Osmotic dehydration Flashcards
typical concentration of osmotic dehydrating solutions
50-75g/100g
types of pre-treatment and why
blanching: inactivate enzymes
SO2: maintain colour, mild antimicrobial/antioxidant
are products shelf stable after treatment
no, require furthur drying/freezing/canning treatment
temp, time and conditions
15-140 minute
20-50C
agitation to promote heat and mass transfer
ingredients that can be added for a functional purpose
sucrose: texture and flavour improver
fructo-oligosaccharides:pre-biotic
conc fruit juice: sweetness and aroma
de-acidified and desalted conc fruit juice: sweetness
sorbitol: pre-biotic, polyols inhibit tooth decay
galactosylosorbitol: pre-biotic
inverted sugar: sweet, texture, flavour improvement
oligofructose: pre-biotic, crystallisation prevention, and water holding
equilibrium “distribution” coeffcients is a function of …
concentration
temp
type of solutes
geometry
food-syrup ratio
two purposes of using solutes
impregnating
de watering
what type of solutes favour impregnating
low molecular weight
what type of solutes favour de watering
high molecular weight
what can occur to biological material
parenchymatic cells (outer layer of apples and strawberries) can die due to osmotic shock
epidermis cells (onion outer) show no change in viability
two major characteristics that make OD different from conventional drying
-soaking achieves a twofold transformation (dewatering and formulation)
-soaking does not generate a shelf-stable product
advantages to OD
quality improvement
energy savings
explain direct formulation effect that results in quality improvement
increase sugar:acid
improved texture, pigment stability
may enhance rehydration properties
protective on natural tissue structure
