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Cereal Science > Exam 2 > Flashcards

Exam 2 Flashcards

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1
Q

Wet milling definition

A

Maceration process in which chemical and physical changes occur in the basic components constituents of the endosperm, in order to bring about the complete separation of the endosperm cell wall contents with the release of starch granules from the protein network

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2
Q

Main product of wet milling

A

Starch, secondary are the co-products

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3
Q

Wet milling maize process goal - Anatomical separations

A

Germ isolation

Pericarp (fiber) isolation

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4
Q

Wet Milling maize process goal - Component separations

A

Starch isolation

Protein isolation

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5
Q

Four co-product of wet maize milling and their uses

A

Starch, Fiber (bran), Protein, oil (germ)

-All can be food or feed

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6
Q

Main source of starch in the US is from

A

Maize wet milling

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7
Q

Wet Milling Maize steps

A

Steep
Germ separations then refining
bran separation
starch and “gluten” protein purifications

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8
Q

Why steep maize in wet milling

A

Plasticization of the bran and germ
germ swells and is easily removed
Facilitates protein-starch separation

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9
Q

Why can’t we use heat damaged corn in wet milling?

A

The proteins don’t swell and the starch doesn’t separate well.

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10
Q

Unique aspects of wet milling maize

A
  • Effluent recovery (only water leaves the system as steam)

- Counter-flow movement of the process water

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11
Q

Steeping of maize

A
  • multiple tanks
  • excess water running counter-current (concentrates the solubles for removal for feed or fermentation)
  • Sulfur Dioxide modifies the protein bonds and allows starch to be released (this is used up in reactions and none remains at the end.)
  • Lactobacillius fermentation (produces lactic acid early which prevents off flavors and odors)
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12
Q

Germ recovery maize wet milling

A

Germ released through gentle grinding

Hydroclones separate the germ

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13
Q

Fiber, protein, and starch separation (maize wet milling)

A

Fine grinding in attrition mill AFTER the germ has been removed

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14
Q

Fiber recovery maize wet milling

A

Overs: to dewatering press then to feed dryer

Thrus; starch and protein

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15
Q

Starch and protein recovery maize wet milling

A

Separated with hydroclones
Then starch is purified by washing and hydrocloning repeatedly, then dried
The protein is concentrated and dried

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16
Q

Native / Pearl Starch (maize)

A

Virtually pure starch (less than 0.3% protein)

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17
Q

Wheat differences from Maize concepts

Wet Milling

A
  • Primary product is vital wheat gluten
  • secondary product is starch
  • starting material is flour
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18
Q

Wheat differences from Maize process

Wet Milling

A
  • Not bottled or counter flow
  • No concentration of the steep (bc of water soluble arbinoxylins)
  • No sulfur dioxide
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19
Q

Why do we want higher quality flours for starting material in wet milling wheat

A

Low grade flours have more damaged starch

  • absorb more water
  • interferes with gluten aglomeration
  • less prime starch per weight
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20
Q

Wheat wet milling steps

A
  • Washing
  • Screen
  • Starch isolation
  • Starch drying
  • starch grading
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21
Q

Washing wheat flour

A

gluten proteins self associate and the starch separates

-water solubles created

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22
Q

Starting material wet milling flour

A

High quality flour, turned into a batter

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23
Q

Screening of the wheat wash water

A

Through: starch, solubles, water
Retained: crude gluten

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24
Q

Starch isolation -how, why

wheat wet milling

A

Centrifuges/hydroclones, or sieves

  • remove remaining gluten
  • produce varying purity of starch
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25
Q

Starch drying danger wheat wet milling

A

Bimodal starch granules.

The small ones can be explosive if mishandled

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26
Q

Prime starch

A

Mostly pure, long lenticular granules

-Most valuable

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27
Q

B-Starch (tailings)

A

Mostly small and/or damaged granules
-cell walls, unextractable arabinoxylans.
(challenged to find a use for this. Feed and fermentation)

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28
Q

Vital Gluten

A
  • Retains most of its functional properties - it will form a dough
  • Makes wheat starch recovery economically possible
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29
Q

___ is a critical step for vitality retention of vital gluten

A

Dry because heat damage reduces functionality

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30
Q

How to dry vital wheat gluten

A

Flash dry with evaporation

freeze drying is great but is slow and expensive.

