UNIT OPERATION IN FOOD PROCESSINGUNIT OPERATION IN FOOD PROCESSING

PREPARATION OF RAW MATERIALS PREPARATION OF RAW MATERIALS BEFORE PROCESSINGBEFORE PROCESSING

PART BPART B(SORTING AND GRADING (SORTING AND GRADING

PROCESS)PROCESS)

Prepared by: Pn Rosliza Bt. Mohd Radzali

ObjectivesObjectives

Explain the sorting and grading process.Explain the sorting and grading process.

Define each types of sorting and grading process.Define each types of sorting and grading process.

Identify types of sorting and grading process.Identify types of sorting and grading process.

Explain the reasons of sorting and grading process.Explain the reasons of sorting and grading process.

Explain and identify the related equipment for each Explain and identify the related equipment for each types of grading and sorting process.types of grading and sorting process.

SORTINGSORTING

Sorting

Separation operation based on the Separation operation based on the differences in physical properties of the differences in physical properties of the food raw material and products.food raw material and products.

Separation based on single properties Separation based on single properties such as such as color or photometric, size, shape color or photometric, size, shape or weightor weight of the food raw material. of the food raw material.

WEIGHT SORTING

The weight of food unit is proportional to the cube of its characteristic dimension sorting.

E.g: meat cuts, fish fillets, fruits such as apples, pears and citrus fruits, vegetables such as potatoes, carrots and onions and eggs.

Typical weight-sorting machines carry fruits in tare canvas pocket attached to pivoted beams fitted with counterbalance weight.

As the beams pass along the sorter, the beam fulcrum is moved toward the counterbalance weight until such time as the weight of the fruit causes the beam to tip, discharging the fruit into padded chutes in weight categories.

Weight Sorting

SIZE SORTING

Size Sorting

Different types of screen are used for size separation of Different types of screen are used for size separation of foods.foods.

The screen designs commonly used in food industry The screen designs commonly used in food industry may be grouped into two types:may be grouped into two types:(i)(i) variable aperture screens using cable, belt, roller or variable aperture screens using cable, belt, roller or

screw screw sorter.sorter.(ii)(ii) Fixed aperture screens using stationary, vibratory, Fixed aperture screens using stationary, vibratory,

rotary, gyratory or reciprocating screens.rotary, gyratory or reciprocating screens.

Fixed aperture screens Fixed aperture screens of flat-bed type are used in of flat-bed type are used in preliminary preliminary sorting of potatoes, carrots and turnips.sorting of potatoes, carrots and turnips.

Multi-decks screen Multi-decks screen are used in are used in size sorting of cereals, size sorting of cereals, nuts, flour, sugar, salt, ground spices and herbs.nuts, flour, sugar, salt, ground spices and herbs.

Drum screen Drum screen are used for sorting peas, beans and other are used for sorting peas, beans and other similar food capable withstanding tumbling action in a similar food capable withstanding tumbling action in a rotary drum screen.rotary drum screen.

Variable aperture screen Variable aperture screen with continuously variable with continuously variable apertures of roller, belt or screw type find use in sorting apertures of roller, belt or screw type find use in sorting of vegetable and fruits.of vegetable and fruits.

SHAPE SORTING

Shape Sorting Shape sorting is adopted when food materials contain Shape sorting is adopted when food materials contain

undesirable material even after size or weight sorting undesirable material even after size or weight sorting and cleaning.and cleaning.

Shaoe sorting on the basis of a combination of length Shaoe sorting on the basis of a combination of length and diameter is useful under such circumstances.and diameter is useful under such circumstances.

A discs sorter A discs sorter used for shape sorting wheat, rice, oats used for shape sorting wheat, rice, oats and barley.and barley.• The disc sorter has indentations on both sides of the vertically The disc sorter has indentations on both sides of the vertically

rotating, discs mounted on a motor driven horizontal shaft.rotating, discs mounted on a motor driven horizontal shaft.• The vertically rotating discs pass through unsorted food held in The vertically rotating discs pass through unsorted food held in

a trough at the lower end of their rotation, collect the food of a trough at the lower end of their rotation, collect the food of correct shape in the indentations and discharge the collected correct shape in the indentations and discharge the collected material into bins at the top of their rotation.material into bins at the top of their rotation.

• Undesirable materials such as weed seeds will not fit into Undesirable materials such as weed seeds will not fit into indentations on the discs and hence will not be collected by the indentations on the discs and hence will not be collected by the rotating discs.rotating discs.

