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What is the quantitative analysis for the oxidation of reducing sugars by Cu+ ions under alkaline condition?

Benedict's test

Give the resultant color for each of the following L*a*b* scores: 1) L* = 50, a*= 50, b* = 50; 2) L* = 50, a*= 0, b* = 0; 3) L* = 40, a*= 10, b* = 40

red, gray, brown

Name three gelling food proteins?

egg white, whey, casein, soy

Name three types of GC detectors using their full name.

FID (Flame Ionization Detector); NPD (Nitrogen phosphorus detector); FPD (Flame Photometric detector);ECD (electron capture detector); MS (Mass Spectrometer); AED (atomic Emission Detector); PID (Photoionization detector); TCD (Thermal Conductivity Detector); ELCD (electrolytic conductivity detector)

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.

In proton NMR, what compound is used as the zero-point reference?

TMS: Tetramethylsilane

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

What do the following abbreviations stand for? PV, FSIS, CFR, PER, DP, NMR, ESR, HPLC

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 liquid chromatography

Name one amino acid that contributes significantly to the absorbance of light at 280nm.

Tryptophan

What does a conductivity meter measure?

The ability of a solution to conduct electric current

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 are the three steps of Kjeldahl method?

Digestion, distillation, titration

What are mohr's titration and volhard titration used for?

determining salt concentration

What color are anothcyanins at acidic pH?

Red

Name 3 major functions of sulfuric acid in the Babcock test?

Dissolve colloid components Dissolve fat globule membranes Produce heat to liquefy fat Provide differences in specific gravity for easier separation of liquid fat

What is the titrant used in the Mohr titration for salt determination and what is the end product of the chemical reaction?

Silver nitrate is used as the titrant and the silver reacts with chloride to form a silver chloride precipitate, silver chromate is the end product.

What analytical method reveals the most information about a lipid? A – fat index, B – solid/ liquid ratio, C – iodine value, D – Cloud point

What is polarography and how is it used in food analysis?

voltage is scanned on a dropping mercury or pulsed electrode surface. At the redox potential of the analyte, diffusion current is established as analytes diffuse to the electrode which is directly related to the concentration. It is used for many food components that exhibit oxidation-reduction behavior

A difference of ___ BCU is estimated to be a visual difference in a product

0.1

What are some of the disadvantages of a liquid-in-glass thermometer?

large sensing element, not possible for continuous or automatic readout, long time constant

What is the most accurate and sensitive method for quantitative determination of metals and metalloids

Inductively Coupled Plasma (ICP) Atomic Absorption spectroscopy

What color is expected when many starches react with iodine?

blue-black

What are the three functions of sulfuric acid in the Babcock test?

generate heat, precipitate protein, digest protein

Define molarity, molality, and normality.

molarity = moles of a substance per liter solution Molality = moles of a substance per kg solvent Normality= equivalents of substance per liter of solution

How can the molecular weight of protein, DNA and RNA be determined?

SDS-PAGE for proteins and Agarose gel for DNA & RNA.

Express water activity in terms of equilibrium relative humidity

Aw = ERH/100

Where is commercial lecithin (food additive) obtained?

soybean

Give 2 ways to calculate water activity.

vapor pressure of the food/vapor pressure of H2O Moles H2O + moles of substrate/moles of H2O

How many grams of HCl are needed in 1 liter of distilled, deionized water to produce 1 molar HCl?

36.45 grams

What is a nonsolvent wet extraction method used to measure fat in foods?

Babcock or Gerber extractions

What does ELISA stand for?

Enzyme linked immunosorbent assay

What is the difference between additive and subtractive primaries?

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

What is a farinograph used for?

shear and viscosity (or properties is acceptable) of dough

What is the primary ingredient in sand?

silica (silicon dioxide)

Which of the following is used to see whether or not milk has been pasteurized? A - phosphatase test, B - refractometer test, C - Jelmeter test, D - Acidophilus test

a – phosphatase test/ Alkaline Phosphatase test.

