Prospect of the
synthesis of entire
genomes for
construction of
“ideal” industrial
yeast
Exploitation of biological complexity
of yeast strain improvement for
example to optimise yeast cell
process.
Metabolic engineering of yeast by directed genetic
modifications and reconstruction to improve
performance of industrial strains
•
Microbiology
•
•
•
•
Genetics engineering
g
g of yyeast by
yg
gene cloning
g and
trnasformation of specific genes for a new desirav=ble
characteristics
Genetics breeding
Mutagenesis and selection
Clonal selection
Isolation and Identification
Adapted from Verstrepen et al. 2006
Yeast Technology in Food Industry
Jakarta September 4, 2007
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Technological Function of Yeast
• Dough Leavening (baker’s yeast)
• Brewing (brewer’s yeast)
• Distilled alcohol beverages fermentation
(distiller’s yeast)
• Wine fermentation (wine yeast)
• Other alcoholic fermentation (ragi)
– Indonesia:
I d
i ttape, brem
b
• Dairy fermentation (kefir grain)
• Soy fermentation (soy sauce, tauco)
Yeast Technology in Food Industry
Jakarta September 4, 2007
Desirable properties of Baker’s Yeast
• S. cerevisiae:
– Rapid maltose fermenting ability
(lean dough yeast)
– Improved osmotolerance (sweet
dough yeast)
– Rapid fermentation kinetics
– Freeze/thaw tolerance
– Substrate metabolism:
• Melibiose utilising ability (beet
molasses as substrate)
• Lactose utilising ability (whey as
substrate)
Yeast Technology in Food Industry
Jakarta September 4, 2007
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Desirable properties of Brewer’s
Yeast
• Bottom fermentation process (ale)
– S.cerevisiae
• Top fermentation process (lager)
– S. uvarum
• Carbohydrate utilization
– Increase metabolism of maltose and
maltotriose in malt wort
– Ferment dextrin and starch
• Efficiency and low calorie (light) beer
Yeast Technology in Food Industry
Jakarta September 4, 2007
Desirable properties of Distiller’s
Yeast
• Natural fermentation: any number of
species may be involved
• Controlled fermentation: S.cerevisiae
– Very alcoholic tolerant and gives a good yield
– Ferments rapidly
y
– Good flavor production
Yeast Technology in Food Industry
Jakarta September 4, 2007
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Wine Yeast
• Controlled fermentation started in 20th century
• Natural fermentation involves different yeast
species such grow succesively at initial.
– In the most active fermentation stage to end
of fermentation: Saccharomyces cerevisiae
• Desirable characteristics:
– Rapid fermentation rate
– Tolerance to SO2
Yeast Technology in Food Industry
Jakarta September 4, 2007
Yeast Preparation based on
Activity
• Yeasts are available in several forms, and
are classified
l
ifi d on th
the b
basis
i off th
their
i activity.
ti it
– Active yeasts include:
• Baker’s yeast
• Brewer’s yeast
• Yeasts for alcoholic beverages
– Inactive yeasts, such as:
• Dried brewer’s yeast
• Primary- grown yeasts
Yeast Technology in Food Industry
Jakarta September 4, 2007
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Yeast Starter Culture Preparation
• Yeast Cream (18-20% solid)
• Compressed yeast (27-32% solid)
• Dry yeast (8% moisture)
– Active Dry Yeast
– Instant Dry Yeast
Perishable, kept
refrigerated
Shelf-life up to 2 y
in suitable
packaging
• Traditional
ad t o a d
dry
y yeast ((ragi)
ag )
• Kefir grain
Yeast Technology in Food Industry
Jakarta September 4, 2007
Storage Stability of Active Dry Baker’s Yeast
in Variuos Atmosphere
Atmosphere
Residual Activity (%)*)
Nitrogen
79.5
Carbon dioxide
81.9
Carbon monoxide
85.2
Argon
80.7
Hydrogen
88.9
Air
43 3
43.3
Vacuum
70.3
*) after storage for 3 d at 55oC
Hill, 1987
Yeast Technology in Food Industry
Jakarta September 4, 2007
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Ragi and Kefir grain
• Kefir grain
• Ragi
– Mixed yeast culture
– Present together with
amylolytic molds
– Mixed
Mi d yeastt culture
lt
– Present together
with lactic acid
bacteria
Yeast Technology in Food Industry
Jakarta September 4, 2007
Yeast Biomass
• B
Baker’s
k ’ Y
Yeast
• Brewer’s Yeast
• Single Cell Protein
Used for food
Used in food is limited
Mainly for feed
Yeast Technology in Food Industry
Jakarta September 4, 2007
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Production Process of Baker’s
Yeast
Raw Materials
FILTRATION
FERMENTATION STAGES
Flask fermentation
BLENDING
Pure culture fermentation
Intermediate fermentation
EXTRUSION AND
CUTTING
DRYING:
tunnel, fluid
bed
Compressed Yeast
Dried Yeast
Stock fermentation
Pitch fermentation
Trade fermentation
PACKAGING
Yeast Technology in Food Industry
Jakarta September 4, 2007
Baker’s yeast fermentation
• Substrate:
– Molasses: beet and/or cane
– Other: whey
• Fermentation condition:
– Aerobic
Yeast Technology in Food Industry
Jakarta September 4, 2007
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Processing aids and additives to
improve activity of Dry Yeast
• Added to yeast cream or press cake prior
to drying:
– Swelling agent:
• Methyl cellulose or carboxymethyl cellulose (1-2%
of yeast solid) (Langejan, 1980)
– To reduce solid leaching
• Monoglycerides,
gy
soya
y lecithin, g
glycerol
y
p
polyesters
y
and sorbitan esters (Hill, 1987)
– To improve storage in air:
• Addition antioxidant
Yeast Technology in Food Industry
Jakarta September 4, 2007
Yeast-Derived Products
• Yeast Extract
• Yeast Autolysates
Contains guanosine 5’monophosphate (GMP),
ionosine 5’monophosphate (IMP),
glutamic acid
• Application:
– Flavoring
g agent
g
in soup,
p, sauces,, g
gravies,,
stew, snack food etc.
