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Copyright © 2013 Pearson Education, Inc. Lectures prepared by Christine L. Case © 2013 Pearson Education, Inc. Lectures prepared by Christine L. Case Chapter.

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Presentation on theme: "Copyright © 2013 Pearson Education, Inc. Lectures prepared by Christine L. Case © 2013 Pearson Education, Inc. Lectures prepared by Christine L. Case Chapter."— Presentation transcript:

1 Copyright © 2013 Pearson Education, Inc. Lectures prepared by Christine L. Case © 2013 Pearson Education, Inc. Lectures prepared by Christine L. Case Chapter 28 Applied and Industrial Microbiology

2 © 2013 Pearson Education, Inc.

3 Learning Objectives Food Microbiology 28-1Describe thermophilic anaerobic spoilage and flat sour spoilage by mesophilic bacteria. 28-2Compare and contrast food preservation by industrial food canning, aseptic packaging, radiation, and high pressure. 28-3Name four beneficial activities of microorganisms.

4 © 2013 Pearson Education, Inc. Historically…  Drying  Osmotic pressure (salt or sugar)  Fermentation

5 © 2013 Pearson Education, Inc. Foods and Disease  Hazard Analysis and Critical Control Point (HACCP)  FDA  USDA

6 © 2013 Pearson Education, Inc. Figure 28.1 The commercial sterilization process in industrial canning. Washing, sorting, blanching Steam box This treatment lowers the microbial population and destroys enzymes that might alter color, flavor, or texture. Cans are filled to capacity, leaving minimal dead space. Steam is used to exhaust, or drive out, dissolved air. The cans are sealed. Cans are sterilized by pressurized steam in a retort, similar to an autoclave. Cans are then cooled by submersion in a water bath or by spraying them with water. Cans are labeled, stored, and delivered for sale. Blanching in hot water or steam softens the product to easily fill the can.

7 © 2013 Pearson Education, Inc. Figure 28.2 Commercial canning retorts.

8 © 2013 Pearson Education, Inc. Figure 28.3 The construction of a metal can. Formation of a side seam Sealing compound Formation of a double seam for top or bottom

9 © 2013 Pearson Education, Inc. Commercial Sterilization  Destroys C. botulinum endospores  12D treatment kills endospores  Thermophilic anaerobic spoilage: surviving endospores multiply, causing the can to swell from gas  Or flat sour spoilage

10 © 2013 Pearson Education, Inc. Low-acid canned food spoilage Flat sourGeobacillus stearothermophilus Can is not swollen Thermophilic anaerobic Thermoanaerobacterium thermosaccharolyticum Swollen can Putrefactive anaerobic Clostridium sporogenes, C. botulinum Swollen can

11 © 2013 Pearson Education, Inc. Food Preservation  Aseptic packaging: presterilized materials assembled into packages and aseptically filled

12 © 2013 Pearson Education, Inc. Figure 28.5 Irradiation logo.

13 © 2013 Pearson Education, Inc. Table 28.2 Approximate Doses Of Radiation Needed To Kill Various Organisms (Prions Are Not Affected)

14 © 2013 Pearson Education, Inc. Ionizing Radiation Low dose1 kGyKilling insects Pasteurizing dose1-10 kGyMeats and poultry High dose>10 kGySterilizing spices

15 © 2013 Pearson Education, Inc. Figure 28.6 A gamma-ray irradiation facility. An irradiation facility, showing the path of the material to be irradiated The irradiation source is submerged in the storage pool. The blue glow is Cerenkov radiation caused by charged particles exceeding the speed of light in water. Irradiation sources lifted from storage pool for processing period Material to be irradiated Conveyors to move material in and out of processing position Shielding

16 © 2013 Pearson Education, Inc. Electron beam Electron gun Bending magnet Figure 28.7 Electron-beam accelerator.

17 © 2013 Pearson Education, Inc. High Pressure  Prewrapped, precooked foods  87,000 psi  Kills Salmonella, Listeria, E. coli  Preserves color and flavor well

18 © 2013 Pearson Education, Inc. Cheese  Curd: solid casein from lactic acid bacteria and rennin  Whey: liquid separated from curd  Hard cheeses are produced by lactic acid bacteria  Semisoft cheeses are ripened by Penicillium on surface

19 © 2013 Pearson Education, Inc. Figure 28.8 Making cheddar cheese. The milk has been coagulated by the action of rennin (forming curd) and is inoculated with ripening bacteria for flavor and acidity. Here the workers are cutting the curd into slabs. The curd is chopped into small cubes to facilitate efficient draining of whey. The curd is milled to allow even more drainage of whey and is compressed into blocks for extended ripening. The longer the ripening, the more acidic (sharper) the cheese.

20 © 2013 Pearson Education, Inc. Figure 28.9 The basic steps in making red wine. Grapes are tested and picked. Grapes are crushed and destemmed. Sulfite is added to kill undesirable yeasts and bacteria. Yeast inoculum is added. Fermentation occurs. Result is pressed to separate solids from wine. Wine is clarified in settling vats. Wine is filtered.Wine is aged. Wine is bottled.

