Food Engineering/Packaging & Labeling

• Match Instrumentation Transducers with Working Principles:
• Strain Gauge $\longrightarrow$ (I) Mechanical deformation to electrical signal: Piezoresistive sensor whose electrical resistance alters proportionally to mechanical strain ($R \propto \Delta L$).
• Thermocouple $\longrightarrow$ (II) Temperature measurement via Seebeck effect: Generates an electromotive force (EMF) at the junction of two dissimilar metallic conductors proportional to temperature difference.
• LVDT (Linear Variable Differential Transformer) $\longrightarrow$ (III) Precision linear displacement: Inductive transducer converting core linear mechanical position into differential secondary AC voltage with extreme linearity.
• Piezoelectric Transducer $\longrightarrow$ (IV) Electrical charge under mechanical pressure/vibration: Asymmetric crystal (quartz, PZT) generating electric surface charge in response to applied dynamic stress.
• Conclusion: A-I, B-II, C-III, D-IV (Option 2).

Correct option: (2) AA,B-I,C-I,D-V.

• Concept of Thermal Death Time (TDT) Curve:
• Mathematical & Kinetic Definition:
• The TDT curve plots the heating time required to achieve a designated lethal destruction of a microbial population against exposure temperature on semi-logarithmic paper.
• Characterizes the relationship between processing temperature and microbial destruction rate, defining the thermal resistance constant ($z$-value, the temperature change needed to alter the $D$-value by a factor of 10).
• Conclusion: The relationship between temperature and microbial death rate (Option 3).

Correct option: (3) The relationship between temperature and microbial death rate

Evaluating the Assertion and Reason concerning Methods of food preservation such as heat processing:

The correct answer is Option 1: Both (A) and (R) are true and (R) is the correct explanation of (A).

• Chronological Sequence of Evaporator Operations:
• In dairy and food engineering, the operational procedure for a falling film or forced circulation evaporator follows a rigorous thermodynamic sequence:

• Step 1: Preheating the feed solution: Raw liquid feed is preheated close to the boiling temperature using regenerate heat exchangers to conserve energy.
• Step 5: Heating the feed solution to its boiling point: The liquid is brought to its saturation boiling point within the evaporation chamber/calandria tubes.
• Step 2: Vaporization of the solvent from the feed solution: Latent heat of vaporization causes rapid water evaporation, concentrating the non-volatile milk solutes.
• Step 3: Condensation of the vaporized solvent to produce distillate: Separated water vapor passes to a condenser (or mechanical vapor recompressor, MVR) to produce condensate.
• Step 4: Removal of concentrated solution or residue: The concentrated product (condensed milk/dairy syrup) is continuously discharged through the bottom extraction pump.
  • Conclusion: The correct chronological sequence is 1 - 5 - 2 - 3 - 4 (Option 1).