1. Food Analysis and Quality Assurance Flashcards
Define Beer’s law.
Concentration and absorbance are proportional in spectroscopy
What application in food 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 electrphoresis
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.
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.
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
Which of the following foods contain the lowest content of water?A) Fresh Carrots B) Fresh Tomatoes C) Whole Milk D) Fresh Celery
C) Whole Milk
What does the iodine value measure and how is it measured?
The amount of unsaturated bonds in fat; grams Iodine reacting with 100 grams fat.
What does the saponification value measure and how is it measured?
Number of fatty acids present; mg KOH needed to saponify 1 g fat.
What does Acid Degree Value measure and how is it measured?
Amount of free fatty acids present; mg KOH needed to neutralize the free fatty acids in 1 g of fat.
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 - nitrogen content
What is a Foss-Let 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 with 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
What does it mean for data to be accurate?
the data is close to the true value for the measurement
What does it mean for data to be precise?
Data points are close together
What does HPLC stand for?
High Performance Liquid Chromatography or High Pressure Liquid Chromatography
What does GC-MS stand for?
Gas Chromatography-Mass Spectrometry
What is the purpose of GC-MS?
To separate volatile compounds and identify them based on mass/charge ratios
What does SPME stand for in analytical chemistry?
Solid Phase Micro Extraction
What is the wavelength range of UV-Vis spectroscopy?
200-700nm (UV=200-350nm
What is BOD COD and what are their units of measurement?
Biological Oxygen Demand
What type of compounds is flame photometric detector (FPD) specific for?
FPD is specific to compounds containing sulfur groups
What does ELISA stand for and what does it detect?
Enzyme-Linked Immunosorbent Assay its an immunological or biochemical test to detect desirable and undesirable substances.
Gel filtration separation of proteins is taking advantage of: A.protein charge B.protein size C.molecular affinity or D.pH?
B. protein size
Atomic Mass Spectroscopy separates molecules according to their m/z ratio. What is the m/z ratio?
ratio of mass to charge
Rank the following membrane separation methods based on increasing pore size: microfiltration - reverse osmosis - ultrafiltration
RO
Name the 4 layers in an ELISA
capture antibody
what colour is anthocyanin at pH 8-9
yellow
the amount of fat allowed in skim milk
0.50%
what the name of the compound that’s also known as wine diamond
tartrates
What is the term for foreign substances that enters the human body?
Xenobiotic
What does HACCP stand for?
Hazard Analysis Critical Control Points
What is the largest professional association for practitioners in the quality field?
American Society for Quality