Spherical weed seeds Spherical weed seeds may be removed from wheat and may be removed from wheat and other cereals by shape other cereals by shape sorting using their tendency to sorting using their tendency to travel down an inclined surface.travel down an inclined surface.

The weed seed will easily roll down while the desired The weed seed will easily roll down while the desired material moves upward along with the belt and is material moves upward along with the belt and is discharged at the upstream end.discharged at the upstream end.

COLOR / PHOTOMETRIC SORTING

Color / Photometric Sorting Photometric sorting uses optical properties of foods to Photometric sorting uses optical properties of foods to

effect separation of desired material from effect separation of desired material from contaminants.contaminants.

Optical properties such as reflectance and Optical properties such as reflectance and transmittance of foods are useful indicators in a variety transmittance of foods are useful indicators in a variety of ways.of ways.

Reflectance properties are used to indicate:Reflectance properties are used to indicate:i) i) Raw material maturity Raw material maturity (e.g: color of fruit, vegetables (e.g: color of fruit, vegetables and meat indicate ripeness and freshness and meat indicate ripeness and freshness characteristics)characteristics)ii) ii) The presence of surface defects The presence of surface defects (e.g:worm holed (e.g:worm holed cereals or nuts and bruised fruits)cereals or nuts and bruised fruits)iii) iii) The extent of heat processing The extent of heat processing (e.g: in the (e.g: in the manufacture of biscuits, bread and potato chips or manufacture of biscuits, bread and potato chips or crisps)crisps)

Mechanical reflectance color sorter Mechanical reflectance color sorter used used

• to sort, clean and grade food such as nuts, cereals to sort, clean and grade food such as nuts, cereals and coffee beans containing worm-hole or other and coffee beans containing worm-hole or other defects.defects.

• Diced vegetables, whole potatoes, onions and fruits Diced vegetables, whole potatoes, onions and fruits which are incompletely peeled.which are incompletely peeled.

• Citrus fruits and tomatoes exhibiting maturity Citrus fruits and tomatoes exhibiting maturity differences.differences.

• Finish food product such as jams, peanuts butter and Finish food product such as jams, peanuts butter and crisps exhibiting differences in processing.crisps exhibiting differences in processing.

Principle of color sorter

The color sorter principles operationThe color sorter principles operation

• Functions on the basis of photometric scanning of Functions on the basis of photometric scanning of each food unit as it moves past or rotated before a each food unit as it moves past or rotated before a photocell.photocell.

• The signal generated by the photocell is compared to The signal generated by the photocell is compared to an adjustable pre-set standard signal automatically an adjustable pre-set standard signal automatically and any imbalance between the two signals is and any imbalance between the two signals is amplified and used to activate the sorting gear.amplified and used to activate the sorting gear.

• Rejection systems of different types are used.Rejection systems of different types are used.

• A pneumatic rejection system is used for small A pneumatic rejection system is used for small particulate foods, the signal from the discriminator particulate foods, the signal from the discriminator being used to operate an air jet which deflects being used to operate an air jet which deflects substandard material into the reject chute.substandard material into the reject chute.

• Electrostatic separation also used which is the Electrostatic separation also used which is the rejected material being charged by an electrode rejected material being charged by an electrode and then withdrawn from the bulk by an and then withdrawn from the bulk by an oppositely charge deflectoroppositely charge deflector

The transmittance sorting The transmittance sorting • A non-destructive internal examination of liquid and A non-destructive internal examination of liquid and

solid foods.solid foods.

• The method requires a very sensitive detection The method requires a very sensitive detection system as only about 0.1% of the incident light system as only about 0.1% of the incident light energy is transmitted through the food.energy is transmitted through the food.

• Apples are sorted by measuring the transmittance at Apples are sorted by measuring the transmittance at 692±3 nm which is related to the chlorophyll content 692±3 nm which is related to the chlorophyll content of the flesh of the fruit and hence to its maturity.of the flesh of the fruit and hence to its maturity.

GRADINGGRADING

Grading Of Raw Materials Is a process to separate a raw materials to different Is a process to separate a raw materials to different

categories of quality .categories of quality .

Grading is carried out by operators to simultaneously Grading is carried out by operators to simultaneously assess a number of variable.assess a number of variable.

For example, cheese and tea, which are assessed for For example, cheese and tea, which are assessed for flavor, aroma ,color.flavor, aroma ,color.

In some cases the grade of food is determined from the In some cases the grade of food is determined from the results of laboratory analyses (for example wheat flour results of laboratory analyses (for example wheat flour is assessed for protein content, dough extensibility, is assessed for protein content, dough extensibility, color, moisture content and presence of insects).color, moisture content and presence of insects).

