Final Flashcards
T or F. Glycosidic bond is more susceptible to acid hydrolysis that peptide bond.
True
T or F. Specific heat of water is lower than specific heat of oil.
False
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
Oxidation of monosaccharides results in the formation of:
Polyhydroxy alcohols
High amylose starch contains:
50% - 70% amylose
Diameter of starch granules is
2-100 micrometer
In waxy starches, amylose content is:
less than or equal to 2%
What is a reducing power of maltopentose compared to reducing power of glucose?
1/5 (20%)
The largest starch granules are from:
potato
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
The Fehling’s test is used to determine:
reducing sugars
Gelatinization is:
the irreversible swelling of starch granules under to influence of heat in an aqueous medium to give a starch paste.
The last enzyme used in production of HFCS is:
isomerase
Beta-amylase hydrolyses amylopectin at:
a(1-4) bonds, two glucose unites from non-reducing end
Stability of native starches depends on pH. Which line in the figure below represents viscosity profile of a paste at pH2?
d
Maltodextrins have a DE of:
5-25
In the figure below, which line presents viscosity development of moderately cross-linked starch?
b
T or F. Naturally occurring unsaturated fatty acids have double bond(s) in cis configuration.
True
T or F. Palmitic acid (16:0) is a fatty acid found in food triglycerides.
True
T or F. Modified starches can be used as fat replacers in salad dressings.
True
Fatty acids in food triglycerides are:
with even number of carbon atoms
Triglycerides are made of:
1 glycerol and 3 fatty acids
Phospholipids are make of:
1 glycerol, 2 fatty acids, 1 phosphate and 1 amino acid
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
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?
6
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:
pH
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?
9%
