Proteins basic concepts Role of proteins 1.Nutrition Energy and
essential amino acids Can possess anti-nutritional properties
Trypsin inhibitors in soy = reduced digestibility Allergens IgE
mediated food allergy attributed to naturally occurring food
proteins (negative immunological response to a protein) Toxins
-amanitin a cyclic peptide found in a poisonous mushroom species
2.Structure Provide structure in living organisms and also foods
Collagen main component of connective tissue Gelatin hydrolyzed
collagen eg. Jello Proteins roughly contain 5-50 % C, 6-7 % H,
20-23 % O, 12-19 % N, and 0-3 % S (Barret, 1985 Chemistry and
Biochem of Amino Acids) Measuring N content is often used to
estimate the protein content in foods 3.Catalysts Enzymes (which
are proteins) catalyze chemical reactions in living tissue and
foods 2
Slide 3
Proteins basic concepts Role of proteins 4.Functional
properties Gelation Emulsifiers Water bonding Increase viscosity
Texture 5.Browning Have amino acids that can react with reducing
sugars Maillard Browning Acrylamide (produced by asparagine rxn
with reducing sugars) Some enzymes can also cause browning
Polyphenol oxidase - Apples 3
Slide 4
Typical protein contents of the edible portion of various foods
4 Food or Beverage Protein g/100g Apples, raw, with skin (09003)
0.26 Beer, regular (14003) 0.46 Milk, human, mature (01107) 1.03
Bananas, raw (09040) 1.09 Cabbage, raw (11109) 1.28 Potatoes,
white, flesh and skin, raw (11354) 1.68 Potatoes, microwaved, flesh
and skin (11675) 2.44 Corn, sweet, yellow, canned, whole kernel,
drained solids (11172) 2.46 Rice, brown, long-grain, cooked (20037)
2.58 Soy milk, original and vanilla, with added Ca, Vitamins A
& D (16139) 2.60 Milk, whole, 3.25% milk fat, with added
vitamin D (01077) 3.15 Ice creams, vanilla (19095) 3.50 Yogurt,
plain, low fat (01117) 5.25 Tofu, soft (nigari) (16127) 6.55
Cereals, ready-to-eat, cornflakes (08020) 6.61 Chocolate, dark,
70-85% cacao solids (19904) 7.79 Rice, brown, long-grain, raw
(20036) 7.94 Lentils, mature seeds, boiled (16070) 9.02 Bread,
white (18069) 9.15 Pasta, fresh-refrigerated, plain (20093) 11.31
Egg, whole, cooked, hard boiled (01129) 12.58 Cod, Pacific, raw
(15019) 15.27 Cod, Pacific, cooked, dry heat (15192) 18.73 Almonds,
dry roasted (12063) 21.06 Chicken, breast meat only, raw (05062)
21.23 Cheese, cheddar (01009) 24.90 Tuna, light, canned in water,
drained solids (15121) 25.51 Lentils, raw (16069) 25.80 Chicken,
breast meat only, roasted (05064) 31.02 Cheese, Parmesan, hard
(01033) 35.75 Values obtained from the USDA National Nutrient
Database, numbers in parentheses are the USDA 5 digit
identifier
Slide 5
Proteins basic concepts 5 Proteins are biological polymers that
fold into a 3D structure with amino acids being their basic
structural unit 20 amino acids common to proteins (L-amino acids =
natural form) 20 essential amino acids book has 21, includes
selenol (contains Selenium) which was discovered in 2002 More amino
acids exist in nature but are not genetically coded Differ by their
side chains (R-groups) All have central C, basic amino group, and a
carboxyl group Amino acid charge behavior Neutral Acidic Basic
Slide 6
Proteins basic concepts Amino acids are generally grouped into
3 classes 1.Charged and polar 2.Uncharged and polar These two
classes of amino acids are found on the surface of proteins
3.Non-polar and hydrophobic These are found more in the interiors
of proteins where there is little or no access to water You are
expected to be able to identify which amino acids are polar or
non-polar 6
Proteins basic concepts 9 Condensation reaction Four levels of
protein structure Primary Secondary Tertiary Quaternary 1. Primary
structure Linear sequence of amino acids of the protein molecule
(backbone) Described by the amino acid sequence that make up a
polypeptide chain Amino acids are linked to each other in a chain
via a peptide bond A covalent bond Sequence always described
N-terminal to C-terminal Amine partial (+), carboxyl partial (-)
This backbone structure dictates rest of the structure (2, 3, etc.
