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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
How many times aspartame is more sweet than sucrose
200
26
A sweetener than is similar to aspartame , but cannot be hydrolyzed by enzymes
neotame
27
neotame sweetness
7000-13000
28
Structure of sucralose
is a sucrose molecule in which three of the hydroxyl groups | are replaced by chlorine atoms
29
Sweetness of sucralose
600
30
What is simplesse
is a reduced calorie fat replacer made of | microparticulated milk and/or egg white proteins
31
Simplesse and ___ are used in fat reduced products
Microcrystaline cellulose
32
Why simplesse is used as fat replace r
 Microparticulation provides the mouthfeel of fat with less than half the calories.
33
Where simplesse cannot be used
the thermal denaturation
34
What is olestra
is a sucrose molecule in which 6 8 of its hydroxyl groups are esterified with fatty acids
35
Olestra properties
It provides the same properties as fats, is heat stable at frying temperatures, and is indigestible (0
36
Is olestra used?
No, because of diarrhea
37
Carbohydrate-fat replacers: examples and digestibility
Carbohydrate based fat replacers may contribute calories (e.g., starch gels) but often are indigestible polysaccharides .
38
Roles of carbohydrates in digestion
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.
39
Fats and oils provide
: fats/oils provide the essential fatty acids ω 3 and ω 6 | fatty acids) and are important carriers of fat soluble vitamins
40
Protein needs are the greatest at what point of time
Protein needs are greatest during pregnancy and childhood (growth).
41
What plant sources lack lysine
Wheat, corn and rice proteins
42
Legumes (soybean) lack
Methionine
43
How protein quality is measured
Protein digestibility and the effects of amino acid | balance/imbalance
44
What is protein efficiency ratio (PER)
Measure of animal's weight gain/gram of protein consumed
45
What is BV
Biological value measures overall nitrogen retention Calculated= nitrogen in protein consumed-nitrogen excreted
46
Net protein utilization formula
NPU=BV*digestibility factor
47
Net protein value (NPV) formula
NPU*%protein in food
48
What is PDCAAS
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 .
49
What is DIAAS
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.
50
Is PDCAAS is accurate
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
51
What is the vitamin
``` 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. ```
52
Food processing and vitamin content
Many food processing operations reduce the vitamin content or availability in foods.
53
Fat soluble vitamins are usually more ___ than water soluble and also more likely to ___ ( organism)
Stable | Excessive amounts
54
3 forms of vitamin A
Retinol Retinal Retinoic acid
55
Where you can find vitamin 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
Roles of vitamin 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
What type of vitamin A can be toxic
Vitamin A itself ( from liver) | But not from beta-carotene
58
Milk in Canada is supplemented with
Vitamin A and D
59
Vitamin d in the body is synthesized from
cholesterol and other sterols upon exposure to sunlight (specifically UV B).
60
Vitamin D is involved in
Vitamin D is involved in the absorption of calcium/phosphorus from the kidneys.
61
Deficiency of vitamin D in children can cause
Rickets
62
How supplement of vitamin D is prepared
(Supplement is prepared by UV irradiation of ergosterol produced by yeasts.)
63
Sources of vitamin D
Good food sources: fish, liver, dairy products, eggs
64
Vitamin E- another name and its function
: Vitamin E α tocopherol) is a natural antioxidant , involved in cell membrane (lipid) stability
65
Where usually vitamin E is found and how it can be lost
Vitamin E is present in most unprocessed vegetable oils but may be lost during processing and refining.
66
Vitamin K roles, food source and how it is synthesized
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
 Water soluble vitamins are generally _____ than fat soluble vitamins and more easily _____ during processing and/or cooking.
less stable lost due to leaching into water
68
Other name for vitamin C
L-ascorbic acid
69
Deficiency disease of vitamin C
Scurvy
70
Scurvy symptoms
: symptoms include anemia, gum degeneration, tooth loss, hemorrhaging in the skin, and mucous membranes (and ultimately death).
71
Where the name ascorbic acid come from
ascorbic acid derives from the anti scurvy ( scorbuticus in | Latin) function of this molecule.
72
Vitamin C is very easily ____
oxidized
73
Vitamin C is only active in its reduced form, so what should be done to preserve its function
Reduce exposure to air
74
Common food sources of vitamin C
Fruits and vegetables
75
RDA for vitamin c
75-90 mg/day
76
In what forms vitamin C is added as an antioxidant
Both L ascorbic acid and its stereoisomer D isoascorbic acid | (erythorbic acid) are food additives employed as antioxidants
77
Why companies might like to use D isoform is vitamin D , but it is not good
D isoascorbic acid is cheaper but has 20 × less vitamin activity
78
Roles of vitamin B
enzyme cofactors
79
RDA for vitamin Bs
values for these vitamins range from a few milligrams/day | down to a few micrograms/day
80
Name vitamin B1, B2,B12,B3, B5 ,B6,B7,B9 and the other one
``` 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
Source of thiamine
``` animal products (meat, liver, fish, poultry, etc.) and grain based products ```
82
Deficiency in vitamin B1 can lead to
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
Vitamain B1 is destroyed when and consequence of that
by its reaction with sulfite , a food additive; | addition of sulfite to meat (a good source of thiamin) is not permitted.
