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Chemistry 3 + 4 > Chapter Twelve : Food and Energy > Flashcards

Chapter Twelve : Food and Energy Flashcards

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1
Q

Monosaccahrides

A 
White crystalline solids
Soluble
Strong reducing agents
Monomers of carbohydrates
Not broken down during digestion
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2
Q

Disaccharides

A

When 2 monosaccharides join to make a carbohydrate
Maltose - 2 glucose molecules
Sucrose - 1 glucose/1 fructose
Lactose - 1 glucose/1 galactose

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3
Q

Polysaccharides

A 
When more than 10 monosaccharides join together
Considered complex carbs
Non-crystalline
Insoluble
Tasteless
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4
Q

Bonding between monosaccharides

A

A condensation reaction between hydroxyl on C1 and C4 occurs giving a glycosidic link

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5
Q

Sweetness/GI/Energy of sugars

A

Sweet -Aspartame>Fructose>Sucrose>Glucose>Lactose
16.7kjg-1
GI - Glucose>Sucrose>Lactose>Fructose>Aspartame

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6
Q

Aspartame

A 
White
Odourless
Soluble crystalline powder
Dipeptide
Made up of aspartic acid, phenylthaline and methanol
200x sweeter than sugar
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7
Q

Types of polysaccahrides

A

Starch
Glycogen
Cellulose

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8
Q

Starch

A

Major storage form of glucose in plants
Condensation polymer of alpha-D-glucose
Made up of amylose and amylopectin

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9
Q

Amylose

A 
20% of starch
Soluble
Smaller than amylopectin
50-300 alpha-D-glucose
Straight chain linkage C1 to C4
Spiral formation
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10
Q

Amylopectin

A

Insoluble
Loosely branched molecule
300-5000 alpha-D-glucose
Both C1 to C4 and C1 to C6 link

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11
Q

Glycogen

A

Storage form of glucose in animals in liver/muscles
Lots of branching from C1 to C6
C6H12O6 + 6O2 -> 6CO2 + 6H2O

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12
Q

Cellulose

A

Condesation polymer of beta-D-glucose
Main structural component of cell wall in plants
Humans cannot hydrolyse cellulose as we do not have the enzyme therefore it doesnt provide energy
Provides fibre

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13
Q

Lactose intolerance

A

When an individual has an insufficient amount of lactase in the body and cannot break down lactose

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14
Q

Glycemic Index

A 
Shows how quickly a carbohydrate is borken down and absorbed into the bloodstream
Glucose is 100
More fibre = lower GI
More amylopectin = Higher GI
More amylose = Lower GI
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15
Q

What factors affect absorption of carbs

A

Ripeness
bran - limits ability of enzymes to reach starch
Fibre - takes up space and slows digestion
Sugars - somesugars have lower GI
Proteins,fats and oils - Slow down stomach emptying
Food processing - Smaller particles have greater surface area
Cooking method - food swells and softens
Acidity - Slows down stomach emptying

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16
Q

Lipids

A 
Fats - solid
Oils - liquid
Energy stores
Components in cell membranes
Hormone production
Protection of vital organs
Transport fat-soluble vitamins
17
Q

Triglycerides

A

A fat or oil formed by condensation reactions between glycerol and 3 fatty acids

18
Q

Types of fatty acids

A

Saturated - all single C-C bonds
Mono-unsaturated - 1 double C=C bond
Poly-unsaturated - Multiple C=C bond

19
Q

Properties of fats/oils

A

Hydrophobic, less dense than water
Saturated fatty acids are solid and are formed from straight-chain fatty acids which have high dispersion forces, high stability
Unsaturated fatty acids have lower dispersion forces disrupting how close they pack together, they are more easily oxidised

20
Q

Hydrogenation

A

Hydrogen is added to unsaturated fatty acids to convert them to saturated fatty acids
The amount of hydrogen added determines melting point

21
Q

Iodine number

A

Measures degree of unsaturation
Mass of iodine that reacts with 100g of fat/oil
Iodine reacts with C=C bonds

22
Q

Oxidation of food

A

When foods go rancid
When food reacts with oxygen
Unsaturated fats are more susceptible from the C=C bonds
Molecules react with O2, free radicals formed cause destructive chemical reactions, the ketones, aldehydes and acids produce bad smells and flavours

23
Q

Preventing rancidity

A

Antioxidants slow down oxidation and prevent food from spoiling
They are reducing agents and therefore preferentially oxidised
Vitamin C is a natural antioxidant
Using vacuum packaging, full containers, dark and cold storage, opaque containersq

24
Q

Essential fatty acids

A

Must come from the diet as they cannot be synthesisesd
Omega 3 fatty acid - double bond on 3rd carbon
Omega 6 fatty acids - double bond on 6th carbon
Needed for processing of inflammation and nervous system
Flaxseed oil, tuna, linseed
Liver, kidney, blood and immune system

25
Q

Calorimetry

A

Is the measurement of the amount of heat released or absorbed in a chemical reaction,change of state or formation of a solution

26
Q

Calorimeters

A

Insulated container with a fixed amount of liquid which the temp rise and fall is measured.
Temp cahnge is converted to energy change

27
Q

Calibration factor(JC-1)

A

VIt/temp change

28
Q

Solution calorimeter

A

Energy change in aqueous solution

Acid-base or dissolution

29
Q

Heat loss in calorimeters

A

Good insulation = little heat loss, temp increases quickly, maintenence of temp when current is off
Bad insulation = lots of heat loss, temp decreases quickly, temp decreases after current is off

30
Q

Bomb calorimeter

A

Used to determine energy changes for gases
Faster reaction than solution calorimeter
However energy content is different to what it is when consumed as the body can’t use fibre and energy can be converted to heat

31
Q

Why is glucose used as a standard for GI values?

A

GI index is a measure of how quickly carbs are hydrolysed to glucose, glucose requires no hydrolysis so will have a high value. it is easy and available for use

32
Q

What does available carbohydrate mean?

A

The fraction of carbohydrates that can be digested by human digestion

33
Q

Why do athletes need high GI carbohydrates?

A

athletes have a high energy demand due to consumption of glucose in muscles
havin high gi foods will allow it to be avialble in a short period of time

34
Q

Electrical calibration

A

kJ/temp change

35
Q

Purpose of calibration

A

Relates the heat change to a temp change so when temp change occurs in a subsequent reaction the enthalpy change can be calculated

Chemistry 3 + 4 (12 decks)

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