structure)
Slide 10
Proteins basic concepts 10 2. Secondary structure Refers to
arrangement of the polypeptide backbone Random coil Helical and
sheet Predictable arrangement of two main secondary structures
(regular spatial arrangement) -helix -sheet a) -helix A coiled
structure formed with internal H bonds (between C=O and N-H)
Amphiphilic both polar and non-polar surfaces Is the main structure
in fibrous proteins (myosin is an ex.) more often in hydrophilic
proteins Less in globular proteins
Slide 11
Proteins basic concepts 11 b) -sheet Flat sheets parallel or
antiparallel structure These sheets are stabilized with regular
bonding of C=O with NH (via H-bonds) between -sheets Antiparallel
are more stable due to better alignment of hydrogen bonding atoms
More stable than -helix High amount in insoluble (hydrophobic)
proteins, but more stable to denaturation c) Random coils Absence
of secondary structure (order) Irregular random arrangement of a
polypeptide chain -sheets
Slide 12
Proteins basic concepts 12 3. Tertiary structure Represents the
secondary structure folding into a 3D conformation/structure This
is the highest degree structure of many proteins The type of
tertiary structure formed is dictated by Amino acid sequence
-helix/ -sheet Proline content -helix breaker Stabilizing forces H
bonding Solvent conditions Dictates where amino acid residues are
located Surface interact w/ solvent Interior interact w/ side
chains (effects stability) -lactoglobulin
Slide 13
Proteins basic concepts 13 4. Quaternary structure A complex of
two or more tertiary structures The units are linked together
through non-covalent bonds -lactoglobulin Milk (pH 6.8) 37 kDa
dimer Cheese (pH 4.5) 144 kDa octamer Some proteins will not become
functional unless they form this structure. Examples: Hemoglobin
Myosin 2 heavy chains, 4 light chains (475 kDa)
Slide 14
Proteins basic concepts Types of forces/bonds that stabilize
the protein structure 14 Solvent-solute interactions
Slide 15
Molecular forces involved in protein structure Type Bond Energy
(KJ/mol) Functional groups from amino acid side chains involved Van
der Waals interactions (dipole) 1-9 Permanent, induced and
instantaneous dipoles Hydrophobic interactions 4-12 Aliphatic and
aromatic side chains Hydrogen bond8-40 Carboxyl, amide, imidazole,
guanidino, amino, hydroxyl and phenolic groups Electrostatic
interactions42-84Carboxyl and amino groups Covalent
bond330-380Disulfide moiety 15
Slide 16
DENATURED STATE Loss of native conformation Altered secondary,
tertiary or quaternary structure May be reversible or irreversible,
partial or complete Results Decrease solubility Increase viscosity
Altered functional properties Loss of enzymatic activity Sometimes
increased digestibility NATIVE STATE Usually most stable Usually
most soluble Polar groups usually on the outside Hydrophobic groups
on inside 16 Proteins exist in two main states Proteins basic
concepts Heat pH Pressure Oxidation Salts
Slide 17
Proteins basic concepts Factors causing protein denaturation pH
Too much charge can cause high electrostatic repulsion between
charged amino acids and the protein structure unfolds As unfolds,
hydrophobic interior is exposed. Unfavorable because of buried
groups phenolic Alkyl etc. 17 %Denatured 0 100 pH012
Slide 18
Proteins basic concepts Factors causing protein denaturation
Temperature High temperature destabilizes the non-covalent
interactions holding the protein together causing it to eventually
unfold Freezing can also denature due to ice crystals &
weakening of hydrophobic interactions (water participation less) 18
%Denatured 0 100 0 T (C)
Slide 19
Proteins basic concepts Detergents Prefer to interact with the
hydrophobic part of the protein (the interior) thus causing it to
open up (e.g. SDS) Lipids/air (surface denaturation) The
hydrophobic interior opens up and interacts with the hydrophobic
air/lipid phase (e.g. foams and emulsion) Shear Mechanical energy
(e.g. whipping) can physically rip the protein apart or introduce
the protein to a hydrophobic phase (air or lipid foaming and
emulsification) 19
Slide 20
Proteins basic concepts Important reactions of proteins and
effect on structure and quality 1. Hydrolysis Hydrolysis of
proteins also referred to as proteolysis Cleaves peptide bond and
adds H 2 O (reverse of peptide bond formation) Proteins can be
hydrolyzed (the peptide bond) by acid or enzymes to give peptides
and free amino acids (e.g. soy sauce, fish sauce etc.) Hydrolyzed
protein usually listed as an ingredient on soy sauce label Modifies
protein functional properties E.g. increased solubility Increases
bioavailability of amino acids Excessive consumption of free amino
acids is not good however (too much N) 20
Slide 21
Proteins basic concepts Important reactions of proteins and
effect on structure and quality 2. Maillard reaction (carbonyl -
amino browning) Can change functional properties of proteins