84
Source of riboflavin
: good food sources include dairy products, meat, liver, | leafy vegetables, and yeast.
85
Riboflavin in milk gives what color
yellow/green
86
Riboflavin is sensitive to ____ and resistant to
heat resistant but light sensitive
87
What metal does vitamin B12 has in its structure
contains cobalt in a porphyrin ring.
88
Sources of vitamin B12
Meat products
89
RDA for cobalamin
3 micrograms/day
90
It is necessary to obtain the RDA of water soluble vitamins from diet on daily basis. True/false
True
91
Definition of minerals (in nutrition):
Inorganic elements required in the | food supply to maintain health and proper functioning of the body.
92
Trace elements: what are they and issues with them
Selenium and cobalt are required in trace amounts | but are toxic at higher levels
93
What metals are toxic even at low levels
Lead and arsenic
94
Role of Na and RDA
Maintain fluid and electrolyte balance; sodium ion channels 2000 mg/day
95
Role of K and RDA
Potassium ion channels 2000 mg/day
96
Role of Cl and RDA
HCl for gastric juices | 2500 mg/day
97
Role of Ca and RDA
Main mineral component of bones and teeth; calcium ion channels 1200 mg/day
98
Role of P and RDA
Energy transfer in the form of ATP/ ADP/ AMP ( present in every cell); mineral component of bones and teeth 1200 mg/day
99
Role of Mg and RDA
Enzyme cofactor | 300 mg/day
100
Role of I and RDA
Part of thyroid hormones | 150 mg/day
101
The most common nutrient deficiency in industrialized countries is
Iron deficiency
102
Role of Fe and RDA
Oxygen transfer ( hemoglobin/ myoglobin) 15 mg/day
103
Role of Zn and RDA
Digestion/ metabolism of proteins 15 mg/day
104
Main job in food preservation is to design ____
processes that minimize | nutrient losses and maximize nutrient bioavailability
105
How much of iron on food is actually absorbed
1-10%
106
stability of vitamin A to oxidation/light
Unstable in both
107
Cooking losses of water-soluble vitamins can be minimized by
Steaming | Microwave cooking
108
stability of vitamin d to oxidation/light
unstable in both
109
stability of vitamin k to oxidation/light
stable to oxidation, unstable to light
110
stability of vitamin E to oxidation/light
unstable in both
111
stability of vitamin C to oxidation/light
Unstable in both
112
stability of vitamin B1 to oxidation/light
unstable to oxidation | Stable to light
113
Stability of vitamin B2
stable to oxidation | unstable to light
114
stability of minerals to oxidation/light
stable to both
115
stability of essential fatty acids to oxidation/light
unstable to both
116
stability of essential amino acids to oxidation/light
stable to both
117
 Some foods contain ____ : processing may reduce their effects and thereby enhance _____of certain food constituents.
antinutritional factors | bioavailability
118
2 examples of antinutritional factors
``` -phytate (cereals and legumes) Trypsin inhibitor (soybean) ```
119
Another name for phytate
(inositol hexaphosphate )
120
Why phytates are bad
Its six phosphate groups bind calcium, iron, phosphorus and other cations in foodstuffs by chelation and hence reduce their bioavailability
121
What has been done to corn to male more nutritious for animals and humans
reduced phytate content by genetic modification
122
What is a trypsin inhibitor
: a protein present in soybeans acts as an inhibitor | of the digestive enzyme trypsin , which is a protease.
123
How to make soy more bioavailable?
Heat processing (cooking) denatures trypsin inhibitor
124
Method of determining protein content and principle
Kjeldahl | Determination of nitrogen content
125
How to determine moisture content and principle
Vacuum oven | Weight difference before/after drying
126
How to determine fat content and principle of this method
Soxhlet | Ether extraction
127
How to determine inorganic content in foods and its principle
Ashing | Combustion
128
Method to determine carbohydrate content
100-(P+M+F+A)
129
What is used in Kjeldahl method and what it assumes
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
How milk adulteration was conducted in China
milk scandal in China was due to adulteration of milk with | melamine (nitrogen content: 75 %) to fool ” the Kjeldahl test.
131
More complex and expensive analytical methods are employed for the determination of:
``` Saturated, monounsaturated, polyunsaturated, and trans fat content  Fiber  Vitamins  Specific minerals, etc. ```
132
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…… ```
bioavailability

Introduction to food science (12 decks)

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