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Introduction to food science > Chapter 7 > Flashcards

Chapter 7 Flashcards

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1
Q

The energy content of a food can be considered as

A

The amount of energy that would be produced if the body converted it to CO2+H2O by aerobic metabolism

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2
Q

How the energy content of food is measured

A

The heat released is termed the heat of combustion and can be
measured in a bomb calorimeter

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3
Q

What is one calorie

A

calorie = amount of heat required to increase the temperature of 1
gram of H 2 O by 1 C

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4
Q

What is the conversion betwen calories and joules

A

1 J = 0.239 cal 1 cal = 4.184 J)

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5
Q

Food calories are usually measured in ___

A

Kilocalories

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6
Q

Why measuring food by burning in a bomb calorimeter is not reliable and give the example

A

because it does not take into
account digestibility .+ if you take apples, you will need to take seeds, because we usually do not eat them, as well as remove the peel maybe, etc.

Combustion of 1 g of cellulose produces the same amount of
heat as combustion of 1 g of starch whereas the human body
completely hydrolyzes starch to its glucose subunits but cannot digest
cellulose.

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7
Q

If the calorimeter is not the reliable source of info about caloric properties of food, so how it is measured

A 
standard values for the heat of combustion of each
class of macronutrients have been adopted.

Accordingly, a common method is
to use analytical chemistry to
determine the amounts of each of the macronutrients in a food
sample and then multiply each amount by the corresponding standard
value.

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8
Q

Carbohydrates: calories and joules

A

4 kcal

16.7 kj/g

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9
Q

Protein: calories and joules

A

4 kcal/g

16.7 kj/g

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10
Q

Fat: calories and joules

A

9 kcal/g

37.7 kj/g

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11
Q

Alcohol: calories and joules

A

7 kcal/g

29.3 kcal/g

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12
Q

Organic acids :calories and joules

A

3 kcal/g

12.5 kj/g

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13
Q

Polyols(sugar alcohols):calories and joules

A

2.4 kcal/g

10 kj/g

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14
Q

Fiber : calories and joules and why it has calories if we day that we cannot digest it

A

2 kcal/g
8.4 kj/g
calories due to organic acids that are going to be metabolized by bacteria

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15
Q

Polyols have calories, but we still them use as sucrose replacer, why?

A

1) The way how sugar alcohols metabolized in a different way in our body , so they wont be converted to fat
2) More sweet than sucrose

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16
Q

Why fat have so many calories

A

because it has a much higher number of carbon atoms per
gram , and accordingly combustion to CO 2 involves reaction with a
larger number of O 2 molecules

In addition to their higher energy content, fats are a compact way to
store energy because they are nonpolar and therefore not hydrated ;

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17
Q

The longer the fatty acid, ____ the caloric intake

A

higher

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18
Q

Calorie reduced foods are usually formulated by ___

A


( using alternative sweeteners to reduce calories derived from sugars

or

(ii) using carbohydrate or protein based fat replacers to mimic certain
functional properties of fat

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19
Q

What are nutritive sweeteners

A


Sugar alcohols polyols ), e.g., xylitol, sorbitol, maltitol, mannitol, etc.:
these are “ nutritive sweeteners ” because they contribute calories
(1.5 3 kcal/g).

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20
Q

Similar properties of sugar and sugar alcohols

A
  • Most the functional properties with fewer calories, like sugar alcohols, they bind water by hydrogen bonding, which contributes
    to the moistness of baked products.
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21
Q

What are non-nutritive sweeteners

A

are substances that do not contribute to the
calorie content of the food. These very sweet substances are used to
replace sugars as a sweetening agent but cannot provide other
functional properties of sugars.

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22
Q

What sweetener have bitter aftertaste and 200X more sweet than sucrose

A

Acesulfame-K

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23
Q

Structure of aspartame

A

is the methyl ester of a dipeptide phenylalanine +

aspartic acid

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24
Q

Does aspartame have caloric content

A

Yes, the same as proteins

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25
Q

How many times aspartame is more sweet than sucrose

A

200

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26
Q

A sweetener than is similar to aspartame , but cannot be hydrolyzed by enzymes

A

neotame

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27
Q

neotame sweetness

A

7000-13000

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28
Q

Structure of sucralose

A

is a sucrose molecule in which three of the hydroxyl groups

are replaced by chlorine atoms

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29
Q

Sweetness of sucralose

A

600

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30
Q

What is simplesse

A

is a reduced calorie fat replacer made of

microparticulated milk and/or egg white proteins

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31
Q

Simplesse and ___ are used in fat reduced products

A

Microcrystaline cellulose

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32
Q

Why simplesse is used as fat replace r

A


Microparticulation provides the mouthfeel of fat with less than half the
calories.

