Summary
Summary food physics FPH20306
- Course
- Institution
Extensive clear summary of food physics FPH20306
[Show more]
Seller
Follow
nlaalbers
Reviews received
Content preview
Bulk rheologyFluids
Rheology: science that studies relation between forces applied and rate of deformation
(stirring souce, chewing apple, stretching dough etc…)
Types of deformation:
- Shear
- Extension
Newtonian fluids:
Non-newtonian fluids:
Shear = extension + rotation
Rotation is for complex systems not zero
Types non-newtonian behavior:
1. Shear thinning: as it starts to flow, the shear decreases →
fluid accelerates (drains faster than Newtonian) (milk,
custard, yoghurt)
Viscosity and stress decreases if flow rate increases
Mechanisms of shear thinning in macromolecular solutions:
Resistance flow higher Resistance lower
, 2. Shear thickening: opposite of shear
thinning (peanut butter)
Viscosity and stress increases if flow rate
increases
3. Bingham and plastic flow behavior:
minimal stress needed for flow: below this
stress fluids behave like solids (dough,
margarine, ketchup, whipped cream)
Bingham: newtonian but minimal stress
needed for flow
Plastic flow: shear thinning but minimal
stress needed for flow
4. Thixotropic behavior and hysteresis: time
dependent behavior: breakdown and
recovery of structures take time
Elastic solids
When G=constant → solid = Hooken elastic solid (gelatin/ globular proteins at small deformations <1%)
, Non-hooken behavior:
1. Strain softening (almost all solid foods) 2. Strain hardening (protein/gelatin gels)
Viscoelastic materials
➔
Determine the elastic and viscous part
➔
Linear viscoelastic materials: G’ and G” are constant
But in general:
Or alternatively
Fast deformation: more elastic
Slow deformation: more viscous because the network has more time to allow for viscous relaxation
Instruments for measuring rheological properties
1. Low viscosity newtonian liquids: capillary viscometers (Ubbelhode viscometer: )
2. Non-newtonian fluids: roto-viscometers (steady shear testing)
3. Viscoelastic fluids/gels: stress controlled rheometers (steady shear, stop flow relaxation, oscillatory
shear testing)
4. Viscoelastic solids: compression/extension devices (texture analyzer)
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller nlaalbers. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $5.42. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
75632 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now