What type of method is the phenol sulfuric acid value, and what does this assay determine?

colorimetric, total carbohydrates

What food components are measured by the following. 1. Karl fisher itration, 2. Nekson’s reagent, 3. Anthrone method

1. Water, 2. Protein, 3. Carbohydrate

Which of these instruments can be used to measure degree of brix?

Refractometer

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

The TBA method (thiobarbituric acid) is used to monitor oxidative rancidity. What does the method actually measure?

concentration of malonaldehyde

Explain 'Ghost peaks' in chromatography.

Ghost peaks are unknown or unwanted peaks that may interfere with the chromatogram and become a concern in qualitative and quantitative analysis. These peaks may appear at the same retention time as that of the analyte of interest, or there may be very less resolution between the analyte and these peaks, due to which the quantitative analysis is adversely affected. The ghost peaks can also be termed extraneous peaks, artifact peaks, system peaks, pseudo peaks, vacancy peaks, eigen peaks, induced peaks, and spurious peaks. These peaks may arise from unknown impurities or artifacts within the system, such as contaminants from a dirty injector, carrier phase, extractable contaminant, autosampler vials, and caps, or from a contaminant carried over from a previous injection.

What does TQM stand for?

total quality management

For what part of a proximate analysis is the Soxhlet apparatus used for?

crude fat

Atomic absorption spectroscopy is typically used to measure what in foods?

Minerals

In SDS-PAGE, what is the use of SDS?

the use of sodium dodecyl sulfate (SDS, also known as sodium lauryl sulfate) and polyacrylamide gel largely eliminates the influence of the structure and charge, and proteins are separated solely based on polypeptide chain length.

What is the distillation method used to measure moisture called?

carl-fisher

Protein A is eluted faster than Protein B on a gel filtration column. Which protein has a higher molecular weight?

Protein A

What sugar is not detected using Nelson’s reagent assay?

Sucrose

What is the IMVIC test?

Indole Methyl Red Voges-Proskauer Citrate

Name 3 way to analyze secondary lipid oxidation compounds.

TBARS, VOC, HPLC, gas chromatography, sensory panel

What does HPLC stand for?

High-performance (or high-pressure) liquid chromatography

What is the quantitative determination of organic nitrogen and therefore protein?

Kjeldahl method

What are the polarities of the staionary and mobile phases in N-HPLC?

mobile is non-polar, stationary is polar

What constituent or property of food does the iodine value measure

degree of unsaturation of fats or oils

What substances in low quantity can be found in food?

Indirect additives

What is the unit of expansion of transmittance of spectrophotometry?

% T (percent Transmittence)

What is a Soxhlet analyzer used to measure?

Fat

SPME is an isolation technique in food analysis, meaning?

Solid phase microextraction

What is isotachophoresis?

technique used to separate out ionic analytes

If the absorption of a sample is being determined spectrophotometrically at 420nm what color is the sample?

Yellow

What does Thiobarbituric acid number or value tell you?

degree of lipid oxidation

What does the Karl Fischer test measure?

Moisture content (usually when present in trace amounts)

What is the most popular instrument for measuring the textural quality of foods?

Instron

You are running a titration to determine the % tartaric acid in juice. You use 20 mLs of 0.1N NaOH for 2 grams of juice. What is the % tartaric acid of the sample?

0.075

Name 3 methods to determine water activity.

Bithermal equilibration, Vapor pressure manometer, Hair hygrometer, Isopeistic hygrometry, Psychrometry, Dew point, Freezing-point depression

A soxhlet extractor was originally designed to extract what from solid foods?

Lipids

What instrument is used to measure soluble solids in foods?

refractometer

The Lane-Eynon method is a titration that measures what in a food sample?

Reducing sugars

What quantitative analysis method is based on the oxidation of reducing sugars by copper ions under alkaline conditions?

Fehling's test

In apple juice, titratable acidity should be reported as which acid equivalent?

Malic acid

What does the AOAC stand for?

Association of Official Analytical Chemists

Provide 3 reasons why the Dumas method, for protein content, is being used more and more versus the Kjeldahl method.

Much faster, 4 minutes per sample No toxic chemicals or catalyst Very easy Many samples can be measured automatically

What beverage is caramel color most used for?

coloring beer

What two reagents test for the presence of reducing sugars?

benedicts and fehlings

Ruhemann's purple is formed by what reaction used in food analysis?