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31
Q

Wheat germ oil storage

A

Highly unsaturated so goes rancid quickly

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32
Q

Wheat germ oil vitamin E

A

High in Vitamin E

-used as a nutritional supplement

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33
Q

Saturated fatty acid stability

A

More stable against oxygen induced rancidity

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34
Q

Higher unsaturation the ___ the melting point

A

lower the melting point

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35
Q

Rice bran oil is

A

by-product of solvent extracted bran production

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36
Q

Maize germ oil -characteristics

A

Light in color, bland flavor - used for cooking and frying

-major cereal source

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37
Q

Expeller

A

Using mechanical pressure, high temps, and a solvent to extract oil from maize germ.

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38
Q

Over heating maize oil may result in

A

Off flavor, off color

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39
Q

Expeller yields

A

Crude oil out

-Foots

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40
Q

Expeller foots

A

Residue

  • foots solvent extracted and sent to feed
  • Hexane is stripped to recover residual oil
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41
Q

Solvent only extraction of maize germ oil

A
  • Large volumes of hexane
  • Sealed system, could be recovered
  • High quality oil
  • BUT possibility of explosion
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42
Q

Maize oil processing after expeller

A
  • Filter press to remove particulates
  • Alkali (base) treatment to convert free fatty acids and polar lipids into water soluble salts (prevents saponification)
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43
Q

Maize oil treatments after Alkali treatment

A

Bleaching
-pigment absorbed by activated clay
Winterization
-remove waxes that would cause cloudiness in the fridge

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44
Q

Deodorizing maize oil

A 
Vacuum distillation (high temp, no oxygen)
Volatile compounds removed (flavors, aromas, some color compounds)
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45
Q

Maize oil packaging importance

A

Must be UV- blocking material

  • UV initiates fatty acid break down and oxidation
  • UV creates free radical scavengers that keep the rancidity reaction going.
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46
Q

Why study starch

A
  • Most abundant food carbohydrate polymer
  • Properties affect all cereal foods
  • Functional component in many non-cereal foods
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47
Q

Ancient uses of starch

A

-Medicinal applications, textiles, cosmetics by ancient romans and Egypytians.

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48
Q

Complex carbohydated (CHO) definition

A

Large, polymeric polysaccharide (many gluclose molecules)

-exist in nature as granules (water insoluable, highly organized structure) main source of energy for plants

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49
Q

Which crops have compound starch granules

A

rice and oats (makes them very tiny)

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50
Q

Unique characteristics of starch CHOs (digestibility)

A

-Digestible by enzymes in monogastic (human) gut. Other polymers its not until the end of the gut

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51
Q

Starch granule the branched polymers are ___ and the linear is ____

A
  • crystalline

- amorphous

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52
Q

Unique characteristics of starch

A
  • inexpensive biopolymer

- Extreme uniformity in granule size (difficult to duplicate non-biologically)

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53
Q

Non-Food uses for starch

A

Textiles

Pharmaceuticals, paper, and misc.

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54
Q

Starch Food Uses (types)

A 
-Adhesion
Binding -pellets
Clouding - drinks
Gel formation - pudding
glazing
-Dusting- candies
Flow- keeps lumps from forming
Thickening - salad dressings
55
Q

Starch sources- world wide

A 
Cereals (maize leader x10)
Roots and tubers
fruits
stems
beans
56
Q

Principal component of starch

A 
Glucose (same thing as dextrose)
-Alpha-D
-As polymers
Minor components
-lipids, minerals (phosphorus & nitrogen)
57
Q

Lipid component in starches

  • From what
  • effect in the starch
A
  • minor

- inhibits water uptake and swelling –> cooking effects

58
Q

Mineral Phosphorus in starches

  • From what
  • linkage
A
  • minor
  • NOT contently linked to starch (only potatoes do naturally)
  • from phospholipids (cereals only)
59
Q

Mineral Nitrogen in starches

  • From what
  • effect in the starch
A
  • minor
  • partly from lipids, partly from protein
  • may make up the coating that interferes with the protein matrix around granules in soft wheat
60
Q

Glucose

-structure

A

Simple 6 carbon monosaccharide that are very specifically oriented
-open chain (linear rope) and ring form (in solution)

