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Fenster schliessen

Thermal processing disadvantages (3) 

1. nutrient quality -> vitamin decomposition, amino acid loss due to browning reactions

2. cell tissue integrity -> protein aggregation, degradation of membranes 

3. oxidation produces new flavors/odors/aromas and/or color change by browning or bleaching 

Fenster schliessen

C-Wert 

- Definition 

- C und F Wert

thermal destruction rate for nutrients similar to microbial inactivation model (cook value) 

related to thermally-induced kinetic process 

-> similar to F value: C value for food, F value for microorganisms 

(F-Wert: Mass für Summe aller Abtötungseffekte während des Gesamten Erhitzungsprozesses) 

Normalerweise: Cvalue > Fvalue 

Fenster schliessen

Q10 - Value 

 

temperatur-koeffizient der die geschwindigkeitsrate eines Prozesses beschreibt, wenn die Temperatur um 10°C erhöht wird. 

Fenster schliessen

protein changes  

 

protein denaturation 

folded (native) <-> unfolded (denaturated) due to heat or cold 

recognized by loss of activity or aggregation 

 

- native state changes (exterior charge and internal connections)

- factors: pH, ionic strength, pressure, denaturants 

Fenster schliessen

protein aggregation: 

definition

abhänhig von 

colloidal combination 

dependence on charge + kovalent interactions 

-> durch aggregation kann gel entstehen 

 

Fenster schliessen

protein recovery:

1. refolding upon time of by Chaperons:  unfolded protein binds to the chaperonin “cage” and enters à chaperonin helps fold protein into correct structure and releases it

2. permanent denaturation: i.e. affregation, hydrolysis, crosslinking 

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polysaccharides:

starch granules 

swelling and melting 

Amylose + Amylopectin

layered starch molecules -> layering = birefringence = Doppelbrechung 

Heating -> melting of crystals 

 

- heat + water -> amorphous regions swell and crystalline regions melt -> gelatinization when heating up further, starch chains break apart (shortening of chains: loss of viscosity and iodine absorption) 

Fenster schliessen

polysaccharides: gums 

- def

-property

 

non-starch polysaccharides with different repeating monosaccharide units 

dispersable in water upon heating 

bring viscosity to water solutions