Reaction of Ninhydrin with amine group of amino acids.

Which Mass spec technique relied on large protein fingerprint for bacteria?

MALDITOF MS

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

Acceptable quality limits

Grams of sucrose per 100g of sample is the definition of what?

Brix

What does the Kjeldahl method measure in foods?

Nitrogen content

Name 3 tests that can be used to measure the fat content of milk.

Primitive Centrifugal Methods, Gerber, Babcock, Rose- Gottlieb, Schmidt Werner

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.

What template is used in conducting real-time PCR?

DNA

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?

990mL water

What is the highest designation of wine quality in Italy?

DOCG

Which detection method can not be used with gradient elution in HPLC? a. RID b. DAD c. FLD

a. RID

What is the standard against which all sweeteners are measured in terms of their quality of taste and taste profile?

sucrose (taste sugar)

Name 1 method of second degree product of rancidity

TBARS, VOCs, sensory evaluation, p-anisidine value, HPLC, GC, mass spectrometry

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 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

For the fluorescent analysis of vitamin C, dehydroascorbic acid is allowed to react with what compound to form a fluorescent derivative?

O-phenylenediamine (or dimethyl-O-phenylenediamine)

In Mohr’s method what is silver nitrate used as?

An indicator, used to measure salt content

SDS-PAGE stands for?

Sodium dodecyl sulphate polyacrylamide gel electrophoresis

A muffle furnace is used in which constituent of proximate analysis?

Ash

Ingles coming procedure is used for what assay?

Fiber Assay

How many significant figures are in the number 0.000401?

Amino acids absorb light at 190-240 nm because of which bond?

peptide

What does the Ninhydrin assay measure?

amino acids

What property of a protein can be determined using SDS electrophoresis?

molecular weight

What is Fiske-Subbarow assay?

measure levels of inorganic phosphate in biological samples

What does GCMS stand for?

Gas chromatography mass spectrometry

In food what method is used to measure heavy minerals?

atomic adsorption

If you take 20 mL of a 0.1M NaOH salutation to titrate 40 mL of an HCL solution to the phenolphthalein end point. What is the molarity of the HCL solution?

0.05M HCL

What does the iodine value measure?

Unsaturated bonds in fats

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.

What is the wavelength range of UV-Vis spectroscopy?

200-700 nm

Cleave of K-casein by rennet gives which 2 peptides?

para-kappa casein and glycomacropeptide

How does HPLC differ from FLPC?

HPLC has higher pressure than FPLC.

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, Xray crystallography

What chemical compound is determined as an indicator of maillard browning?

hydroxymethylfurfural

Name a solvent extraction method used to measure fat in foods?

Soxhlet, Goldfish or Mojonnier

What type of analysis estimates the "moisture", "crude fat", "crude protein", "ash" and "carbohydrate by difference" in a food product?

Proximate analysis

What does HETP stand for in column design?

Height equivalent to theoretical plate

Balancing cost speed and ease of use, which rapid quality control for syrup measuerment was used by industry?

Hygrometer ©, NIR, Reflux distillation, Force drop oven

What does the Fiske-Subbarow assay measure?

Levels of inorganic phosphate in biological samples

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

What is the name of the heat resistant enzyme in Thermos aquaticus used for modern PCR?

TAG DNA polymerase

Which amino acid gives strong reaction with the Folin-Ciocalteu reagent?

tyrosine (aromatic ring)

What is Kjeldahl test used for?

Determination of nitrogen content

In food chemistry what does the TBA stands for and what is it used to measure?

Thiobarbituric acid, measures oxidation of fatty acids with three or more double bonds

What is reverse osmosis?

applying pressure to exceed the osmotic pressure of the solution

What is the general nitrogen to protein conversion factor used in food analysis?

6.25, kjeldahl method

What is the CDC's gold standard for microbe fingerprinting?

