QUIZ

Question 1

You suspect mercury contamination in fish caught from an industrial area. Which statements is true?
a. dry ashing will show the presence of mercury in fish
b. ashing following by metal detection is required for determining presence of mercury
c. HPLC can be used for determining the presence of mercury
d. all the above statement are correct

Answer 1

b. ashing following by metal detection is required for determining presence of mercury

Question 2

The black spot found in crucible after ashing chocolate samples for ash determination.
a. is indicative of incomplete digestion
b. is resulting from the trapping of minerals by carbohydrate in the sample
c. can be removed by reashing after the addition of dilute nitric acid
d. all the above

Answer 2

d. all the above

Question 3

Wet ashing is preferred over dry ashing for which of the following reasons
a. wet ashing allows characterization of ash obtained
b. wet ashing minimize loss of volatile metals/minerals
c. wet ashing is generally faster than dry ashing
d. because of all the above reasons
e. because of the reasons given in B & C

Answer 3

e. because of the reasons given in B & C

Question 4

White fumes during wet ashing carried out on hot plates are suggestive of
a. decomposition of sulfuric acid
b. completion of ashing
c. incomplete digestion

Answer 4

a. decomposition of sulfuric acid

Question 5

The principle agent responsible for digestion of matrix in Plasma ashing is
a. molecular oxygen
b. electro magnetic radiation
c. X-ray
d. Nascent oxygen

Answer 5

d. Nascent oxygen

Question 6

Generally the amount of water insoluble ash will be higher than acid insoluble ash
a. true
b. false

Answer 6

a. true

Question 7

According the FDA proprionic acid is considered as a fatty acid.
true
false

Answer 7

false

Question 8

If you skip the acid hydrolysis part of sample preparation for crude fat determination in meat sample, …
a. the crude fat determination will be an overestimate of actual value
b. the crude fat determined will be an underestimate of actual value
c. it will not affect the crude fat analysis

Answer 8

b. the crude fat determined will be an underestimate of actual value

Question 9

Which of the following ranking is correct for the time required for fat analysis in raw fish ?
a. IR < Mojonnier method < soxhlet
b. IR > Mojonnier method > soxhlet
c. IR < soxhlet < Mojonnier method

Answer 9

a. IR < Mojonnier method < soxhlet

Question 10

Which of the following methods of fat determination are volumetric?
a. soxhlet
b. Gerber
c. Goldfish
d. Mojonnier method
e. Babcock
A, B, C
B and E only

Answer 10

B and E only

Question 11

Why “channeling” does not occur in Soxhlet extraction ?
a. sample in the thimble is always surrounded by solvent
b. the solvent vapour does not pass through sample before condensation
c. both of the above reasons

Answer 11

c. both of the above reasons

Question 12

Goldfish method of fat determination in food is an example of
a. crude fat determination using semi-continuous extraction
b. crude fat determination using continuous extraction
c. crude fat determination using discontinuous extraction

Answer 12

b. crude fat determination using continuous extraction

Question 13

You are tasked with determining protein content in an egg white product. the sample was exposed to boiling temperature that caused coagulation of protein. will it affect the crude protein estimation using Kjeldahl method?
a. yes, because the tertiary structure of protein is lost
b. yes, because protein is degraded
c. no, because the nitrogen content remains the same

Answer 13

c. no, because the nitrogen content remains the same

Question 14

Mushrrom amples showed unusually high crude protein content. what will be the primary reason?
a. Chitin and chitosan content of mushroom
b. copper compounds used as food preservative
c. Salt (NaCl) contetn in the mushroom

Answer 14

a. Chitin and chitosan content of mushroom

Question 15

Which of the following statement best describes Kjeldahl method protein estimation?
a. Kjeldahl method is sensitive and specific
b. Kjeldahl method is sensitive but not specific
c. Kjeldahl method is not senstive but speific

Answer 15

b. Kjeldahl method is sensitive but not specific

Question 16

Potassium sulfate in b. Kjeldahl method is used …
a. to increase the boiling point of H2SO4
b. as catalyst to speed up the reaction
c. to break the metal-ammonia complex

Answer 16

a. to increase the boiling point of H2SO4

Question 17

If the glass tube conveying ammonia was not fully immersed in boric acid solution during the distillation of ammonia to boric acid the crude protein estimate will …
a. overestimation
b. underestimation
c. not be affected

Answer 17

b. underestimation

Question 18

The major difference between Lowry’s and Biuret method of protein determination
a. Cu1+ and Cu2+ forming coordination complexes with dye molecules and proteins molecules
b. difference in the chemistry of dye binding to proteins
c. oxidation of copper by peptide bonds

Answer 18

a. Cu1+ and Cu2+ forming coordination complexes with dye molecules and proteins molecules

Question 19

Specificity of Duma’s method is less than that of Kjeldhal’s method for protein determination because
a. non selective absorption maxima of ammonia and nitrogen
b. Duma’s method will also measure nitrogen form inorganic salts
c. Duma’s method will also measure nitrogen form vitamins

Answer 19

b. Duma’s method will also measure nitrogen form inorganic salts

Question 20

Most widely used carrier in Dumas analyzer
chlorine
fluorine
helium
nitrogen

Answer 20

helium

Question 21

Silver wool in post combustion tube of Dumas analyzer
a. is optional
b. will absorb halogens and sulfur
c. will absorb CO2
d. will absorb moisture

Answer 21

b. will absorb halogens and sulfur

Question 22

Absorbance at 280nm can be used for
a. accurately determining protein content in any liquid food
b. determining nucleic acid content
c. rough estimation of protein content in clear fluids
d. differentiating peptides and protein

Answer 22

c. rough estimation of protein content in clear fluids

Question 23

Primary characteristics considered for inclusion of a substance as dietary fiber according to codex alimentarius
a. non-digested by human enzymes
b. below 10 saccharide units
c. should have a beneficial physiological function
d. solely obtained from edible portion of the plant
a, b, c
a & c
a, b, c & d

Answer 23

a & c

Question 24

Crude fiber estimation in food is done by
a. acid and alkali treatment of dried defatted sample
b. enzyme treatment of dried defatted sample
c. both are considered crude fiber

Answer 24

a. acid and alkali treatment of dried defatted sample

Question 25

(TF) the enzymes used for total dietary fiber analysis are sourced form human small intestine.

Answer 25

False

Question 26

Reason for using ethanol in the final step of fibre analysis is
a. to precipitate sugar and amino acids
b. to precipitate soluble fiber
c. to remove minerals

Answer 26

b. to precipitate soluble fiber

Question 27

The portion of reside obtained after amyloglucosidase enzyme digestion w/o ethanol precipitation mostly contain
a. soluble dietary fiber
b. insoluble dietary fiber
c. resistant starch

Answer 27

b. insoluble dietary fiber

Question 28

The major challenge in estimating total carbohydrate in food is
a. carbohydrate get oxidized fast
b. lack of unique property
c. carbohydrates reacts w/ other food components

Answer 28

b. lack of unique property

Question 29

According to codex alimentarius, raffinose is a
polysaccharide
trisaccharide
oligosaccharide
disaccharide

Answer 29

trisaccharide

Question 30

Phenol-sulfuric acid methods can be used for the estimation of total carbohydrate in a fruit juice.
a. true, if the sample is prepared to remove interfering compounds
b. false, it only detects reducing sugars
c. true, it can used directly w/o sample preparation

Answer 30

a. true, if the sample is prepared to remove interfering compounds