A fruit juice of viscosity µ and density ρ is agitated using an impeller of diameter D at a speed of N revolutions per minute. The terms X = P/(ρN³D⁵), Y = D²Nρ/µ, Z = N²D/g represent three process related numbers, where P is power imparted by impeller and g is acceleration due to gravity. Which of the following is correct representation of these numbers?
A. X = Power, Y= Froude, Z = Reynolds
B. X = Power, Y = Reynolds, Z = Froude correct
C. X = Froude, Y= Reynolds, Z = Power
D. X = Reynolds, Y = Power, Z = Froude
Q9NAT1 mark
The energy required to reduce the size of a food material from a mean diameter of 12 mm to 4 mm is 10 kJ kg⁻¹. From Rittingers’ law, the energy needed to reduce the same material from a diameter of 1.2 mm to 0.4 mm in kJ kg⁻¹ is __________
Correct: 100
Q10NAT2 marks
Saccharomyces cerevisiae (mean doubling time 3.2 h) is grown in a batch fermenter with an operating volume of 12 m³. A 2% (v/v) inoculum, which contains 5 kg cells per 100 m³ is mixed with the substrate. The residence time in the fermenter is 24 h and the density of broth is 1010 kg m⁻³. The mass of S. cerevisiae obtained from the fermenter, in kg, is ________
Correct: 2.1 to 2.2
Q11MCQ2 marks
Make the correct combination of operations in Column I with the machines in Column II
Make the correct combination of underlying principles in Column I with the processes in Column II
Column I: 1) Carbonyl derivatives react with free amino acids to yield aldehydes 2) Starch aggregates and forms micro-crystals 3) Starch granules swell and leach amylose 4) Pyranose or furanose rings open up by pyrolytic reactions to form furfural derivatives
Column II: P) Gelatinization Q) Strecker degradation R) Caramelization S) Retrogradation
A. 1-Q, 2-R, 3-P, 4- S
B. 1-Q, 2-S, 3-P, 4-R correct
C. 1-R, 2-S, 3-P, 4- Q
D. 1-Q, 2-P, 3- S, 4-R
Q15MCQ2 marks
Which one of the following statements is FASLE?
A. The peptide bond is planar offering restricted rotation around its axis.
B. Full range of water activity is 0 ≤ aw ≤ 1 and it has well defined unit. correct
C. The autooxidation of lipids proceeds via free radical mechanism.
D. The carbonyl group of sugar reacts with nucleophilic amino group of amino acids in Amadori rearrangement.
Q16MCQ2 marks
Which one of the following statements is TRUE?
A. Pectate lyase hydrolyzes methyl ester bond of pectin.
B. α-Solanine is a non-toxic compound found in solanaceae plants.
C. Egg proteins have lower digestibility than pea proteins.
D. Lipoxygenase catalyses the conversion of cis, cis-1,4-pentadiene to hydroperoxides. correct
Q17NAT2 marks
Fish fillet having 84% moisture (wet basis) is frozen from top using an air blast freezer maintained at −32°C. The initial temperature of the fillet (density 1050 kg m⁻³) is −2°C (freezing point). Convective heat transfer coefficient of air is 25 W m⁻² K⁻¹, thermal conductivity of frozen fish is 1.0 W m⁻¹ K⁻¹ and latent heat of crystallization is 340 kJ kg⁻¹. The freezing time, in min, for a 20 mm thick block of fish fillet weighing 1 kg is __________
Correct: 74 to 76
Q18MCQ2 marks
Make the correct combination of properties in Column I with their dimensions in Column II
Column I: 1) Dynamic viscosity 2) Thermal conductivity 3) Specific heat 4) Force
Column II: P) m² s⁻² K⁻¹ Q) kg m s⁻² R) kg m⁻¹ s⁻¹ S) kg m s⁻³ K⁻¹
A. 1-R, 2-S, 3-Q, 4- P
B. 1- Q, 2-S, 3-P, 4- R
C. 1-R, 2-S, 3-P, 4-Q correct
D. 1- S, 2-R, 3-P, 4-Q
Q19MCQ2 marks
The viscosity and density of a fruit juice at 21°C are 6.3 x 10⁻³ Pa s and 1029 kg m⁻³, respectively. The juice flows at the rate of 0.12 m³ min⁻¹ in a 2.54 cm inner diameter steel pipe. Correct combination of the Reynolds number (NRe) and the nature of flow of juice is
A. NRe = 1048, Laminar
B. NRe = 2056, Laminar
C. NRe = 16375, Turbulent correct
D. NRe = 28656, Turbulent
Q20MCQ2 marks
For a typical food sorption isotherm curve (Figure 1), which one of the following statements is CORRECT ?
A. Y-coordinate of A represents monolayer water content of food, A-B represents water absorbed in the multilayer within the food and B-C represents free water within the capillary network of the food. correct
B. Y-coordinate of B represents monolayer water content of food, A-B represents water absorbed in the multilayer within the food and B-C represents free water within the capillary network of the food.
C. Y-coordinate of A represents monolayer water content of food, Y-coordinate of B represents water absorbed in the multilayer within the food and B-C represents free water within the capillary network of the food.
D. Y-coordinate of A represents monolayer water content of food, A-C represents water absorbed in the multilayer within the food and Y-coordinate of C represents free water within the capillary network of the food.
Q21NAT2 marks
10,000 kg milk (7% fat) is passed through a cream separator to obtain cream (40% fat) and skim milk (0.1 % fat). The cream, thus obtained, is churned to make butter of 80.5% fat. If a loss of 0.5% of initial milk fat occurs during the manufacturing process, the % overrun is _________________
Correct: 22 to 22.2
Q22NAT2 marks
A 50 mm thick pack of farm fresh berries is cooled at one side from 24°C to 7°C. The relevant properties of berries are: density 1025 kg m⁻³, specific heat 3.78 kJ kg⁻¹K⁻¹, convective heat transfer coefficient 30 W m⁻²K⁻¹, and thermal conductivity 0.3 W m⁻¹ K⁻¹. The Fourier number for a cooling span of 30 min is ________________
Correct: 0.055 to 0.057
Worked solutions are not printed here — every one of these questions carries a
full explanation inside the test itself, which is where it is actually useful:
after an answer has been committed.
Sit the 2014 paper.