Changes color (browning) Changes flavor (roasted, buttery, burnt
etc.) Decreases nutritional quality (participating amino acid lost
from a nutritional standpoint) 21
Slide 22
Proteins basic concepts Important reactions of proteins and
effect on structure and quality 3. Alkaline reactions Soy protein
concentrates (textured vegetable protein) 0.1 M NaOH for 1 hr @ 60C
or greater Denatures proteins by hydrolysis Some amino acids become
highly reactive NH 3 groups in lysine SH groups and S-S bonds
become very reactive (e.g. cysteine) Loss of some aa as a result
(cysteine, cystine, serine, and threonine), nutritional quality
(minimal) 22
Slide 23
Proteins basic concepts Important reactions of proteins and
effect on structure and quality 3. Alkaline reactions
A.Isomerization (racemization) L- to D-amino acids (we cannot
digest D-amino acids) B.Lysinoalanine formation (LAL) Lysine
becomes highly reactive at high pH and reacts with dehydroalanine
forming a cross-link = lysinolalanine Lysine, an essential amino
acid, becomes unavailable (problem because is limiting aa in cereal
grains) 23 Lysinoalanine
Slide 24
Proteins basic concepts 4. Heat Mild heat treatments lead to
alteration in protein structure and often beneficially effect
digestibility or bioavailability ( solubility) However, severe
(above 200 C) heat treatment drastically reduces protein solubility
and functionality and may give decreased
digestibility/bioavailability Pyrolysis Degradation of cysteine
Amide crosslinking (isopeptide bond formation) 24 Leads to terrible
flavor problems H 2 S(g) Need severe heat for this reaction - not
very common
Slide 25
5. Oxidation Lipid oxidation Aldehyde, ketones as a result of
lipid oxidation react with lysine making it unavailable Usually not
a major problem Methionine oxidation (no major concern) Produces
sulfoxide, sulfone also possible Oxidized by; H 2 O 2, ROOH etc.
Met sulfoxide still active as an essential amino acid Met sulfone
no or little amino acid activity Proteins basic concepts 25
Slide 26
Proteins functional properties Functional properties defined
as: physical and chemical properties of proteins that affect the
behavior of molecular constituents in food systems. Relates to:
PreparationProcessing StorageConsumption QualityOrganoleptic
(sensory) attributes Many food products have functionality because
of food proteins Protein functionality plays a key role in the
(1)improvement of existing products (2) new product development (3)
protein waste products utilized as new ingredients 26
Slide 27
Proteins functional properties 27 Example of protein functional
properties in different food systems Functional Property Food
System SolubilityBeverages, Protein concentrates/isolates
Water-holding abilityMuscle foods, cheese, yogurt, surimi
GelationMuscle foods, custards, eggs, yogurt, gelatin, tofu, baked
goods, surimi EmulsificationSalad dressing, mayonnaise, ice cream,
gravy, frozen desserts FoamingMeringues, whipped toppings, angel
cake, sponge cake, marshmallows, yeast-leavened breads
Slide 28
Example functional proteins ProductMajor functional protein(s)
Representative protein ingredient CerealsGlutenin, gliadinWheat
gluten Legumes11S Globulin, 7S Globulin Soy protein concentrates or
isolates Meat, PoultryMyosinSurimi FishCollagenGelatin
EggsOvalbuminDried egg white MilkCaseinCaseinates Milk
-lactalbumin, - lactoglobulin Whey protein concentrates (50-80 %
protein) or isolates (90 % protein) 28
Slide 29
The properties of food proteins are altered by environmental
conditions, processing treatments and interactions with other
ingredients 29
Slide 30
Proteins functional properties 30 I. Solubility Functional
properties of proteins depend on their solubility Affected by the
balance of hydrophobic and hydrophilic amino acids on its surface
Hydrophilic surface = good water solubility Charged amino acids
play the most important role in keeping the protein soluble The
proteins are least soluble at their isoelectric point (no net
charge) The protein become increasingly soluble as pH is increased
or decreased away from the pI
Slide 31
Proteins functional properties 1. Solubility Salt concentration
(ionic strength) is also very important for protein solubility At
low salt concentrations protein solubility increases (salting-in)
At high salt concentrations protein solubility decreases
(salting-out) Salt concentration %Solubility 31
Slide 32
Denaturation of the protein can both increase or decrease
solubility of proteins condition dependent pH - very high and low
pH denature but the protein is soluble since there is much
repulsion Temperature (very high or very low) on the other hand
will lead to loss in solubility since exposed hydrophobic groups of
the denatured protein lead to aggregation (may be desirable or
undesirable in food products) Proteins functional properties 32 + +
+ + + + + + + ++ + Low pH Insoluble complex
Slide 33
Proteins functional properties How do we measure solubility?
