Fsc 455 Exam 1

Front 1

What would be the effect onmoisture content determination if the particle size of the molecule is verylarge? Overestimate or underestimate?

Back 1

Underestimate of moisture. Large particles cant evaporate well because they are trapped inside of the food

Front 2

What would be the effect onmoisture content determination if there is a high concentration of volatileflavor compounds present in the product? Overestimate or underestimate?

Back 2

Overestimate. Anything volatilemight be incorporated into the measure

Front 3

What would be the effect onmoisture content determination if the sample undergoes sucrose hydrolysis? Overestimate or underestimate?

Back 3

Underestimate. Waterparticipating in reaction that hydrolyzes bond between glucose and sucrose.Some of the water is going to be reacting with the food (sucrose) and notevaporating (what you’re measuring)

Front 4

What would be the effect onmoisture content determination if the samples were not placed in a dessicator after being removed from thedrying oven? Overestimate or underestimate?

Back 4

Overestimate. Presumably alreadydriven off all the water in drying oven, the humid air is going to replacewater back into sample. (Water going to move from high concentrationâ airâ tolowâ sample)

Front 5

What moisture analysis method(s) is a method of choice to determinemoisture content on many low-moisture foods including dried fruits and vegetables, candies, chocolate, roasted coffee, oils and fats, & low-moisture food high in sugar/protein?

Back 5

Karl Fischer Titration

Front 6

In what moisture analysis method(s) is I2 is reduced bySO2 in presenceof water and the endpoint of titration is reached when excess I2 present thatcannot react with water?

Back 6

Karl Fischer Titration

Front 7

What is used tocalculate % moisture in the Karl Fischer Titration method?

Back 7

Volume of titrant

Front 8

What are the 4 Oven Drying Methods?

Back 8

Forceddraft oven, Vacuumoven, Microwaveanalyzer, Rapidmoisture analyzer

Front 9

In what moisture analysis method(s) is the sampleis heated to evaporate off water?

Back 9

Oven Drying Methods

Front 10

What equals moisture content in oven drying methods?

Back 10

Weight loss

Front 11

What is the calculation for % moisture with oven drying methods?

Back 11

((wet weight-dry weight)/(wet weight)) x 100

Front 12

What are 3 sources of error in Oven Drying Methods of moisture analysis?

Back 12

Particlesize, Volatilecompounds present, Lipidoxidation

Front 13

In what moisture analysis method(s) is the sample is heated in toluene (an immiscible liquid), and the tolueneand water are co-distilled?

Back 13

Distillation (Refluxdistillation with toluene)

Front 14

How is moisture found with the reflux distillation method?

Back 14

1. Collect mixture that distills off and 2. Measure volume of water removed

Front 15

Why do the forced-air oven drying methods givedifferent results depending on temperature?

Back 15

Highertemperature would not only increase the amount of water driven off from thesample, but increase the likelihood of loss of non-moisture compounds.

Front 16

What 2 moisture analysis methods are directmeasures of moisture loss, and will thus give more accurate results, especially for low moisture foods?

Back 16

Distillation method and Karl Fischer titration

Front 17

What 2 moisture analysis methods are preferred for low-moisture foods?

Back 17

Distillation method and Karl Fischer titration

Front 18

Regarding moisture content, experimentalerror will be inherently larger with ___ (distillation/oven) methods.

Back 18

Oven

Front 19

What are 3 advantages of the reflux distillation method for moisture content?

Back 19

1. Good accuracy for low moisturefoods 2. Less thermal decomposition thanoven drying 3. Water is measured directly

Front 20

What are 3 disadvantages of the reflux distillation method for moisture content?

Back 20

1. May be harder to measureaccurately the amount of water, 2. Emulsion formation, 3. Possible sample decomposition

Front 21

What are 3 advantages of the Karl Fischer method for moisture content?

Back 21

1. Rapid (although one sample at atime), 2. Accurate (for low-moisture foods), 3. Uses no heat

Front 22

What are 3 disadvantages of the Karl Fischer method for moisture content?

