Title: Midterm
Course: Food Analysis Labs > Section: Course Content

Midterm Exam will be given at the midpoint of the class.

Q: What are the three major reasons that we analyze foods?
Feedback: 1) Consumers demand it, 2) Competition in food industry demands it, 3) Government regulations demand it

Q: What is an official method?
Feedback: A method of analysis developed and endorsed by one of several non-profit organizations, allowing comparison of results across labs, and the evaluation of less standard procedures. May be developed by the FDA, the AACC, or the AOAC, for example.

Q: Put these in the right order - what would be your first choice, second choice, and third choice in selecting a method of analysis for nutritional labeling?

a) a method you find by Google search, b) a method in the 'Official Methods of Analysis' by the AOAC, c) An available FDA analysis method
Feedback: c) then b) then a). The FDA methods are only created where required, the AOAC methods are the second best bet, and any other method would be your last choice if nothing else is available.

Q: Nutrient content claims, such as 'healthy' or 'no added sugar' have specific, regulated meanings in nutritional labeling.
- True
- False
A: True

Q: You learned that the FD&C Act was the beginning of regulation of the food industry by the FDA. If violations of the FD&C Act are discovered, what are potential outcomes for the company?
Feedback: The FDA can issue warnings, seizures, injunctions, and recalls. Criminal charges could be recommended to the justice department.

Q: Define accuracy. How is it different from precision?
Feedback: Accuracy is how close a particular measurement is to the actual value, whereas precision is how close the measurement values are to each other.

Q: The process of taking samples from a food item is called sampling. Give an example of why sampling is important in food analysis - how could poor sampling lead to misleading data?
Feedback: For example, if you sampled a chocolate chip cookie by grabbing pieces of it with tweezers, and got mostly chocolate chips, you could have a misleading representation due to sampling.

Q: What does HACCP stand for, and what is it used for?
Feedback: Hazard Analysis Critical Control Point systems - is used to provide an approach for hazard risk reduction and control.

Q: Explain the difference between qualitative and quantitative analysis.
Feedback: Qualitative analysis identifies constituents of the sample, quantitative analysis measures how much of the constituent is present.

Q: Give an example of a method of analysis that can be used to measure total carbohydrate. Indicate whether it is an official method or not.
Feedback: The Phenol Sulfuric acid determination (performed in lab!) is a measure of total carbohydrate. It is an official method.

Q: Describe two major potential sources of interference in a colorimetric analysis of food.
Feedback: Other components present in the food that absorb light at the same wavelength, and the presence of colloids (bubbles, turbidity, etc) that can scatter light.

Q: Which vitamins are the fat-soluble vitamins?
Feedback: A, D, E, and K; vitamins that are stored in fat - vitamins that extract into organic solvents.

Q: Describe the difference between a vitamin measurement in units of IU as compared to % Daily Value. How do these two units of measurement differ?
Feedback: IU is 'international units', and is based on biological activity, whereas % Daily Value is a newer unit of measure based on the quantity recommended for a 2000-calorie adult diet.

Q: What is the missing word? In analyzing for the vitamin C content of orange juice, you used the Indophenol method. This method of analysis, a type of titration, determines the concentration of an unknown solution by titrating it with a solution where the is already known.
Feedback: concentration

Q: You performed the Indophenol method to analyze for Vitamin C in orange juice. If you wanted to analyze the orange juice for Vitamin D instead, for the same purpose, you could use the exact same method.
- True
- False
A: False

Q: Some minerals are toxic at high levels.
- True
- False
A: True

Q: Describe the difference between macro-minerals and trace minerals.
Feedback: Macro-minerals are required at more than 100 mg/day. Trace minerals are required in only milligram or microgram quantities per day.

Q: You analyzed soft drinks for sodium using ion sensitive electrodes. You also analyzed these samples for sodium using atomic emission spectroscopy. Give an example of one advantage of using the electrodes over the spectroscopy.
Feedback: The electrodes are faster and less expensive to use.

Q: Name two resources that would be good to consult when trying to find a good method of analysis for a polysaccharide.
Feedback: Answers could include: FDA laboratory methods, FDA website, the Nielsen textbook, the Nielsen lab manual, the AOAC Official Methods published by the AACC.

Q: When you analyzed for sodium in the soft drink samples by atomic emission spectroscopy, you diluted the samples prior to analysis. Give two reasons for doing this.
Feedback: Acceptable answers include: Running undiluted samples would have damaged the instrument, due to the high content of sugar. Diluting the samples puts it within the linear detection range of the instrument. Diluting the samples brings them into the range of the standard curve.