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Midterm Flashcards

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1
Q

Why is the angle between the two hydrogen atoms in a water molecule 104.5°?

A

This is because while oxygen is covalently bonded to two hydrogen atoms it has two lone pairs of electrons and this causes there to be repulsion between the negative electron clouds causing the bond of 109.28 to be reduced to 104.5 degrees.

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2
Q

What are the definitions of cohesion, adhesion, and capillary action?

A

Cohesions is when water is attracted to water
Adhesion is water being attracted to other substances
Capillary action is when water molecules tow each other along in a thin glass tube.

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3
Q

What affects the physical properties of water

A

Temperature (gives energy)
Pressure (affects how closely molecules are packed)

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4
Q

Why does an increase in the hydrogen bonding lead to an increase in cohesion density and viscosity, while the adhesion and density and thermal conductivity decrease?

A

Cohesion, density (under certain conditions), and viscosity increase due to stronger intermolecular forces holding the molecules together more tightly.
Adhesion decreases because molecules are less likely to interact with different substances when they are strongly bonded to each other.
Thermal conductivity decreases because the restricted molecular motion limits the transfer of heat energy.

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5
Q

Provide two examples of anomalous properties of water.

A
  1. A high melting point
  2. A high boiling point
  3. Large heats of fusion and vaporization
  4. High heat capacity
  5. high surface tension
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6
Q

Why does ice have lower density than water?

A

Due to empty space in hexagonal structure

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7
Q

What is the definitions of bound water?

A

Bound water is associated with ions and macromolecules and its molecular structure. Has little to no mobility does not freeze at 0 degrees Celsius only low temperatures that are below freezing point. Cannot partake in chemical reactions or support microbial growth and can’t act as a solvent, for example, water in cacti.

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8
Q

What is free water?

A

Free water behaves like normal water like water in lemon juice and can be easily extracted from foods by cutting, squeezing pressing, acts as a solvent for salts and sugars and can freeze at moderate temps

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9
Q

What is trapped water?

A

Trapped water is confined in pored and capillaries that are in food matrices, they have restricted mobility like water in pectin gels, fruits and veggies. but if freed it can act like free water, freeze like free water and flow like free water

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10
Q

What is the density and vapour pressure of free water, bound water and entrapped water like?

A

Free water has low density and VP
Bound water has high density due to molecules packed close toegther but no VP
and trapped water if freed is just like free water

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11
Q

Water dissolves compounds by __

A

hydration, hydration is the process by which water molecules surround and interact with solutes. (ions are very soluble in water due to dipole-hydrogen bonds)

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12
Q

Trapped water facilitates ___ in food

A

deletrious reactions

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13
Q

Explain hydrophobic, hydrophilic and amphiphilic

A

Hydrophibic molecule is repelled by water and is non soluble in water like oil
hydrophilic is soluble in water like sugar and salts
amphipilic are both where 1 portion is philic and 1 is phobic like soap and detergents

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14
Q

What are the types of emulsions?

A

Two types – Water in oil (butter), oil in water (salad dressing)

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15
Q

How do emulsifiers stabilize emulsions?

A

Emulsifiers use amphiphilic to reside at the interface between water and oil and stabilize the emulsion by creating a barrier between oil and water so that they don’t touch, so that it does not separate. Like egg whites.

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16
Q

What are the definitions of water content? and water activity?

A
  • Water content is how much water is in a food.
  • Water activity is a measure of the availability of water molecules to enter into microbial enzymatic and chemical reactions (bound, trapped and free) the higher the free water the higher the water activity)
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17
Q
  1. How do water activity and moisture content affect reaction rates?
A

Water activity influences reaction rates in foods by limiting microbial growth and enzymatic reactions. When water activity is low, microbes struggle to access nutrients and eliminate waste, and enzymes may denature because they can’t diffuse to substrates. Additionally, very low water activity increases stability against oxidation, further reducing degradation rates. Foods with lower water activity are more stable since both microbial growth and enzymatic reactions require water to occur. To lower water activity, sugars and table salt are often used, as they bind moisture and reduce the availability of water for reactions that lead to food degradation.

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18
Q

What are sorption isotherms and the three zones in these isotherms?

A

Sorption isotherms describe how a substance (like a gas or solute) is adsorbed onto a solid surface at different concentrations or pressures. They help illustrate the relationship between the amount of substance adsorbed and its concentration in the surrounding environment.
Zone 1: Structural water or water of hydration, it cannot dissolve solutes and be frozen and it behaves as if it were a part of a solid.
Zone 2: Multilayer water, moisture is still unfreezeable, but molecular mobility is increased and acceleration of degradation occurs
Zone 3: is Bulk water where glass-rubber transitions, decrease in viscosity and a large increase in molecular mobility.

