Industrial microbiology lecture 2
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Transcript of Industrial microbiology lecture 2
BIO 425Industrial Microbiology
Lecture 2Major classes of products and processes and microorganisms involved in these
processes
Content outline
• Major classes of products
• The ‘fermentation’ concept
• The yeast
• Oriental fermented food and typical examples
M/o’s and industry
• Overall reaction characterizing the application:
• Substrate (raw material) + m/o’s
New products
Major classes of products
• Pharmaceutical compounds(Antibiotics, steroid drugs, Insulin and interferon etc.)
• Commercially valuable chemicals(Solvents, enzymes etc.)
• Food supplements(Mass production of bacteria, yeast, algae)
• Alcoholic and non-alcoholic beverages
Major classes of products-contd
• Vaccines(Immunizing antigens)• Deterioration of material by microorganisms
(including leather, wood, textiles, metals)• Analytical microbiology(A variety of products are
assessed through microbial products - like aminoacids, antibiotics and vitamins), other: evaluating wood, paint preservation, efficacy testing of sterilization procedure
History of fermentation
• Dates back hundreds of years.
• Fermented foods are available since Roman times by utility and manipulation of several cell constituents.
Fermentation
• Fermentation • Nominated by Pasteur, 18th century.• Observed: Alcohol production from grape
yeast mixtures during production of sour wine.
• Each type of fermentation: mediated by a specific microorganism which gains energy during the process.
Function of yeast
• Commonly used a leavening agent in baking during ancient times by Jews, Egyptians, Greeks and Romans.
• Pure cultures of Saccharomyces cerevisiae (Baker’s yeast): mixed with the bread dough to bring derived changes in texture and flavor-e.g. for process
Simple reaction for Baker’s yeast
• C6H12O6 Ethanol + CO2
Fermented foods are universal
• Principal thing is sugar conversion to lactic acid by the action of lactobacilli.
• Mold action on different compounds are also applicable.
• E.g. Lactic acids, drinks, cheese making and pickles throughout the world.
• Oriental foods in Japan, e.g Shoyu, Miso….• Oriental foods in Africa e.g. Idli, Kishk, Ogi,
Mahewu
Traditional fermented food
• Koji method:
• Japanese produced several enzymes through solid state cultures of several m/o;
• on a number of cereals, e.g. barley, wheat, soybeans and rice.
Traditional fermented food
• Species: Molds like Aspergillus, Rhizopus, Monascus
• Enzyme source in the manufacture of shoyu, miso and saké(wine from rice) .
More about ‘koji’
• A mold-cultured meal.
• Aspergillus, Rhizopus spp., cultured on parts of rice or wheat and water to make mash,
• then subjected to enzymatic saccharification, lactic fermentation and yeast fermentation.
Shoyu
Digest mold cultured soybeans & wheat in different ratios; (50:50 usual.) in the presence of about 17% salt,
Ferment the mash with Lactobacilli and yeasts
Press the well-aged mash (after 6-8 months)
Liquid part obtained is pasteurized to make the final product
(Miso. approx. the same thing)
Saké
• Rice wine
• Prepared by digesting a mixture of cooked rice and molded rice (rice-koji) in water,
• while fermenting the mash with Lactobacilli and yeasts
• Japanese annual consumption: 1,220,000 kL
High quality Saké rice- var. Yamada Rishiki
Saké making
Tempeh
• Indonesian food
• Cooked whole soybeans, cultured with Rhizopus oligosporus,
• wrapped in banana leaves left for about 40 hours at about 30°C (Eaten fresh or after deep frying).
Miso
• Japanese semi-solid salty food.
• Made from soybeans, rice or barley;
• and salt by fermentation of Lactobacillus (after addition of Aspergillus oryzae).
Milled rice, 600kgSoybeans,1000kg Koji starterAspergillus oryzae
Soaked in water
Steaming, 45 min.
Cooling to 30° C
Koji making
Dehulled
Soaked in water
Autoclaving
Fermentation, 30° C, 1-3 months
Remove to another tank , pasteurize, obtain Miso, 3300 kg
(0.1 % for rice, 109 spore/g)
Koji making unit
Alcoholic beverage production
Wine: ♣ Raw material: Mainly grapes, cherry, tangerine,
orange, blueberry, raspberry, strawberry and banana
♣ Fruity character: by volatile compounds like terpenes.
♣ Mainly blend of flavor and chemical complexity at fermentation stage (tannins, phenolics, malic acid).
Wine production
• Two steps of fermentation:
• Alcoholic fermentation (yeast)
• Malolactic fermentation (lactics)
(Malic acid Lactic acid + CO2)
Important microbial genera
• Introduced by grape skins:
• Yeasts: Kloeckera, Hanseniaspora (mainly present)
• Candida, Metschnikowia, Cryptococcus, Pichia and Kluvyeromyces.
• Saccharomyces cerevisiae (< 50 cfu / g)
Important microbial genera-2
• Lactobacillus, Leuconostoc and Pediococcus spp.
• Gluconobacter oxydans
• Acetobacter aceti
• Acetobacter pasteurianus (main acetic acid bacteria spp.)
LITERATURE CITED
• Forsythe, S.J. The Microbiology of Safe Food, Blackwell Science, Cambridge, 2000.
• Wood, B. J. B., Microbiology of Fermented Foods, Vol.1 and 2, Blackie Academic and Professional, London, Second edition, 1998.