What does the acronym associated w/food analysis techniques 'SEM' stand for?
Scanning electron microscopy
What property of a protein can be determined using SDS electrophoresis?
Molecular weight
What does the term “LOD” stand for in analytical chemistry?
Limit of Detection
What does the acronym associated w/food analysis techniques 'SDS-PAGE' stand for?
Sodium dodecyl sulfate polyacrylamide gel electrophoresis
Name the science of managing and analyzing biological data using advanced computing techniques.
Bioinformatics
What are the three steps of Kjeldahl method?
Digestion, distillation, titration
Identify the terms BOD, COD, SS, and FOG wrt water quality analysis and their units of measurement.
BOD - biological (or biochemical) oxygen demand; COD - chemical oxygen demand; SS - suspended solids; FOG - fats, oils, and grease. Units for all is mg/L or ppm.
What is the full form of N with respect to unit of concentration?
Normality
What does LCL stand for wrt statistical analysis?
Lower Control Limit
Botswick measures what?
The Bostwick Consistometer measures the flow or consistency of semi-solid foods (e.g., ketchup, sauces, baby foods). It quantifies how far a sample flows in a set time.
A soxhlet extractor was originally designed to extract what from solid foods?
Lipids
What food components are measured by the following. 1. Karl Fischer Titration, 2. Nessler’s reagent, 3. Anthrone method
1. Water, 2. Protein, 3. Carbohydrate
Atomic absorption spectroscopy is typically used to measure what in foods?
Trace metals and minerals
What is polarography and how is it used in food analysis?
Polarography is an electrochemical method using a dropping mercury electrode to measure the current that results from the reduction or oxidation of analytes. In food, it can determine vitamins, preservatives, and metal ions.
What is DSC and what is it used for?
Differential Scanning Calorimetry. It is used to measure thermal transitions in foods such as melting point, crystallization, and glass transition, often for fats, starches, and proteins.
What molecular characteristics are measured by IR absorbance?
Vibrational modes of functional groups, such as stretching and bending of bonds in molecules
What is 'regression analysis'?
Statistical method to analyze relation between 2 or more variables such that one of them can be predicted by using information of the other
What color is expected when many starches react with iodine?
Blue-black
What does 'c' stand for in E=mc^2?
Speed of light
What does it mean for data to be precise?
Data points are close together
What does PAGE stand for?
Polyacrylamide Gel Electrophoresis
If you take 20 ml of .1 M NaOH to titrate 40 mL of an HCl solution to the phenolphthalein end point what is the molarity of the HCl solution?
0.05 M HCl
When working with data, what is the measure of dispersion or variation in a group of scores?
Standard Deviation
Which statistical tool is commonly used to monitor process variability over time?
Control charts (SPC).
Define defect action level.
The term used to describe the allowable tolerances of natural or unavoidable foreign material in foods which could be a health hazard to the public
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
Gas Chromatography (GC) is a staple in food analysis. Name the two primary components of the "mobile phase" and "stationary phase" in a standard GC setup used for flavor analysis.
Mobile phase: An inert carrier gas (e.g., Helium, Nitrogen, or Hydrogen). Stationary phase: A microscopic layer of liquid or polymer on an inert solid support inside the column.
What does CI stand for wrt statistical analysis?
Confidence Interval
What is the difference between additive and subtractive primaries?
Additives all together produce white light, subtractives all together theoretically produce black light
What statistical value measures how likely it is that any observed difference between groups is due to change?
p-value
What is the full form of ASQC?
American Society for Quality Control
Which enzymes are used in the AOAC method for fiber determination?
Alpha-amylase, protease, and glucoamylase/amyloglucosidase
Name one advantage of Kjeldahl over Dumas method.
In Dumas method, the sample size is too small compared to Kjeldahl method, so the interruption due to air has higher probability, hence greater error.
What are the major components of HPLC?
Solvent reservoir, pump, column, detector
Which Mass spec technique relied on large protein fingerprint for bacteria?
MALDI-TOF MS
Name three detectors used in HPLC.
UV-Vis, Refractive Index Detector, Fluorescence Detector
How to express in concentration, ppm equivalent as weight per volume?
mg/L or microg/ mL
What does COD stand for regarding measuring organic compounds in water?
Chemical Oxygen Demand
What is the principle behind adsorption chromatography?
Polarity of compounds
What metabolic end product does the Voges-Proskauer test detect?
Acetoin
Amino acids absorb light at 190-240 nm because of which bond?
Peptide
In statistics, what is a Type I Error?
Rejecting a true hypothesis
In statistics, the basic regression model is Yi = bo + b1Xi + ei. What do the parameters bo and b1 represent?
bo = y-intercept; b1 = slope
In Reverse phase HPLC, what component retains highly hydrophobic impurities from going onto the analytical column and permanently interacting with the stationary phase which ultimately prolongs the analytical column's capacity?
Guard column
Which technique measures the color of food using L*, a*, and b* values?
Colorimetry (CIE Lab color system)
What chromatographic detector is commonly used for sugars and alcohols without chromophores?
Refractive index detector
Name an official method of food analysis for protein determination.
Kjeldahl, Dumas
Name an official method of food analysis for ash determination.
Dry ashing
What is the full form of QA wrt food analysis?