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19
Q

What is hysteresis?

A

In adsorption processes, hysteresis can occur when the adsorption and desorption curves do not overlap. This indicates that the amount of substance adsorbed may differ when increasing the concentration compared to when decreasing it, often due to changes in the structure of the material or the nature of the adsorption process.

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20
Q

Chemical formula of carbs

A

CH2On

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21
Q

Carbohydrates are divided into what 5

A

Mono saccharides
Disaccharides
trisaccharides
oligosaccharides
polysaccharides

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22
Q

Glycemic and non glycemic

A

Glycemic are readily metabolized while non-glycemic are not readily metabolized

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23
Q

Monosacchardides

A

The simplest carb and serve as the building blocks of higher molecule weight carbohydrates AKA sugars, or simpla sugars eg. glucose, fructose, galactose

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24
Q

Simple sugars refers to

A

Mono saccharides

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25
Q

Sugars are dived into what two classes?

A

Aldose (acycylic carbonyl group [c=o] is an aldehyde end
Ketone (acycylic carbonyl group [c=o] is a ketone (non end)

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26
Q

When it’s H-C=O at the end its a ____ and when its c=o in the middle its a ___

A

aldose, ketose

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27
Q

What is chiralty

A

Mirror structures that are superimposable (chiral carbon is one that is bonded on all 4 atoms)

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28
Q

Configuration

A

It’s arrangement of stereogenic centers, Permanent unless a chemical reaction occurs like changing glucose to galactose (building blocks) whether or not a sugar can react with a specific enzyme

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29
Q

Confirmation

A

sugars arrangement in space, flexible and can change without breaking bonds (like changing the shape of a sugar ring) (bending paper clip) can change physical properties like solubility

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30
Q

D and L configuration

A

If OH group is on the chiral carbon furthest from the carbonyl and
is pointing left then it’s L
if it’s on the right it’s D

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31
Q

Why are ring sugars important

A

Sugars are put in an aqueous solution and form a ring because its more thermodynamically stable. (furanose is less stable than pyranoses [6])

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32
Q

How are sugars classified

A

Based on structure and number of simple sugar units
Monosacharides

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33
Q

What is a Fischer projection?

A

Structural representation used to visualize the stereochemistry of chiral molecules includes D and L notation

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34
Q

What is a haworth projection?

A

Represents cyclic ring structure of sugars and other cyclic molecules in a simplifiec form. Uses alph and beta anomers includes furnaose (5 membered) and puranose (6 membered)

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35
Q

Why do we need the haworth projection?

A

Shows ring form of linear structures and helps to understand different anomers, shows stereochemistry and helps to understand sugar chemistry like how glycosilic bonds form in glucose.

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36
Q

Explain enantiomer, diastereomer. epimer, cis trans isomer

A

enantiomer - mirror images of each other
Diastereomer = not mirror images
Epimer = diastereomer where only the configuration of one chiral center is different.
Cis has functional groups on same side of plane
Trans has it one opposite sides

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37
Q

Mutarotation

A

The inter-conversion between two anomeric forms and two ring types when the sugar is in solution
required re -conversion to the linear form
higher temp increases mutarotation catalyzed by acid base and enzymes
beta structure more stable

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38
Q

Anomeric carbon

A

Carbon in a sugar molecule that was originally part of the carbonyl group before the structure became a ring sturcture
This becomes the new sterecenter the chiral center

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39
Q

Furanose and pyranose can exist in different conformations which refers to __

A

The shape of the rings and the positions of the various groups of sugars which is locked during hemiacetalization
Different isomers (boat, chair, half-chair, skew, sofa, envelope and twist)

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40
Q

The most stable conformtaion fo cyclohexane is__ the less stable is___

A

Chair and boat. Chair is more stable because of steric hindrance

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41
Q

Monnosaccharides cannot be broken down by ___

A

hydrolysis

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42
Q

Monosaccharides come together and form ___ and ____ which can be broken by ___

A

oligosaccharides and polysaccharides which are broken by hydrolysis

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43
Q

Reducing sugar is

A

Any sugar capable of being oxidized by acting as a reducing sugar . Must have or be able to rearrange to have a free aldehyde group, includes cyclic sugars that have free hemiacetal and hemiketal.

