Exam 1 Flashcards
What is proximate analysis?
- Measures the major components of food
- Moisture, ash, lipid, protein, carbs
- No structural information
What do the letters TD and TC mean on a piece of glassware?
- To Deliver - graduated cylinders/volumetric pipettes
- To Contain - volumetric flask
What are the objectives of food analysis?
Trade, legal, official, QC
List 7 reasons for evaluating the composition of foods.
- Quality assurance
- Product development
- Process development
- Nutritional labeling
- Health claims
- Safety
- Regulation compliance
List 5 types of samples and why they would be analyzed.
- Raw materials - prevent fraud
- Process control - check if production meets standards
- Final product - nutritional labeling
- Consumer complaints - possible recall
- Competitor products - product comparison
What are the 3 basic steps in food analysis?
1) Select and prepare analysis
2) Perform the assay
3) Calculate and interpret results
List the full name and abbreviation of 3 organizations that publish “official” methods for food analysis.
- Association of Analytical Communities International (AOAC)
- American Association of Cereal Chemistry (AACC)
- American Society of Oil Chemistry (AOCS)
What agency regulates most foods manufactured in the US?
FDA
What are the two fundamental provisions of the FD&C Act of 1938?
- Assured consumers that food was safe, wholesome, and truthfully labeled
- Addressed misbranding, allowing for SOIs
What organization is responsible for regulating the composition of meat products in the US?
USDA
What organization is responsible for assuring that products imported into the US are safe and not economically deceptive?
US Customs Service
What is Codex Alimentarius?
- 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
What organization is responsible for advertising related to food?
Federal Trade Commission
What is accuracy and what statistics are used to assess it?
- Proximity to true value
- Mean, % error and confidence interval
What is precision and what statistics are used to assess it?
- Reproducibility
- Mean, std dev, %CV
Define absolute error.
Difference btwn experimental value and true value
Define relative error.
Difference btwn experimental value and true value against true value
5 techniques for assessing precision
- Std dev
- CV
- Confidence Interval
- Relative deviation
- Relative error
What is the formula for %CV?
(Std dev)100%/mean
What fraction of a normally distributed data set can be found within 1, 2 and 3 SD of the mean value?
1- 68%
2- 95%
3- 99.7%
Define systematic error and give an example.
- Results consistently deviate from true value
- Example: pipette calibrated incorrectly
Define random error and give an example.
- Can fluctuate and are unavoidable
- Example: differences btwn balances
Define blunders and give an example.
- Big “screw-ups”
- Example: pipetting 0.5 mL instead of 1 mL
Define sensitivity.
Magnitude of change in measurement with change in concentration of compound
Define the term limit of detection.
Lowest possible increment that we can detect with statistical significance
Describe the Q-test and how it can be used to reject analytical data.
- 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
What are the units of “Normality”?
Mole equivalents of solute/liter of solution
Define the term equivalent weight.
Molecular weight / number of equivalent
Define titratable acidity.
- Total acidity
- Better predictor of acid’s impact on flavor than pH
- Not so useful for microbial issues
Describe volatile acidity.
Difference between titratable acidity and fixed acidity.
Define predominant acid.
- The most abundant acid present in a food
- Kept in mind when calculating TA
At what pH does the phenolphthalein indicator go from colorless to pink? Why is this value important?
- pH 8.0-9.6; 8.2
- This is the equivalence point where there are equal equivalence numbers of both acid and base
Describe the three types of water in food.
- Free water - not chemically bound
- Adsorbed water - held tightly within other structures
- Water of hydration - chemically bound
What is the purpose of the addition of sand during drying of some products?
Prevent surface crust from forming and to disperse the sample so evaporation of moisture is less impeded.
What is an operational definition?
Something unobservable can be legitimate in science if the concept can be linked to something observable
What is attribute sampling?
Performed to decide on the acceptability of a population based on whether the sample possesses a certain characteristic or not
What is case hardening and how can it be minimized?
- When sample burns during drying
- Higher surface temperatures create dry skin that traps moisture on inside, negatively affect drying rate
- Use sand
