Proteins VI Flashcards
<p>\_\_\_\_\_\_ are digestible substantially faster than muscle proteins</p>
<p>Fish proteins</p>
<p>Fish proteins are composed of:
- 65-75% \_\_\_\_\_\_\_\_ proteins
- 20-30% \_\_\_\_\_\_\_\_ proteins
- 3-10% \_\_\_\_\_\_\_\_\_\_ proteins</p>
<p>myofibrillar
sarcoplasmic
connective tissue</p>
<p>The proportion of myofibrillar proteins in fish total protein is \_\_\_\_\_ than in mammalian total protein, and the relative proportions of the individual proteins are \_\_\_\_\_\_</p>
<p>higher
| similar</p>
<p>The heat stability of the fish myofibrillar proteins is \_\_\_\_ than that of their mammalian counterparts, and protein hydrolysis by trypsin is \_\_\_\_\_\_.</p>
<p>lower
| faster</p>
<p>Which two properties account for the good digestibility of fish proteins?</p>
<p>- The heat stability is low
| - The protein hydrolysis by trypsin is fast</p>
<p>Fish sarcoplasmic proteins are mostly \_\_\_\_\_\_\_</p>
<p>enzymes</p>
<p>When \_\_\_\_\_\_ proteins are separated electrophorically, patterns are discerned, which is helpful in fish taxonomy</p>
<p>sarcoplasmic </p>
<p>The amino acid composition of fish myoglobin is \_\_\_\_\_\_\_\_ to that of mammalian myoglobin.</p>
<p>different</p>
<p>Fish myoglobin contains a \_\_\_\_\_ residue that is absent in mammalian myoglobin. Myoglobin and other pigments are concentrated in the \_\_\_\_\_ muscle.</p>
<p>cysteine
| dark</p>
<p>\_\_\_\_\_\_\_\_\_ is absent in some mollusks and in Antarctic fish with colorless blood.</p>
<p>Hemoglobin</p>
<p>In strongly pigmented fish, pigment degradation reactions can inducse \_\_\_\_\_\_\_\_\_</p>
<p>meat discoloration</p>
<p>The content of connective tissue protein in fish muscle is \_\_\_\_\_ than in mammalian muscle.</p>
<p>lower</p>
<p>\_\_\_\_\_\_ is the main component of connective tissue in fish, and the remainder is \_\_\_\_\_\_</p>
<p>Collagen
| elastin</p>
<p>The shrinkage temperature of \_\_\_\_\_ collagen is 45oC as compared to 60-65 °C for \_\_\_\_\_\_\_ collagen.</p>
<p>fish
| mammalian</p>
<p>What are the two factors that render fish more tender than mammalian meat?</p>
<p>- Lower content of connective tissue protein
| - Lower shrinkage temperature</p>
<p>The \_\_\_\_\_\_\_\_\_ account for the low congealing temperature of polar fish of Arctic regions</p>
<p>antifreeze serum glycoproteins</p>
<p>The amino acid sequence of antifreeze glycoproteins is characterized by a high degree of \_\_\_\_\_\_</p>
<p>periodicity</p>
<p>The molecular weight of \_\_\_\_\_\_\_\_ is in the range of 10.5-27 kilodaltons, and the conformation is generally stretched, with several -helical regions.</p>
<p>antifreeze serum glycoproteins</p>
<p>The antifreeze effects of serum glycoproteins are attributed to the \_\_\_\_\_\_ residues as well as the \_\_\_\_\_ side chains of the peptide moiety</p>
<p>disaccharide
| methyl</p>
<p>\_\_\_\_\_\_\_\_ is the predominant free amino acid in fish with dark-colored flesh (tuna, mackerel).</p>
<p>Histidine</p>
<p>\_\_\_\_\_\_'s content in the flesh is typically 0.6-1.3% of the fresh weight and can even exceed 2%. </p>
<p>Histidine</p>
<p>During bacterial decay of the flesh, a large amount of \_\_\_\_\_\_\_\_\_ is formed from \_\_\_\_\_\_\_.</p>
<p>histamine
| histidine</p>
<p>Fish with dark-colored flesh have more free \_\_\_\_\_\_ than fish with light-colored flesh</p>
<p>histidine</p>
