৩

Explain 12D concept. Calculate the D-value of an organism that shows 50 survivors 6 from initial inoculums of 2×10⁶ spores after 10 minutes at 250°F. 

১

Describe the principles and methods of food preservation.

১

Explain thermophysical properties of foods with examples. A wet food product contain 70% water. After drying, it is found that 80% of original water is removed. Determine (i) mass of water removed per kg of wet food and (ii) composition of dried food.

২

Define and discuss the rheological properties of common food products like sauces, dough and emulsions in context of food engineering. How do these properties affect to choose processing methods?

২

Describe the working principle with mechanism of a vapour compression refrigeration cycle with a flow diagram. It is wished to freeze 15 tonnes of fish per day from an initial temperature of 10°C using a stream of cold air. Estimate the maximum capacity of the refrigeration plant required, if it is assumed that the maximum rate of heat extraction from the product is twice of the average rate. If the heat transfer co-efficient from the air to the evaporator coils is 22 Jms°C, calculate the surface area of the evaporator coil required if the LMTD drop across the coil is 12°C and specific heats of fish are 3-18 and 1-67 KJkg¹°C above and below freezing, respectively.

৩

Explain the principles and factors of drying process. "Drying involves both heat and mass transfer processes simultaneously"-Justify the statement.