Back 22

1. Possibly incomplete moistureextraction, 2. Reaction of atmosphericmoisture/humidity, 3. Reaction of other food componentswith KF reactants

Front 23

What are 3 physical methods of moisture analysis?

Back 23

1. Dielectricmethod, 2. Specificgravity (hydrometry), 3. Refractometry

Front 24

What physical method of moisture analysis is basedon bending of light (i.e., refraction) as it hits surface of product?

Back 24

Refractometry

Front 25

What is the equation for water activity (regarding vapor pressure)?

Back 25

(Vapor pressure above food sampleat defined temp)/ (Vaporpressure above pure water at defined temp)

Front 26

What is ash?

Back 26

Inorganic residue remaining aftereither ignition or complete oxidation of organic matter

Front 27

What ash analysis method principle is: Whensample is heated to high temperatures, all organic matter is incinerated,leaving inorganic material to be quantified gravimetrically

Back 27

Dry ashing, muffle furnace

Front 28

What ash analysis method determines total ash content and is sometimes used as preparation for specific mineral analysis by Atomic Absorption Spectroscopy?

Back 28

Dry ashing, muffle furnace

Front 29

What are 3 advantages to dry ashing?

Back 29

1. Requires little technician time, 2. Can analyze many samples at onetime, 3. Relatively safe

Front 30

What are 3 disadvantages to dry ashing?

Back 30

1. Minerals can be hard to resolubilize, 2. Minerals can be volatilized, 3. Takes long time to get results

Front 31

What are 3 sources of error in dry ashing?

Back 31

1. Samplenot representative, 2. Microelementcontamination, 3. Lossof sample in drying before ashing

Front 32

What ash analysis method refers to oxidizing inorganicsubstances with acids and oxidizing agents, or their combination in liquid?

Back 32

Wet ashing

Front 33

When sample is heated to hightemperatures, all organic matter is incinerated, leaving inorganic material tobe quantified gravimetrically is the principle of ___ (wet/dry) ashing

Back 33

Dry

Front 34

Organicmatter is vigorously oxidized using acids and oxidizing agents, leaving solubleinorganic matter is the principle of ___ (wet/dry) ashing

Back 34

Wet

Front 35

Wet ashing typicallyuses a combination of ___ (acids/bases) and ___ (oxidizing/reducing) agents

Back 35

Acids, oxidizing

Front 36

What are 3 advantages to wet ashing?

Back 36

1. Minerals stay in solution, 2. Little or no volatilization, 3. Short time

Front 37

What are 3 disadvantages to wet ashing?

Back 37

1. Requires nearly constant operatorattention, 2. Handle small number of samples, 3. Can be extremely dangerous

Front 38

Closed-vessel microwave digestionsystems and open-vessel microwave digestionsystems are ___ (wet/dry) digesters

Back 38

Wet

Front 39

___ (Wet/Dry) digesters reachtemperature of 1200oC and use Quartzfiber crucibles

Back 39

Dry

Front 40

What is the advantage to microwave ashing?

Back 40

Shorttime for ashing

Front 41

What are 2 disadvantages to microwave ashing?

Back 41

1. High initial cost and maintenanceof equipment, 2. Limited number of samples can be ashed at one time

Front 42

Whatmethod would be preferable for moisture analysis of ice cream?

Back 42

Karl Fischer (high sugar content)

Front 43

What method would be preferable for moisture analysis of meat?

Back 43

Karl Fischer (high protein content)

Front 44

What are 3 solvent extraction methods for lipid analysis?

Back 44

1. Pre-drying sample, 2. Particle size reduction, 3. Acid hydrolysis

Front 45

With lipid analysis, ___ (ethyl ether/petroleum ether) is generally better solvent for fatand is more expensive

Back 45

Ethyl ether

Front 46

With lipid analysis, ___ (ethyl ether/petroleum ether) is selective for more hydrophobiclipids and is cheaper

Back 46

Petroleum ether

Front 47

What is the principle for solvent extraction methods of lipids?

