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Chapter 7

Unit Operations in Food

Processing

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Material handling

Cleaning

Separating

Size Reduction

Pumping (fluid flow) Mixing

Heat exchanging

Unit Operations in Food Processing

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Concentration

Drying

Forming Packaging

Controlling

Overlapping operations Conserving energy

New processes

Unit Operations in Food Processing

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Material handling

HarvestingTrucking

Transportation

Conveying

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Material handling

Bacterialgrowth

Quality

Losses

Sanitary

conditions

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Cleaning

EquipmentsRawmaterial

Floors

Walls

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Cream separator

Clarification Membrane processes

Separating

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Membrane processes

Reverse osmosis (RO)

Ultrafiltration (UF)

Microfiltration (MF)

Separating

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Slicing

Dicing Cutting

Grinding

Size Reduction

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Two different types of pumps

Centrifugal pump

Positive pump

Pumping (fluid flow)

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The efficiency of mixing depends on

Design of impeller

Diameter of impeller

Speed

Baffles

Mixing

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Heat exchanging

Heat

exchanging

Heating

Cooling

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Heat exchanges

Plate heat exchanges

Tubular heat exchanges

Swept surface heat exchangers

Heat exchanging

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Evaporation

Reverse osmosis

Concentration

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Sun or tray drying

Spray drying

Freeze drying

Drying

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Compacting

Extrusion Molds

Powders and binding agents

Heat and pressure

Forming

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Purposes

Shipping

Dispensing

Improving the usefulness

Protection from microbial

contamination, dirt, insects, light,moisture, drying, flavor changes,and physical alterations

Packaging

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Valves

Thermometers Scales

Thermostats

Others

Controlling

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Overlapping operations

Conserving energy New processes

Unit Operations in Food Processing

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Unit operations make up the basicsof food processing.

These include material handling,cleaning, separating, size reduction,fluid flow, mixing, heat transfer,

concentration, drying, forming,packaging, and controlling.

Summary

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Most food processing involves acombination or an overlap of

these unit operations.

Summary

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Where unit operations overlap orare combined, complex controls

ensure the proper function ofeach operation.

Summary

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Review Questions

Question 1

Why are foods packaged?

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Review Questions Answer 1

Packaging is used for a variety of purposeincluding shipping, dispensing, improving theusefulness of the product, and protection frommicrobial contamination, dirt, insects, light,moisture, drying, flavor changes, and physical

alterations. Attractive packaging also helps with marketing

of the food product.

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Review Questions

Question 2

Name the three methods forseparating foods.

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Review Questions

Answer 2 Cream separator, clarification,

and membrane processes.

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Review Questions

Question 3

What are the two types of fluidflow pumps?

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Review Questions

Answer 3 Centrifugal pump and positive pump.

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Review Questions

Question 4

List the four factors affecting themixing of food products.

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Review QuestionsAnswer 4

Design of impeller, diameter of impeller,speed, and baffles.

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Review Questions

Question 5

Why is it important tohandle food materialscarefully?

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Review Questions

Answer 5 To maintain sanitary conditions,

minimize losses, maintain quality,and minimize bacterial growth.

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Review Questions

Question 6

Explain the three commonmethods of drying foods.

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Review Questions

Answer 6 Sun or tray drying, spray drying,

and freeze drying.

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Review Questions

Question 7

List three membrane processesfor separating food products.

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Review Questions

Answer 7

Reverse osmosis, ultrafiltration, andmicrofiltration.