Final Flashcards by Leah Odom

T or F. Glycosidic bond is more susceptible to acid hydrolysis that peptide bond.

True

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T or F. Specific heat of water is lower than specific heat of oil.

False

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T or F. If two polysaccharides, one linear and one highly branched, have the same molecular weight and make solutions of the same concentration, solution of the linear polysaccharide will be more viscous.

True

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Oxidation of monosaccharides results in the formation of:

Polyhydroxy alcohols

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High amylose starch contains:

50% - 70% amylose

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Diameter of starch granules is

2-100 micrometer

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In waxy starches, amylose content is:

less than or equal to 2%

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What is a reducing power of maltopentose compared to reducing power of glucose?

1/5 (20%)

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The largest starch granules are from:

potato

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Consider two corn syrups with DE of 25 and 85. The corn syrup that has a thicker texture (more viscous) and less sweetness is one with:

DE ~25

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The Fehling’s test is used to determine:

reducing sugars

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Gelatinization is:

the irreversible swelling of starch granules under to influence of heat in an aqueous medium to give a starch paste.

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The last enzyme used in production of HFCS is:

isomerase

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Beta-amylase hydrolyses amylopectin at:

a(1-4) bonds, two glucose unites from non-reducing end

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Stability of native starches depends on pH. Which line in the figure below represents viscosity profile of a paste at pH2?

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Maltodextrins have a DE of:

5-25

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In the figure below, which line presents viscosity development of moderately cross-linked starch?

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T or F. Naturally occurring unsaturated fatty acids have double bond(s) in cis configuration.

True

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T or F. Palmitic acid (16:0) is a fatty acid found in food triglycerides.

True

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T or F. Modified starches can be used as fat replacers in salad dressings.

True

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Fatty acids in food triglycerides are:

with even number of carbon atoms

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Triglycerides are made of:

1 glycerol and 3 fatty acids

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Phospholipids are make of:

1 glycerol, 2 fatty acids, 1 phosphate and 1 amino acid

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Which fatty acid (FA) of those listed below is the most susceptible to autoxidation?

a. Saturated FA at sn-2 in a triglyceride
b. Saturated FA at sn-2 in a phospholipid
c. Saturated free FA
d. Polyunsaturated Free FA

d. Polyunsaturated Free FA

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Phospholipids are:

have both hydrophobic and hydrophilic parts

Oelstra is:

non-digestible fat replacer

If a fatty acid has 18 carbons and the first double bond occurs at w3, at which carbon (from omega side) will the second double bond occur?

In which step of autoxidation reactions of lipids metal ions have a significant role?

initiation

The most stable fat crystals are:

Beta

"o/w" stands for:

oil disperse phase in an emulsion and water is continues phase.

Which of the fatty acids (FA) listed below is the least susceptible to autoxidation? a. Saturated FA in at sn-2 in a triglyceride b. Unsaturated FA in a phospholipid c. Saturated free FA d. Unsaturated free FA e. Unsaturated FA at sn-3 in a triglyceride

a. Saturated FA in at sn-2 in a triglyceride

Which of the following fatty acids will have the highest melting point? a. Caprylic (8:0) b. Stearic (18:0) c. Oleic (18:1c9) d. Linoleic (18:2c6) e. Linolenic (18:3c3)

b. Stearic (18:0)

Beta-galctosidase hydrolyses:

Lactose

Enzyme that serves as an indicator for efficiency of blanching:

Peroxidase

Chymosin (renin) is used for:

milk clotting and formation of curds

Formation of bitter taste in cheeses can result from activity of:

protease

a-amylase hydrolyses a-1-4 glycosidic bond in amylose and amylopectin:

randomly splits a-1-4 glycosidic bonds

Pectin methylesterase is more active on:

HMP

Proteolytic enzyme (protease) found in papaya is:

Papain

The figure represents reaction rate of an enzyme as a function of:

Preheating of potato slices at ~60 degrees Celcius (prior to frying) activates an enzyme after which activity the chips stay firmer during and after frying. This enzyme is:

pectin methylesterase

Enzyme that converts glucose to fructose and is used in production of HFCS is:

isomerase

Cleaving the glycosidic bonds between methylated galacturonic acids happens at pH>5 or due to enzymatic reaction. The enzyme responsible for this reaction is:

pectin lyase

Two enzymes used for removal of glucose from a food product and oxygen fro a headspace are:

glucose oxidase and catalase

Enzyme that has Fe as co-enzyme is:

Peroxidase

Polygalacturonase is commonly used as a processing aid in production of:

fruits and vegetable juices

Polyphenol oxidases cause discoloration/browning of food by acting on:

phenolic compounds

For preparation of gels with fresh pineapple, which gelling hydrocolloid should be avoided?

Gelatin

What is the enzyme that catalyzes this reaction? H2O2 + AH2 = 2H2O + A

POD

Peeled potatoes (and apples) are commonly submerged in cold water (that can be sometimes acidified) while waiting for the next processing step. This is done to:

Exclude molecular oxygen and reduce rate of reactions catalyzed by PPO.

