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HDSO Food Science > Lecture 8 > Flashcards

Lecture 8 Flashcards

1
Q

What are natural fats composed of?

A

Composed of Esters of glycerol with fatty acids

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2
Q

what are the components of a fatty acid?

A

Alcohol and carboxylic acid

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3
Q

What is the most common glyceride?

A

triglyceride

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4
Q

What is butyric fat in?

A

Give dairy products flavour

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5
Q

What is the difference in structures of stearic, oleic, linoleic.

A

Stearic straight line

oleic curved like U shaped

linoleic straight but soft curved like Z shaped

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6
Q

Where are the double bonds in oleic and linoleic fats?

A

oleic= 9C

linoleic= 9 and 12 C

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7
Q

What are the 2 classes of lipids?

A

Simple structure

Complex structure

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8
Q

What are simple lipids?

A

Fats (oils): Glycerol + F.A.

Waxes: Long chain alcohol + F.A.

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9
Q

What are complex lipids?

A

Phospholipids: Glycerol + F.A. + P + others

Example:
-Phosphatides: Lecithin found in egg yolk

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10
Q

What is the structure like of dry fats?

A

they are more complex

EX: Fat soluble vitamins, carotenoids, steroids

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11
Q

What is the difference between visible and invisible fats?

A

Visible: butter on toast

Invisible: cooked/baked into things

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12
Q

How do we name saturated and unsaturated fatty acids?

A

Saturated F.A. ………. Suffix “anoic”

Unsaturated F.A. …… Suffix “enoic”

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13
Q

What are the major groups of fats and oils?

A

1) Lauric Acid Group
2) Palmitic Acid Group
3) Oleic-Linoleic Acid Group
4) Linolenic Acid Group
5) Vegetable Butter
6) Marine Oils
7) Animal Fat

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14
Q

What are characteristics of Lauric acid groups?

A

Coconut oil, palm kernel oil

Highly saturated

High in medium chain fatty acids C:10-C:14

High content of Lauric acid C:12

Melting range 25-30oC

Solid at room temperature

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15
Q

What do we mean when oils are highly stable?

A

Highly stable, so wont oxidized as easily and maintaining all properties

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16
Q

What are characteristics of palmitic acid groups?

A

Palm oil

Highly saturated C:16:0,

Palmitic acid

Crude palm oil is bright red due to high conc. of carotenoids

Melting range 38-450C , solid at room temperature

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17
Q

What are characteristics of oleic-linoleic acid groups?

A

Olive, peanut, cotton, sesame, corn, safflower, sunflower

Liquid at room temp.

Unsaturated

Major fatty acid:
Oleic acid C:18:1, Linoleic C:18:2 (ω-6)

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18
Q

What are characteristics of linolenic acid groups?

A

Soybean, flaxseed, canola

Significant amount of linolenic C:18:3 (ω 3)

Susceptible to oxidation

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19
Q

What are characteristics of vegetable butter?

A

Enrobing fat

Cocoa butter (Melting Point:32-35oC)

Fats in cocoa butter, solid at room temp and melting temp close to body temp

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20
Q

What are characteristics of marine oils?

A

Long chain fatty acids: EPA C:20:5 and DHA C:22:6

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21
Q

What are characteristics of animal fats?

A

Fat derived from animal body

Cholesterol
-Fats contain cholesterol, for examplee lard

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22
Q

What are the physical properties of fats that can be altered?

A

Melting point

Viscosity

Iodine#

Stability

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23
Q

What factors affect melting point?

A

Natural fats vs. Pure fats
Chain length ↑  m.p. ↑
Unsaturation ↑  m.p. ↓

Melting range for natural fats and meelting poiint for pure fat (only one type)
• Natural fats have differeent kindds

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24
Q

What are the factors affecting viscosity?

A

Chain length ↑  η ↑

Unsaturation ↑  η ↓

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25
Q

What are the factors affecting iodine #?

A

Unsaturation ↑  I # ↑

Higher iodine value higher level of unsaturation

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26
Q

What properties affect stability?

A

unsaturated vs saturated
-Saturatde fats more stable than unsaaturated

vegetable vs animal fat
-Veg fats are more stable than animal fats although they are more unsaturated but its because they contain natural antioxidants and are therfore more stable than animal fats whiich can be oxidized more readily

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27
Q

What are the 3 ways fats can deteriorate?

A

Lipolysis (hydrolytic ranidity)

Flavour reversion

Auutoxidation

28
Q

What is lipolysis?

A

Lipase cleaves Ester bonds > Free Fatty Acids

results in the production of a lot of Free fatty acids with:

  • decrease smoke point (undesirable)
  • creates off flavours
29
Q

What is the flavour reversion?

A

Linolenic acid > Off Flavour
-by addition of UV
Visible, light, Heat
O2, Fe, Copper

results in a Beany, Painty, Fishy flavours

30
Q

What is Autoxidation?

A

Oxidative rancidity most common

31
Q

What are the 3 steps to autoxidation?

A

1)Initiation: RH R + H
(R = Free Radical)
-Formation of free radical. When oiil/fat comes into contact with oxidative properties, free radicals start

2) Propogation: R + O2  ROO
- Free readical reactiwith O2 and more free readicals form

3)Termination:
 R  + R >   RR
RO + R  > ROR
ROO + R  >   ROOR
-When free readical react with one another

Rate ↑ as the process goes on

32
Q

What causes autoxidation (oxidative rancidity)?

A 
Heat 
Light
Ionizing Radiation
Metals (Fe and Cu)
Enzymes (Lipoxygenase)

To inhibit autoxidation keep away from all these

33
Q

What are antioxidants relationship to fat?

A

Antiodxidants combinw with free radical react with fats and then no more ar being form

34
Q

What are the synthetic antioxidants?