Quality Assurance
What is the full form of OMA wrt food analysis?
Official Methods of Analysis
What does the acronym NPN stand for in food analysis?
Non-protein nitrogen
What does the 'E' stand for in the Beer-Lambert Law?
E is Molar Extinction Coefficient (L·mol⁻¹·cm⁻¹)
The Kjeldahl method is the gold standard for measuring the concentration of which specific element in food, used to estimate protein content?
Nitrogen
For the fluorescent analysis of vitamin C, dehydroascorbic acid is allowed to react with what compound to form a fluorescent derivative?
What does Thiobarbituric acid number or value tell you?
Degree of lipid oxidation, specifically secondary oxidation products (malondialdehyde)
Ruhemann's purple is formed by what reaction used in food analysis?
Reaction of Ninhydrin with amine group of amino acids.
How much volume of 37% HCl (the commercial product) is required to make a litre of 1 M HCl with DI water?
82 ml (80-85 ml acceptable)
What is the full form of ppm?
Parts per million
What is the full form of QE wrt food analysis?
Quality Evaluation
What is the principle of accelerated solvent extraction?
Extraction by exposing a solid or semi-solid sample to a solvent under elevated temperature and pressure conditions
Explain the principle of the Kjeldahl method and what component of food it estimates.
The Kjeldahl method determines total nitrogen content by digesting organic nitrogen into ammonium sulfate using sulfuric acid, followed by neutralization, distillation, and titration. The measured nitrogen is converted to crude protein using a conversion factor, typically 6.25, assuming proteins contain about 16% nitrogen.
For which food component are the following tests used? Sudan 3, Iodine, Benedicts
What does the acronym associated w/food analysis techniques 'NMR' stand for?
Nuclear Magnetic Resonance
The degree of unsaturation of a fat is measured by the ______value.
iodine value
How can the molecular weight of protein, DNA and RNA be determined?
Proteins: SDS-PAGE, SEC, MS
DNA: Agarose gel electrophoresis
RNA: Denaturing Gel Electrophoresis
What does the saponification value tell about a fat and what is the difference between high and low SAP value?
The saponification number indicates the average molecular weight of the sample; mg KOH required to saponify 1 g fat; lower values indicate longer fatty acid chains.
What instrument is used to measure soluble solids in foods?
refractometer
Which analytical technique separates compounds based on differential partitioning between stationary and mobile phases?
Chromatography
What does SPME stand for in analytical chemistry?
Solid Phase Micro Extraction
Which method is commonly used to determine moisture content in foods?
Oven drying.
Which four heavy metals are most commonly tested for in food products?
Mercury, cadmium, lead, arsenic
How are free fatty acids usually measured?
By titration with NaOH
Which standard is used to calibrate pH meters?
Buffer solutions.
What is 30% of 180 bushels?
54 bushels
A muffle furnace is used in which constituent of proximate analysis?
Ash
Name one amino acid that contributes significantly to the absorbance of light at 280nm.
Tryptophan (also Tyrosine, to a lesser extent)
What common lipid analysis method involves titration with sodium thiosulfate to measure the amount of iodine consumed by the fatty acid double bonds?
Iodine Value
What is AAS and what is the principle of its use?
Atomic absorption spectroscopy; it is an analytical method for determination of elements based on absorption of radiation from a light source by the free atoms
Measurement of protein content of food uses specific factors based on the type of food, to convert nitrogen to protein content. What is the name of these specific factors?
Jones factor
Give the Osborne protein classification.
Osborne developed a classification of plant proteins based on their solubility in a series of solvents. 1. Albumin (in water). 2. Globulin (in dilute salt). 3. Prolamin (in 70% alcohol) 4. Glutelin (in dilute alkali, 0.1M NaOH solution)
COD, BOD, and TOC are all methods used to measure pollutants in water. Which method is the cheapest but takes the longest time to complete?
BOD
What does GC-MS stand for?
Gas Chromatography-Mass Spectrometry
Name 1 method of second degree product of rancidity.
TBARS, VOCs, sensory evaluation, p-anisidine value, HPLC, GC, mass spectrometry
Which chromatography technique separates compounds based on volatility?
Gas chromatography.
In statistical analysis, what does PCA stand for?
Principal component analysis
What is a double-blind experiment in nutritional studies?
Both the subjects and the researchers do not know which subjects are in which group.
List the colors of the electromagnetic spectrum in order of their appearance, from highest energy to lowest.
Violet, indigo, blue, green, yellow, orange, red
What is the purpose of using a Brix refractometer?
To measure soluble solids (primarily sugars) in a solution
What is the unit of measurement of heat in peppers?
Scoville
The Kjeldahl method is the standard method for determining the concentration of what macronutrient?
Protein (or Nitrogen)
What is the most accurate and sensitive method for quantitative determination of metals and metalloids?
Name two gravimetric and two volumetric methods to measure milk fat.
Volumetric - Babcock and Gerber;
Gravimetric - Mojonnier and Roese Gottlieb
What is the purpose of GC-MS?
To separate volatile compounds and identify them based on mass/charge ratios
In what test is Kovac's reagent used?
Indole test of IMViC (to detect indole production from tryptophan metabolism by bacteria)
The Babcock centrifuge was originally designed to measure what?