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33
Q

Where simplesse cannot be used

A

the thermal denaturation

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34
Q

What is olestra

A

is a sucrose molecule in which 6 8 of its hydroxyl groups are
esterified with fatty acids

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35
Q

Olestra properties

A

It provides the same properties as fats, is heat stable at frying
temperatures, and is indigestible (0

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36
Q

Is olestra used?

A

No, because of diarrhea

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37
Q

Carbohydrate-fat replacers: examples and digestibility

A

Carbohydrate based fat replacers may contribute calories (e.g.,
starch gels) but often are indigestible polysaccharides .

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38
Q

Roles of carbohydrates in digestion

A

Carbohydrates : both sugars and starch assist the body in utilizing fats
more efficiently by producing organic acids that are required to
convert fats fully to CO 2 and water ( extract maximum energy from
fat metabolism).

The roles of indigestible carbohydrates ( fiber ) in promoting health
have been increasingly recognized over the past few decades.

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39
Q

Fats and oils provide

A

: fats/oils provide the essential fatty acids ω 3 and ω 6

fatty acids) and are important carriers of fat soluble vitamins

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40
Q

Protein needs are the greatest at what point of time

A

Protein needs are greatest during pregnancy and childhood (growth).

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41
Q

What plant sources lack lysine

A

Wheat, corn and rice proteins

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42
Q

Legumes (soybean) lack

A

Methionine

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43
Q

How protein quality is measured

A

Protein digestibility and the effects of amino acid

balance/imbalance

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44
Q

What is protein efficiency ratio (PER)

A

Measure of animal’s weight gain/gram of protein consumed

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45
Q

What is BV

A

Biological value measures overall nitrogen retention

Calculated= nitrogen in protein consumed-nitrogen excreted

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46
Q

Net protein utilization formula

A

NPU=BV*digestibility factor

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47
Q

Net protein value (NPV) formula

A

NPU*%protein in food

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48
Q

What is PDCAAS

A

Protein Digestibility Corrected Amino Acid Score (PDCAAS)

The protein quality rankings are determined by comparing the amino acid
profile of the specific food protein against a standard amino acid profile
with the highest possible score being a 1.0.

1.0 score means, after digestion of the protein, it provides per unit of
protein 100% or more of the indispensable amino acids required .

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49
Q

What is DIAAS

A

Digestible Indispensable Amino Acid Score (DIAAS)

It determines amino acid digestibility, at the end of the small intestine ,
providing a more accurate measure of the amounts of amino acids
absorbed by the body and the protein’s contribution to human amino acid
and nitrogen requirements.

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50
Q

Is PDCAAS is accurate

A

PDCAAS is based on an estimate of crude protein digestibility determined
over the total digestive tract, and values stated using this method generally
overestimate the amount of amino acids absorbed

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51
Q

What is the vitamin

A 
Organic compounds (other than essential
amino acids and essential fatty acids) required in the food supply to
maintain health and proper functioning of the body.
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52
Q

Food processing and vitamin content

A

Many food processing operations reduce the vitamin content or
availability in foods.

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53
Q

Fat soluble vitamins are usually more ___ than water soluble and also more likely to ___ ( organism)

A

Stable

Excessive amounts

54
Q

3 forms of vitamin A

A

Retinol
Retinal
Retinoic acid

55
Q

Where you can find vitamin A

A

Vitamin A is only found in animal derived food products but β
carotene , found in plants, is a precursor and is thus known as pro
vitamin A (but is not a vitamin

56
Q

Roles of vitamin A

A

Retinol
Strengthens mucous membranes;
keeps skin flexible

Retinal
Plays a fundamental role in vision:
vitamin A deficiency
affects night vision

Retinoic acid
Regulates gene expression/
protein production in cell nucleus

57
Q

What type of vitamin A can be toxic

A

Vitamin A itself ( from liver)

But not from beta-carotene

58
Q

Milk in Canada is supplemented with

A

Vitamin A and D

59
Q

Vitamin d in the body is synthesized from

A

cholesterol and other sterols upon exposure to sunlight (specifically
UV B).