Most methods are highly empirical as results vary greatly with
protein concentration, pH, salt, mixing conditions, temperature
etc. Generally, the assay consists of putting the protein in
samples of different pH and centrifuging The more protein that
stays in solution (supernatant), the more soluble the protein is
The bigger the pellet the less soluble the protein is 33 Protein
samples at different pHs at 0.1M NaCl Centrifuge at 20,000g for 30
min More soluble Less soluble pellet
Slide 34
Proteins functional properties II. Gelation Gel; a continuous
3D network of proteins that entraps water Works by protein -
protein interaction and protein - water (non-covalent) Texture,
quality and sensory attributes of many foods depend on protein
gelation on processing Sausages, cheese, yogurt, custard A gel can
form when proteins are denatured by Heat, pH, pressure, shearing,
solvent 34 Gel Solution
Slide 35
Proteins functional properties 35 Thermally induced food gels
(the most common) Involves unfolding of the protein structure by
heat which exposes its hydrophobic regions which leads to protein
aggregation, which forms a cross-linked network This aggregation
can be irreversible or reversible & usually cooling too
Slide 36
Proteins functional properties A. Thermally irreversible gels
(also known as thermoset) Thermoset gels form chemical bonds that
will not break during reheating of the gel (remains rigid even if
reheated) Examples - Muscle proteins (myosin), egg white proteins
(ovalbumin) Balancing act of forces is critical in gel formation:
If the attractive forces between the proteins are too weak they
will not form gels If the attractive forces are too strong the
proteins will precipitate 36 Denaturation (%) Gel
strength/Viscosity cooling T heating
Slide 37
Proteins functional properties 37 Denaturation (%) cooling T
Gel strength/Viscosity heating B. Thermally reversible gels
(thermoplastic) Gels form on cooling (after heating) and then
revert fully or partially back to solution on reheating (melt)
Collagen breakdown product gelatin is this type of gel
Proteins functional properties 39 Factors influencing gel
properties 1.pH Highly protein dependent Some protein form better
gels at pI No repulsion, get aggregate type of gels Soft and opaque
Others give better gels away from pI More repulsion, string-like
gels Stronger, more elastic and transparent Too far away from pI
you may get no gel too much repulsion (stays soluble) By playing
with pH one can therefore play with the texture of food gels
producing different textures for different foods
Slide 40
Proteins functional properties 40 2.Salt concentration (ionic
strength) Again, highly protein dependent Some proteins need to be
solubilized with salt before being able to form gels, e.g. muscle
proteins (myosin) Some proteins do not form good gels in salt
because salt will minimize necessary electrostatic interactions
between the proteins + + + + NaCl + + + + Cl- Loss of repulsion
Loss of gel strength Loss of water-holding
Slide 41
Proteins functional properties 41 How do we measure gel
quality? Many different methods available Gel texture and gel
water-holding capacity most commonly used One of the better texture
methods is to twist a gel in a modified viscometer (torsion meter)
