Boiling Point of Water under Vacuum (Triple Point):
In freeze-drying (lyophilization), the thermodynamics of phase transition require operating near the triple point of water ($0.01^\circ\text{C}$ and $611.7\text{ Pa}$ or $0.00612\text{ bar}$).
When the pressure is reduced to $0.006\text{ bar}$ ($4.58\text{ mm Hg}$), the boiling/vaporization point of liquid water drops to $0^\circ\text{C}$. Below this pressure, ice sublimes directly into water vapor without melting.
Correct Option: Option 1 (0.006 bar).
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12
ICAR JRF Fish Processing Technology 29 Jun 2024Shift 1
MCQ (Single Correct)+4−1
The process of removing air from food cans is called
Exhausting: The critical thermal or mechanical unit operation of removing air and dissolved oxygen from the can contents and headspace immediately prior to hermetic double seaming.
Methods include thermal exhausting (passing filled open cans through a steam chamber at $85-95^\circ\text{C}$ for $5-10\text{ minutes}$), mechanical vacuum exhausting, or steam-flow closure.
Objectives: Creates an internal vacuum ($35-50\text{ kPa}$) upon cooling, prevents can ends from bulging during retorting, inhibits internal can corrosion, and preserves vitamin and lipid stability.
Correct Option: Option 1 (Exhausting).
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13
ICAR JRF Fish Processing Technology 29 Jun 2024Shift 1
MCQ (Single Correct)+4−1
Processing of heating in hermatically sealed container are referred as
Thermal Sterilization in Sealed Cans: Appertisation:
Appertisation: The process of preserving foods by hermetically sealing them in airtight containers (cans, glass jars) followed by high-temperature thermal sterilization.
Coined in honor of the French inventor Nicolas Appert (1810), the "father of canning", who demonstrated that heating hermetically sealed glass jars prevented microbial food spoilage.
Correct Option: Option 3 (Appertisation).
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14
ICAR JRF Fish Processing Technology 29 Jun 2024Shift 1
Clostridium botulinum Type A and B spores: The most heat-resistant foodborne spore-forming pathogen of public health significance in low-acid canned seafoods.
In thermal death kinetics, the standard recognized $Z$-value for Clostridium botulinum spores is $10^\circ\text{C}$ ($18^\circ\text{F}$), with a reference decimal reduction time of $D_{121.1} = 0.21\text{ minutes}$ (used to calculate the $12D$ thermal process lethality, $F_0 \ge 2.52\text{ minutes}$).
Correct Option: Option 1 (10°C).
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15
ICAR JRF Fish Processing Technology 29 Jun 2024Shift 1
MCQ (Single Correct)+4−1
Identify one of the drawbacks in the pulsed electric field for food processing
Pulsed Electric Field (PEF): A non-thermal preservation technology that applies short bursts of high-voltage electric fields ($15-40\text{ kV/cm}$) to cause electroporation and inactivation of microbial cell membranes.
Major Drawback: The presence of air or gas bubbles in the food liquid causes severe dielectric breakdown, dielectric field distortion, and dangerous electrical arcing (sparking) between the electrodes, scorching the food and damaging equipment.
Correct Option: Option 1 (Presence of bubbles).
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