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# Food Microbiology

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1.Herschley-Bulkley Model

Please describe in detail this model indicating the meaning of each parameter and their range.
Please list and describe alternative THREE PARAMETER Models.

2.Creep Test

Please describe in detail this test and explain why is so useful in characterizing viscoelasticity.

3.Relaxation test

Please describe in detail this test and explain why is so useful in characterizing viscoelasticity

4.Capillary Tube

Provide information related to:
How does this instrument work?
Fundamental equations
Limitations

5.Rotational Rheometers

Provide information related to:
Principle of operation
Geometries associated with the instrument
Fundamental equations
Limitations
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https://brainmass.com/biology/microbiology/food-microbiology-104355

#### Solution Preview

See the attached file.
1. Hershel-Buckley
The Hershel-Buckley model describes the behavior of a fluid that behaves in an unusual manner (rheology; see http://www.tipmagazine.com/tip/INPHFA/vol-10/iss-2/p29.html). The BH equation is given as (also given in attachment 0gl99112):

shearing stress=yield stress + consistency (shear rate) ^ power law exponent

The three parameters of HB are yield stress, consistency and shear rate. BH model requires a certain amount of stress (a threshold) to initiate flow but require less stress as sheer increases. Yield stress is the amount of force required to cause deformation. Consistensy describes the ability to flow. Its range is dependent on temperature and solute content. Sheer stress is defined as the force divided by the area parallel to the force. From my understanding the ranges of these parameters depends on the material and experiemtnal design. I've found a few studies for you to review for more information (the last link is a good overview):
http://cat.inist.fr/?aModele=afficheN&cpsidt=1959601
http://sst-web.tees.ac.uk/external/U0000504/Notes/colloids/colloids07/FdRheo02.html

Other alternative rheology models are:
Newtonian model- having a ...

#### Solution Summary

The solution discusses food microbiology.

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## Food Microbiology - Nonthermal Technologies

1. Please mention 5 nonthermal technologies to process foods and thoroughly describe all of them.

2. Please explain the Preservation of Foods by Oscillating Magnetic Fields. Please provide a critical evaluation of this technology. Explain the possible mechanism of microbial inactivation by this approach.

3. Please sketch the design of a plant to process juices using Pulsed Electric Fields. The plant should have a capacity to process 5000 liters per our. Please try to be as realistic as possible and document as much as possible your design.

4. Please explain two possible approaches to design a high pressure vessel. Please provide as much details as possible.

5. Please define bacteriocins and mention at least three with potential food applications. Please describe in details how the microbial inactivation takes place.