Transcript INTRODUCTION TO MYCOLOGY

MIC 303
INDUSTRIAL AND
ENVIRONMENTAL
MICROBIOLOGY
INDUSTRIAL PRODUCTS FROM
MICROBIAL PROCESSES
Advantages of using micro-organisms
very rapid growth rates.
utilise waste products as substrates e.g. agricultural wastes.
can be grown continuously and on a large scale so there
are less shut-downs and less re-sterilisations → economic
advantages.
high protein content.
high yields from small factories.
can be genetically manipulated.
usually produce less toxic or non-toxic waste products.
living organisms are used → temperatures used are lower
than in chemical production which is therefore reduced
cost
FOOD PRODUCTION
Soya Sauce
Miso (Tempe)
Citric acid
Lactic acid
Classification of Soy Sauce
It probably arrived in Japan from China with the
introduction of Buddhism.
Five types of soya sauce
Typical compositions of five varieties of soy sauce
 Koikuchi (Deep brown) – 90% of total market.
 Usukuchi (Light brown)
 Tamari/ Tanari (Dark brown)
 Saishikomi (Dark brown)
 Shiro (Yellow)
All soy sauces comprise 17-19% salts, seasoning and
flavour enhancer.
Classification of Soya Sauce by Japan
Classification
Koikuchi
 Most abundant in Japan
 90 % Japanese production
 Reddish chocolate in colour
 Used in all food for cooking
 Aromatic and strong flavour
Usukuchi
 10 % Japanese production
 Colour not very dark, flavor and strong
 Used for cooking purpose
Classification of Soya Sauce by Japan
Classification
Tamari/ Tanari
 Produced and originated in China
 Strong flavor and dark chocolate in colour
 Sweet and liquid tanari
Saishikomi
 Process alcohol
 Preferred in Japan
Shiro
 Possess reducing sugar
 Often very sweet
 High amount of reducing sugar
PRODUCTION OF SOYA SAUCES
Soaking and
cooking of
soya beans
Soya beans
Cooked in water
(10-12 hours)
Koji
Production
Rice steamed / wheat
bran + soya beans
(soaked in water) +
Aspergillus oryzae spore
Roasting and
cracking of
wheat
Wheat
Roasted
Incubate (3-5 days) at 30ºC
Cooked until soft
Seed koji
cooled
0.1 – 0.2 %
50 %
Mix
Crushed
roasted
50 %
Spread on trays (5 cm thick)
Incubate (25 - 30ºC) for 3
days
Mix with NaCl (17-19% +
water)
Lactic acid fermentation (Pediococcus
or P. soyae, followed by yeast
fermentation by S. rouxii for 2 months)
Brine
Fermentation
and Mash
(Moromi)
stage
Pressed
Filter
Bottling
Pasteurization (5-10 min)
Market
Refining
stage
Production of soya sauces
Two different processes:
 Soaking and cooking of soybeans
 Roasting and cracking of wheat
Soaking and cooking of soybeans
The soybeans (starting material) are soaked at room
temperature (30°C) for 12-15 h → doubling of their weight.
The water either flows continuously over the beans or is
added batch wise with changes every 2-3 h → prevent
heat accumulation and the development of sporeforming bacteria.
The swollen material is drained, recovered with water and
steamed → induced softening and afford pasteurization.
Followed by rapid cooling to less than 14°C on 30cm trays
over which air is forced to avoid spoilage.
Production of soya sauces
Roasting and cracking of wheat
Wheat (or wheat flour or bran) is roasted to generate the
desired flavouur characteristics.
Products include vanillin and 4-ethylguaiacol from the
degradation of lignin and glycosides.
The degree of roasting will also impact the colour.
Production of soya sauces
Koji production
“Koji’ means ‘bloom of mould’.
Involves the cultures of mixed strains of Aspergillus oryzae
or Aspergillus sojae on either steamed polish rice or a mix
of wheat bran and soybean flour – 0.1-0.2% to produce
koji.
Important characteristics of selected strains, different
ability to generate high levels of several enzymes
(protease, amylase, lipase, cellulase and peptidase)
A 1:1 soybean: wheat mixture is spread in 5cm layers on
bamboo (or steel) trays with the koji starter for 2-5 days.
Moisture and temperature (25-35°C) control is important to
allow mycelial growth and reduce formation of spores.