Fat content in milk
In spectrophotometric analysis, the absorbance is proportional to the concentration of the sample. What governs this phenomenon?
Beer's Law (accepted Beer-Lambert Law)
What does HETP stand for in column design?
Height equivalent to a theoretical plate
What type of analysis estimates the "moisture", "crude fat", "crude protein", "ash" and "carbohydrate by difference" in a food product?
Proximate analysis
What is a TTC test? What is it used for?
2,3,5 triphenyl tetrazolium chloride test, used for detection of antibiotics in milk
What does PFPD stand for wrt GC?
Pulsed Flame Photometric Detector
What are the polarities of the stationary and mobile phases in N-HPLC?
Mobile is non-polar, stationary is polar
If the absorption of a sample is being determined spectrophotometrically at 420 nm what color is the sample?
Yellow/orange
What instrument is a recording dough mixer that measures and records the torque developed by the action of the blades on Joe during mixing?
Farinographs measure and record the resistance to deformation of a flour/water dough against the mixing action of blades over time and at a specific speed (rpm) and temperature.
What does QMS stand for wrt food analysis?
Quality Management Systems
Which of the following is a response surface experimental design?
A. Plackett–Burman design B. Full factorial C. Simplex Centroid D. Box-Behnken
D. Box-Behnken
The S/N ratio, important to all chromatographers, is the signal to noise ratio. Name two types of noise.
Statistical noise (which includes shot noise and Johnson noise), environmental noise, baseline drift, electronic noise (thermal or shot noise)
What analytical method is commonly used to determine moisture content by weight loss on drying?
Gravimetric oven drying
What does Phenol sulfuric acid value tell you?
Total carbohydrate content
The TBA method (thiobarbituric acid) is used to monitor oxidative rancidity. What does the method actually measure?
Concentration of malondialdehyde (MDA)
What term describes the point in a titration where the number of equivalents of titrants equals the number of equivalents of the titrated substance?
Equivalence point
Which chromatographic technique is most commonly used to quantify volatile flavor compounds?
Gas chromatography (GC), often GC-MS.
What is the range of visible light in nanometers?
400-800 nm
Alcohol insoluble solids content in vegetables is indicator of what?
Maturity, fiber content, and textural quality
Absorbtivity is a proportionality constant dependent on: A. molecular properties of species, B. Wavelength, C. Chemical Environment, or D. All of the above?
D. All of the Above
What is isotachophoresis?
Isotachophoresis is an electrophoresis technique where ions are separated based on their electrophoretic mobility, using a discontinuous buffer system. It allows fast and focused separation, often used in analytical chemistry and microbiology.
How many grams of pure HCl are needed in 1 liter of distilled, deionized water to produce 1 molar HCl?
36.45 grams
Name 2 wet methods for determination of fat content in milk.
Gerber and Babcock
In proximate analysis, what component is determined by the Kjeldahl method?
Protein (nitrogen content).
What does the microscopic technique 'CLSM' stand for?
Confocal Laser Scanning Microscopy
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 chromatographic detector is most appropriate for quantifying volatile flavor compounds at trace levels?
Flame ionization detector (FID) or mass spectrometry (GC–MS preferred).
What is the name of the reagent used in food analysis which forms a fluorescent compound with primary amines?
Fluorescamine
What common analytical titration is used to measure lipid oxidation via peroxide formation?
Peroxide value titration
In apple juice, titratable acidity should be reported as which acid equivalent?
Malic acid
What is the analytical method for measuring total carbohydrates?
Phenol-sulfuric acid method
What does ANSI stand for?
American National Standards Institute
The Peroxide Value (PV) is a measure of what type of quality degradation in edible fats and oils?
Primary Oxidation (or Rancidity)
Please name a common detector specifically used to measure volatile sulfur compounds such as dimethyl sulfide.
Flame Photometric Detector (FPD) or Sulfur Chemiluminescence Detector (SCD)
What are the 3 types of antigens targeted in immunoassays for detection of microorganisms?
Surface antigens: Found on the outer membrane or cell wall (e.g., lipopolysaccharides in Gram-negative bacteria).
Intracellular antigens: Found inside the microorganism, often detected after lysis.
Toxins or secreted antigens: Produced and released by microbes, such as exotoxins.
Various microscopic techniques are used to evaluate the microstructure of foods and food products. What do the following microscopic techniques stand for: CLSM, SEM, and TEM
CLSM= Confocal Laser Scanning Microscopy; SEM= Scanning Electron Microscopy; TEM=Transmission Electron Microscopy
Name an official method of food analysis for moisture determination.
Oven methods, Karl Fischer
What does a hydrometer measure?
Specific gravity (relative density) of liquids, often used to assess sugar content in beverages or milk
In polysaccharide structure analysis, which analysis is for characterizing the linkage types?
Methylation analysis or NMR spectroscopy
A technique that separates readable pattern of DNA fragment is
A. Genetic engineering
B. Recombinant DNA
C. Gel electrophoresis
C. Gel electrophoresis
Knowing the water and sugar content of foods and beverages is important. Name 3 methods to measure the sugar content in food and 2 to determine the water content.
What does Kjeldahl measure and how does it quantify proteins?
