Food Analysis

Question 1

Define Beer’s law.

Answer 1

Concentration and absorbance are proportional in spectroscopy

Question 2

What is ELISA used for?

Answer 2

Detection of aflatoxin-to detect and quantify

Question 3

What is the iodine value?

Answer 3

Number of centigrams of iodine absorbed by 1 gram of fat

Question 4

What does p mean in pH?

Answer 4

-log

Question 5

What is the gel most common used for protein analysis?

Answer 5

PAGE-polyacrylamide gel electrophoresis

Question 6

What is the amount of energy to raise the temperature of 1 gram of water from 14.5 C to 15.5 C?

Answer 6

1 Calorie

Question 7

What is phenolphthalein use for?

Answer 7

pH indicator, acid=colorless, base=red violet

Question 8

What is Ohm’s Law and what is Power Equation?

Answer 8

V=IR and P=VI or I x I x R

Question 9

What does Reichert-Meissert Number measure?

Answer 9

Primary butyric acid also caproic acid.

Question 10

Name the most common functional property of phospholipids in food systems.

Answer 10

Emulsification

Question 11

What are the two underlying principals of the Babcock test?

Answer 11

To dissolve fat from solids-non fat (SNF). To separate fat from SNF by centrifugal force.

Question 12

The Delvo test is a commonly used rapid method for detection of antibiotic residue in milk. What organism is used in this test?

Answer 12

Bacillus Stearothermophilus

Question 13

What are the Delvo and Charm tests used for?

Answer 13

Testing for the presence of antibiotics in milk.

Question 14

Full name of WVTR?

Answer 14

Water vapor transmission rate

Question 15

Isotherm water activity chart, x and y axis?

Answer 15

X: Aw, y: moisture.

Question 16

Phases of colloidal dispersion?

Answer 16

Continuos phase or dispersion medium and dispersed phase or internal

Question 17

Colligative properties of water?

Answer 17

Freezing point, boiling point, vapor pressure, osmotic pressure. Properties that depend on the number of solute molecules in water.

Question 18

Define triple point?

Answer 18

Pressure-Tº at which substance is at solid, liquid and vapour phase at same time. For water is 611.73 Pa and 273.16 K.

Question 19

What does Kjeldahl and how does it quantify proteins?

Answer 19

Measures nitrogen content

Question 20

Michaelis menten equation?

Answer 20

Used for many enzyme kinetic, relates the velocity of a reaction with the concentration of substrate.

Question 21

Henderson- Hasselbach equation?

Answer 21

pH = pKa + log[dissasociated salt]/log[associated salt]

Question 22

What is pH?

Answer 22

The negative log of the concentration of hydrogen ion in solution.

Question 23

Two isotopes used for food irradiation?

Answer 23

Co60 and Cs137

Question 24

Test to detect carcinogenic antigen?

Answer 24

AMES test

Question 25

NMR is often used as the technique to characterize the linkage types.

Answer 25

False, should be methylation analysis

Question 26

If you have a method that you want to use to measure % fat in a product and it is not AOAC approved, how would you determine if it is accurate?

Answer 26

Take known fat percentages and run them with the method to perform a standard curve so that you can determine the linear range of your method and assure its accuracy

Question 27

What does AOAC stand for?

Answer 27

Association of Official Analytical Chemists

Question 28

What is a kjeldahl apparatus used for?

Answer 28

To measure net proteins in foods in terms of nitrogen

Question 29

What is a Soxhlet analyzer used for?

Answer 29

To measure % fat

Question 30

How would you measure fat oxidation in meat products?

Answer 30

Thiobarbituric acid (TBA) analysis

Question 31

The TBA analysis is a colorimetric reaction; what does this mean?

Answer 31

the analyte of interest does not have a chromaphore and must react with a substance so that a chromaphore is created and absorbance can be read to determine the concentration of an analyte

Question 32

Why is absorbance generally used in spectroscopy experiments instead of transmittance?

Answer 32

absorbance has a linear relationship with concentration based on Beer's Law; transmittance does not have a liner relationship w/ concentration

Question 33

What is spectroscopy?

Answer 33

production, measurement, and interpretation of spectra arising from the interaction of electromagnetic radiation with matter

Question 34

What type of HPLC utilizes a polar column and a less polar solvent (stationary phase)?

Answer 34

Normal Phase HPLC

Question 35

What does FID stand for?

Answer 35

Flame Ionization Detector

Question 36

what characteristic of compounds is usually utilized to separate compounds in gas chromotography?

Answer 36

molecular weight

Question 37

how many significant figures is in the number 0.000401?

Answer 37

3

Question 38

what CHO is only naturally produced in milk?

Answer 38

Lactose

Question 39

which of the following is NOT a method used to determine the fat content of a food: A. soxhlet extraction, B. mojonnier extraction, C.goldfish method, D.karl fischer

Answer 39

karl fischer

Question 40

what is the moisture content of corn flakes after exiting the oven and cooling?

Answer 40

3-5% moisture