60
Q

Vitamin D is involved in

A

Vitamin D is involved in the absorption of calcium/phosphorus from
the kidneys.

61
Q

Deficiency of vitamin D in children can cause

A

Rickets

62
Q

How supplement of vitamin D is prepared

A

(Supplement is prepared by UV irradiation of ergosterol produced by
yeasts.)

63
Q

Sources of vitamin D

A

Good food sources: fish, liver, dairy products, eggs

64
Q

Vitamin E- another name and its function

A

: Vitamin E α tocopherol) is a natural antioxidant , involved
in cell membrane (lipid) stability

65
Q

Where usually vitamin E is found and how it can be lost

A

Vitamin E is present in most unprocessed vegetable oils but may be
lost during processing and refining.

66
Q

Vitamin K roles, food source and how it is synthesized

A

Vitamin K has several roles in the human body, including a role in
blood clotting

Good food sources: spinach/cabbage

Vitamin K is also synthesized by microorganisms in the intestinal
tract

67
Q


Water soluble vitamins are generally _____ than fat soluble
vitamins and more easily _____ during
processing and/or cooking.

A

less stable

lost due to leaching into water

68
Q

Other name for vitamin C

A

L-ascorbic acid

69
Q

Deficiency disease of vitamin C

A

Scurvy

70
Q

Scurvy symptoms

A

: symptoms include anemia, gum
degeneration, tooth loss, hemorrhaging in the skin, and mucous
membranes (and ultimately death).

71
Q

Where the name ascorbic acid come from

A

ascorbic acid derives from the anti scurvy ( scorbuticus in

Latin) function of this molecule.

72
Q

Vitamin C is very easily ____

A

oxidized

73
Q

Vitamin C is only active in its reduced form, so what should be done to preserve its function

A

Reduce exposure to air

74
Q

Common food sources of vitamin C

A

Fruits and vegetables

75
Q

RDA for vitamin c

A

75-90 mg/day

76
Q

In what forms vitamin C is added as an antioxidant

A

Both L ascorbic acid and its stereoisomer D isoascorbic acid

(erythorbic acid) are food additives employed as antioxidants

77
Q

Why companies might like to use D isoform is vitamin D , but it is not good

A

D isoascorbic acid is cheaper but has 20 × less vitamin activity

78
Q

Roles of vitamin B

A

enzyme cofactors

79
Q

RDA for vitamin Bs

A

values for these vitamins range from a few milligrams/day

down to a few micrograms/day

80
Q

Name vitamin B1, B2,B12,B3, B5 ,B6,B7,B9 and the other one

A 
B 3 : Niacin

B 5 : Pantothenic acid

B 6 : Pyridoxine, pyridoxal, pyridoxamine

B 7 : Biotin (formerly known as vitamin

B 9 : Folacin/folic acid

Choline
81
Q

Source of thiamine

A 
animal products (meat,
liver, fish, poultry, etc.) and grain based products
82
Q

Deficiency in vitamin B1 can lead to

A

beri beri (leading to muscle atrophy and death)
was associated with consumption of a diet largely made up of
polished ” rice (bran removed contains the thiamin)

83
Q

Vitamain B1 is destroyed when and consequence of that

A

by its reaction with sulfite , a food additive;

addition of sulfite to meat (a good source of thiamin) is not permitted.

84
Q

Source of riboflavin

A

: good food sources include dairy products, meat, liver,

leafy vegetables, and yeast.

85
Q

Riboflavin in milk gives what color

A

yellow/green

86
Q

Riboflavin is sensitive to ____ and resistant to

A

heat resistant but light sensitive

87
Q

What metal does vitamin B12 has in its structure

A

contains cobalt in a porphyrin ring.

88
Q

Sources of vitamin B12

A

Meat products

89
Q

RDA for cobalamin

A

3 micrograms/day

90
Q

It is necessary to obtain the RDA of water soluble vitamins
from diet on daily basis.

True/false

A

True

91
Q

Definition of minerals (in nutrition):

A

Inorganic elements required in the

food supply to maintain health and proper functioning of the body.

