MIC 303 INDUSTRIAL AND ENVIRONMENTAL MICROBIOLOGY

1
MIC 303INDUSTRIAL AND ENVIRONMENTAL MICROBIOLOGY

• INDUSTRIAL PRODUCTS FROM MICROBIAL PROCESSES

2
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

3
FOOD PRODUCTION

• Soya Sauce
• Miso (Tempe)
• Citric acid
• Lactic acid

4
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.

5
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

6
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

7
(No Transcript)
8
Lactic acid fermentation (Pediococcus or P.
soyae, followed by yeast fermentation by S.
rouxii for 2 months)
Refining stage
9
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 (30C) 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 spore-forming bacteria.
• The swollen material is drained, recovered with
  water and steamed ? induced softening and afford
  pasteurization.
• Followed by rapid cooling to less than 14C on
  30cm trays over which air is forced to avoid
  spoilage.

10
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.

11
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 11 soybean wheat mixture is spread in 5cm
  layers on bamboo (or steel) trays with the koji
  starter for 2-5 days.
• Moisture and temperature (25-35C) control is
  important to allow mycelial growth and reduce
  formation of spores.

12
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.

13
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.

14
PRODUCTION OF MISO
Drain
Incubate 40-50 days at 30ºC
15
Set aside for 2-3 weeks (aging)
Package Pasteurization
16

INDUSTRIAL ORGANIC ACID PRODUCTION
17
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.

18
Citric acid Biosynthesis

• Primary metabolites.
• Metabolic pathway invlved Embden-Meyerhof-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.

19

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 precipitate Ca citrate)
Lime addition
20
Filtration and washing
Precipitation of calcium citrate
(Convert Ca Citrate to respective organic acid)
H2SO4
Filtrate to effluent treatment
Regeneration of citric acid
Filtration
Active carbon (Decolorization treatment)
(CaSO4) Gypsum disposal
Filtration
Mother liquor recycle
Concentration
Crystalization
Centrifugation
Drying
Sieving
Packaging
21
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
  L-lactate dehydrogenase.

22

LACTIC ACID PRODUCTION
23