Measures nitrogen content and therefore, protein indirectly.
pH value is a measure of acidity. what is a pKa value the measure of?
The acid dissociation constant; it reflects the strength of an acid — specifically, the pH at which half of the acid is dissociated
If you have 2 different foods, food A w/pH=4 and food B w/pH=6. Which one is more acidic and by how many times?
A, 100 times more acidic than B
What type of flask is used for the flotation, separation and analysis of extraneous matter?
Wildman trap flask
Give 2 ways to measure ethylene.
There are several ways to measure ethylene: 1) gas chromatography (best but expensive); 2) kitagawa tubes, or equivalent; 3) other types of chemical sensors; or 4) another plant that is sensitive to ethylene.
Name two situations in which a chemist is confronted with theoretical plates.
Gas chromatography, liquid chromatography, and distillation.
In Gas Chromatography (GC), what component separates the volatile compounds by partitioning them between a mobile phase and a stationary phase?
Column
In statistics, what is the Mode of a set of numbers?
The value which occurs most frequently in a set of numbers
Name an official method of food analysis for fat determination.
Soxhlet, Mojonnier
Name five antioxidant assays with their full names.
What is the highest designation of wine quality in Italy?
Denominazione di Origine Controllata e Garantita (DOCG)
What does TQM stand for?
Total Quality Management
How does HPLC differ from FPLC?
HPLC has higher pressure than FPLC
What is the commercially available electronic instrument used in the food industry which has a relationship to the olfactory response of humans?
Electronic Nose
In titration, what is the term for the point at which the indicator changes color, signaling that the titration is complete?
End point
Based on the National institute of alcohol abuse and alcoholism, what is the volume in fluid ounces of a standard drink for the following, beer (5%), malt liquor, wine and distilled spirit?
12 fl oz of beer, 8-9 fl oz of malt liquor, 5 fl oz of wine, 1.5 fl oz of distilled spirits
At low water activity what is the main deteriorative concern?
Lipid oxidation
The AOAC International is the standard-setting body for what kind of testing methods?
Name 3 way to analyze secondary lipid oxidation compounds.
TBARS, VOC, HPLC, gas chromatography, sensory panel
What is the general nitrogen to protein conversion factor used in Kjeldahl method?
6.25
The IMViC tests are a group of individual tests used in microbiology lab testing to identify an organism in the coliform group; what tests are involved in the IMViC?
Indole, Methyl Red, Voges Proskauer, and Citrate
In Proximate Analysis, the Kjeldahl method is used to determine nitrogen content. To calculate the "crude protein" content of most foods, the nitrogen value is multiplied by a standard conversion factor. Provide that standard factor and explain why it is used.
The factor is 6.25. It is used because most proteins are assumed to contain approximately 16% nitrogen (100 / 16 = 6.25).
Name 3 major functions of sulfuric acid in the Babcock test?
Digest and dissolve proteins; dissolve fat globule membranes; produce heat to liquefy fat; provide differences in specific gravity for easier separation of liquid fat
Which detection method can not be used with gradient elution in HPLC? a. RID b. DAD c. FLD
a. RID
What is the full form of TA wrt food analysis?
Titratable Acidity
What is the most common method for measurement of acidity?
Titration
What is the name of the heat resistant enzyme in Thermus aquaticus used for modern PCR?
Taq DNA polymerase
What type of chromatography is generally used to separate positively charged molecules: A. Anion exchange chromatography, B. Affinity Chromatography, C. Cation Exchange Chromatography, or D. Reverse-Phased Chromatography?
C. Cation Exchange Chromatography
In statistics, what is the Arithmetic Mean?
It is what is commonly known as the average; it is the sum of all values divided by the number of values.
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.
What does the acronym QC stand for wrt food analysis?
Quality Control
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)
Which experimental design is used in consumer testing when there are too many samples?
Balanced Incomplete Block Design
In reversed-phase chromatography, state the type of mobile phase and stationary phase used.
Polar mobile phase and non-polar stationary phase
What does it mean for data to be accurate?
That data is close to the true value of measurement
CRISPR stands for?
Clustered regularly interspaced short palindromic repeats (enzyme used is cas9)
What are the Delvo and Charm tests used for?
Testing for the presence of antibiotics in milk
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.
Silver nitrate is used as a titrant in food analysis to determine what food component?
Salt (sodium chloride). The silver reacts with the chloride to precipitate silver chloride in the Mohr or Volhard Titrations.
A sample of oil has a Saponification Value of 190. Explain what this value measures and what the given value suggests about the average molecular weight of the fatty acids in the oil.
The Saponification Value measures the number of milligrams of Potassium Hydroxide (KOH) required to neutralize the fatty acids released from 1 gram of fat. A higher saponification value (like 190) indicates a lower average molecular weight (or shorter chain length) for the fatty acids in the fat.
Define the saponification number.
Milligrams of KOH to saponify 1 gram of fat
What constituent or property of food does the iodine value measure?
The iodine value measures the degree of unsaturation in fats and oils. It is the amount of iodine (in grams) absorbed by 100 grams of fat.
In statistics, what is a Type II Error?
Accepting a false hypothesis
According to Codex Alimentarius, what is the difference between extra virgin olive oil and olive oil?
