This download link is referred from the post: PTU B.Tech 5th Semester Last 10 Years 2011-2021 Previous Question Papers|| Punjab Technical University
Roll No. [ ] [ ] [ ] Total No. of Pages : 02
Total No. of Questions : 18
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B.Tech. (Food Technology) (Sem.=5)
FOOD PROCESSING ENGINEERING
Subject Code : BTFT-506
M.Code : 78651
Time : 3 Hrs. Max. Marks : 60
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INSTRUCTIONS TO CANDIDATES :
- SECTION-A is COMPULSORY consisting of TEN questions carrying TWO marks each.
- SECTION-B contains FIVE questions carrying FIVE marks each and students have to attempt any FOUR questions.
- SECTION-C contains THREE questions carrying TEN marks each and students have to attempt any TWO questions.
SECTION-A
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Write briefly :
- Differentiate between equivalent diameter and geometric mean diameter.
- Which size reduction law is used to calculate energy in-coarse grinding? Define the same.
- Define thermal death time.
- Differentiate between dead-end filtration from-cross flow filtration.
- What is the difference between dew point and wet bulb temperature?
- Define water activity. How it differs from moisture content?
- “The freezing time predicted by Plank’s equation is less than that of actual freezing time.” Comment and give reasons.
- How dry steam differs from wet steam at the same pressure.
- How boiling point elevation influence the evaporation process?
- What is Mollier diagram? Can it be used to determine properties of wet steam?
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SECTION-B
- a) What is difference between sorting and grading? Write a brief on the various graders and sorters used for fruits.
b) Describe various types of mixers used for low viscosity liquid mixing. Mention their distinguished features and applications. - A tunnel dryer is used to dry potatoes from initial moisture content of 75% (w.b.) to final moisture content of 5% (w.b.). An experimental drying curve for the potatoes indicate that the critical moisture content is 30% (w.b.) and the time for constant drying is 10 min. Based on this data, estimate the total drying time for the potatoes.
- Differentiate between sedimentation and centrifugation. With suitable line sketch describe the construction, working and applications of any centrifuge used in dairy industry.
- Name the four common ways of breaking solids in size-reduction machines. Write in brief the construction, operation and applications of hammer mill.
- Discuss the methods to improve the economy of an evaporator.
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SECTION-C
- a) Differentiate between Survivor curve and thermal death time curve. Derive an expression for microbial inactivation rate at constant temperature.
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b) A thermal process is accomplished by instantaneous heating to 138°C followed by a 4 sec hold and instantaneous cooling. Estimate the lethality at 121°C when the thermal resistance constant (z) for the microorganism is 8.5°C. - a) Explain the crystallization process using different theories. Describe a batch crystallizer with a neat diagram.
b) A food block of size 25cm x 50cm x 75cm is to be frozen in refrigerated with the plate temperature at 239 K. How long it will take to freeze if the food is wrapped in a package of 0.1 cm thickness. What would be the freezing time without packaging? Assume that for the plate freezer surface heat transfer coefficient is 600J/ms°C, thermal conductivity of frozen meat and packaged material is 1.6 and 0.06 J/ms°C. The latent heat of fusion of the food is 256 kJ/kg and density is 1090 kg/m³. Assume that meat freezes at 271K. Use Plank’s equation and take values of shape factors P= 0.275 & R=0.078. - a) Discuss the criteria for the selection of a suitable evaporator. Explain the factors that influence the rate of heat transfer and economy of evaporators.
b) The orange juice is being concentrated from 5 to 30% solids in a single-effect continuous evaporator. The juice at 20°C is fed to the evaporator at 5000 kg/h. Steam is available at 100°C. The saturation temperature of vapour in the evaporator is 50°C. The condensate leaves the evaporator at 75°C and the solution has a negligible boiling point elevation. The latent heat of vaporization at 50°C is 2382.7 kJ/kg. The specific heat of orange juice is 4.05 kJ/kg°C. Calculate the steam requirement and steam economy.
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NOTE : Disclosure of Identity by writing Mobile No. or Making of passing request on any page of Answer Sheet will lead to UMC against the Student.
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This download link is referred from the post: PTU B.Tech 5th Semester Last 10 Years 2011-2021 Previous Question Papers|| Punjab Technical University