Non reducing has acetal and ketal

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44
Q

enolization

A

turns ketoses into aldoses as ketone groups cannot oxidize in the same manner as aldehyde groups

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45
Q

Sugars can be detected by

A

exploiting their reducing power

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46
Q

D-gluconic acid constituent of

A

fruit juices and honey

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47
Q

Use of sugar alcohols

A

used in low calorues foods for diabetics because they can’t be metabolized as efficiently as sugars

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48
Q

Xylitol is

A

sugar alcohol used in non- cariogenic gum

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49
Q

Sorbitol is

A

Sugar alchol added to dried fruits as a humectant to prevent sweating

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50
Q

Maltitol used to form

A

low calorie ice creams can be used as one to one replacement of subrose due to same freezing point of depression

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51
Q

Glycosylation

A

Hemiacetal/Hemiketal groups in the sugar can react with alcohols to produce full acetals and ketal fi the alchol is a non sugar then the molecule becomes a glycon and aglycon

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52
Q

Glycosidic bond

A

sugars have special parts called an “alcohol group” and a “hemiacetal group.” When a sugar donates its alcohol group to another sugar, they form a bond called an O-glycosidic bond. This bond can be easily broken when boiled in acid.

In this process, the sugar that donates its hemiacetal group is called the non-reducing end, while the sugar that donates its alcohol group is called the reducing end. Essentially, the non-reducing end is the stable part, and the reducing end is more reactive.

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53
Q

Deoxy sugars

A

Sugars that have an -OH group replaced by -H group

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54
Q

Amino Sugar

A

-OH group replaced by -NH group

55
Q

Esterfied sugar

A

Many OH react with COOH and form esters form olestra which cannot be absored by the body but can be digested in gut bacteria

56
Q

Dextrose Equivalent is a

A

measure of the amount of reducing sugar present in a product, expressed as a percentage of the total dry substance (degree of starch hydrolysis)

57
Q

Higher De and Lower De indicate

A

Higher DE means more simple sugars in product = sweeter
low DE means less sweet molecules longwer glucose units so more bulky product and less sweet

58
Q

Carmelization

A

heating both reducing (glucose) and non-reducing sugar (sucrose) in absence of amine-containing compound.
- Controlled burning of sugar in absence of oxygen will form bitter and burned aroma

59
Q

Maillard browing requires

A

Reducing sugar and amine

60
Q

Maillard and carmelization are different becuase

A

Carmelization requires high temps and is initiated by low pHs

61
Q

Hydrogenation is process where

A

hydrogen atoms are added across a double bonds. In carbs it includes adding hydrogen atoms to the oxygen and carbon of the carbonyl group of aldose and ketose and turns them into polyhydroxy alcohols

62
Q

Sugar crystallization is desirable and non desirable in

A

desirable in fudge and fondant non desirable in chocolate and opaque + stickiness in hard candies

63
Q

invert sugar is

A

produced by hydrolyzing sucrose in presence of enzyme or acid and is called invert because sucrose rotated polarized light to right but once its hydrolyzed the light rotate to the left.

64
Q

Glucose syrup comes from

A

Corn involves breaking down starch into small molecules using ezymes or acids

65
Q

Low De in glucose syrup results in

A

Candy with chewy texture

66
Q

Hemiacetals and hemiketals are

A

not stable and dehydration occurs because mono saccharides want to connect to other monosaccharides

67
Q

Sucrose comes from

A

Sugar cane and sugar beets

68
Q

Sucrose is what kind of reducing sugar

A

non reducing

69
Q

What in the human intestinal tract catalyzes the hydrolysis of sucrose

A

sucrase

70
Q

Sucrose examples in food

A

Beverages, soft drinks, processed foods

71
Q

Advantages of substituting sucrose with high fructose corn syrup is that

A

Cost-Effectiveness
* Sweetness Control
* Enhanced Stability
* Improved Texture
* Liquid Form
* Widespread Availability

72
Q

Maltose

A

obtained by hydrolysis of starch using the enzyme - amylase
produced during the malting of grains and can be obtained by hydrolysis of starch using beta amylase enzyme

73
Q

Maltose is what kind of sugar

A

It is a reducing sugar, has free aldehyde group

74
Q

How does maltose work in beer

A

Grains first cooked -> liquid contains maltose -> fermentation yeast consumes maltose -> alcohol

75
Q

Lactose

A

“Milk Sugar” energy source for infacts and developing mammals
Involves conversion of lactose to lactic acid and fermented dairy products contain less lactose because some is converted to lactic acid during fermentation

76
Q

Lactose intolerance

A

When lactose is partially or not digested.
Lactose moves to the large intestine, where anaerobic bacteria ferment it into lactic
acid and other short-chain acids.
* Leads to more fluid retention, lower pH, and irritation of the colon lining.
* Results in increased bowel movement, diarrhea, bloating, and cramping.