and measure its response (stress and strain) until it breaks called
a torsion test The results can be related to the sensory properties
of the gel
Slide 42
Proteins functional properties III. Water binding The ability
of foods to take up and/or hold water is of paramount importance to
the food industry More H 2 O = higher weight = More $$ Product
quality may also be better, more juiciness 42
Slide 43
Proteins functional properties III. Water binding Water is
associated with protein at several levels (Back to Water) Surface
monolayer Very small amount of water tightly bound to charged
groups on proteins Vicinal water Several water layers that interact
with the monolayer, slightly more mobile Bulk phase water Mobile
water like free water but... Trapped mostly by capillary action
Freely flowing water in a food product This is the water we are
interested in when it comes to water binding 43
Slide 44
Proteins functional properties What factors influence water
binding in a food system? 1. Protein type More hydrophobic = less
water uptake/binding More hydrophilic = more water uptake/binding
2. Protein concentration More concentrated = more water uptake 3.
Protein denaturation Temperature - if you form a gel on heating
(which denatures the proteins) then you would get more water
binding Salt type & concentration 44
Slide 45
Example how thermal denaturation may have an effect on water
binding SPS = Soy protein isolate forms gel on heating Caseinate =
Milk proteins (casein) does not gel on heating WPC = Whey protein
concentrate forms gel on heating 45
Slide 46
Proteins functional properties 46 I. Salts/ionic strength This
is highly protein dependent muscle proteins Na + Cl - NaCl
Slide 47
Salt brine Cook 10% reduction Salt brine phosphate Cook 100%
reduction some phosphate Cook 30% reduction Phosphate salts (in
combination with NaCl) are frequently used in food processing to
make food proteins bind and hold more water 47
Slide 48
Proteins functional properties II. pH (protein charge) Great
influence on the water uptake and binding of proteins Water binding
lowest at pI since there is no effective charge and proteins
typically aggregate (i.e. dont like to be in contact with water)
Water binding increases greatly away from pI Muscle proteins and
protein gels are a good example pI 48
Slide 49
Proteins functional properties How do we measure water binding
and uptake? Usually designed for a specific product or application,
most common methods are: Water-uptake (sorption) - Measuring water
uptake of a protein or protein food (e.g. protein gel) by adding it
to a sorbent (usually a dry powder), then remove and measure the
change in water content of the sorbent Water-binding (also called
water-holding capacity or expressible moisture) - Subject your
sample to an external force (centrifuge or pressure) and then
measure how much water is squeezed out Test needs to be carefully
designed so that the actual internal structure of the gel or food
is not destroyed when the pressure is applied 49
Slide 50
Proteins functional properties IV. Emulsification Proteins can
be excellent emulsifiers because they contain both hydrophobic and
hydrophilic groups that decrease the interfacial tension which
allows for stability LOOP TRAIN + ENERGY 50
Slide 51
Proteins functional properties IV. Emulsification 51 Whey
protein stabilized emulsion Both phases Whey protein stabilized
emulsion Lipid phase removed (protein matrix showing)
Slide 52
Proteins functional properties Factors that affect
protein-based emulsions Type of protein To form a good emulsion the
protein must be able to: 1.Rapidly migrate to the oil-water
interface 2.Rapidly and readily open up and orient polar and
non-polar side chains into the proper phases 3.Form a stable film
around the oil droplet 52
Slide 53
Proteins functional properties Factors that affect
protein-based emulsions The following are important for the protein
emulsifiers 1.Solubility of protein Insoluble will not form a good
emulsion (cant migrate well) If at pI is not good Increasing
solubility increase emulsification ability (up to a point)
2.Distribution of hydrophobic vs. hydrophilic amino acids Need a
proper balance Generally increased surface hydrophobicity will
increase emulsifying properties 3.Shape of protein Globular is
better than fibrous 4.Flexibility of protein More flexible it is,
easier it opens up 53
Slide 54
Proteins functional properties How do we measure emulsifying
properties? Most are highly empirical Two common methods
Emulsification capacity - Oil titrated into a emulsion that is
using protein as the emulsifier with mixing and the max amount of
oil that can be added to the protein solution is measured
Emulsification stability - Emulsion formed, then monitor breakdown
(separation of water and oil phase) with time 54
Slide 55
Proteins functional properties V. Foaming Foams are very
similar to emulsion where air is the hydrophobic phase instead of
oil Principle of foam formation is similar to that of emulsion
formation (most of the same factors are important) Foams are
typically formed by Injecting gas/air into a solution through small
orifices producing bubbles (sparging) Mechanically agitate a
