Food Processing Unit Operation 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 Food Processing Unit Operation flashcards as text
Which unit operation best describes the removal of alcohol from fermented beer using a vacuum and gentle heat?
Answer: Vacuum stripping (thin-film evaporation)
Vacuum stripping or thin-film evaporation lowers the boiling point of ethanol, allowing gentle removal with minimal flavor loss.
The HTST (High Temperature Short Time) pasteurization condition for fluid milk in the US is:
Answer: 72°C for 15 seconds
US FDA mandates HTST pasteurization at a minimum of 72°C (161°F) for at least 15 seconds to eliminate pathogens including Coxiella burnetii.
In extrusion cooking of breakfast cereals, the die pressure primarily controls:
Answer: Product expansion ratio and texture after exiting the die
Die pressure determines the degree of flash evaporation and starch expansion upon exiting, directly controlling puff texture and bulk density.
Membrane filtration processes are ranked by pore size from largest to smallest as:
Answer: Microfiltration → Ultrafiltration → Nanofiltration → Reverse Osmosis
MF has the largest pores (~0.1–10 µm), followed by UF (~0.001–0.1 µm), NF (~0.001 µm), and RO which rejects nearly all solutes.
In a spray drier, atomization of the feed liquid is performed to:
Answer: Maximize surface area-to-volume ratio for rapid moisture evaporation
Atomization creates millions of tiny droplets with enormous surface area, allowing water to evaporate within seconds even at moderate temperatures.
Which psychrometric property of air is held constant during adiabatic (isenthalpic) humidification in a spray-drying system?
Answer: Wet-bulb temperature
During adiabatic saturation, enthalpy is constant and the process follows a constant wet-bulb temperature line on the psychrometric chart.
What is the function of a homogenizer valve in milk processing?
Answer: To force milk through a narrow gap, disrupting fat globules to prevent creaming
High-pressure homogenization forces milk through a tiny valve gap, reducing fat globule size from ~4 µm to <1 µm to create a stable emulsion.