Chapter 4

Question 1

How fats and oils are usually characterized

Answer 1

Hydrolyzing all the ester bonds with a strong base and then analyzing the composition of the resulting mixture with Gas chromotography

Question 2

How much free FAs are there in fat or oil

Answer 2

Less than 1 % with the exception of olive oil

Question 3

Physical properties of fats and oils are determined by

Answer 3

Fatty acid composition

Question 4

Relationship of FAs structure and melting points

Answer 4

increases with increasing chain length

decreases with increasing number of cis double bonds

increases with isomerization of cis double bonds to trans double bonds

Question 5

Why coconut oil is the exception from the rule

Answer 5

Lipids from animal sources tend to be more saturated and are fats .

Lipids from plant sources tend to be more unsaturated and are oils .

Tropical oils such as coconut and palm are exceptions : They are
highly saturated but have relatively low melting points because the
fatty acids have short chain lengths

Question 6

Lipids from fish sources are highly___

Answer 6

PUFAs

Question 7

What is catalytic hydrogenation

Answer 7

A process of conversion of vegetable oils to fats by decreasing their degree of unsaturation (addition of H 2 across the double
bonds)

Question 8

Risk of catalytic hydrogenation

Answer 8

Cis to trans isomerization

Question 9

Hydrogenated fats have been widely used for

Answer 9

Hydrogenated fats have been widely used in the manufacture of
margarines and vegetable oil based shortenings

Question 10

Now research show that trans fats are bad for cardiovascular disease, what industry have done with it

Answer 10

The fats & oils industry is now extensively using an alternative process
interesterification ) to convert liquid oils to solid

Question 11

Advantages of hydrogenation

Answer 11


longer shelf life than oil or lard

greater stability and lower production costs than lard

faster dissolving and setting properties in chocolate production

Question 12

Nutrition importance of fats and oils

Answer 12


Concentrated source of energy

Source of essential fatty acids : linoleic acid, linolenic acid

Precursors for membrane lipids and prostaglandins

Carriers of fat soluble vitamins (A, D, E,

Help regulate body temperature

Protect vital organs from injury

Participate in cell production

Produce hormones and other secretions

Question 13

Role of fats and oils in frying

Answer 13


Heat transfer agents : Frying oils can reach very high temperatures
200 o C).

Transfer of heat to the surface of a food immersed in the oil drives
off water as steam.

Both the high temperature and the loss of water are conditions that
promote the Maillard reaction

During frying, oil is absorbed by the food and contributes to the
sensory characteristics of the product (as well as its caloric content

Question 14

What do fats do in backed goods

Answer 14

Lipids tenderize baked products

Fats shorten flour s protein strands , which cause chewiness and toughness

Aeration : Because lipids and air are both hydrophobic ; one of the
functions of fats in baking is to incorporate air bubbles , which expand
at baking temperatures and contribute to the volume and height of the
baked product.

Question 15

Fat to flour ratio determines ___ of the baked good

Answer 15

Flakiness

Question 16

Lipids with high melting point work best for ___

Answer 16

work best for biscuits, pies, and puff pastry

Question 17

Oils can be used in ___ (baking)

Answer 17

mix batters for products like pancakes, muffins,

and waffles

Question 18

Function of fats and oils in bread and salads

Answer 18

Lubricating agents : for foods such as bread and salads , usually in the
form of emulsions : oil in water (o/w) or water in oil (w/o).

Salad dressing is an o/w emulsion.

Butter is a w/o emulsion.

Question 19

Much of the flavor of the food is due to

Answer 19

Much of the flavor in food is due to the addition of salt, sugar, and fats

Question 20

Common lipids that season foods

Answer 20

Common lipids that season foods are butter, margarine, and mayonnaise

Question 21

Fats ___ and ___ flavor compounds

Answer 21

Dissolve and disperse

Question 22

Rating of the most flavorless oils

Answer 22

Cottonseed oil is one of the most flavorless oils, followed by vegetable shortening and soybean and canola

Question 23

Other properties of fats and oils in products

Answer 23

Contributors to texture/mouthfeel

Contributors to feeling of satiety (feeling

Question 24

What is plasticity and solid fat content

Answer 24

However, fats and oils are always composed of mixtures of
triglycerides , and hence they melt ” over a wide temperature range

Within this temperature range, the substance is a mixture of solid fat
and liquid oil , defined by its solid fat content (SFC).

The plasticity of the fat ( ability to be molded or spread ) depends on
the SFC.

Question 25

Substituents of fat in calorie-reduced products

Answer 25

olestra, a sugar polyester . It is not absorbed or

metabolized by the body; hence, it does not contribute calories, but have laxative effect

Question 26

What is fat/oil autoxidation

Answer 26

refers to reactions that occur in fats and oils over time in
the presence of O 2

Autoxidation causes fats and oils to become unpalatable because the
oxidation products are responsible for off flavors (oxidative
rancidity).

Question 27

Type of fat and autoxidation properties

Answer 27


The rate of autoxidation is very slow for totally saturated fat but
increases exponentially with increasing number of double bonds in
the fatty acyl (aliphatic) chains of triglyceride molecules.

Accordingly, highly polyunsaturated oils are particularly susceptible
to oxidative rancidity-> cancer risk, oxidative stress

Question 28

What are added to oils to delay autoxidation

Answer 28

Antioxidants

Question 29

What is lipolysis

Answer 29

Hydrolysis of triglycerides, producing free fatty acids.

Lipolysis occurs at high temperatures in the presence of water : these
conditions are encountered during frying (with the water coming from
the food immersed in the oil).

Question 30

Result of different smoke points between TGs and FFAs

Answer 30

Because free fatty acids have a much lower boiling point than
triglycerides, lipolysis results in a reduction in the smoke point of a
frying oil (making it necessary to discard the oil).

Question 31

What is smoke and flame points

Answer 31


Smoke point is the temperature at which fatty acids break apart and
produce smoke

Flash point is the temperature at which lipids will flame

Question 32

Phospholipids are natural ___, because they have hydrophylic and hydrophobic chains

Answer 32

Emulsifiers

Question 33

Composition of phospholipids

Answer 33

2 FAs, glycerol and phosphocholine

Question 34

Phospholipids are important for food scientists as ___ and ___

Answer 34

Structural ad nutritional

Question 35

Phospholipids are abundant in ___

Answer 35

Egg yolk

Question 36

Third group within the lipids is ___

Answer 36

Sterols

Question 37

Sterols include

Answer 37

Vitamin D
Steroid hormones, including sex hormones
Cholesterol

Question 38

Recommendation for healthy living in terms of cholesterol

Answer 38

• exercise
• healthy weight
• limit saturated fat and cholesterol
• and read labels

Question 39

how many calories can come from fat

Answer 39

20-35%