protein solution (whipping) Gas release in food, e.g. leavened
breads (a special case) 55
Slide 56
Proteins functional properties V. Foaming 56 FOAM FORMATION
FOAM BREAKDOWN
Slide 57
Proteins functional properties Factors that affect foam
formation and stability 1.Type of protein is important Good foaming
proteins exhibit: High rates of diffusion/adsorption at the
interface Ability to unfold/denature at the interface Ability to
form intermolecular associations with other molecules (that results
in film formation) Increased surface hydrophobicity is good
Partially denaturing the protein often produces better foams
Globular is better than fibrous 57
Slide 58
Proteins functional properties Factors that affect foam
formation and stability 2.pH Foam formation is often better
slightly away from pI Foam stability is often better at pI The
farther from pI the more repulsion and the foam breaks down
Example; Egg foams (meringue) addition of cream of tartar increases
stability 58
Slide 59
Proteins functional properties Factors that affect foam
formation and stability 3.Salt Very protein dependent Egg albumins,
soy proteins, gluten Increasing salt usually improves foaming
(stability) since the net charge is decreased (proteins lose
solubility salting-out) Whey proteins Increased salt negatively
affect foaming (they get more soluble salting in) 59
Slide 60
Proteins functional properties Factors that affect foam
formation and stability 4.Lipids Lipids in food foams usually
inhibit foaming by adsorbing to the air-water interface and
thinning it Only 0.03% egg yolk (which has about 33% lipids)
completely inhibits foaming of egg white! Cream an exception where
very high level of saturated fat stabilizes foam Cold coalesced fat
droplets surround protein encapsulated air bubbles 60
Slide 61
Proteins functional properties Factors that affect foam
formation and stability 5.Stabilizing ingredients Ingredients that
increase viscosity of the liquid phase stabilize the foam (sucrose,
gums, polyols, etc.) We add sugar to egg white foams at the later
stages of foam formation to stabilize Addition of flour (protein,
starch and fiber) to foamed egg white to produce angel cake (a very
stable cooked foam) 61
Slide 62
Proteins functional properties Factors that affect foam
formation and stability 6.Energy input The amount of energy (e.g.
speed of whipping) and the time used to foam a protein is very
important To much energy or too long whipping time can produce a
poor foam Proteins become too denatured The foam structure breaks
down 62
Slide 63
Proteins functional properties 63 How do we measure foam
formation and stability? 1.Overrun (foam formation) Start with a
known volume of protein solution (e.g. 100 mL) foam it (usually by
whipping), then measure the volume of foam vs. that of the liquid:
% Overrun = 2.Foam stability (drainage) Using a special cylinder
measure the amount of liquid that drains from the foam on storage
to get a mL/min or mL/hr drain value (the smaller the value, the
more stable the foam)
Slide 64
Proteins functional properties Protein modification to improve
function Some proteins dont exhibit good functional properties and
must be modified Other proteins are excellent in one functional
aspect but poor in another but can be modified to have a broader
range of function 1.Chemical modification Reactive amino acids are
chemically modified by adding a group to them Lysine, tyrosine and
cysteine Increases solubility and gel-forming abilities Modified
protein has to be non-toxic and digestible Retain 50-100% of
original biological/nutritive value Often used in very small
amounts due to possible toxicity Not the method of choice for food
proteins 64
Slide 65
Proteins functional properties Protein modification to improve
function 1.Chemical modification Example of types of chemical
groups that can be added to proteins 65
Slide 66
Proteins functional properties Protein modification to improve
function 2.Enzymatic modification a)Protein hydrolysis Proteins
broken down by enzymes to peptides (smaller) Improved solubility
and biological value b)Protein cross-linking Some enzymes
(transglutaminase) can covalently link proteins together Great
improvement in gel strength c)Amino acid modification
Peptidoglutamiase converts Glutamine glutamic acid (negatively
charged) Asparagine aspartic acid (negatively charged) Can convert
an insoluble protein to a soluble protein 66
Slide 67
Proteins functional properties 3.Physical modification Most of
the methods involve heat to partly denature the proteins Texturized
vegetable proteins TVP (e.g. soy meat) A combination of heat (above
60C), pressure, high pH (11) and ionic strength used to solubilize
and denature the proteins which rearrange into 3D gel structures
with meat like texture Good water and fat holding capacity Cheaper
than muscle proteins often used in meat products Protein based fat
substitutes (e.g. Simplesse TM by CPKelco former NutraSweet
subsidiary) Milk or egg proteins heat denatured and mechanically
sheared and on cooling they form small globular particles that have
the same mouthfeel and juiciness as fat Simplesse TM is very
sensitive to high heat (protein based so can denature) limits its
use in processing 67