77
Q

Oligosaccharide

A

2-20 sugar units connected by glycosidic covalent bonds.
Undergo hydrolisis catalyzed by acid.

78
Q

Naturally occurring oligosaccharides include

A

lactose and sucrose other are genertaed through hydrolysis of polysaccharides

79
Q

Food oligosaccharides include

A

Beans and sugar beets contain trisaccharides (rafinose) and a tetrasaccharide (staychyose) both are indigestable

80
Q

Raffinose

A

found in beans, cabbage, aspargus
Humans do not hav enzymes to digest so they pass unchanged through the colon and intestinal bacteria ferment them into gas.
- Dietary raffinose increases soluble dietary fiber in large intestine

81
Q

Stachyose

A

Found in beans and peas
Cannot be broken down with endogenous enzymes

82
Q

Cyclodextrins

A

Glucose oligosaccharides that are cyclized by cyclodextrin glycosyltransferases.
- even number are more soluble than odd number of glucose residues
Internal diameter of cyclodextrin depens on number of glucose molecules from parent dextrin.
-has hydrophilic character on surface due to oh group being away from hole.

83
Q

The _____ allows it to form complexes with hydrophobic
compounds.
* Used for _____

A

The hydrophobic interior allows it to form complexes with hydrophobic
compounds.
* Used for the encapsulation, stabilization and controlled release of
drugs, vitamins, flavors and nutraceuticals.
* Used to remove bitter compounds from citrus fruits (grapefruit)

84
Q

Fructo-oligosaccharides and inulin

A

Found in onions, garlic, bananas,asparagus.
Inulin is in chicory and jeursalen artichoke
Inulin has prebiotic properties as they can fermented by gut bacteria to form acetate, propimoate and butyrate.
Inulin can prevent colon cancer, reduce serum TAG and cholersterol and promone mineral absorption

85
Q

Animal polysaccharides include

A

Chitin found in the exoskeletons of athropods and in fungi (insoluble in water)
Chistosan is a deacetylated form of chitin (soluble in acidic solutions)

86
Q

Polysaccharides in plants

A

Cellulose is insoluble in water due to hydrogen bonding
Hemicellulose (cell wall)
Pectin (cell wall)

87
Q

Mucilages

A

yellow mustard, flaxseed, psyllium

88
Q

Exudate gums

A

Gum Arabic, Gum tragacanth, gum karaya, gum ghatti

89
Q

Seaweed polysaccharides

A

Soluble in hot water Alignates, carageenan, agar

90
Q

Microbial polysaccharides

A

Xanthan, dextran, gellan, pullulan

91
Q

Charges polysaccharides

A

Contain sugar acids sugar amines or charges esterified groups

92
Q

Polysaccharide hydration

A

Polysaccharides can modify and control the mobility of water in
foods.
Hydration (or plasticizing) of water with hydrogen bonding solvates polysaccharide molecules helps with stability during freezing.
molecules motion are retarded but they can exchange freely and rapidly with other water molecules

93
Q

Water hydration takes up what space in gels and fresh tissue foods (Polysaccharide hydration)

A

Only small part of total water in gels and fresh tissue foods, excess water is in capillaries and cavities of various sizes
freezing forms crystals which destroys structure of food

94
Q

Poly saccharides crystallites

A
  • adopt helical shape (highly branched can’t)
  • certain like cellulose have flat ribbon like structure
  • uniform linear chains undergo hydrogen bonding with each other to form
    crystallites (fringed micelles) separated by amorphous regions
    these crystallites of linear chains that give cellulose fibers, like wood and
    cotton fibers, their great strength, insolubility, and resistance to breakdown.
95
Q

Polysaccharide Solution Viscosity and Stability

A

Polysaccharides are primarily used to thicken or gel aqueous
solutions, as well as to modify and control the flow properties and
textures of liquid foods, beverages, and the deformation properties of
semisolid foods.
They are typically used in food products at concentrations of 0.25-
0.50%, demonstrating their significant capacity to increase viscosity
and form gels.

