Exam 1

Question 1

What is proximate analysis?

Answer 1

• Measures the major components of food
• Moisture, ash, lipid, protein, carbs
• No structural information

Question 2

What do the letters TD and TC mean on a piece of glassware?

Answer 2

• To Deliver - graduated cylinders/volumetric pipettes

- To Contain - volumetric flask

Question 3

What are the objectives of food analysis?

Answer 3

Trade, legal, official, QC

Question 4

List 7 reasons for evaluating the composition of foods.

Answer 4

• Quality assurance
• Product development
• Process development
• Nutritional labeling
• Health claims
• Safety
• Regulation compliance

Question 5

List 5 types of samples and why they would be analyzed.

Answer 5

• Raw materials - prevent fraud
• Process control - check if production meets standards
• Final product - nutritional labeling
• Consumer complaints - possible recall
• Competitor products - product comparison

Question 6

What are the 3 basic steps in food analysis?

Answer 6

1) Select and prepare analysis
2) Perform the assay
3) Calculate and interpret results

Question 7

List the full name and abbreviation of 3 organizations that publish “official” methods for food analysis.

Answer 7

• Association of Analytical Communities International (AOAC)
• American Association of Cereal Chemistry (AACC)
• American Society of Oil Chemistry (AOCS)

Question 8

What agency regulates most foods manufactured in the US?

Answer 8

FDA

Question 9

What are the two fundamental provisions of the FD&C Act of 1938?

Answer 9

• Assured consumers that food was safe, wholesome, and truthfully labeled
• Addressed misbranding, allowing for SOIs

Question 10

What organization is responsible for regulating the composition of meat products in the US?

Answer 10

USDA

Question 11

What organization is responsible for assuring that products imported into the US are safe and not economically deceptive?

Answer 11

US Customs Service

Question 12

What is Codex Alimentarius?

Answer 12

• Book of Food
• Collection of standards, codes of practive, guidelines and recommendations regarding food/food production/food safety
• Collaboration between UNFAO and WHO
• Voluntary compliance
• Used internationally

Question 13

What organization is responsible for advertising related to food?

Answer 13

Federal Trade Commission

Question 14

What is accuracy and what statistics are used to assess it?

Answer 14

• Proximity to true value

- Mean, % error and confidence interval

Question 15

What is precision and what statistics are used to assess it?

Answer 15

• Reproducibility

- Mean, std dev, %CV

Question 16

Define absolute error.

Answer 16

Difference btwn experimental value and true value

Question 17

Define relative error.

Answer 17

Difference btwn experimental value and true value against true value

Question 18

5 techniques for assessing precision

Answer 18

• Std dev
• CV
• Confidence Interval
• Relative deviation
• Relative error

Question 19

What is the formula for %CV?

Answer 19

(Std dev)100%/mean

Question 20

What fraction of a normally distributed data set can be found within 1, 2 and 3 SD of the mean value?

Answer 20

1- 68%
2- 95%
3- 99.7%

Question 21

Define systematic error and give an example.

Answer 21

• Results consistently deviate from true value

- Example: pipette calibrated incorrectly

Question 22

Define random error and give an example.

Answer 22

• Can fluctuate and are unavoidable

- Example: differences btwn balances

Question 23

Define blunders and give an example.

Answer 23

• Big “screw-ups”

- Example: pipetting 0.5 mL instead of 1 mL

Question 24

Define sensitivity.

Answer 24

Magnitude of change in measurement with change in concentration of compound

Question 25

Define the term limit of detection.

Answer 25

Lowest possible increment that we can detect with statistical significance

Question 26

Describe the Q-test and how it can be used to reject analytical data.

Answer 26

- A Q-value is calculated and compared to table values - If calculation is larger than table value, then the questionable measurement can be rejected at the 90% confidence level

Question 27

What are the units of “Normality”?

Answer 27

Mole equivalents of solute/liter of solution

Question 28

Define the term equivalent weight.

Answer 28

Molecular weight / number of equivalent

Question 29

Define titratable acidity.

Answer 29

- Total acidity - Better predictor of acid’s impact on flavor than pH - Not so useful for microbial issues

Question 30

Describe volatile acidity.

Answer 30

Difference between titratable acidity and fixed acidity.

Question 31

Define predominant acid.

Answer 31

- The most abundant acid present in a food | - Kept in mind when calculating TA

Question 32

At what pH does the phenolphthalein indicator go from colorless to pink? Why is this value important?

Answer 32

- pH 8.0-9.6; 8.2 | - This is the equivalence point where there are equal equivalence numbers of both acid and base

Question 33

Describe the three types of water in food.

Answer 33

- Free water - not chemically bound - Adsorbed water - held tightly within other structures - Water of hydration - chemically bound

Question 34

What is the purpose of the addition of sand during drying of some products?

Answer 34

Prevent surface crust from forming and to disperse the sample so evaporation of moisture is less impeded.

Question 35

What is an operational definition?

Answer 35

Something unobservable can be legitimate in science if the concept can be linked to something observable

Question 36

What is attribute sampling?

Answer 36

Performed to decide on the acceptability of a population based on whether the sample possesses a certain characteristic or not

Question 37

What is case hardening and how can it be minimized?

Answer 37

- When sample burns during drying - Higher surface temperatures create dry skin that traps moisture on inside, negatively affect drying rate - Use sand