Back 47

1. Fat is extracted withsolvent, 2. Fat content is measured by weightloss of sample or by weight of fat removed (i.e., gravimetric analysis); similar principle as used inoven drying methods for moisture analysis

Front 48

The fat content on thenutritional facts label of foods is derived from what method?

Back 48

Gas chromotography

Front 49

What is the equation for %protein from N content?

Back 49

%Nx 6.25 = % Protein

Front 50

What is the main method of protein analysis?

Back 50

Kjeldahl method

Front 51

What protein analysis method is recommended for foods used as sole source ofnourishment e.g., infant formula, foods for special dietaryconditions, and novel food products

Back 51

Amino acid analysis

Front 52

What are 3 advantages to UV absorbance for protein analysis?

Back 52

1. Rapid, 2. Non-destructive, 3. Accurate

Front 53

What are 3 disadvantages to UV absorbance for protein analysis?

Back 53

1. Accurate only for a pure protein, 2. Protein must be soluble, 3. Sample must be completelytransparent

Front 54

What is the equation for determining total carbohydrate composition?

Back 54

100% - [% Moisture + % Ash + %Lipid + % Protein ]

Front 55

What is a method for total carbohydrate analysis?

Back 55

Phenol-Sulfuric Acid Method

Front 56

What is the principle for the Phenol-Sulfuric Acid method?

Back 56

Carbohydratesheated inthe presence of strongacid and high temp. first, undergohydrolysis to monosaccharides

Front 57

What is the principle for Reducing Sugar Analysis?

Back 57

All based on reduction of Cu2+ions in alkaline solution to Cu+ ions by reducing sugars; Amountof Cu+ ions generated is then quantifiedto determineamount reducingsugars

Front 58

What are 3 advantages to enzymatic methods for carb analysis?

Back 58

1. Usually specific for substancebeing measured, 2. Kits commercially available, 3. Generally have low detectionlimits

Front 59

What are 3 disadvantages to enzymatic methods for carb analysis?

Back 59

1. May be interfering compoundspresent, 2. Not always 100% specific, 3. Not useful for measuring totalcarbohydrates, a class of carbohydrates, or all carbohydrates individually

Front 60

What is the principle of the enzymatic method for starch analysis?

Back 60

Starch(gelatinized) is converted totally into D-glucose by enzymes specific forstarch*, and D-glucose is quantified enzymatically

Front 61

What are 2 advantages to enzymatic methods for starch analysis?

Back 61

1. Commercial kits available, 2. Enzymes make the analysis veryspecific

Front 62

What are 2 disadvantages to enzymatic methods for starch analysis?

Back 62

1. Amylases must be pure (no other enzymes present thatwould generate glucose or destroy peroxide) , 2. May not be quantitative forhigh-amylose starch or samples high in resistant starch

Front 63

What is resistant starch?

Back 63

Starch that is: 1. Physically inaccessible toamylases; trapped in matrix, 2. Accessible but resistant tohydrolysis due to packing within the starch granule, 3. Retrograded starch; resistant todigestion

Front 64

Resistantstarches behave like what?

Back 64

Fiber

Front 65

What is the principle for the AOAC Method for Total DietaryFiber?

Back 65

1. Dried defatted sample is enzymatically digested with α-amylase, amyloglucosidase, and protease to remove starchand protein, 2. Soluble fiber is precipitated byadding ethanol, 3. Dried residue (i.e., soluble andinsoluble fiber) is corrected for ash and protein contents; Gravimetric analysis

Front 66

Total dietary fiber is the sum of what 2 types of fiber?

Back 66

Soluble and insoluble fiber

Front 67

What is 1 advantage to AOAC Method for Total DietaryFiber?

Back 67

Includes all fiber components,including resistant starch

Front 68

What are 2 advantages to AOAC Method for Total Dietary Fiber?

Back 68

1. Very time consuming, 2. Overestimates fiber content infoods with high content of simple sugars, unless you first extract food with80% ethanol

Front 69

T or F: Resistant starch may beclassified as dietary fiber

Back 69

True-- They are resistantto digestion

Front 70

T or F: Like the simple sugars, solublefiber is soluble in 80% hot ethanol

Back 70

True