<p>Fish muscle tissue has a high content of \_\_\_\_\_\_, which is derived from \_\_\_\_\_, but lacks a \_\_\_\_\_\_ group</p>
<p>taurine
cysteine
carboxyl</p>
<p>\_\_\_\_\_\_ is a concentrate of insoluble fish muscle proteins that forms a solid cohesive gel when warmed.</p>
<p>Surimi</p>
<p>\_\_\_\_\_\_ production is a highly mechanized process that starts with mechanical filleting and deboning of fresh, lean (\_\_\_\_\_-muscle) fish (most commonly \_\_\_\_\_\_\_\_\_\_\_ followed by comminution at 5-10 °C.</p>
<p>Surimi
white
Alaskan pollock</p>
<p>The minced Alaskan pollack is extracted with water until basically only \_\_\_\_\_\_, \_\_\_\_\_\_, \_\_\_\_\_, and small amounts of \_\_\_\_\_</p>
<p>myosin
actin
actomyosin
collagen</p>
<p>The purpose of the process of surimi is to remove strong \_\_\_\_\_\_\_ compounds and pigments as well as \_\_\_\_\_\_\_\_ proteins that can interfere with the gelation of the myofibrillar proteins</p>
<p>flavor
| water-soluble</p>
<p>The resulting odorless and flavorless high-protein fish flesh, termed “raw surimi”, has enhanced \_\_\_-forming, \_\_\_\_-holding, and \_\_\_\_-binding properties by comparison with the original minced fish.</p>
<p>gel
water
fat</p>
<p>Paramyosin is a protein that is similar to \_\_\_\_\_\_ that is present in the \_\_\_\_ filaments of all invertebrates</p>
<p>myosin
| thick</p>
<p>The addition of \_\_\_\_\_\_\_ in surimi further enhances the gel-forming abilities</p>
<p>paramyosin</p>
<p>After elimination of excess water, \_\_\_\_\_\_\_ (such as sugars or sugar alcohols) are added and the surimi is then frozen</p>
<p>cryoprotectants</p>
<p>The further processing of surimi involves gelation induced by addition of \_\_\_\_ + \_\_\_\_\_\_.</p>
<p>salt
| heating</p>
<p>The role of the added salt in surimi is to \_\_\_\_\_\_ the \_\_\_\_\_\_\_ proteins.</p>
<p>solubilize
| myofibrillar</p>
<p>In surimi, in addition to salt, \_\_\_\_ and \_\_\_\_ may be added</p>
<p>starch
| egg white</p>
<p>The first step in the gelation of surimi is the setting of the gel, characterized by the formation of a loose 3D network by partially denatured \_\_\_\_\_ and \_\_\_\_ </p>
<p>actin
| myosin</p>
<p>The second step in the gelation of surimi is the formation of \_\_\_\_\_\_\_\_\_\_, characterized by the conversion of the loose network to an ordered, non-transparent gel that is more cohesive and elastic</p>
kamaboko
<p>The protein content of \_\_\_\_\_\_ is 9.7-10.6%, depending on the age of the hen.</p>
<p>albumen</p>
<p>In eggs, \_\_\_\_ content is about 0.03%, while \_\_\_\_ can reach a level of almost 1%.</p>
<p>lipid
| carbohydrates</p>
<p>The carbohydrates in albumen are either \_\_\_\_ (mostly glucose) or combined with \_\_\_\_ </p>
<p>free
| protein</p>
<p>Ovalbumin, ovotransferrin, ovomucoid, and lysozyme are the major \_\_\_\_\_\_\_ proteins.</p>
<p>egg-white</p>
<p>The major globular protein in albumen is \_\_\_\_\_\_\_</p>
<p>ovalbumin</p>
<p>\_\_\_\_\_\_\_\_ is a phosphoglycoprotein, with a molecular weight of about 44.5 kDa.</p>
<p>Ovalbumin</p>
<p>\_\_\_\_\_\_\_ is the only egg-white protein to contain a free sulfhydryl group</p>
<p>Ovalbumin</p>
<p>\_\_\_\_\_\_\_\_ readily coagulates, a process which is observed when egg white sets on heating</p>
<p>Ovalbumin</p>
<p>\_\_\_\_\_\_\_ is also easily denatured when exposed to a new surface and is important in conferring stability to foams.</p>
<p>Ovalbumin</p>