92
Q

Trace elements: what are they and issues with them

A

Selenium and cobalt are required in trace amounts

but are toxic at higher levels

93
Q

What metals are toxic even at low levels

A

Lead and arsenic

94
Q

Role of Na and RDA

A

Maintain fluid and electrolyte balance;
sodium ion channels

2000 mg/day

95
Q

Role of K and RDA

A

Potassium ion channels

2000 mg/day

96
Q

Role of Cl and RDA

A

HCl for gastric juices

2500 mg/day

97
Q

Role of Ca and RDA

A

Main mineral component of bones and teeth;
calcium ion channels
1200 mg/day

98
Q

Role of P and RDA

A

Energy transfer in the form of ATP/
ADP/ AMP ( present in every cell);
mineral component of bones and teeth
1200 mg/day

99
Q

Role of Mg and RDA

A

Enzyme cofactor

300 mg/day

100
Q

Role of I and RDA

A

Part of thyroid hormones

150 mg/day

101
Q

The most common nutrient deficiency in industrialized countries is

A

Iron deficiency

102
Q

Role of Fe and RDA

A

Oxygen transfer (
hemoglobin/ myoglobin)
15 mg/day

103
Q

Role of Zn and RDA

A

Digestion/
metabolism of proteins

15 mg/day

104
Q

Main job in food preservation is to design ____

A

processes that minimize

nutrient losses and maximize nutrient bioavailability

105
Q

How much of iron on food is actually absorbed

A

1-10%

106
Q

stability of vitamin A to oxidation/light

A

Unstable in both

107
Q

Cooking losses of water-soluble vitamins can be minimized by

A

Steaming

Microwave cooking

108
Q

stability of vitamin d to oxidation/light

A

unstable in both

109
Q

stability of vitamin k to oxidation/light

A

stable to oxidation, unstable to light

110
Q

stability of vitamin E to oxidation/light

A

unstable in both

111
Q

stability of vitamin C to oxidation/light

A

Unstable in both

112
Q

stability of vitamin B1 to oxidation/light

A

unstable to oxidation

Stable to light

113
Q

Stability of vitamin B2

A

stable to oxidation

unstable to light

114
Q

stability of minerals to oxidation/light

A

stable to both

115
Q

stability of essential fatty acids to oxidation/light

A

unstable to both

116
Q

stability of essential amino acids to oxidation/light

A

stable to both

117
Q


Some foods contain ____ : processing may reduce
their effects and thereby enhance _____of certain food
constituents.

A

antinutritional factors

bioavailability

118
Q

2 examples of antinutritional factors

A 
-phytate (cereals and legumes)
Trypsin inhibitor (soybean)
119
Q

Another name for phytate

A

(inositol hexaphosphate )

120
Q

Why phytates are bad

A

Its six phosphate groups bind calcium, iron, phosphorus and other
cations in foodstuffs by chelation and hence reduce their
bioavailability

121
Q

What has been done to corn to male more nutritious for animals and humans

A

reduced phytate content by genetic modification

122
Q

What is a trypsin inhibitor

A

: a protein present in soybeans acts as an inhibitor

of the digestive enzyme trypsin , which is a protease.

123
Q

How to make soy more bioavailable?

A

Heat processing (cooking) denatures trypsin inhibitor

124
Q

Method of determining protein content and principle

A

Kjeldahl

Determination of nitrogen content

125
Q

How to determine moisture content and principle

A

Vacuum oven

Weight difference before/after drying

126
Q

How to determine fat content and principle of this method

A

Soxhlet

Ether extraction

127
Q

How to determine inorganic content in foods and its principle

A

Ashing

Combustion

128
Q

Method to determine carbohydrate content

A

100-(P+M+F+A)

129
Q

What is used in Kjeldahl method and what it assumes

A

Protein content is derived from the nitrogen content of the food
using a conversion factor : although the true conversion factor
depends on the amino acid composition of the protein, a factor of
6.25 is generally used.

Assumes that all nitrogen is coming from protein

130
Q

How milk adulteration was conducted in China

A

milk scandal in China was due to adulteration of milk with

melamine (nitrogen content: 75 %) to fool ” the Kjeldahl test.

131
Q

More complex and expensive analytical methods are employed for
the determination of:

A 
Saturated, monounsaturated, polyunsaturated, and trans fat content

Fiber

Vitamins

Specific minerals, etc.
132
Q

The fraction of the absorbed nutrient that reaches the systemic
circulation is nutrient

Absorptivity
b.
Daily intake
c.
Bioavailability
d.
Digestibility
e.
None of the above……
A

bioavailability

Introduction to food science (12 decks)

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