Production of soya sauces
Brine Fermentation and Mash (moromi) stage
Mature Koji, mixed with an equal volume of saline (15-19%
sodium chloride). Less → allows the development of
putrefactive organisms.
If [salts] is too high → inhibition of desirable osmophilic and
halophilic organisms.
Function of salt: to destroys the koji mycellium.
Production of soya sauces
Refining
The final process in soy sauce fermentation is refining,
includes pressing, filtration, pasteurization and packaging.
The aged moromi is pressed in a vertical automatic press
to separate the soy sauce from the residue.
After pressing, the filtered raw soy sauce is pasteurized in a
heat-exchanger at 70-80 ~ for a few minutes to ensure
clarity, to inactivate residual enzymes, and to inactivate
any undesirable microorganisms.
It may be necessary to clarify the soy sauce additionally
by centrifugation or sedimentation.
The sauce is treated with caramel as a coloring agent,
and then packaged either in clean glass bottles,
enameled gallon cans or in plastic containers.
PRODUCTION OF MISO
Soya beans + barley
soaked in water
Drain
Soya beans (soaked in
water) + steamed
Cooked by steamed
Drain
Spread on trays + cooled
(30 days) at 20 -30ºC
Inoculate ascospores
Incubate 40-50 days at
30ºC
Cooled to get 30 – 60 %
moisture content
70 %
Seed koji
30 %
Mix
Mix
Seed Koji
Mixture
Addition of NaCl (14-15%)
Fermentation (2-3 months at 25-30 ºC)
by lactic acid bacteria
Followed by yeast fermentation
Set aside for 2-3 weeks (aging)
blending
Package + Pasteurization
Market
INDUSTRIAL ORGANIC
ACID PRODUCTION
CITRIC ACID
widely used in the food industry as an acidulant and
flavouring agent in beverages, confectionary and
other foods and in leavening systems for baked
foods.
Until 1920s, citric acid mainly prepared from lemon
juice.
In 1923, Pfizer began operate a fermentation-based
process in USA, using A. niger grown in surface culture
on a medium of sucrose and mineral salts.
In 1940s, submerged fermentations have become
the principle mode.
Many bacteria, filamentous fungi, yeasts (Candida
lypolytica) were used, but A. niger remains
predominant industrial producer.
Citric acid Biosynthesis
Primary metabolites.
Metabolic
pathway
invlved
EmbdenMeyerhof-Parnas
(EMP)
pathway and TCA cycle.
Removal of iron, an
activator of aconitase →
Inhibition of continuation
of TCA cycle and to
accumulate citrate. Ex:
addition of copper to
diminishes
aconitase
activity.
CITRIC ACID PRODUCTION
Substrate preparation (Aspergillus niger)
Inoculums fermented
Production fermented fermented
Harvest tank
Broth filter (Mould mycelium throw up)
Filtrate receiver
Fermented liquor
(to produce
Lime addition precipitate Ca citrate)
Precipitation of calcium citrate
(Convert Ca Citrate to
respective organic acid)
Filtration
(CaSO4)
Gypsum
disposal
+ H2SO4
Regeneration of citric acid
Active carbon
(Decolorization treatment)
Mother liquor recycle
Crystalization
Centrifugation
Drying
Sieving
Packaging
Filtration and
washing
Filtrate to effluent
treatment
Filtration
Concentration
LACTIC ACID
Primarily used in the food industries as a preservative,
an acidulant or in the preparation of dough
conditioners.
Lactic acid is produced in 20,000 – 100,000L
fermentations using Lactobacillus delbruckii or other
homolactic bacteria (L. bulgaricus).
The media contain a complex nitrogen source and
vitamin supplements, with up to 12% (w/v) sucrose or
glucose as carbon source.
Thse carbohydrates are metabolized to pyruvate via
the EMP pathway, which is then converted to Llactate dehydrogenase.
LACTIC ACID PRODUCTION
15 % maize sugar
10% CaCO3
0.5% malt sprout
74.4 % H2O
O.25 (NH4)2PO4
Shake flask culture (Lactobacillus)
Production fermenter
Batch fermentation (1 week)
Slurry + Lime
Filter Press
Evaporator
Calcium lactate
+ H2SO4
Acid conversion tank
Filter (remove CaSO4)
Cake slurry tank
Evaporator
Filter Press
Storage
Lactic acid [50%]