<p>During storage of eggs, \_\_\_\_\_\_\_\_ converts to S- a more stable form with increased resistance to denaturation.</p>
<p>ovalbumin</p>
<p>Separation and purification of \_\_\_\_\_\_\_ is commonly performed by half-saturating the egg white with \_\_\_\_\_\_\_, followed by the addition of \_\_\_\_\_\_\_\_ to \_\_\_\_ the pH to its isoelectric point</p>
<p>ovalbumin
ammonium sulfate
sulfuric acid
lower</p>
<p>Three to six \_\_\_\_\_\_\_ procedures are necessary to produce pure ovalbumin.</p>
<p>recrystallization</p>
<p>\_\_\_\_\_\_\_\_\_\_methods based on \_\_\_\_\_\_\_\_\_\_ have also been reported for the high-yield purification of ovalbumin.</p>
<p>Liquid chromatography
| ion exchange</p>
<p>From a functional standpoint, \_\_\_\_\_\_ proteins such as \_\_\_\_\_\_ are known to have good gelling ability.</p>
<p>globular
| ovalbumin</p>
<p>\_\_\_\_\_\_\_\_ forms a transparent gel or a turbid gel upon heating, depending on the \_\_\_\_\_\_\_\_ and the \_\_\_ of the solution.</p>
<p>Ovalbumin
ionic strength
pH</p>
<p>Ovotransferrin is also known as \_\_\_\_\_\_\_\_</p>
<p>conalbumin</p>
<p>\_\_\_\_\_\_\_\_\_ accounts for 12% of the egg- white protein content and has a molecular weight of about 77-80 kDa.</p>
<p>Ovotransferrin</p>
<p>The \_\_\_\_\_\_\_ family is a group of iron-binding proteins widely distributed in biological fluids</p>
<p>transferrin</p>
<p>The \_\_\_\_\_-sequestering properties of transferrin are responsible for its bacteriostatic and bactericidal activities.</p>
<p>iron</p>
<p>During the separation of ovalbumin from albumen, \_\_\_\_\_\_\_\_\_ is transported with ovalbumin into the filtrate resulting from half- saturation with ammonium sulfate.</p>
<p>ovotransferrin</p>
<p>Further fractional precipitation with \_\_\_\_\_\_\_\_ or \_\_\_\_ fractionation produces pure ovotransferrin. Ovotransferrin may also be purified by \_\_\_\_\_\_\_\_ chromatography.</p>
<p>ammonium sulfate
alcohol
ion-exchange</p>
<p>\_\_\_\_\_\_\_\_\_ is the most easily heat-denatured egg protein but it is less susceptible to surface denaturation than ovalbumin.</p>
<p>Ovotransferrin</p>
<p>\_\_\_\_\_\_\_ is less susceptible to surface denaturation than \_\_\_\_\_\_\_\_</p>
<p>Ovotranferrin
| ovalbumin</p>
<p>\_\_\_\_\_\_\_\_ is also present as a component of the egg-yolk proteins, differing only by its carbohydrate prosthetic group.</p>
<p>Ovotransferrin</p>
<p>\_\_\_\_\_\_\_\_\_ is a glycoprotein consisting of three tandem homologous domains, each cross-linked by three disulfide bonds, with a total molecular weight of 28 kDa.</p>
<p>Ovomucoid</p>
<p>The carbohydrate in \_\_\_\_\_\_\_\_ is present as three polysaccharide chains, each attached to the polypeptide through an asparaginyl residue.</p>
<p>ovomucoid</p>
<p>Ovomucoid can be precipitated from albumen after the removal of \_\_\_\_\_\_ and \_\_\_\_\_\_ by complete saturation with \_\_\_\_\_\_\_ or by the addition of excess \_\_\_\_\_.</p>
<p>ovalbumin
ovotransferrin
ammonium sulfate
alcohol</p>
<p>Among the egg-white proteins, \_\_\_\_\_\_ is unique in its resistance to heat coagulation.</p>
<p>ovalbumin</p>
<p>\_\_\_\_\_\_\_\_ can be heated at 100 °C under acidic conditions for long periods without any apparent changes in its physical or chemical properties.</p>
<p>Ovalbumin</p>
<p>\_\_\_\_\_\_\_\_ represents about 3.4% of egg white. It has a total of 129 amino acid residues and contains four disulfide bridges.</p>
<p>Lysozyme</p>