Oleic acid
Which reagent is used in the Kjeldahl method to digest organic nitrogen?
Concentrated sulfuric acid.
The Schiff test is used to detect the presence of what type of compounds often involved in browning reactions?
Aldehydes
What type of spectroscopy is commonly used to determine food color values (L*, a*, b*)?
Colorimetry using a HunterLab or Minolta colorimeter
With respect to spectrometric analytical techniques, what does SIMS stand for?
Secondary Ion Mass Spectrometry
How can infrared energy be detected?
Thermal detectors (e.g., thermocouples, bolometers, pyroelectric detectors) or quantum detectors (e.g., photoconductive cells like lead sulfide or mercury cadmium telluride detectors)
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)
What function does SDS have in SDS-PAGE?
It denatures the protein by breaking disulfide bonds, making it linear.
NMR is often used as the technique to characterize the linkage types.
True. Nuclear Magnetic Resonance (NMR) identifies chemical structures, including linkage types in carbohydrates, proteins, and other macromolecules.
What is the toluene distillation used for?
Moisture content determination
What is the test to detect carcinogenic antigens?
ELISA (Enzyme-Linked Immunosorbent Assay) or Ames test (for mutagenicity, often related to carcinogens)
What color are anothcyanins at acidic pH?
Red
What is the molarity of 40% w/v NaOH solution?
10 M
What is the principle of a refractometer used in measuring sugar concentration?
It measures the refractive index of a solution, which correlates with solute concentration.
Define Beer's law.
Concentration and absorbance are proportional in spectroscopy
Describe the Soxhlet extraction method used for fat analysis.
A weighed sample is placed in a thimble.
Solvent (e.g., petroleum ether) repeatedly washes through the sample by reflux.
Fat dissolves and accumulates in a flask.
Solvent is evaporated; fat residue is weighed for percent fat.
What sugar is not detected using Nelson’s reagent assay?
Sucrose
For what part of a proximate analysis is the Soxhlet apparatus used for?
Crude fat
In SDS-PAGE, what is the use of SDS?
Largely eliminates the influence of the structure and charge, and proteins are separated solely based on polypeptide chain length.
Protein A is eluted faster than Protein B on a gel filtration column. Which protein has a higher molecular weight?
Protein A
B.O.D. stands for biological oxygen demand.
No. Biochemical
In food what method is used to measure heavy minerals?
ICP-AAS or ICP-OES
Grams of sucrose per 100g of sample is the definition of what?
Brix
What type of HPLC utilizes a polar column and a less polar solvent (stationary phase)?
Normal Phase HPLC
What does TOC stand for regarding water quality?
Total Organic Carbon
Express water activity in terms of equilibrium relative humidity.
Aw = ERH/100
Give 2 ways to calculate water activity.
Vapor pressure of the food/vapor pressure of H2O
Moles H2O + moles of substrate/moles of H2O
Give the temperature of liquid nitrogen in celcius, farenheit, kelvin, and rankin units.
–196 °C; –320.8 °F; 77 K; 138.6 °R
What do the following abbreviations stand for? PV, FSIS, CFR, PER, DP, NMR, ESR, HPLC, AA, ICP- AES, SEM, SDS-PAGE, FTIR, TLC, HETP, GFC, SFC, SEC, CRISPR
PV: Peroxide Value
FSIS: Food Safety and Inspection Service
CFR: Code of Federal Regulations
PER: Protein Efficiency Ratio
DP: Degree of Polymerization
NMR: Nuclear Magnetic Resonance
ESR: Electron Spin Resonance
HPLC: High Pressure/Performance Liquid Chromatography
AA: Atomic Absorption
ICP-AES: Inductively Coupled Plasma Atomic Emission Spectroscopy
SEM: Scanning Electron Microscopy
SDS-PAGE: Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis
FTIR: Fourier Transform Infared Spectroscopy
TLC: Thin Layer Chromatography
HETP: Height Equivalent to a Theoretical Plate
GFC: Gel Filteration Chromatography
SFC: Super critical Fluid Chromatography
SEC: Size Exclusion Chromatography
CRISPR: Clustered Regularly Interspaced Short Palindromic Repeats
The most common contaminant which is used to hold vacuum in the isolation apparatus, and causes large, widespread peaks in the gas chromatogram which mask peaks of many important flavor compounds is _______.
Silicon grease
For the following food components, which functional groups are measured by IR? triglycerides, proteins, sugars
Triglycerides: C=O (carbonyl), C–H (aliphatic)
Proteins: Amide I and II bands (C=O stretch, N–H bend)
Sugars: O–H stretch, C–O stretch
What is phenolphthalein used for?
pH indicator, acid=colorless, base=red violet
What two analytical techniques rely on the spin of electrons?
EPR and ESR
What is the quantitative determination of organic nitrogen and therefore protein?
When evaluating baking and frying conditions, what unit is used to quantify the lightness of the baked crust or crumb?
Baking Contrast Units, or BCU
If a solution of ascorbic acid obeys Beer's Law and a 1 M solution gives an optical density of 0.75, what will be the optical density of a 2 M solution?
1.5 absorbance units
What does the acronym associated w/food analysis techniques 'FTIR' stand for?
Fourier Transform Infared Spectroscopy
Define molarity, molality, and normality.
