9D Flashcards
what does a moisture sorption isotherm depict?
change in (water) weight in relation to RH
what’s the relationship between aw and RH?
Aw = RH/100
what information can be derived from a moisture sorption isotherm? (5)
- expected moisture sorption behavior
- effect of temperature on moisture sorption isotherm
- determine the expected Aw
- predicting final moisture content at specific temp/RH
- telling of packaging requirements
what factors affect the drying process?
- latent heat
- pressure
- makeup/structure of product
how much of a rise in temperature do you need for the air to hold twice as much vapor?
15C
what is case hardening?
when drying is too fast so only the outside dries leaving the inside moist
what is sulfiting?
adding sodium bisulfite and boiling for 30 mins
- controls enzymes
negative effects of sulfiting?
- extends drying time
- bad for allergies
what is sulfuring?
exposing fruits to fumes from burning sulfur for up to 4 hours to control enzymes
advantages of sulfuring?
- shortened drying time
- inhibited mold growth
- repels insects
- minimal effect on heat sensitive components
- destroy thiamin
what percent moisture can be achieved using a belt dryer?
5-7%
what kinds of food commodities are the most suitable for drum drying?
brittle when dry
- mashed potatoes
- mashed sweet potatoes
- tomato pastes
what’s the fastest drying method?
spray drying
what are the heated trays/shelves called in vacuum drying?
platens
what drying method is used for fruit juices?
vacuum drying