<p>\_\_\_\_\_\_\_ is a \_\_\_\_\_\_\_ enzyme commonly found in nature that catalyzes the hydrolysis of the glycosidic linkage between NAM acid and NAG in the polysaccharides of certain bacterial cell walls.</p>
<p>Lysozyme
| bacteriolytic</p>
<p>\_\_\_\_\_\_ is used as a natural food preservative and is extracted by a combination of \_\_\_\_\_\_ and \_\_\_\_\_ precipitation</p>
<p>Lysozyme
chromatography
salting-out</p>
<p>\_\_\_\_\_\_\_ is a heat-stable enzyme</p>
<p>Lysozyme</p>
<p>\_\_\_\_\_\_\_ exhibits enzymatic activity over a broad range of temperatures, and can withstand boiling water for 1-2 minutes</p>
<p>Lysozyme</p>
<p>\_\_\_\_\_\_ is stable in freeze-drying and thermal drying processes and maintains its activity when redissolved in water</p>
<p>Lysozyme</p>
<p>Lysozyme has optimum activity for \_\_\_\_\_\_ foods</p>
<p>low-acid</p>
<p>\_\_\_\_\_\_ is a strongly basic minor albumen protein</p>
<p>Avidin</p>
<p>\_\_\_\_\_\_\_ is employed in biomedical research by taking advantage of its high affinity for biotin in immunoassays, affinity chromatography, and molecular labelling</p>
<p>Avidin</p>
<p>\_\_\_\_\_\_\_\_ appear to be important in the foaming properties of albumin</p>
<p>Ovoglobulins</p>
<p>\_\_\_\_\_\_\_\_ is a multi-type serine protease inhibitor with a molecular weight of 50 kDa, and comprises seven domains conferring trypsin,chymotrypsin,and elastase inhibitory activity.</p>
<p>Ovoinhibitor</p>
<p>\_\_\_\_\_\_\_\_\_ is made of an apoprotein that also binds riboflavin, a B group vitamin</p>
<p>Flavoprotein</p>
<p>Avidin, ovoglobulin, ovoinhibitor, and flavoprotein are \_\_\_\_\_</p>
<p>minor albumen proteins</p>
<p>Egg yolk consists of 48.7% \_\_\_\_, 16.4% \_\_\_\_\_, and 32.9% \_\_\_\_\_</p>
<p>water
protein
fat</p>
<p>What are the three reasons that explain why egg yolks are good emulsifiers?</p>
<p>- High lipid content
- High proportion of phospholipids
- More than 90% of lipids present in the yolk are associated with proteins to form lipoproteins</p>
<p>What are the four classes of proteins found in egg yolk?</p>
<p>- Lipoproteins
- Livetins
- Phosphoproteins
- Minor proteins, including enzymes</p>
<p>Lipoproteins from egg-yolk are separated by \_\_\_\_\_\_\_\_ into \_\_\_\_\_\_ (68%), and \_\_\_\_\_\_ (14%)</p>
<p>ultracentrifugation
LDLP
HDLP</p>
<p>\_\_\_\_\_\_\_ lipoprotein has a density of 0.98</p>
<p>LDLP</p>
<p>\_\_\_\_\_\_\_ forms the lipovitellenin fraction</p>
<p>LDLP</p>
<p>\_\_\_\_\_\_\_\_\_\_ accounts for one-third of the yolk and contains large amounts of lipids</p>
<p>LDLP</p>
<p>The lipid composition of LDLP is mostly composed of \_\_\_\_\_ and \_\_\_\_\_\_\_</p>
<p>Triglycerides
| phospholipids</p>
<p>The LDLP fraction is primarily present in the form of \_\_\_\_\_\_ suspended in the \_\_\_\_\_\_ fraction</p>
<p>tiny micelles
| plasma</p>
<p>LDLP micelles have a core of \_\_\_\_\_\_ with \_\_\_\_\_\_ and proteins radiating toward the surface of the micelle and interacting with water, making a stable \_\_\_\_\_\_\_ emulsion</p>
<p>triglycerides
phospholipids
oil-in-water</p>
<p>\_\_\_\_\_\_\_ form the lipovitellin fraction</p>
<p>HDLP</p>
<p>\_\_\_\_\_\_\_ has a density of > 1.0</p>
<p>HDLP</p>
<p>\_\_\_\_\_\_ makes up the insoluble granules in egg yolk</p>
<p>HDLP</p>
<p>The lipid portion of HDLP is primarily composed of \_\_\_\_\_\_\_ (60%) and \_\_\_\_\_\_ (40%)</p>
<p>phospholipids
| triglycerides</p>