21 © 2013 Pearson Education, Inc. Alcoholic Beverages and Vinegar  Beer and ale are fermented starch  Malting: germinating barley converts starch to maltose and glucose  For sake, rice starch is converted to sugar by Aspergillus  Wine is fermented plant sugars  Yeast ferment sugars to ethanol and CO 2  Grape wine requires bacterial malolactic fermentation  Acetobacter and Gluconobacter convert ethanol to acetic acid

22 © 2013 Pearson Education, Inc. SugarEthanol + CO 2 Saccharomyces cerevisiae Malic acidLactic acid Lactic acid bacteria EthanolAcetic acid Acetobacter or Gluconobacter Microbial Metabolism

23 © 2013 Pearson Education, Inc. Check Your Understanding Is botulism a greater danger in spoilage of canned goods under thermophilic or under mesophilic conditions? 28-1 Canned foods are usually in metal cans. What sorts of containers are used for aseptically packaged foods? 28-2 Roquefort and blue cheeses are characterized by blue-green clumps. What are these? 28-3

24 © 2013 Pearson Education, Inc. Learning Objectives Industrial Microbiology 28-4Define industrial fermentation and bioreactor. 28-5Differentiate primary from secondary metabolites. 28-6Describe the role of microorganisms in the production of industrial chemicals and pharmaceuticals. 28-7Define bioconversion, and list its advantages. 28-8List biofuels that can be made by microorganisms.

25 © 2013 Pearson Education, Inc. Biotechnology  Use of microorganisms, cells, or cell components to make a product  Classical: fermentation  Recombinant DNA

26 © 2013 Pearson Education, Inc. Figure 28.10a Bioreactors for industrial fermentations. Steam for sterilization Cooling jacket Acid/base for pH control Motor Foam breaker Flat-bladed impeller Culture broth Baffle Diffuser Sterile air Section of a continuously stirred bioreactor Liquid level Harvesting drain

27 © 2013 Pearson Education, Inc. Figure 28.10b Bioreactors for industrial fermentations. Bioreactor tank, at left

28 © 2013 Pearson Education, Inc. Figure 28.11a Primary and secondary fermentation. Time Cell weight or numbers (a) A primary metabolite, such as ethanol from yeast, has a production curve that lags only slightly behind the line showing cell growth. Ethanol produced Cells

29 © 2013 Pearson Education, Inc. Figure 28.11b Primary and secondary fermentation. Time Cell weight or numbers (b) A secondary metabolite, such as penicillin from mold, begins to be produced only after the logarithmic growth phase of the cell (tropophase) is completed. The main production of the secondary metabolite occurs during the stationary phase of cell growth (idiophase). Penicillin produced Cells TropophaseIdiophase

30 © 2013 Pearson Education, Inc. Figure Immobilized cells. Bacteria Silk fibers

31 © 2013 Pearson Education, Inc. Industrial Products  Xanthan  Amino acids  Citric acid  Enzymes  Vitamins  Antibiotics  Steroids

32 © 2013 Pearson Education, Inc. Xanthan Xanthomonas campestris producing gooey xanthan. Applications of Microbiology, unnumbered figure, page 808.

33 © 2013 Pearson Education, Inc. Figure Biological leaching of copper ores. Leaching: Fe 3+ in acidic leaching solution oxidizes insoluble copper sulfide (Cu + ) to soluble CuSO 4 (Cu 2+ ). CuSO 4 precipitates as copper (Cu 0 ); Fe 3+ is changed to FeSO 4 (Fe 2+ ). Oxidation pond: T.Ferrooxidans oxidizes FeSO 4 to Fe 3+ + H 2 SO 4 (acidic leaching solution). Leach dump of copper sulfide ore Fe 0 (metallic scrap iron) Pregnant (metal-bearing) solution, CuSO 4 Barren solution, no copper, iron as FeSO 4 Pump Oxygen in aerated pond Copper for industrial uses

34 © 2013 Pearson Education, Inc.  Cellulose digested by cellulase  Sugars fermented to ethanol or higher alcohols or hydrogen  Algal oils Alternative Energy Sources Using Microbes BiomassMethane Ethanol Hydrogen Bioconversion

35 © 2013 Pearson Education, Inc. Figure Methane production from solid wastes in landfills. Gas flaring stacks Microturbines produce electricity from methane

36 © 2013 Pearson Education, Inc. Industrial Microbiology and the Future  Food processing  Pharmaceuticals from rDNA technology  Ethanol and hydrogen  And more

37 © 2013 Pearson Education, Inc. Check Your Understanding Are bioreactors designed to operate aerobically or anaerobically? 28-4 Penicillin is produced in its greatest quantities during the trophophase of fermentation. Does that make it a primary or secondary metabolite? 28-5 At one time, citric acid was extracted on an industrial scale from lemons and other citrus fruits. What organism is used to produce it today? 28-6

38 © 2013 Pearson Education, Inc. Check Your Understanding Landfills are the site of a major form of bioconversion—what is the product? 28-7 How can microbes provide fuels for cars and electricity? 28-8


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