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What is Food Chemistry?
Submitted by Deb Dommel
Modified from IFT Experiments Series “Food Chemistry”
What is food chemistry? Food Science deals with the production, processing,
distribution, preparation, evaluation, and utilization of food. Food chemists work with
plants that have been harvested for food, and animals that have been slaughtered for food.
Food chemists are concerned with how these food products are processed, prepared, and
distributed. For example, to address consumer demands, some food chemists are
involved with finding fat and sugar substitutes that do not alter food taste and texture.
Basic food chemistry deals with the three primary components in food:
carbohydrates, lipids and proteins.
Carbohydrates make up a group of chemical compounds found in plant and
animal cells. They have an empirical formula CnH2nOn or (CH2O)n. Since this formula is
essentially a combination of carbon and water these materials are called “hydrates of
carbon or carbohydrates”. Carbohydrates are the primary product of plant
photosynthesis, and are consumed as fuel by plants and animals. Food carbohydrates
include the simple carbohydrates (sugars) and complex carbohydrates (starches and
fiber).
Lipids include fats, oils, waxes, and cholesterol. In the body, fat serves as a
source of energy, a thermal insulator, and a cushion around organs; and it is an important
component of the cell. Since fats have 2.25 times the energy content of carbohydrates
and proteins, most people try to limit their intake of dietary fat to avoid becoming
overweight. In most instances, fats are from animal products – meats, milk products,
eggs, and seafood and oils are from plants – nuts, olives, and seeds. We use lipids for
flavor, to cook foods, and to improve the texture of foods.
Proteins are important components of food. Every cell requires protein for
structure and function. Proteins are complex polymers composed of amino acids. There
are 20 amino acids found in the body. Eight of these are essential for adults and children,
and nine are essential for infants. Essential means that we cannot synthesize them in
large enough quantities for growth and repair of our bodies, and therefore, they must be
included in our diet. Proteins consist of long chains of 100-500 amino acids that form
into three-dimensional structures, their native state. When you change the native state of
the protein, you change the three-dimensional structure, which is referred to as
denaturation. Factors that cause denaturation include heating, acid, beating and freezing.
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Vocabulary – Food Chemistry
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Amino acids – contain carbon, hydrogen, nitrogen and sometimes sulfur and
serve as the monomers to make peptides and proteins. Amino acids have a basic
structure that includes an amino group (NH2) and a carboxyl group (COOH)
attached to a carbon atom. There are 20 amino acids found in the body.
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Amylase – an enzyme (protein) in saliva that breaks down starch.
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Antioxidant – substance that prevents or slows down oxidation; inhibits reactions
promoted by oxygen; often used as a preservative.
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Carbohydrate – a compound of carbon and water. Carbohydrates are the most
abundant of all carbon-containing compounds, composing nearly three-fourths of
the dry mass of all plant life on earth. It is the product of photosynthesis.
Examples: glucose, sucrose (table sugar), starch, and cellulose.
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Casein – a protein from milk.
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Coagulation – transformation of a liquid into a soft or solid mass.
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Denatured – changed from its natural state. In a denatured protein, its
characteristics or properties have been altered in some way, by heat, chemicals, or
enzymatic action, resulting in the loss of its biological activity.
•
Digestion – the chemical breakdown of large food compounds into smaller
molecules that can be absorbed by the intestines in humans and animals. The
smaller food molecules travel in the blood and are used by cells to make other
components or produce energy needed by the body. Digestion begins in the
mouth as salivary amylase begins to break down starch into simple sugars. It
involves the hydrolysis of proteins to amino acids.
•
Emulsion –a property where two liquids are evenly spread out in each other, yet
not dissolved in each other. Oil and water form the most common emulsions, and
milk is an emulsion of butterfat in water. Emulsions are important in the
production of foods that contain water and fat, such as mayonnaise or margarine.
These products require the addition of an emulsifier, to stabilize food emulsions.
•
Enzymatic browning – a biochemical process in which fruit or vegetable tissues
turn brown when exposed to oxygen. This process is catalyzed by polyphenol
oxidase.
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Enzymes – protein catalysts, which control specific chemical reactions in living
systems (plants and animals). Enzymes are active at low concentrations.
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•
Ester bonds – bonds between fatty acids and glycerol molecules.
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Fatty acid – building blocks of fats, having hydrogen atoms attached to chains of
carbon atoms and a oxygen containing carbonyl group (-C=O). Fatty acids are
found in every cell of the human body.
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Glycerol – backbone for fatty acid molecules.
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Glucose – a simple sugar (C6H12O6) and the primary source of energy for all
mammals and many plants. It is also known as dextrose, grape sugar, and corn
sugar. It is about half as sweet as table sugar.
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Hormones – substances that can influence enzyme action, metabolism, and
physiology.
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Insoluble – not capable of being dissolved. Fats are insoluble in water. On the
other hand, sugar is soluble in water unless more is added than what a certain
volume of water can dissolve, which means that the solvent has become saturated
with sugar.
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Lecithin – emulsifier found in eggs and soybean oil.