Pulsed Field Gel Electrophoresis (PFGE)

Expand the following: TLC, HETP, HPLC, GFC, SFC

TLC (Thin layer chromatography), HETP (Height equivalent theoretical plates), HPLC (High pressure or High performance liquid chromatography, GFC (Gel Filteration Chromatography), SFC (Super critical Fluid Chromatography)

Name a reagent used to determine the amount of reducing sugar present in food.

Benedict's reagent

Name 2 wet methods for determination of fat content in milk.

gerber and babcock

What test would you use to measure oxidation in meat products?

Thiobarbituric acid analysis (TBA)

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

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.

Inosine methylene blue agar is used for?

Lactose fermenting

What type of flask is used for the flotation, separation and analysis of extraneous matter?

wildman trap flask

Name 5 food components as identified by “proximate” analysis.

Protein, carbohydrate (NFE), water, ash, lipid, fiber

What color is observed when red, green, and blue pigments are mixed in equal amounts?

white

What are the 3 main steps of the original Kjeldahl method for measuring protein content?

digestion, neutralization and distillation, titration

A mojonnier flask is generally used for what?

extraction of fat (normally from milk)

What is the purpose of the Englis-Cummings procedure?

measure the total, soluble and insoluble fiber content

Name heat resistant enzyme use in modern PCR.

TAQ DNA Polymerase

Alcohol insoluble solids content in vegetables is indicator of

Maturity and ripeness

What is the Molish test used for?

Carbohydrates

What is the pH range of the indicator phenolphthalein?

8-9.6

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

absorbance has a linear relationship with concentration based on Beer’s Law and transmittance does not.

Please name a common detector specifically used to measure volatile sulfur compounds such as dimethyl sulfide.

PFD – pules flame photometric detection ( other acceptable answers PFD, pulse flame detection or SCD – sulfur chemiluminescence detector)

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

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. hygrometer d. NIR

c. hygrometer

How much volume of 37% HCl is required to make a litre of 1 M HCl with DI water?

82 ml (80-85 ml acceptable)

What is the name of the reagent used in food analysis which forms a fluorescent compound with primary amines?

Fluorescamine

What test is used to measure the viability of starter culture during the fermentation of cottage cheese?

Ta, TTA, or titratable acidity

For which food component are the following tests used? Sudan 3, Iodine, Benedicts

Sudan 3: triglycerides, Iodine: starch, Benedicts: reducing sugars

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

What is the difference between direct and indirect ELISA?

-direct ELISA- only one antibody used, indirect ELISA-2 antibodies used for detection

The following acronyms related to food analysis stand for, AA, ICP- AES and HPLC.

Atomic absorption, Inductively coupled plasma Atomic emission spectroscopy, High performance liquid chromatography

The type of chromatography used to separate color pigments is A) GC, B) Thin layer, C) HPLC and D) Paper

Paper

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.

Sugar - refractometry, density, titrations (Rebelein, Lany-Eynon), UV/VIS spectroscopy (anthrone method, phenol-sulfuric acid method), chromatography, enzymatic Water – Karl Fischer titration, thermogravimetric analysis, spectroscopic analysis, GC, density, refractometry

What does TBA stand for in food analysis?

Thiobarbaturic acid

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 titration

What does FID stand for?

Flame ionization detector

How to express in concentration, ppm equivalent as weight per volume?

mg/L or microg/ mL

What enzyme is measured when the Falling number test is used on cereal-based products?

amylase

Botswick measures what?

Popular for measuring consistency, flow rate and viscosity in a variety of viscous materials.

Five different modes of chromatography.

Adsorption; partition; size exclusion/gel permeation/gel filtration; ion exchange; affinity. PAISA.

What does the acid degree value measure?

amount of free fatty acids

Methods to determine the lengths of polysaccharides.

NMR, HPLC (Size exclusion column), Gel electrophoresis, osmotic pressure, light scattering

CRISPR stands for?

Clustered regularly interspaced short palindromic repeats (enzyme used is cas9)

Name five antioxidant assays.

ORAC, CUPRAC, beta carotene, TIAC, FRAP, PRSC

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 do you have to correct for after total dietary fiber

nitrogen in ash fro protein

What does Phenol sulfuric acid value tell you?

total carbohydrate

Flashcard Info

Food analysis and quality assurance