<p>Lipovitallin can be separated into two components, that differ by their \_\_\_\_\_\_ content</p>
<p>phosphorus</p>
<p>\_\_\_-lipovitellin (0.48% phosphorus), and \_\_\_\_-lipovitellin (0.27 phosphorus)</p>
<p>a
| f</p>
<p>\_\_\_\_\_\_\_ also contains phosvitin</p>
<p>HDLP</p>
<p>\_\_\_\_\_\_\_ is a phosphorus-rich, lipid-free protein that is strongly associated with lipovitellin</p>
<p>Phosvitin</p>
<p>\_\_\_\_\_\_\_\_ are lipid-free globular glycoproteins represent about 10% of egg-yolk total solids.</p>
<p>Livetins</p>
<p>\_\_\_\_\_\_\_\_ are water soluble and correspond to blood serum proteins of the chicken.</p>
<p>Livetins</p>
<p>\_\_\_\_\_\_\_\_, which makes up ~10% of total yolk protein, is the most highly phosphorylated protein known to date.</p>
<p>Phosvitin</p>
<p>Almost 50% of \_\_\_\_\_\_\_'s amino acids are serine, of which 90% are phosphorylated.</p>
<p>phosvitin</p>
<p>The isoelectric point of \_\_\_\_\_\_ is 4.0. At neutral pH, it is highly \_\_\_\_\_\_\_ charged owing to ionization of the \_\_\_\_\_\_ groups.
</p>
<p>phosvitin
negatively
phosphate</p>
<p>Phosvitin has a high affinity for \_\_\_\_\_\_, particularly \_\_\_\_ ions</p>
<p>metal
| ferric</p>
<p>\_\_\_\_\_\_ is soluble in weak salt solutions and to some extent in water</p>
<p>Phosvitin</p>
<p>\_\_\_\_\_\_ is associated with the granules due to strong ionic bonding to \_\_\_\_\_\_\_ proteins and is not found in the \_\_\_\_\_\_ fraction of the egg yolk</p>
<p>Phosvitin
lipovitellin
plasma</p>
<p>\_\_\_\_\_\_\_\_ causes an increase in the time period required to whip egg whites.</p>
<p>Pasteurization</p>
<p>Pasteurization denatures the \_\_\_\_\_\_\_\_\_\_ network, thus resulting in the longer whip time.</p>
<p>ovomucin-lysozyme</p>
<p>The \_\_\_\_ is another important factor that affects performance and stability of egg white foams.</p>
<p>pH</p>
<p>Adjustment of \_\_\_\_\_ to pH 8.75 results in \_\_\_\_\_ in whip time and volume of cake.</p>
<p>albumen
| increases</p>
<p>Egg white is more \_\_\_\_\_ to heat treatment when the pH is adjusted to 7.6 using lactic acid, hydrochloric acid or potassium acid tartrate.</p>
<p>stable</p>
<p>\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_performs more favourably than acetic or citric acid at pH 6.0, but \_\_\_\_\_\_\_\_\_\_ is important in that it sequesters the iron and prevents a red discoloration of the meringue due to conalbumin-iron complex.</p>
<p>Potassium acid tartrate
| citric acid</p>
<p>\_\_\_\_\_\_\_\_\_\_ sequesters the iron and prevents a red discoloration of the meringue due to conalbumin-iron complex.</p>
<p>Citric acid</p>
<p>The pH of albumen should be adjusted to \_\_\_\_ before pasteurization, thereby protecting the ovalbumin, lysozyme and ovomucoid against damage by heat.</p>
<p>7.0</p>
<p>Define heat coagulation of eggs.</p>
<p>Designates the process of thermal denaturation and aggregation of proteins in albumen and in yolk.</p>
<p>Denaturation of proteins involves the breaking of \_\_\_\_\_\_\_ bonds, the uncoiling of \_\_\_\_\_\_ chains, and the exposure of \_\_\_\_\_\_ groups.</p>
<p>hydrogen
polypeptide
reactive</p>
<p>Aggregation of denatured albumen proteins occurs by the formation of \_\_\_\_\_\_, \_\_\_\_\_\_, and \_\_\_\_\_\_ linkages.</p>
<p>hydrophobic
electrostatic
disulfide</p>
<p>The denaturation temperature of albumen proteins is highest in \_\_\_\_\_\_\_\_, and lowest in \_\_\_\_\_\_\_\_</p>
<p>ovalbumin