96
Q

The viscosity of a polymer solution depends on ___ and the bonds ___
(polysaccharide)

A

the size and shape of its
molecules and the conformations they assume in the solvent, which, in
foods and beverages, is typically an aqueous solution containing other
solutes.
* The shapes of polysaccharide molecules in solution are determined by the
oscillations around the bonds of their glycosidic linkages.
* The more internal flexibility at each glycosidic linkage, the greater the
number of possible conformations available to each segment of the
molecule.

97
Q

Polysaccharide starch solubility

A

When starch is heated in water, it swells and gelatinizes. The starch granules break down, and amylose leaches out, forming a viscous solution or gel.

98
Q

What is a polysaccharide gel

A

A gel is a three-dimensional network of molecules or particles (like crystals, droplets, or molecular aggregates) that trap a large amount of liquid, similar to how a sponge holds water.

99
Q

Polysaccharide Gels in Food is made of __

A

In food products, the gel structure is made up of polymers (polysaccharides and/or proteins) that are connected at junction zones. These junctions are formed by:

  • Hydrogen bonds
  • Hydrophobic interactions (attraction between non-polar molecules)
  • Ionic cross-bridges (bonds involving ions)
  • Van der Waals forces
    Covalent bonds (strong chemical bonds)
  • Molecular entanglements (interlocking of chains)
  • The liquid inside the gel is usually an aqueous solution (water-based) containing small molecules and parts of the polymer chains.
  • This process gives gels their structure, helping them hold liquids and contribute to the texture of food.
100
Q

Cellulose and its modified forms serve as

A

dietary fiber
Do not contribute significant nutritional content or calories as they are mostly not absorbed by the human digestive system.
* Ruminants have the necessary bacteria and enzymes (β-glucosidase) to break down cellulose.

101
Q

Microcrystalline Cellulose (MCC):

A

Produced by acid hydrolysis of cellulose, which removes the amorphous regions but keeps the crystalline parts acts as a fat replacer, bulking agent, and enhances frying performance

102
Q

Carboxymethylcellulose (CMC):

A

A modified cellulose that is charged and can be soluble or insoluble depending on pH.
serves as a thickener, stabilizer in ice cream, and can form gels in the presence of ions, making it useful for encapsulation and various food applications.

103
Q

Methylcellulose and Derivatives (HPMC)

A

polysaccharides that gel when heated due to hydrophobic interactions stabilizing hydrogen bonds. They are commonly used as general-purpose thickeners in food, with their substituted structure preventing crystallization, which increases solubility and hydration.

104
Q

Glycogen

A

multi-branched polysaccharide of glucose that serves as a form of
energy storage for humans and animals.
* Not in meat products, during conversion of muscle to meat –glycogen
is depleted, and lactic acid accumulates.

105
Q

Pectins

A

Holds plant cells together
texture of nonwoody vegetative plant material depends on pectin content for fruits and tubers

106
Q

Explain the zones in pectin

A

Junction zones - where pectin molecules link together forming a stable network for the gel structure. Happens due to hydrogen bonds, hydrophobic interaction or ionic bonds depending on pectin

Interruption zones - pectin chain do not interact or form creating breaks in network. weaken gel and affect final texture.

107
Q

Two types of pectin are

A

High methoxy pectin and low methoxy pectin HMP LMP

108
Q

HMP junction zone formation requires

A

Sucorse and low pH

109
Q

LMP forms gels in the presence of

A

Calcium ions as they create a better gel like structure in jam are good bases for low calorie food

110
Q

Pectin regions

A

Smooth important for gelation
Hairy for structual diversity and functional properties

111
Q

Galactomannans are

A

abundant group of storage polysaccharides from leguminous seeds
include
guar gum, tara gum, and locust bean gum

112
Q

Guar and locust bean gum

A

formed by ground endosperm
important thickeining polyglycan for food and non food uses
Guar is highly soluble in cold water
locust dissolves only after heating (bad for baking)

113
Q

xanthan gum and glucomannans

A

synergetic with galactomannans and glucomannans
when xanthan and guar gum come together they provide bettwe sttructure because xanthan gum gives stability and guar gum gives felixbillity resulting in thicker cohesive gel

114
Q

Carrageenans

A

Dissolve in water to make high viscous solution
stable over wide range of pH
used in many foods like dairy and milk
lambda used for thickening without forming gel in beverages
synergetic with locust bean gum