Molarity is moles of substance per liter solution. Molality is moles of substance per kg solvent. Normality is equivalents of substance per liter solution.
What do the following abbreviations stand for: SPC, ANOVA, TQM?
SPC: Statistical process control, ANOVA: analysis of variance, TQM: total quality management
Which detector is commonly used in HPLC for non-volatile compounds?
UV–Vis detector.
Which instrumental method is most commonly used to determine peroxide value in fats?
Iodometric titration.
What is the gel most common used for protein analysis?
Polyacrylamide gel electrophoresis
What is the purpose of proximate analysis?
It quantifies the food's five major components; it's based on gravimetric (weight) based procedures.
What is the purpose of a Brix measurement?
It determines the soluble solids (mainly sugars) concentration in a solution, expressed as °Brix.
What protein is used as a reference to measure the Protein Digestibility Corrected Amino Acid Ratio?
Casein
In reversed phase gas chromotography, is the stationary phase polar or non-polar, and do polar or non-polar compounds elute first?
Stationary phase is non-polar, Polar compounds elute first
Name three protocols for measuring reducing sugars.
Somogyi-Nelson, Fehling's, Benedict's methods, DNS (3,5-Dinitrosalicylic acid) method
What is the basic assumption of the null hypothesis?
There is no difference between samples.
What is the measurement of how much KOH or NaOH is needed to break down one gram of fat?
Saponification value
If the temperature of a solution is -40°F, what will be its temperature in °C?
-40 °C.
Name 3 methods for determination of protein content in a purified protein solution.
Lowry, BCA, UV at 280 or 220, Bradford, Dumas, Kjeldahl, Biuret
CMC is a subgroup of the society of Dyers and Colorists of great britain. This subgroup is the organization that developed and published in 1988 a more logical, ellipse-based equation based on L*C*h˚ color space for computing DE (see delta E*) values as an alternative to the rectangular coordinates of the CIELAB color space.What does CMC stand for?
Color Measurement Committee
Name 3 methods used for protein determination in food and what type of food are they suitable for?
Name a solvent extraction method used to measure fat in foods.
Soxhlet, Goldfish or Mojonnier
Balancing cost, speed, and ease of use, which rapid quality control for syrup is used by the industry? a. forced draft oven b. reflux distillation c. hydrometer d. NIR
c. Hydrometer
Cleave of K-casein by rennet gives which 2 peptides?
Para-kappa casein and glycomacropeptide
Name three methods to determine the lengths of polysaccharides.
Size-exclusion chromatography (SEC), Gel permeation chromatography (GPC), Viscometry (intrinsic viscosity measurements), Light scattering (static or dynamic), Nuclear Magnetic Resonance (NMR) spectroscopy
What is the difference between SDS-PAGE and Urea-PAGE?
SDS-PAGE separates proteins solely based on size, whereas Urea-PAGE separates proteins based on their charge to size ratio.
In proton NMR, what compound is used as the zero-point reference?
TMS: Tetramethylsilane
What is the full form of UCL with respect to statistics?
Upper Control Limit
Name four statistical tools often used for solving food quality problems.
The degree of liquid drainage or foam collapse (foam reduction) after a given time, the time for total or half-drainage (or half-reduction in volume), or the time before drainage starts.
Fats and oils are soluble in what kind of solvents?
Hydrophobic/non-polar solvents
What is a farinograph used for?
Shear and viscosity (or properties is acceptable) of dough
Near and Mid-IR can both be used to analyze foods. Which is most commonly used for quantitative analysis?
Quantitative - Near-IR; Qualitative - Mid-IR.
What does M stand for with respect to unit of concentration?
Molarity
What does GPC stand for wrt food analysis?
Gel Permeation Chromatography
Which of the following can be an official method of analysis or an AOAC method for certain food matrices: A. Dumas, B. Soxhlet, C. Karl Fischer Titration, D. Muffle Furnace Dry Ashing, or E. All of the above?
E. All of the Above
The Beer-Lambert Law is A=ECL; what does the 'L' stand for?
L the length of the light path, usually in cm
What does the Karl Fischer test measure?
Moisture content (usually when present in trace amounts)
In statistics, what is the Median?
The middle of a distribution; half of the values are above, and half of the values will be below.
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 the unit of transmittance in spectrophotometry?
% T (percent Transmittence)
Potassium permanganate is an oxidant and is used in many titrations. Name 3 types of titrations that utilize potassium permanganate as the titrant and indicator.
Iron (Fe2+) or Mohr’s salts, oxalic acid (oxalate), hydrogen peroxide, Copper (II), tannins (other redox reactions)
What chromatographic technique is commonly used to analyze fatty acid methyl esters (FAMEs)?
Gas chromatography (GC)
Name 2 functions of H2SO4 in the Babcock milk fat test.
Digest protein to release fat, generate heat to melt fat, increase density of serum
What two reagents test for the presence of reducing sugars in food?
Benedicts and Fehlings reagents
What is a neutralization value?
Parts by weight of bicarbonate required to neutralize one part acidulant
What is the distillation method used to measure moisture called?
Karl Fischer method
You have a solution with a concentration of 2 mg/L. Please convert this concentration to ug/L, ng/mL, and ug/g
2000 ug/L, 2000 ng/mL and 2 ug/g
What are Mohr's titration and Volhard titration used for?
