Food analysis

In the UV determination of protein concentration, what wavelength of light is used?

280 nm, primarily absorbed by tyrosine and tryptophan (and also phenylalanine).

State the mathematical constant pi rounded to 5 decimal places.

3.14159

2 radians are equal to how many degrees?

360 degrees

What is the range of visible light in nanometers?

400-800 nm

What is 30% of 180 bushels?

54 bushels

What is the pH range of the indicator phenolphthalein and what color does it exhibit?

8.3-10.0; Pink

What is Gerber acid and what is it used for?

90% sulfuric acid; it is used as a reagent in crude fat analysis of milk (dairy products)

If you had 10 mL of sweetened iced tea that was 10% sucrose, how much water would you add to dilute the tea to 0.1% sucrose?

990 mL water

The Beer-Lambert Law is A=ECL; what does the 'A' stand for in the Beer-Lambert Law?

A is absorption

What is Solid Fat Index and what does it indicate?

A measure of the percentage of solid fat present at different temperatures, indicating plasticity and mouthfeel of fat-based products.

What does the term "polydisperse" describe?

A sample with particles or molecules of varying sizes (e.g., a polydisperse protein mixture has multiple molecular weights)

What is the basis of all reducing sugar tests?

Ability of reducing sugars to donate electrons (reduce) metal ions, commonly cupric ions (Cu²⁺) to cuprous ions (Cu⁺) under alkaline conditions (e.g., Benedict's, Fehling’s tests)

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

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

Quality assurance employees in beef packing plants routinely perform AQL tests. What does the acronym AQL represent?

Acceptable quality limits (It defines the maximum number of defective items considered acceptable during random sampling of a production lot)

In statistics, what is a Type II Error?

Accepting a false hypothesis

What metabolic end product does the Voges-Proskauer test detect?

Acetoin

What would you do to convert temperature reading from Fahrenheit to degrees Rankine?

Add 459.67

What is the difference between additive and subtractive primaries?

Additives all together produce white light, subtractives all together theoretically produce black light

Which type of chromotography is described by : a substrate is covalently bound to the column matrix; as the effluent passes through, a specific targeted compound attaches to the bound substrate and becomes trapped on the stationary phase.

Affinity Chromotography

The Schiff test is used to detect the presence of what type of compounds often involved in browning reactions?

Aldehydes