Agricultural/Bioengineering: Food Engineering Flashcards
7 cards from real Agricultural/Bioengineering practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Agricultural/Bioengineering: Food Engineering flashcards as text
High-pressure processing (HPP) of food at 600 MPa is most effective at inactivating:
Answer: Vegetative bacteria and most viruses
HPP at commercial pressures (400–600 MPa) effectively inactivates vegetative bacteria, yeasts, and molds but is largely ineffective against bacterial spores and prions.
Water activity (aw) of 0.85 represents the approximate lower limit for growth of:
Answer: Most spoilage bacteria
Most spoilage bacteria require aw above 0.91–0.95, while 0.85 is near the lower limit for the most salt-tolerant bacteria.
In freeze-drying, the primary drying stage involves:
Answer: Sublimation of ice directly to vapor under vacuum
Primary drying in freeze-drying removes ice by sublimation — the direct solid-to-vapor phase transition — under high vacuum and controlled low temperature.
The emulsifying capacity of soy protein isolate is mainly attributed to its:
Answer: Amphiphilic structure with both hydrophilic and hydrophobic regions
Soy proteins stabilize emulsions by adsorbing at the oil-water interface due to their amphiphilic structure, which has both water-loving and fat-loving regions.
Which packaging atmosphere modification is used to slow ripening and extend shelf life of fresh-cut produce?
Answer: Reduced O2 and elevated CO2
Modified atmosphere packaging for fresh-cut produce uses low O2 (2–5%) and elevated CO2 (5–10%) to reduce respiration rate and microbial growth.
During spray drying, the 'outlet temperature' of the drying chamber primarily controls:
Answer: Final product moisture content
The outlet temperature determines the extent of drying and thus the residual moisture content of the spray-dried powder.
The phenomenon of 'tempering' chocolate involves:
Answer: Controlled crystallization of cocoa butter into stable polymorphic Form V
Tempering guides cocoa butter into the stable beta (Form V) polymorph, giving chocolate its characteristic snap, gloss, and melt-in-mouth properties.