Chloride ion concentration (indirectly salt concentration)
What is the difference between direct and indirect ELISA?
Direct ELISA- only one antibody used; Indirect ELISA-2 antibodies used for detection
Provide 3 reasons why the Dumas method, for protein content, is being used more and more versus the Kjeldahl method.
Speed: Dumas is faster (few minutes per sample).
No hazardous chemicals: Kjeldahl uses concentrated sulfuric acid, while Dumas avoids corrosive reagents.
Automation and throughput: Dumas is easily automated, making it suitable for high-throughput labs.
What does the microscopic technique 'TEM' stand for?
Transmission Electron Microscopy
What primary standard is commonly used to standardize NaOH?
Potassium hydrogen phthalate.
What method used for protein analysis aids the researcher in determining relative percentage of alpha helix and beta sheets in a single protein?
IR spectroscopy, circular dichroism spectroscopy, X-ray crystallography
What type of method is the phenol sulfuric acid value, and what does this assay determine?
Colorimetric, total carbohydrates
The Beer-Lambert Law is A= ECL; what does the 'C' stand for?
C is concentration in moles/L
The type of chromatography used to separate color pigments is A) GC, B) Thin layer, C) HPLC and D) Paper
Paper
What test is used to measure the viability of starter culture during the fermentation of cottage cheese?
List and briefly describe three types of sensory panels.
Discrimination panel – detects differences between products.
Descriptive panel – quantifies specific sensory attributes.
Affective panel – measures consumer preference or acceptance.
What is the measurement of the oxygen used in the stabilization of organic matter by microorganisms over a 5-day period at 20C called?
Biochemical Oxygen Demand (B.O.D).
Describe the phenol-sulfuric acid method for total carbohydrates.
The Phenol-Sulfuric Acid Method is a widely used colorimetric assay for determining total carbohydrates in a sample. Concentrated sulfuric acid hydrolyzes polysaccharides and oligosaccharides into monosaccharides. The monosaccharides then undergo dehydration, forming furfural (from pentoses) or hydroxymethylfurfural (from hexoses). These furfural derivatives react with phenol, producing an orange-yellow complex. The intensity of this color is proportional to the carbohydrate concentration in the sample.
What is the pH range of the indicator phenolphthalein and what color does it exhibit?
8.3-10.0; Pink
What does ELISA stand for, and what does it detect?
Enzyme-Linked Immunosorbent Assay, its an immunological test to detect and quantify specific proteins, antigens, antibodies, or hormones in a sample.
In statistics, what is the term for the smallest value of alpha for which you would reject the null hypothesis?
p-value
What extraction method, invented in 1897, is still used to extract fat from solids?
Soxhlet
The TBA analysis is a colorimetric reaction; what does this mean?
The analyte of interest does not have a chromophore and must react with a substance so that a chromophore is created and absorbance can be read to determine the concentration of an analyte
What is meant by sensitivity in a biological assay?
Magnitude of a change of an analytical instrument w/ changes in compound concentration
Name three methods for protein quality determination.
Protein efficiency ratio, biological value, net protein utilization, PDCAAS (protein digestibility corrected amino acid score), Digestible Indispensable Amino Acid Score (DIAAS)
What is the wavelength range of UV-Vis spectroscopy?
200-700nm (UV=200-350nm, Vis=350-700)
Which amino acid gives strong reaction with the Folin-Ciocalteu reagent?
Tyrosine (aromatic ring)
Does UV/Vis spectroscopy measure electronic, vibrational, or rotational energy level transitions?
Electronic energy levels
In the UV determination of protein concentration, what wavelength of light is used?
280 nm, primarily absorbed by tyrosine and tryptophan (and also phenylalanine).
What does AES stand for?
Atomic Emission Spectroscopy
Describe the steps of a standard moisture analysis using an oven-drying method.
Weigh a clean, dry crucible.
Add a known mass of sample.
Dry in an oven (usually 105°C) until constant weight.
Cool in a desiccator.
Reweigh; moisture (%) = [(initial weight – dry weight) / initial weight] × 100.
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)
What conditions are necessary for ketoses to give (+) reducing sugar results?
Alkaline conditions (ketoses converted to aldoses)
What characteristic of compounds is usually utilized to separate compounds in gas chromotography?
Molecular weight, polarity, volatility
What does SG stand for in food analysis?
Specific Gravity
The Folin-Ciocalteu measures what food constituents?
Phenolic compounds
What method is used to determine the fat content of milk?
Mojonier, Gerber, Babcock, Rose-Gottlieb
What is the titrant used in the Mohr titration for salt determination and what is the end product of the chemical reaction?
Titrant: Silver nitrate (AgNO₃)
End product: Silver chloride (AgCl) precipitate; endpoint is detected by the formation of red-brown silver chromate (Ag₂CrO₄) with potassium chromate as the indicator.
Wavelength of 420nm is in which spectrum?
Visible spectra (390-750nm)
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
Atomic Mass Spectroscopy separates molecules according to their m/z ratio. What is the m/z ratio?
Ratio of mass to charge
What does MS stand for in food analysis?
Mass Spectrometry
The Beer-Lambert Law is A=ECL; what does the 'A' stand for in the Beer-Lambert Law?
