Food Processing Contaminants and Sorting Methods

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Questions and Answers

What is the primary function of the programmable logic controller in sorting systems?

To increase conveyor speed

To control pre-set programs for product detection (correct)

To store product types

To directly manage air jet operations

How do light-sensitive cells, or pixels, contribute to the detection of defects in products?

By adjusting the conveyor speed based on light intensity

By producing voltage that corresponds to light intensity (correct)

By enhancing the color of the products being inspected

By emitting additional light for better visibility

What is the maximum operational speed of conveyors used in these sorting systems?

300 m per min

250 m per min

150-180 m per min (correct)

100 m per min

What mechanism is used to remove defective items from the conveyor?

Electrically controlled air jets Signup and view all the answers

In the system that scans vegetables in free fall, how many times per second are they scanned?

What does the photodetector measure in the sorting process?

The reflected color of each piece Signup and view all the answers

How does the system control the velocity of particles in microprocessor-controlled color sorting equipment?

By altering the chute's angle and shape Signup and view all the answers

What types of light can be used for illuminating products in sorting systems?

Infrared and ultraviolet, among other options Signup and view all the answers

What is the primary advantage of weight sorting compared to other methods?

It is more accurate and reliable. Signup and view all the answers

What is the purpose of candling in the egg sorting process?

To evaluate their freshness and quality. Signup and view all the answers

In flotation sorting, what characteristic is primarily used to separate the items?

Variability in density. Signup and view all the answers

How is collation sorting typically performed in modern processes?

Automatically by a microcomputer. Signup and view all the answers

What distinguishes grading from sorting in the context of food processing?

Grading involves a higher number of variables. Signup and view all the answers

What is the specific gravity range used for flotation sorting of peas and lima beans?

1.1162 - 1.1362 Signup and view all the answers

Which process is NOT a type of sorting described in the content?

Mechanical cleaning Signup and view all the answers

What is a common issue with collation sorting associated with fill-weight legislation?

Inaccuracy in declared pack weight. Signup and view all the answers

What is the mass mean diameter of the particles calculated from the data provided?

4.68 µm Signup and view all the answers

Which factor is NOT mentioned as influencing the suitability of food for processing?

Texture of the food Signup and view all the answers

Which method is primarily used for size sorting of solids?

Vibrating screens Signup and view all the answers

What is the cumulative percentage of mass retained at an aperture size of 4.00 µm?

82.6% Signup and view all the answers

Which of the following sorting methods is noted for high costs and space requirements?

Manual sorting by colour Signup and view all the answers

In what scenario is uniform size of food pieces considered particularly important?

For efficient heating or cooling Signup and view all the answers

Which type of sorting system is reported to have lower operating costs compared to manual methods?

Image processing sorting systems Signup and view all the answers

What is an example of food shape impacting its market value mentioned in the content?

Round potatoes Signup and view all the answers

What is a major advantage of flash peeling compared to abrasion peeling?

It results in lower product loss. Signup and view all the answers

In what situation is knife peeling particularly efficient?

During the peeling of citrus fruits. Signup and view all the answers

What is a significant limitation of abrasion peeling?

It results in irregular product surfaces. Signup and view all the answers

Which statement about caustic peeling is accurate?

It often uses high-pressure washing to remove skins. Signup and view all the answers

What characteristic distinguishes flash peeling from other peeling methods?

It leads to concentrated waste that is easier to dispose of. Signup and view all the answers

What factor limits the throughput of the abrasion peeling method?

The need for every piece to contact abrasive surfaces. Signup and view all the answers

Which of the following best describes dry caustic peeling?

Food is dipped in a strong sodium hydroxide solution. Signup and view all the answers

What is a notable trend in the adoption of flash peeling technology?

It enhances the appearance of the peeled surface. Signup and view all the answers

What principle is utilized in the physical separation of round foods from contaminants?

The ability to roll down an inclined conveyor belt Signup and view all the answers

Which method is most suitable for detecting small metal fragments in processed foods?

Use of X-rays to penetrate materials Signup and view all the answers

What is a key disadvantage of permanent magnets in food processing?

They might accumulate contaminants leading to potential recontamination Signup and view all the answers

Which equipment uses ultraviolet light for contaminant detection?

Microprocessor-controlled color sorting equipment Signup and view all the answers

What is the primary function of a disc separator?

Separating grain from weed seeds based on size Signup and view all the answers

What characteristic of contaminants does recent technology focus on for removal in food processing?

Color and shape differences Signup and view all the answers

Why are screens used in food processing to remove contaminants?

They effectively filter particles and contaminants by size Signup and view all the answers

What is a common risk if permanent magnets are not regularly inspected in food processing?

They can sporadically release contaminants all at once Signup and view all the answers

Study Notes

Removing Contaminants and Foreign Bodies

Air velocity is crucial for separating contaminants from grain and vegetables.
Round foods like peas, blackcurrants, and rapeseed are separated by rolling them on an inclined conveyor belt.
Disc separators use precisely engineered indentations to separate grain from weed seeds.
Screens are used to remove contaminants from foods.
Metal detectors are used to prevent contamination by metal fragments.
Permanent magnets and electromagnets are used to remove ferrous metals.
Permanent magnets are cheaper but need regular inspection to avoid contamination.
Microprocessor-controlled colour sorting equipment identifies contaminants by colour and shape.
Coffee beans are viewed under UV light to detect fluorescent bacteria.
X-rays are used to detect metal and other solid contaminants in raw materials and packaged foods.

Size Sorting

Uniform size is important for food processing and consumer preference.
Screens with fixed or variable apertures are used for size sorting.
Screen types include stationary, rotating, and vibrating.

Colour Sorting

Machine vision sorting systems are more accurate and cost-effective than manual sorting.
Systems include monochrome, bichrome, and trichromatic options.
Programmable logic controllers control the sorting process.
Light-sensitive cells in the camera detect color variations.
Defective items are removed by electronically controlled air jets.
Vegetables in freefall are scanned using laser light beams and a high-speed rotating mirror.
Microprocessor-controlled color sorting equipment sorts small-particulate foods at high rates.
Photodetectors measure reflected color and compare it to pre-set standards.

Weight Sorting

Weight sorting is used for valuable foods like eggs, cut meats, and tropical fruits.
Eggs are graded by candling and then sorted by weight.
A slatted conveyor transports eggs above counterbalanced arms that weigh them individually.
Aspiration and flotation sorting use differences in density to separate foods.
Microcomputers automate collation sorting, selecting the best combination of items for uniform weight packs.

Grading

Grading assesses overall quality of food using multiple attributes.
Sorting based on one characteristic is part of the grading process.
Operators are trained to assess multiple variables simultaneously.

Peeling

Flash peeling uses steam and pressure to remove skin.
Knife peeling uses stationary or rotating blades to peel.
Abrasion peeling uses carborundum rollers or bowls to remove skin.
Caustic peeling uses a dilute solution of sodium hydroxide to soften the skin.

Peeling Methods Comparison

Flash peeling has lower water consumption, minimal product loss, and high throughput, but can damage some products.
Knife peeling is suitable for citrus fruits but can damage other products.
Abrasion peeling has low energy costs, but high product loss and large volumes of waste.
Caustic peeling can cause color changes and has high costs.

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Description

This quiz covers the methods used in food processing to remove contaminants and sort food by size. Explore the technologies involved, including air velocity, disc separators, and advanced detection methods like X-rays and UV light. Test your knowledge on how these techniques enhance food safety and quality.