115
Q

Alignate used for

A

gelling and thickening in fruit filling cooked means bakery fillings and glazes used in zero carb low calorie sugar free and low sodium

116
Q

Gum arabic

A

Used as stabilizer like in a beverage because it prevents solids from seperating and can be used as emulsifier

117
Q

Two main polysaccharides in starch

A

Amylopectin and amylose

118
Q

Amylose is hydrophilic due to

A

-oh groups and unbranched nature of amylose causes intermolecuar hydrgen bond with other OH groups
amylose-amylose interaction reduces solubility and releases water and will render an amylose
solution opaque.
Amylose can form helices. These
helices can complex compounds
such as iodine, monoglycerides,
and fatty acids
with iodine it is pure blue

119
Q

Amylopectin

A

branched nature of amylopectin makes
intermolecular hydrogen bonding difficult.
with iodine it is blue-violte

120
Q

Startch exists as

A

Granules which are composed of amylose and amylopectin and a little lipids, proteins and phosphorus

121
Q

Starch granules are crystalline with

A

amorphus regions

122
Q

Starch granules are dense and only slightly ___ in __ water

A

hydrate, cold
cooking increases ability to build viscosity

123
Q

Gelatinization refers to the

A

loss of molecular order, while pasting refers to the disruption of the starch granule.

124
Q

Starch gelatinization involves

A

startch granules absorbing water until they rupture which causes loss of crystallinity and develops viscosity and solubilization of startch

125
Q

During gelatinization, the properties of a starch slurry change

A

Increase in granule size (increases viscosity)
* Decrease in granule size after cooking (decreases viscosity)
* Release of amylose (increases viscosity)

126
Q

Pasting refers to

A

rheological changes during and after
gelatinization.
* Pasting = The formation of a “paste”.
* Pastes with plenty of soluble amylose will have a longer texture. Pastes with
minimal amylose will have a short texture.

127
Q

Starch Retrogradation

A

change results from the breaking of some of the hydrogen bonds holding the
gel together in a continuous network and the re-formation of other hydrogen
bonds as amylose molecules shift around within the gel.
* Over a period of time, there is a tendency for amylose molecules to orient
themselves in crystalline regions. This more orderly alignment of amylose,
termed retrogradation, is detected on the tongue as a somewhat gritty texture

128
Q

Syneresis

A

Water is trapped within the
starch gel.
* A layer of water is hydrogen
bonded along the individual
amylose molecules, as well as
to the surface molecules of the
granules.
* Additional free water (not
actually bound) is also trapped
within the network of the gel.
* As gels age, amylose
molecules draw together, and
some water is squeezed out of
the gel.
* This loss of liquid

129
Q

Starch- Acid Modified Starch

A

Starch slurry steeped for 24 ours below geatinization temp
then acid hydrolyzes starch
then amorphous region become hydrolzyed while the crystalline portions remain relatively
intact. The granule remains intact because it isn’t gelationized
Paste has low viscosity

130
Q

Starch- Pregelatinized

A

tarch slurry is heated until it gelatinizes, and then it is dried via
drum or spray drying
The resulting starch is soluble in cold water and rehydrates very
quickly. Useful in “instant” situations and where cooking is undesirable:
* Instant puddings
* Cake frostings
* Baby foods
* Pie fillings

131
Q

Starch-Crosslinking

A

Cross-linked starches are starches where two polymer chains are
covalently bonded.
involves using chemical agents
that can react with the hydroxyl groups (−OH) in starch molecules, forming covalent bonds between them.

Cross-linked starches are highly resistant to swelling and rupturing of the
starch granule.
* Resistant to acid hydrolysis (great for low pH foods)
* No rupture = No gel formation = No syneresis problems
* Cross-linked starches are excellent for applications that require thickening
and stabilization.
* Cross-linked starches can retain viscosity in the face of heat, shear and acid. Salad
dressings.
* Cross-linked starches have excellent freeze-thaw stability.
* Cross-linked starches have lower peak viscosities compared to their native
counterparts.
* Too much cross-linking = poor swelling characteristics.
* Some cross-linked starches are s

132
Q

Starch-Substituted Starches

A

Substituted starches are those starches where a substituent is
attached to one of the three free –OH groups in the glucose units of starch.
The main aim of substitution is to prevent retrogradation. The
addition of the “blocker” prevents interaction of starch polymers
Substituted starches do not form gels and retrograde because of
charge repulsion and/or steric hindrance.
* Substituted starches reduce the stability of the granule

133
Q
A

Food Chemistry (2 decks)

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