A is absorption
Where is commercial lecithin (food additive) obtained?
Soybean, also from egg yolks, sunflower seeds, and rapeseed
What is a blind experiment?
The subjects do not know if they are in the experimental group or control group.
Explain the purpose of using a standard curve in spectrophotometric analysis.
It establishes a relationship between concentration and absorbance, allowing quantification of unknown samples.
If you have a method that you want to use to measure the % 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.
How much time must pass after a new analytical method has been published in the Journal of AOAC before it is included in the AOAC handbook?
2 years
What is the Schreiber melt test?
Used melt test for cheese where sample discs of known dimensions are heated in an oven and the final diameter of the melted disc is measured.
Does IR radiation have a longer or shorter wavelength than visible light?
IR radiation has a longer wavelength than visible light.
What does SDS-PAGE stand for?
Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis
What is the full form of RLU, a unit of measurement used to quantify the amount of light emitted by a sample?
Relative Light Units
What does HPLC stand for?
High Performance Liquid Chromatography
The Lane-Eynon method is a titration that measures what in a food sample?
Reducing sugars
Which one of the followin values would give you the most information about the melting properites and mouthfeel of fats? a. Oil stability index b. Solid fat index c. IV d. Cloud point
Solid fat content
How many meters is 1 Angstrom?
10^-10 meters
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
What template is used in conducting real-time PCR?
DNA
Explain 'Ghost peaks' in chromatography.
"Ghost peaks" are unexpected or unexplained peaks in a chromatogram that do not correspond to any known analyte. They may be caused by: Contamination (from solvents, columns, or glassware), Carryover from previous injections, Degradation of compounds or reagents, Mobile phase impurities or instrumental artifacts
What is the full form of RI?
Refractive Index
Gel filtration separation of proteins is taking advantage of: A. protein charge, B. protein size, C. molecular affinity, or D. pH?
B. protein size
For what test is the Methylene Blue reduction used?
Estimate of bacterial population in milk
What analytical technique separates compounds based on volatility and interaction with a stationary phase?
Gas chromatography
Why is titratable acidity an important measurement in food products?
It predicts the acid's impact on flavor in a food product
What does the Ninhydrin assay measure?
Free amino acids and amines
In polyacrylamide gel electrophoresis (PAGE) what purpose do ammonium persulfates (APS) and TEMED serve?
They act as catalysts, speeding the polymerization of acrylamide.
Does the iodine value increase or decrease during autoxidation?
Decrease
What does AE-HPLC stand for?
Anion Exchange High Performance Liquid Chromatography
How do you calculate the coefficient of variation?
Divide the standard deviation by the mean and multiply by 100.
What type of compounds is flame photometric detector (FPD) specific for?
FPD is specific to compounds containing sulfur and phosphorous compounds
What is the Molisch test used for?
Carbohydrates. It detects the presence of all carbohydrates (monosaccharides, disaccharides, and polysaccharides) by dehydrating them with sulfuric acid to form furfural derivatives, which then react with α-naphthol to produce a violet or purple ring.
In Mohr’s method what is silver nitrate used as?
Titrant
What does a conductivity meter measure?
The ability of a solution to conduct electric current
What do you have to correct for after total dietary fiber?
Nitrogen in ash from protein
What is the most common instrument used for sugar concentration measurement in solution?
Refractometer
In food chemistry what does the TBA stands for and what is it used to measure?
Thiobarbituric Acid (TBA) used to measure lipid oxidation by detecting malondialdehyde (a secondary oxidation product)
List and describe three classical proximate analysis methods for food composition.
Moisture: Oven drying or Karl Fischer titration
Protein: Kjeldahl or Dumas nitrogen analysis
Fat: Soxhlet extraction
What is the name of the commonly used melt test for cheese where sample discs of known dimensions are heated in an oven and the final diameter of the melted disc is measured?
Schreiber melt test
What is the full form of FW in food analysis?
Formula Weight
Explain the principle of Near-Infrared (NIR) spectroscopy and its application in food analysis.
NIR measures overtones of molecular vibrations (C–H, O–H, N–H) and is used for rapid, non-destructive analysis of moisture, fat, and protein.
In statistics, when sample size is 30 or larger, the t-distribution approximates what distribution?
Z-distribution (Normal)
Balancing cost speed and ease of use, which rapid quality control for syrup measuerment was used by industry?
Handheld refractometer
What does BOD stand for regarding water quality?
Biochemical Oxygen Demand
Which is more sensitive, fluorescence or absorbance spectroscopy?
Fluorescence spectroscopy
Explain what beer's law equation is used for, state the equation, and explain what each variable is.
Beer's law is used in calculations dealing with spectrophotmetric analyses. Absorbance = elc. E is the molar absorbtivity constant, L is the length of the cell holder/cuvette and c is the concentration of the solution
What instrument is used for specific volatile aroma compounds quantitation?
Gas chromatograph
What quantitative analysis method is based on the oxidation of reducing sugars by copper ions under alkaline conditions?
Fehling's test and Benedict's test
What enzyme is measured when the Falling number test is used on cereal-based products?
α-amylase
What would you do to convert temperature reading from Fahrenheit to degrees Rankine?
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