Food Analysis Flashcards
Define Beer’s law.
Concentration and absorbance are proportional in spectroscopy
What is ELISA used for?
Detection of aflatoxin-to detect and quantify
What is the iodine value?
Number of centigrams of iodine absorbed by 1 gram of fat
What does p mean in pH?
-log
What is the gel most common used for protein analysis?
PAGE-polyacrylamide gel electrophoresis
What is the amount of energy to raise the temperature of 1 gram of water from 14.5 C to 15.5 C?
1 Calorie
What is phenolphthalein use for?
pH indicator, acid=colorless, base=red violet
What is Ohm’s Law and what is Power Equation?
V=IR and P=VI or I x I x R
What does Reichert-Meissert Number measure?
Primary butyric acid also caproic acid.
Name the most common functional property of phospholipids in food systems.
Emulsification
What are the two underlying principals of the Babcock test?
To dissolve fat from solids-non fat (SNF). To separate fat from SNF by centrifugal force.
The Delvo test is a commonly used rapid method for detection of antibiotic residue in milk. What organism is used in this test?
Bacillus Stearothermophilus
What are the Delvo and Charm tests used for?
Testing for the presence of antibiotics in milk.
Full name of WVTR?
Water vapor transmission rate
Isotherm water activity chart, x and y axis?
X: Aw, y: moisture.
Phases of colloidal dispersion?
Continuos phase or dispersion medium and dispersed phase or internal
Colligative properties of water?
Freezing point, boiling point, vapor pressure, osmotic pressure. Properties that depend on the number of solute molecules in water.
Define triple point?
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.
What does Kjeldahl and how does it quantify proteins?
Measures nitrogen content
Michaelis menten equation?
Used for many enzyme kinetic, relates the velocity of a reaction with the concentration of substrate.
Henderson- Hasselbach equation?
pH = pKa + log[dissasociated salt]/log[associated salt]
What is pH?
The negative log of the concentration of hydrogen ion in solution.
Two isotopes used for food irradiation?
Co60 and Cs137
Test to detect carcinogenic antigen?
AMES test
NMR is often used as the technique to characterize the linkage types.
False, should be methylation analysis
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?
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
What does AOAC stand for?
Association of Official Analytical Chemists
What is a kjeldahl apparatus used for?
To measure net proteins in foods in terms of nitrogen
What is a Soxhlet analyzer used for?
To measure % fat
How would you measure fat oxidation in meat products?
Thiobarbituric acid (TBA) analysis
The TBA analysis is a colorimetric reaction; what does this mean?
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
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
What is spectroscopy?
production, measurement, and interpretation of spectra arising from the interaction of electromagnetic radiation with matter
What type of HPLC utilizes a polar column and a less polar solvent (stationary phase)?
Normal Phase HPLC
What does FID stand for?
Flame Ionization Detector
what characteristic of compounds is usually utilized to separate compounds in gas chromotography?
molecular weight
how many significant figures is in the number 0.000401?
3
what CHO is only naturally produced in milk?
Lactose
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
karl fischer
what is the moisture content of corn flakes after exiting the oven and cooling?
3-5% moisture