Grading Of Raw Materials Grading is Grading is quality separation on the basis quality separation on the basis

of an overall assessment of those of an overall assessment of those properties, which effect this acceptance properties, which effect this acceptance of the food raw material for processing, of the food raw material for processing, and finished food product for consumer and finished food product for consumer acceptance and safety.acceptance and safety.

Factors of Grading Process suitabilityProcess suitability Consumer safetyConsumer safety Conformity with legal requirementsConformity with legal requirements Consumer acceptance.Consumer acceptance.

Types of Grading MANUAL GRADINGMANUAL GRADING

• Is done by trained operators whoa are able to assess Is done by trained operators whoa are able to assess a number of grading parameters simultaneously.a number of grading parameters simultaneously.

• E.g: E.g: eggs are graded manually by candling. eggs are graded manually by candling. • This is non-destructive examination of the egg This is non-destructive examination of the egg

contents through the translucent shell when the egg contents through the translucent shell when the egg is spun in front of a powerful light in a darkened is spun in front of a powerful light in a darkened booth. booth.

• The presentation of each egg is automatic and a The presentation of each egg is automatic and a candling operator can separate several thousand candling operator can separate several thousand eggs an hour into 3 or 4 grades taking into account eggs an hour into 3 or 4 grades taking into account up to 20 different grading parametersup to 20 different grading parameters

Types of Grading

• In certain cases, light of specific wavelength may be In certain cases, light of specific wavelength may be used to grade food units. used to grade food units.

• Thus blood spots in eggs are detected when light of Thus blood spots in eggs are detected when light of wavelength 577 and 597 nm is used while green rot wavelength 577 and 597 nm is used while green rot is revealed by fluorescence at 490 and 510 nm.is revealed by fluorescence at 490 and 510 nm.

DISADVANTAGESDISADVANTAGES• CostlyCostly• Boredom and fatigue reduce grading efficiency.Boredom and fatigue reduce grading efficiency.

Types of Grading MACHINE GRADINGMACHINE GRADING

• Carried out by combining a group of sorting Carried out by combining a group of sorting operations so as to separate the food units on quality operations so as to separate the food units on quality basis.basis.

• Wheat graded by a combination of cleaning and Wheat graded by a combination of cleaning and sorting operation.sorting operation.

• Peas of small size are recognized to be most tender Peas of small size are recognized to be most tender and of highest quality so that size sorting of cleaned and of highest quality so that size sorting of cleaned peas results in quality grading.peas results in quality grading.

• Potatoes of high density, desirable for manufacturing Potatoes of high density, desirable for manufacturing french fries, potatoes crisps and dehydrated mashed french fries, potatoes crisps and dehydrated mashed potato may be graded using flotation in brines.potato may be graded using flotation in brines.

• Mechanical grading is cost effective and efficient.Mechanical grading is cost effective and efficient.

Sorting Process

Grading Process

Thank you

Post-testPost-testState whether these statement are State whether these statement are TrueTrue oror FalseFalse

1.1.The present of contaminant such as fungal and The present of contaminant such as fungal and yeast can reduce the quality of food product. yeast can reduce the quality of food product. 2.2. Filtration and brushing are types of wet cleaning Filtration and brushing are types of wet cleaning method.method.3.3.Soaking is a wet cleaning method.Soaking is a wet cleaning method.4.4.Aspiration is a dry cleaning method.Aspiration is a dry cleaning method.5.5.wet cleaning have low cost production because it wet cleaning have low cost production because it produce low effluent.produce low effluent.6.6.Spray drum washer is an equipment that used in Spray drum washer is an equipment that used in wet cleaning method.wet cleaning method.

Post-testPost-testFill in the blank this statement with the right answerFill in the blank this statement with the right answer

1.1. _______ use detergent and water to remove soil and dust _______ use detergent and water to remove soil and dust from foods.from foods.

2.2. ________ use principles of different buoyancy to remove ________ use principles of different buoyancy to remove debris from the foods.debris from the foods.

3.3. _________is one of contaminant type of chemical elements._________is one of contaminant type of chemical elements.4.4. __________ can detect metal particles.__________ can detect metal particles.

Wet cleaning

aspiration

pesticides

Magnetic cleaning

answeranswer

Part A Part A 1.1. TrueTrue2.2. FalseFalse3.3. TrueTrue4.4. TrueTrue5.5. falsefalse6.6. TrueTrue

Part BPart B1.1. Wet cleaningWet cleaning2.2. AspirationAspiration3.3. PesticidesPesticides4.4. Magnetic cleaning Magnetic cleaning