Microboilogy and Food Technology - Essay Example

Autoclaving is one way of sterilization that substantially eliminates major food-borne pathogens such as Salmonella, Listeria monocytogenes, Campylobacter, and Escherichia coli O157.

1. a.) Mesohalophilic microprobe
b.) Aerobic fermenters
c.) Thermophilic facultative aerobes

3.) average 63.5 (64)
64 x 10/11.64 (0.946)
64 x 0.946=60.5 x 105
6.05 x 106 cfu/gm

4.) average 63.5 (64)
64 x 10/11.64 (0.946)
64 x 0.946=60.5 x 105
6.05 x 106 cfu/gm (from plates 105 )

average 56
56 x 10/11.64
56 x 0.946=53 x 105
5.3 x 106 cfu/gm (from plates 104)

These counts would not be indicative of accurate serial dilution since the values are also close to each other. Diluting from 105 to 104 should have reduced values to a greater extent, moreover, that reduction of count cited above is considered too low to be considered serial dilution.
The clerical error must have occurred.


5. a.) Melted agar should be cooled to 45-47 degree Celsius before pouring it onto the agar plate since pouring it at a higher temperature might kill the organisms and thus falsely decrease the microbial count.

b.) Petri dishes are incubated bottom side up to prevent droplets of moisture from contaminating the agar which hinders accurate identification and count of the microorganism.

c.) Aseptic technique should always be employed to prevent another microorganism from contaminating the set-up. Any contamination would lead to difficulty, if not, production of the erroneous microbial count.

6.) Used media may contain harmful and infectious organisms; moreover, it should always be treated as biologically hazardous waste. Required waste disposal can be costly; nevertheless used media can never be disposed of directly into the waste basket. To date, autoclaving serves as a cheap but effective way to sterilize waste materials in microbiology laboratories. The fact that most microorganisms can not withstand autoclaving, this simple technique would conveniently address the issue of the proper disposal of used media.

An autoclave must be available for the laboratory and must be operated by properly trained personnel. Regularly, biological indicators or spore strips should be included in autoclave loads to verify their functionality and efficiency of sterilization. Temperature-sensitive tape, thermograph, or other biological indicators should also be used to monitor each autoclave.
After autoclaving, the used media can be safely disposed of by employing the standard waste disposal used in the laboratory setting.

7. a.) Yeast
• yeast activity in bread dough is essential to the texture and quality of bread ( Saccharomyces )
• yeast is used in alcohol production, or wine fermentation (Saccharomyces Calsbergensis)
• Yeast can contribute to food spoilage
• some medical reports suggest that products processed with yeast can be harmful to certain medical conditions.
• Genetically engineered yeast is currently used to produce enzymes that are important in food production
b.) Bacteria

• Responsible in whole or part for the production of certain foods such as buttermilk, cheeses, pickles, yogurt, coffee, vanilla, vinegar, pickles, cocoa, etc.
• Responsible for food spoilage of refrigerated foods (Psychrophilic bacteria) and processed foods ( Thermophilic bacteria), common unprocessed foods (Mesophilic bacteria)
• Scientists have investigated microbial behavior in areas such as Clostridium botulinum in modified atmospheric processing, Escherichia coli in apple processing, Salmonella and E. coli in vegetable seed sprouting, etc.

• Some studies show that bacteria convert food processing waste into hydrogen addressing the problem of waste disposal
• Genetically engineered bacteria are currently used to produce enzymes that are important in food production.
• Lactic acid bacteria (Lactobacillus and Bifidobacterium) are used as probiotics which are potentially health beneficial. They act by lowering pH and thus preventing spoilage. They intend to prevent gastrointestinal infections by assisting the body’s natural flora and they potentially improve the immune system.

c.) Molds
• Production of chemicals such as citric, lactic acid, and many enzymes
• Can produce poisons ( Mycotoxins)
d.) Bacteria-eating Virus
• Food additive against harmful bacteria such as Listeria Read More