Milling of Cereals Questions and Answers

Answer: A

Correct answer: Both A and R are true, and R is the correct explanation of A

Both are true and the reason explains why the measurement works. Mineral matter is concentrated in the bran and especially the aleurone, and is low in the starchy endosperm, so the ash left after incineration is essentially a measure of how much of the outer grain has reached the flour. That makes it an objective proxy for grade, unlike colour, which depends on the observer.

Answer: B

Correct answer: 1 and 2 only

Statements 1 and 2 describe the two roll types correctly. Statement 3 misstates the purifier’s principle: sieves classify by size, and a bran flake may be exactly the size of a semolina granule. The purifier works by combining a sieve with a rising air current, so the separation is by density and aerodynamic behaviour rather than by size alone.

Answer: C

Correct answer: 1 and 2 only

Statements 1 and 2 name the two principal operations correctly. Statement 3 is the reverse of the truth - polishing removes the last traces of bran to add gloss, so it reduces the yield slightly rather than raising it. Its purpose is appearance and market value, not quantity.

Answer: D

Correct answer: 1 and 2 only

Statements 1 and 2 are correct: extraction is flour as a percentage of wheat milled, and raising it brings in fractions nearer the bran, so ash rises. Statement 3 is well out - wholemeal is by definition the whole grain, so its extraction is about 100 per cent. Seventy-five per cent is roughly the figure for ordinary white flour.

Answer: A

Correct answer: 1 and 2 only

Statements 1 and 2 correctly assign each law to the range it suits: Kick, which depends only on the size ratio, for coarse crushing, and Rittinger, which follows the new surface, for fine grinding. Statement 3 misattributes Rittinger’s premise to Bond - Bond’s law involves the square root of particle size and sits between the other two.

Answer: B

Correct answer: A-2, B-1, C-4, D-3

The grain divides into four fractions with four fates. The pericarp and seed coat become the bran. The starchy endosperm becomes white flour, or milled rice. The germ is oil-rich and is removed as a separate by-product. And the aleurone, a single mineral-rich cell layer just inside the seed coat, is the main source of the flour’s ash and leaves with the bran.

Answer: C

Correct answer: A-2, B-1, C-4, D-3

The four operations run in sequence and each removes something different. Hulling takes off the husk, leaving brown rice. Whitening abrades away the bran layers and the germ. Polishing removes the last traces of bran and adds gloss. Grading then separates the whole kernels from the brokens, which is what determines the head rice yield.

Answer: D

Correct answer: A-2, B-1, C-4, D-3

Each machine has one duty in the flow. The conditioner adds water and tempers the grain before anything else happens. The break rolls open the kernel and scrape the bran. The purifier then separates bran flakes from the semolina by air current. And the reduction rolls grind the purified semolina down to flour.

Answer: A

Correct answer: A-2, B-1, C-4, D-3

Four measures of four different things. Ash indicates how much bran has contaminated the flour. Head rice yield is the proportion of whole kernels. Extraction rate is the flour obtained per unit of wheat. Degree of milling is how much bran has been scoured from brown rice, and it is the figure the appearance and keeping quality both turn on.

Answer: B

Correct answer: Purification of semolina

Purification belongs to wheat milling: it separates bran flakes from semolina by air current before the reduction passages. Rice milling has no semolina and no purifier. Its stages are cleaning and paddy separation, hulling, whitening, polishing and grading, and the last of these is what determines the head rice yield.