| ovotransferrin</p>
In a mixture of all egg-white proteins, aggregation occurred at ____ distinct coagulation temperature range
two
Heating albumen increases its _____ and ______. As the temperature is increased, a ____ forms.
viscosity
opacity
gel
The strength of the albumen gel ______ as temperature and heating time increase
increase
In yolk, ______ begins to increase at 65°C, and by 70°C, ______ is gone.
viscosity
fluidity
________ has been preferred over ______ or mixed whole egg (magma) as a gelling agent in foods.
Egg white
egg yolk
______ is preferred as a gelling agent since it only contains trace amounts of ______, and therefore it has a good _______ stability
Egg white
lipids
oxidative
The influence of pH on the gels is primarily related to the ________ of the proteins in solution.
net charge
At the isoelectric point (pI), the net charge is _____ and _________ is favored
0
aggregation
At the isoelectric point, gels are ____, _____, low in _______, and lacking a _____________
curdy
opaque
cohesiveness
continuous protein matrix
As the net charge is increased by raising the pH, protein _______ is favored over aggregation
denaturation
At a higher pHs, gels are_____ and quite _____, with an extensively ________________
translucent
elastic or rubbery
cross-linked 3D matrix
The coarse, open microstructure of gels at low pH accounts for the ____________ and texture.
poor water binding
Enhanced ______ and _________ ability of gels at pH 9.0 are due to the high degree of cross-linked, uniformity of gels networks and minimal ____ size.
firmness
water-binding
pore
When egg white is added to food systems, its pH is ______ and egg white functions much _____ effectively in gelling.
lowered
less
Gel strength and cohesiveness are ________ at pH values close to isoelectric point where net charge is minimal
minimal
At pH values far from the pI and at low ionic strength, ______ aggregates are formed.
linear
With _______ electrostatic repulsion at _____ ionic strength or at 7.0 > pH > pI, three dimensional networks form a transparent gel.
decreasing
low
Which pH would result in the formation of a transparent gel?
7.0 > pH > pI
At ____ ionic strength or at pH values near the pI, proteins aggregate to from a turbid gel composed of random aggregates.
high
The ________ and ___________ gels exhibit higher gel strength and water holding capacity.
transparent
opaque/translucent
_________ significantly improves the foaming, gelling, and emulsifying properties of egg white proteins
Dry heating
A ___________ structure is formed during dry heating
partially denatured
The two-step heating method is used to produce ______________ over a wide range of ______ concentrations
transparent gels
salt
The two-step heating method gives ______ gels with higher _______, greater ______, firmer ______
transparent gels
water-holding capacity
elasticity
texture
The functional properties of egg white could also be improved by conjugation with a ___________ moiety.
polysaccharide
The _____________ was used as a consumer friendly alternative for the functional modification of egg white proteins and in particular _______, the major egg white protein.
Maillard reaction
ovalbumin
Polysaccharides are believed to protect proteins from thermal denaturation by favouring ___________ interactions, and improved their functionalities by increasing their ________ character.
protein-protein
amphiphilic