A

BHA [Butylated hydroxy anisole]

BHT [Butylated hydroxy toluene]

35
Q

What are the natural antioxidants?

A

Vit E. Tocopherol, α, β, γ, δ
Vitamin C,
Beta-Carotene

36
Q

What does citric acid do?

A

Citric Acid is a chelating agent which binds with iron and copper and inhibit oxidation
-When Fe and Cu are bound with citric acid they are no longer in the fre forma nd cant cause oxidation

37
Q

What are the different ways of extracting fats/oils?

A

Pressing

Solvent Extraction

38
Q

What is oil pressing?

A

Oil Seeds  Machine (screw press)  Squeeze the oil out  Crude Oil
-physical pressing

39
Q

What is solvent extractions?

A

Uses hexane to dissolve oil from the oilseed flakes

Two types:

1) Immersion: Seed-Flakes are totally submerged in Hexane
2) Percolation: Seed-Flakes are placed into baskets and Hexane is sprayed on top (hexane percolates through)

40
Q

What is a micelle?

A

(solvent + oil) is then collected

  • The crude oil is recovered from micella by distilling off the solvent
41
Q

What are the things that we want to remove from fats/oils when they are processed?

A 
Suspended solids
Gums, pigments
Lipoproteins, phospholipids
Mycotoxins
Others
42
Q

What are the different ways to remove unwanted particulate matter?

A 
Settling and Degumming
Neutralization
Bleaching
Deodorizing by Steam Distillation
Winterization
43
Q

What is settling and degumming?

A

By adding dilute H3PO4, Brine…

Removes: 
Non-Oil Impurities
Protein
Phospholipids: Lecithin
Vegetable Gums

Cude oiil put in the cone, so impuritiessetle to the bottom and theen open the valve and remove the bottomm

44
Q

What is neutralization?

A

Alkali (NaOH) added to oil

Free Fatty Acids Insoluble soaps (i.e. Na-salt) are filtered out

45
Q

What is bleaching?

A

Elimination of undesirable colours

Involves filtering through activated charcoal & clay

Also removes pigments, traces of gums, soaps

46
Q

What is Deodorizing. by steam distillation?

A

Removes flavour and odour compounds

Mild odor desired

Pump oil into chamber and pump stream in and vacuum the odors out

47
Q

What is winterization (Winterizing oil)?

A

is the process of holding fat at cold temp until cloud formation and then filtering high melting point fats.

The final oil stays clear at cold temp.

The winterized oils are used in salad dressings that need to stay clear in the refrigerator.

48
Q

How can we modify fats and oils?

A

Hydrogenation

Partial hydrogenation

49
Q

What is hydrogenations effects on melting point, stability, viscosity, Iodine #?

A

Increease melting point stability and viscosity because you have less double bonds

Iodine value would decrease because less double bonds

50
Q

What is partial hydrogenation?

A

Partial: don’t convert all double in to single, if they did complete the final fat would be hard and brittle and not very functional which Is why this is common in industry

51
Q

What is hydrogenation?

A

To icrease stability of fats and oils

Adding H to convert double bonds to single bonds , at high temp with a catalyst

52
Q

What is selective hydrogenation?

A

Used in manufacture of ? …. Margarine
Requires high temp (200oC) & low pressure (6psi)
Hydrogenation of Linoleic  Oleic predominates over hydrogenation of Oleic to Stearic
-Selective hydrogenation of these, higher trans fats and a softer fat

53
Q

What does selective hydrogenation result in?

A

Result> Softer Fat and high amount of Trans Fats

54
Q

What is non selective hydrogenation?

A

Used in the manufacture of ? …. Frying Fat

Requires lower temp (135oC) & higher pressure (40psi)

Oleic and Linoleic are hydrogenated simultaneously

Result  Harder Fat

55
Q

What is interesterificatoin?

A

Modify the physical properties of oil by randomizing the order of fatty acids on glycerol backbone

56
Q

What are the 2 ways we can achieve interesterification?

A

1) Heating the fat in the presence of Sodium Methoxide under anhydrous conditions
- Breking ester bonds to replace unsaturated FA with a searin asid, increeaseing the solid conted of fat

2) Biological Catalysts (Enzyme)
Lipase can replace Sodium Methoxide
Milder Condition
-Don’t have to use high heat with this

57
Q

What is polymorphism in fats?

A

Liquid Fat >Diff. patterns of molecular packing

Chilled at different rate > Diff. Crystal Structures

58
Q

What are the 3 main forms of fat crystal structure?

A

Hexagonal

  • randomly oriented
  • 5 micron
  • alpha

Parallel

  • 20-30 micron
  • beta

Needle shaped

  • alternating
  • 1micron
  • beta prime
59
Q

What do beta crystals result in?

A

Coarse and Grainy Texture (Not Desirable)

-i.e. Margarine, Shortening

60
Q

What is shortening?

A

Fat + Entrapped Air

61
Q

What is the best fat crystal structures?

A

Beta prime

Has smallest size and will be a smoother and creeamier fat

62
Q

What type of air bubbles are in beta and beta prime fat crystals?

A

Beta prime: Lots of small air bubbles (Desirable)

beta: Few large air bubbles (Not Desirable)

63
Q

What kind of mix is margin?

A

Water in oil emulsion

a Controlled Crystallization = Better Texture

64
Q

What is enrobing fats?

A

Found in Cocoa Butter

At Room Temp Hard and Brittle
Absence of Liquid Fat

At Mouth Temp Rapid Melting
(Cocoa Butter)

65
Q

What is tempering?

A

Process of holding fat at selected temp. to allow interconversion of crystalline forms
-Mke sure you have beta prime crystals

HDSO Food Science (17 decks)

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