– Main component of savoury spreads:
Vegemite and Marmite
Yeast Technology in Food Industry
Jakarta September 4, 2007
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Yeast Extract Components
•
•
•
•
•
•
•
Amino acids
Peptides
Nucleotides
Proteins
Carbohydrates
Vitamins
Flavor compounds
Yeast Technology in Food Industry
Jakarta September 4, 2007
Product definition
• Yeast Extract:
– Yeast extract comprises the water soluble
components of the yeast cell, the composiiton
of which is primarily amino-acids, peptides,
carbohydrates and salts. Yeast extract is
produced through the hydrolyses of peptide
bonds by the naturally occurring enzymes
present in edible yeast or by the addition of
food grade enzymes
The Food Chemical Codex
Yeast Technology in Food Industry
Jakarta September 4, 2007
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Product definition
• Yeast Autolysates/Autolysed yeast:
– Autolysed yeast is the concentrated,
concentrated not
extracted, partially soluble digest obtained
from food-grade yeast. Solubilisation is
accomplisehd by enzyme hydrolysis or
autolysis of yeast cells. Autolysed yeast
contains both soluble and insoluble
components derived from the whole yeast
cells.
The Food Chemical Codex
Yeast Technology in Food Industry
Jakarta September 4, 2007
Composition
Yeast Extract
Yeast Autolysate
• Protein content: 5075%
• Total carbohydrate: 413%
p content: very
y
• Lipid
little
• Protein content: 5069%
• Total carbohydrate
content: 15-25%
• Lipid content: 3-10%
Yeast Technology in Food Industry
Jakarta September 4, 2007
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Preparation of Yeast Extract
• Requires disruption of cell walls:
– Autolysis by endogenous enzymes*)
– Plasmolysis: modified autolyses in the
presence of accelerator, i.e. salt or organic
solvent
– Mechanical desruption
p
– Hydrolysis by acid or by exogenous enzymes
*)practical on industrial scale
Yeast Technology in Food Industry
Jakarta September 4, 2007
Production Process of Yeast
Extract
Absent in
production of
yeast
autolysate
Yeast cream
Clarification
Plasmolyses
Concentration
Autolyses
y
Liquid: 50-65% dry matters
Paste: 70-80%
70 80% dry matters
Pasteurisation
Packed in
pails, drums
Spray, roller
drying
Yeast Technology in Food Industry
Jakarta September 4, 2007
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Source of yeast cream
• Conventional:
– Baker’s Yeast
– Brewer’s Yeast
• Alternative:
• Candida utilis
• Kluyveromyces marxianus
Enriched yeast extract in amino acid cystein produced
through the application of GE-yeast to over express and over
produce the yeast cystein-rich protein metallothionein (Stam
et al., 2000)
Yeast Technology in Food Industry
Jakarta September 4, 2007
Condition for Yeast Extract Production
Steps
Autolyses and
Plasmolyses
Pasteurisation
Concentration
Condition
55 oC for 24 h, pH 5.5
1st : 70oC for 15 h
2nd: 70-75oC for 2-5 h
(after clarification)
Temperature <55oC
Adapted from Biocatalyst Ltd
Yeast Technology in Food Industry
Jakarta September 4, 2007
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Common problem encountered in yeast extract
production
Problem
Solution*)
Enzyme not working
Ensure no direct heat
Low yield autolysis
Check pH and temperature of slurry at
each stage
Extend autolyses time
Add protease
Over heat
Add protease
Clarification problems caused by Add glucanase
insoluble glucans
Keep final temperature <55oC during
final evaporation
Treatment with protease followed by nuclease resulted in the highest 5’-GMP
(Chae et al., 2001)
Burnt flavor
*)Adapted from Biocatalyst Ltd
Yeast Technology in Food Industry
Jakarta September 4, 2007
Other yeast-derived products
• Colorants
– Pigmented yeasts such as Rhodotorula,
Phodospondium, Cryptococcus,
Sporidiobolus, Sporobolomyces, GESaccharomyces, Candida
• Yeast Polysaccharides:
– Food application and nutraceutical potential
– Potential species S.
S cerevisiae,
cerevisiae Pichia holstii
holstii,
Hansenula sp, Candidia, Rhodotorula
• Yeast Enzymes
Yeast Technology in Food Industry
Jakarta September 4, 2007
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Conclusion and future outlook
• The economic important of yeast to the
food industries continues to outweigh all
other commercial uses of yeast
• Modification and tailoring yeast for an
increasing array of application provide
added promise for the application of yeast
in the food industries
Yeast Technology in Food Industry
Jakarta September 4, 2007
Thank you
Further information:
[email protected]
Http://www.seafast.ipb.ac.id
p
p
Yeast Technology in Food Industry
Jakarta September 4, 2007
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