40 Questions
What is the primary objective of tempering in the wheat milling process?
To soften the bran
What is the purpose of the disk separators in wheat processing?
To separate grains of different shapes and sizes
What is the typical range of water added to the wheat during tempering?
14% to 18% of the weight of the wheat
What happens to the bran during the resting period of tempering?
It becomes pliable and soft
What is the purpose of the resting period in the tempering process?
To allow for the even distribution of moisture throughout the grain
What is the purpose of disk separators in wheat processing?
To separate grains of different shapes and sizes
What is the result of tempering on the endosperm?
It remains unchanged
What is the ultimate goal of the tempering process?
To optimize the milling process
What is the purpose of scouring in grain processing?
To remove any adhering dirt, mud clods, or other impurities.
What is the function of an air table in gravity separation?
To float grains and separate them from lighter impurities.
What is the purpose of destoning in grain processing?
To separate grains from heavier debris like small stones.
How do color sorters remove discolored or damaged grains?
By using cameras and sensors and compressed air.
What is the purpose of magnetic separation in grain processing?
To remove metal fragments or tiny iron particles.
What is the function of an aspirator in grain processing?
To remove chaff, small pieces of straw, etc.
What is the purpose of a receiving or milling separator?
To remove sticks, stones, and other foreign material.
What is the purpose of winnowing in grain processing?
To separate lightweight impurities like dust, husks, or chaff.
What is the main reason for adding water to the grain during the tempering process?
To weaken the protein-starch bond in the grain
What is the result of soft and pliable bran during milling?
Easier separation from the endosperm
What happens to the endosperm during the tempering process?
It becomes softer and easier to grind
What is the primary mechanism of action in a roller mill?
Pairs of cylindrical rollers rotating in opposite directions
What is the benefit of properly conditioned wheat during milling?
Easier milling with fewer bran specks and higher-quality flour
What is the purpose of the resting period in the tempering process?
To allow the water to break the protein-starch bond
What is the result of high moisture content in the bran during milling?
It stays in large pieces and is easier to remove
What type of wheat is often used in the roller milling process?
Common wheat
What is the primary function of sieves in the milling process?
To separate particles based on their size
What is the main advantage of using plansifters in modern mills?
They can process large quantities of flour simultaneously
What is the purpose of grading in the milling process?
To classify the product into various categories like fine flour, coarse flour, and bran
What happens to larger particles during repeated sifting?
They are sent back for further grinding
How do purifiers separate particles in addition to size?
By weight
What is the main benefit of using purifiers in the milling process?
They improve the purity of the endosperm fraction
What is the purpose of recovery in the purifying process?
To recover fine endosperm particles that might still be attached to larger bran particles
What does the concept of 'extraction yield' or 'extraction' represent in the milling industry?
The efficiency with which the endosperm is separated and recovered during the milling process
What is the purpose of the cleaning process in grain milling?
To ensure the efficiency and longevity of the milling equipment
What is the primary step in grain cleaning?
Screening
What is the purpose of using screens or sieves of varying sizes in the cleaning process?
To remove impurities such as straw and chaff
What is the result of removing the bran and germ during the milling process?
The flour has a longer shelf life
What is the benefit of using whole grain products?
They have a higher content of fiber, vitamins, and minerals
What is the advantage of using refined flour in baking?
It produces baked goods with a softer texture and milder taste
What is the purpose of aspiration in the cleaning process?
To use controlled air flow to remove impurities
What is the economic benefit of the milling industry?
It allows for specialization and maximizing economic returns
Study Notes
Wheat Milling Process
- Wheat passes through a cockle cylinder to separate grains of similar density
- The machine consists of a series of disks mounted on a horizontal central shaft with pocketed sides to pick up grain of a certain shape and size
Conditioning (Tempering)
- Water is added to cleaned wheat to toughen the bran and mellow the endosperm, optimizing the milling process
- Tempering process involves:
- Water addition: 14% to 18% of the wheat's weight, depending on type and initial moisture content
- Resting: Allowing even distribution of moisture throughout the grain
- Bran softening: Softening the bran to remove lightweight impurities
- Gravity separation: Dense and healthy grains sink, while broken grains and foreign bodies float or remain suspended
Cleaning Process
- Receiving or milling separator: Removes sticks, stones, and other foreign material that is larger or smaller than the grain
- Screenings: Passes through screens or sieves of varying sizes to remove impurities
- Aspiration: Controlled air flow to remove chaff, small pieces of straw, etc.
- Sieves: Separate particles based on size, with smaller particles falling through openings while larger ones are retained
Milling Process
- Roller mills: Pairs of cylindrical rollers rotating in opposite directions to grind the wheat
- Plansifters: Multiple stacked sieves to classify flour into various particle sizes simultaneously
- Purifiers: Separate particles by size and weight, blowing lighter bran particles away from heavier endosperm particles
- Repeated sifting: Ensures larger particles are sent back for further grinding, while finer particles move on in the process
Milling Implications
- Nutritional: Removal of bran and germ decreases nutritional value, making whole grain products more nutritious
- Shelf Life: Refined flour has a longer shelf life due to the removal of oil-rich germ
- Texture and Taste: Refined flour produces softer, milder-tasting baked goods
- Economic: The milling industry caters to diverse markets, producing various grades and types of flour
This quiz is about the process of separating grains of similar density using disk separators. It explains how the machine works and identifies the desired grain based on size and shape.
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