D-Glucose= right handed rotation in water /polarized

61
Q

Beta Glucose structure

A

Hydroxyl (OH) group is cis (same side) as C6 group

62
Q

Open chain glucose

  • name
  • function
A

Aldehyde

  • can reduce Cu2+ in assays (turns potato blue)
  • BC it is a reducing sugar
63
Q

Ring form glucose

  • name
  • function
A

Heiacetal

  • can’t reduce Cu2+
  • not a reducing sugar
  • functions as a fiber when digested
64
Q

Alpha form of glucose

A

OH (hydroxyl) is opposite

-C1 linked to C4 using an alpha bond

65
Q

As we break down polymers we increase the number of ____

A

reducing groups, which increases the reducing capacity

66
Q

Amylose

  • what/location
  • structure
A
  • minor polymer of starch

- linear (only tiny branches) but flexible

67
Q

Amylose behaviors

A
  • linear structure
  • forms a double helix in water
  • strong interactions with self and others
  • results in strong gels and films
68
Q

Four classifications of protein

A

Albumins - water soluable
Globulins- soluable in salt
Prolamins- soluable in 70% ethyl alcohol (large storage)
Glutelins- soluable in dilute acids or base (large storage)

69
Q

What proteins does whole wheat flour have that refined doesn’t

A

Albumins and Globulins which are found in the Alueron, germ, and pericarps. Are high in limiting amino acids

70
Q

wheat protein content controlled by

A

Genetics and environment will affect end-use

71
Q

Good conditions late in seed development of wheat affects protein starch by

A
  • more starch synthesis
  • Higher yields
  • Lower protein
72
Q

Drought or frost damage to wheat plant affects protein and starch by

A

-Higher protein content

73
Q

Good moisture and climate increases yield and ____ protein

A

decreases

74
Q

wheat with a low percent protein content will have large amounts of ___ and ___

A

albumins and globulins

75
Q

As the percent protein in wheat increases, the total amount of ___ and ___ increases, but the relative proportion _____ because___

A

albumins and globulins… decreases because you are getting more storage proteins.

76
Q

In wet millingwheat ___ and ___ come off as soluables

A

albumins and globulins

77
Q

In wet milling wheat ___ and ___ are insoluables

A

prolamines and glutelins

78
Q

Glutelins are further fractionated into

A

Glutenins

79
Q

Prolamines are further fractionated into

A

Gliadins

80
Q

Gliadins (prolamines) and Glutenins (glutelins)

  • FOrm what
  • amounts present relative to eachother
  • controlled by
A
  • Gluten forming proteins (form strong doughs that will retain gas)
  • present in equal amounts
  • Under genetic control
81
Q

Gliadins

  • gives gluten which characteristics
  • present in varieties
A
  • Allows gluten to be stretchy and extensible
  • Not all wheat cultivars have these proteins, it is under genetic control. Bred for selectively
  • Single chains with no inter-chain linking
  • puts a kink in the chain influencing functionality
82
Q

Glutenins

-gives gluten which characteristics

A
  • Rubbery, snap back, wants to stay together

- Become very large cross-linked molecules

83
Q

Glutenin polymerization

  • starts when
  • gives what to doughs
A
  • starts at flowering in early seed development
  • results in huge polymers
  • Gives dough strength and elasticity
84
Q

Cereal with the highest percent protein

A

oats

  • good amino acid balance
  • mostly globulins
85
Q

Cereal with the lowest percent protein

A

Rice

  • relatively good amino acid balance
  • difficult to solubilize
  • protein is in protein bodies
86
Q

Proteases

-function

A

break peptide bonds of amino acids

87
Q

Endoproteases

-work where

A

Work on the interior structure of proteins to produce chunks of amino acids

88
Q

Exo-proteases

A

Work on the ends of proteins, won’t change gluten elasticity

89
Q

Rye proteins

-kind and amounts

A

Double in albumins and globulins

Has more prolamine than glutelin (wheat has equal amounts)

90
Q

Proteases have a ___ variety of specificity and function

A

wide

91
Q

Unique characteristics of gluten

A

35% glutamine
very hydrophobic
has a kink/bend which makes it very different in shape
very low charge density makes it dense

92
Q

viscous

A

resistance to flow - thick

93
Q

Elastic

A

will return to its size and shape instantaneously when stretched and released.

