Unit Operations in Food Processing - PTP

8/14/2019 Unit Operations in Food Processing - PTP

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UNIT OPERATIONS

in FOOD PROCESSING


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Food Processing

Raw Materials Meat, Eggs, Milk Cereal & Legumes

Fruits & Vegetables Seafood Etc.

FoodProcessing

Products


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Unit Operations in Food Processing

Most of food processing is comprised as aseries of physical processes that can bebroken down into a number of basic operations

These unit operations can stand alone &depend upon logical physical principles

Examples ?


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Unit Operations in Food Processing

Materials handling Cleaning Separating Size reduction Fluid flow Heat transfer

Mixing Drying Forming Packaging Controlling


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Including :The variety of operations from harvestingTransportationConveying the product from truck to bin

Concerning:Sanitary conditionsLosses minimized

Quality mantainedBacterial growth minimized All transfer and deliveries of materials mustbe on time

Materials Handling


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Materials Handling

Examples : Refrigerated trucking of perishable produce Conveying product from truck to storage

All transfers & deliveries must be on time & thattime kept to a minimum for efficiency & quality


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Cleaning & Separating

Washing Sorting Grading Peeling Filtration Centrifugal separation Separation by membrane


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Cleaning

Removal of dirt and bacteria from the food tomaintain the quality of the product

Using : brushes, high velocity air, steam, water,

magnets, filtration The floors and walls of the processing facility

must also be cleaned


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Shape Sorting


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Separating

Basis: density, size, shape Cream separator

- milk cream & skim ; based on the densitydifference between fat and nonfat solids ofmilk ; using a disc type centrifuge

Clarificationremove sediment and microorganismscentrifugally in a clarifier (a disc typecentrifuge); example : recover yeast cells fromthe fermentation broth


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Size Reduction

Using high shear forces, graters, cutters,slicers, example : emulsions with very small fatglobule droplets are made in a homogenizer

Equipments : grinder, slicer, chopper. Size increase : aggregation, agglomeration,

gelation


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Membrane Processes Reverse osmosis

-uses membrane with the smallest pore-separate water from other solutes-uses the highest pressure pump

Ultrafiltration-larger pores-retain protein, salts and sugar-allowing smaller molecules to pass (permeate)

Microfiltration-pores less than 0.1 micron-separate fat from protein, reduce microorganism

from fluid systems


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Size Reduction Slicing Dicing Cutting Etc.


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Mixing


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Heat Transfer

Heating & cooling Pasteurization Sterilization Refrigeration Freezing Etc.


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Thermal processing

Sterilization complete destruction of microorganisms,at least 121 oC, 15 to destroy all spores

Commercial sterility products may contain viablespores, but they will not grow under normal conditions

Pasteurization comparatively low-energy thermalprocess; decreasing number of spoilage organismspresent; shelf-life extension; product is not sterile & willbe subject to spoilage


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DRYING

Sun drying Cabinet drying (placed in trays and dried in a

current of hot air), ex: raisins from grapes.

Spray drying- applied to fluid products

Freeze drying

- for heat sensitive food- the moisture is removed by sublimation, ex:instant coffee


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Forming

Some foods often need to be formed intospecific shapes, for example:confectionary, snack foods, cereals, cheeses,variety breads and sausages.

Processes can include :Compacting, extrusion, molding with theapplication of binding agents, heat and pressure


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Forming


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Packaging

Used for :- protection from microbial contamination,dirt, insects, light, moisture, flavor

changes and physical alteration- shipping- improving the usefulness of the product- helps with marketing of food product

The kind of packages :- metal cans, glass/plastic bottle, paper,cardboard, plastic and metallic films.


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Packaging


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Controlling & Measuring

Unit operations are combined into a complexprocessing operation

To ensure the quality of a food product, foodprocessors need to measure & control theseoperations

pressure, temperature, fluid flow, acidity, weight,viscosity, humidity, time, etc.


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Overlapping Operations

A combination of unit operations to achieve the totalproces.

Production of :

Dried fruit :Cleaning Size Reduction Drying (cabinet drying)

Packing Ice cream :

Mixing Pasteurization Homogenization Freezing Milk powder :

Mixing Spray Drying Sieving Packing


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Reference :

Parker,Rick. (2003). Introduction to FoodScience. Delmar. Australia.

Fellows,P. (2000). Food Processing TechnologyPrinciples and Practice. Woodhead PublishingLimited. England.

Documents

Unit Operations in Food Processing - PTP