Xanthophylls are:

Carotenoids containing oxygen

Anthocyanin is:

sugar + anthocyanidin

Betalains are:

Red pigments

Solubility of chlorophylls is dictated by the presence of:

Phytol side chain

Addition of small amounts of baking soda (increase pH) to water for cooking of green vegetables will result in:

Bright green color

Oxygenation of myoglobin results in formation of:

Oxymyoglobin

Chlorophyllase is a plant enzyme that:

Removes phytol from chlorophyll

Oxidation of myoglobin happens when:

Iron (II) in a myoglobin losses one electron and becomes iron (III)

Magnesium ion can be easily removed from chlorophyll molecule by:

Acids

Processing step that affects carotenoids the most (causing bleaching) is:

Dehydration (drying with heated air)

Lycopene is good:

antioxidant

Potential disadvantage of high concentration of ascorbic acid in food products is in possibility to:

Act as a proxidant and/or cause browning

Vitamin C is:

L-ascorbic acid

Vitamin B that contains sulfur and easily degrades at pH >7 is:

Thiamin

Vitamins that have antioxidant activity are:

A,C,E

Beta-galactosidase hydrolyses:

Lactose

In waxy starch, amylose content is approximately:

less than or equal to 2%

Sweetness that has to be lace led with the statement "phenyketonurics: contain phenylalanine":

aspartame

Most commonly used inorganic acid in the food industry is:

H3PO4

Parabens are most efficient as antimicrobials at:

pH does not affect their antimicrobial efficiency

Baking powder is:

Baking soda + dry acid

Benzoic acid has pKa of 4.2. This means that benzoic acid has effective ant microbial properties:

at pH

A common acidulate that had antimicrobial properties (at levels used in foods) is:

Acetic Acid

Baking soda is:

NaHCO3

Sucralose is:

Non-caloric sweetener

Cation in carbonate or bicarbonate salts that decompose at elevated temperatures and do not require acid for their activity as leaveners is:

(NH4)+

A common acidulate that also acts as a chelating agent is:

Citric acid

Chemical leavaners are used in concentration:

1%-2%

Aspartame is:

L-aspartyl-L-phenylalanine methyl ester

Salts used to inhibit formation of C. Botulinum toxin, gas formation in Gouda cheese, and/or to produce characteristic color and flavor of some meat products are:

Nitrates and Nitrites

Mons commonly used acid in the food industry is:

Citric acid

Chemical leavens are added to food in order to produce:

CO2

The first increase in toughness during cooking of meat (~40 - 50 degrees C) happens due to:

denaturation of actomyosin

Vitamin that contains sulfur and easily degrades at pH >7 is:

Thiamin

T or F. Compounds that have provitamin A activity are good antioxidants.

True

Lecithin is:

Phospholipid naturally occurring in egg yolk

Casein micelles stay dispersed in milk due to:

highly hydrophilic and charged part of kappa-casein

Myosin molecules are held together in thick filaments due to:

ionic interactions

Collagen (gelatin) gels forming junctions zones caused by:

Hydrogen bonds

Gels containing raw pineapple should not be prepared with gelatin because of:

Bromelain activity

To be 'detected' as a fragrance or smell, a compound must be:

Volatile

Protein content in milk is:

3-5%

T or F. a-tocopheryl acetate is an excellent antioxidant used to prevent autoxidation in lipid-containing foods.

False

EDTA stands for:

Ethylene diamino tetraacetic acid

MAG stands for:

Monosodium glutamate

IMP is used as:

Flavor enhancer

GMP stands for:

Guanosine mono phosphate

Maltol is used as a flavor enhancer in:

ice creams and candies

Tartaric acid is predominant acid in:

Grapes

Thermoresistant enzyme used as an indicator of proper blanching is:

Peroxidase

Potential disadvantage of high concentration of ascorbic acid in food products is in possibility to:

act as a pro oxidant and/or cause browning

T or F. Gluten is soluble in water.

False

Maltodextrin have a DE of:

5-25

T or F. Addition of ammonia compounds is allowed in production of certain caramels.

True

Which sugar/sweetner provides a cooling effect during dissolving?

come polyols

Trigylcerides are made of:

1 glycerol and 3 fatty acids

High amylose starch suntans:

50-70% amylose

Required substrate(s) for caramelization reactions is:

only carbohydrates

Hysteresis of sorption isotherms is common in:

tissue products

If solutions were prepared in water with the same concentration of sugars and amino acids and were heated 2 hrs at 100 degrees celcius, which one will have the most of the Maillard reaction products:

glucose, lysine, pH9

The major reaction during dough formation is:

Sulfhydryl-disulfide interchange (intra-intermolecular) in gliadins and glutelins

How much volume of water increases during (slow) freezing is?