94
Q

Glass transition

A

transition from vicious state to glassy state

*most important physical property of amphorous polymers

95
Q

Modulus definition

A

Resistance to deformation (stiffness)

ie. stiff doesn’t move much when you push on it

96
Q

glass definition

A

rigid, fragile, brittle

97
Q

rubbery definition

A

flexible. Higher molecular weight, higher the rubbery platue .
Stretch and snap back

98
Q

Plasticizer definition

A

Small molecule added to soften a polymer. Water is the universal plasticizer in foods
Lower the Tg temp by reducing friction between molecules and make them more flowable

99
Q

Glass transition temperatue

A

Midpoint of temp range between glassy and rubbery state
-varies with temperature (energy) an moisture - ie. larger molecules need more energy to get moving so have a higher Tg temp

100
Q

Below Tg the state is

A

glass-like

no segmental motion or interaction

101
Q

Above Tg the state is

A

Leathery into rubbery
-chain motion increases
-inter-chain interaction increases
Modulus of elasticity- change of how it feels

102
Q

Modulus of elsaticity

A

change of how it feels, the bite

103
Q

Cross linked polyers and glass transition

A

They don’t have a glass transition, they will go right into decomposition

104
Q

Tg in dry milling tempering when
Toughening the bran
Mellowing endosperm

A

-cellulose undergoes glass transition as water diffused into the kernel

105
Q

Wheat gluten glass transition occurs

A

At room temp with excess water

106
Q

What happens at Tg

A

Polymers make dramatic changes in their modulous

107
Q

Why we can’t get dough from maize proteins

A

Dense protein bodies and very high Tg means water can’t penetrate at room temp

108
Q

Why is wheat dough so unique in its glass transition

A

it will occur at room temp with excess water

109
Q

Cellulose linkage, crystalinity and digestability

A

Beta 1,4
partially crystalline
-non digestable by monogastrics -its fiber

110
Q

Minor consitituents, low in __ high in___

A

low in percentage, high in importance likely to the plant

111
Q

Hemicellulose

  • structure
  • includes
A

Vary widely in sugars and size

include beta glucans, arabinoxylans

112
Q

Lignin

function

A

Cell wall strength

-complex and diverse structure lacking a primary structure

113
Q

Wheat hemicellulose exsist as __ and __

A

Water Extractable and water Unextractable in a 2:1 ratio

114
Q

WE_AX

-role in dough

A

Increase water absorption and viscosity

stabilize gas in cells in the oven

115
Q

WU_AX

-role in dough

A

destabilize dough, forms physical barriers in gluten network. Interferes with starch extraction in wet milling (requires enzymes to break down)

116
Q

Wheat hemicellulose arabinogalatan peptides

A

Involved in coating on soft wheat that prevent the protein matrix from bonding tightly with starch granules.

117
Q

Barely hemicellulose beta-glucans characteristics

A

highly viscous, potentially gel-forming

118
Q

Non-starch degrading enzymes

A

Wide variety in function and therefore enduse.

break down betaglucans, cellulose, etc

119
Q

Germ has the ____ sugar content

A

highest, for germination

120
Q

Phytic acid

  • made of
  • function
A

Major form of phosphorus in cereals

-Chelates cations such as Ca, Mg, Fe, Zn. Decrease absorption of these minerals so not good nutritionally

121
Q

Most minerals are in the

A

Aluerone

122
Q

Most vitamins are in the

A

aleurone or scutellum (especially b-vitamins)

123
Q

Fatty Acid definition

A

Caryboxylic acids with long hydrocarbon chains

124
Q

Highest lipid concentration is in the

A

germ

125
Q

Lipid in cereals are predominately

A

nonpolar and unsaturated

126
Q

Tocopherols function

A

antioxidants (vitamin E wheat) that slow rancidity by interrupting free radicals that feed the oxidation reactions

127
Q

Wax definition lipids

A

High melting point fat

128
Q

Rice lipids are mostly in the ___ which is unique

A

bran

129
Q

Free fatty acids will go __ faster when seperated

A

rancid

130
Q

LIpases

A

breakdown fatty acids, highest in oats and barely. Will cause more rapid rancidity

131
Q

cellulose is easily removed in milling bc

A

it is primarily in the hull and bran

132
Q

Barley has the highest ___ content of the cereals

A

sugar - important for malting and brewing

133
Q

Oats have lipid in the ___ which is unique

A

endosperm, why it requires stabilization

Cereal Science (4 decks)

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