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Lipids – compounds commonly of fatty acids and glycerol. Lipids are the most
efficient source of fuel in living things. Food lipids are divided into 1) fats,
which usually come from animal sources and are solid at room temperature; and
2) oils, which usually come from plant sources and are liquid at room
temperature. Another type of lipid is cholesterol. Cholesterol is a sterol
compound made by animals and is used to make certain steroid hormones in the
body. It is not found in plants.
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Melanin – any of a group of brown or black pigments occurring in plants and
animals.
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Organic – related to the branch of chemistry dealing with carbon compounds.
Though all living things contain carbon and thus are considered to be organic,
other carbon-containing compounds have been produced in the laboratory.
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Peptide bonds – covalent bonds between two amino acid molecules.
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Peptides – short chains of amino acids.
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Photosynthesis – process by which a plant uses water and carbon dioxide to
produce a simple sugar (glucose) and oxygen. Plants store excess sugar as starch.
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Polymers – contain ten or more monomers. Starch is a polymer of the monomer
glucose. A protein is a polymer of amino acids.
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•
Polyphenol oxidase – a copper-containing enzyme, also called phenolase, that
catalyzes the oxidation of phenolic compounds contained in plant tissue.
Example – it speeds the process of browning of cut apple slices.
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Polyunsaturated – fatty acids that have multiple double bonds.
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Proteins – complex polymers composed of amino acid monomers. Some
examples of protein are muscle, hair, skin, hormones, and enzymes.
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Rennin – enzyme used to make cheese.
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Shortening – crystalline form of a solid fat.
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Soluble – capable of being dissolved. Gases or solids that dissolve are called
solutes, while the liquid that does the dissolving is called the solvent. Like
substances are usually soluble in like solvents.
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Starch – a polymer of glucose. It is a complex carbohydrate found in green
plants and an important source of energy for animals and humans. During the
day, green plants store energy by converting glucose to starch. At night, plants
convert starch back to glucose for growth.
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Triacylglycerol - a lipid compound consisting of three fatty acids linked to one
glycerol molecule. This compound is an important source of energy for the
human body.
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Vegetable oils – come from plants like corn or soybeans and are an important
source of polyunsaturated fats.
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NAME______________________________
Freaky Fats: Fill in the blank spaces with the appropriate terms to complete the
sentences. Solve hidden message by entering the boxed letters in the spaces at the bottom
of the page.
1.
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__
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are long chains of carbon and hydrogen atoms that combine with glycerol
molecules to form a lipid.
2.
__ __ __
extracted from olives, canola, and corn are plant lipids and are liquid at room
temperature.
3.
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is a phospholipid emulsifier found in eggs and soybean oil.
4.
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are found between the fatty acids and the glycerol molecules in triacylglycerols.
5.
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is a crystalline form of solid fat.
6.
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are used to prevent the cocoa butter from separating out of chocolate bars.
7.
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fatty acids have multiple double bonds.
8.
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molecules form the backbone of attachment for fatty acid molecules.
9.
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fat is saturated because it contains all single bonds and is solid at room
temperature.
10.
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oils like corn and soybean are important food sources of polyunsaturated fatty
acids in our food supply.
HIDDEN MESSAGE:
In the United States, this once popular oil is no longer used by the food industry as an
ingredient, because it was reported to increase blood cholesterol level. It was used
primarily in cookies, cakes, and snack foods.
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NAME______________________________
Powerful Proteins: Fill in the blank spaces with the appropriate terms to complete the
sentences. Solve the hidden message by entering the boxed letters in the spaces at the
bottom of the page.
1.
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are short chains of amino acids.
2.
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of amino acids make up protein molecules.
3.
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are the building blocks of proteins.
4.
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can influence enzyme action, metabolism, and physiology.
5.
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is a proteolytic enzyme that is used to make cheese.
6.
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is a milk protein.
7.
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involves the hydrolysis of proteins to amino acids.
8.
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is a protein enzyme that breaks down starch in the mouth.
9.
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is the transformation of a liquid into a soft semi-solid or solid mass.
10.
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proteins are used for their foaming properties in desserts, cakes, and whipped
toppings.
HIDDEN MESSAGE:
Elementary school children frequently use this casein-based adhesive that was introduced
by Borden® over 50 years ago. Hint: There is a picture of Elsie the cow on the
container.
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1. Absorb (v): a. if sth absorbs liquid or gas, it soaks up or draws it in b. if sth absorbs heat or light, or another form of energy, it takes it in rather than reflects it (receive); Absorbent (adj): material, which soaks up liquid easily; Absorption (n); Absorbed (adj); 2. Abundant(adj): rich, full in something; having or containing sthg in large quantity Abundance (n): a large amount of something 3. Alter (v): change sthg into sthg different; convert to ; 4. Attach to(v); stick on to sthg; conjoin; attachment(n): a link; a joint 5. Backbone (n): the spinal column, the spine ; the basic structure of sthg (metaph.,) 6. Bond (n): an attractive force that holds together the atoms, ions, or groups of atoms in a molecule or crystal ; : a uniting or binding element or force : tie 7. Break down (phr. Vb): break sthg to its components or parts 8. Carbon :άνθρακας 9. Carboxyl (organic chemistry) A univalent functional group consisting of a carbonyl and a hydroxyl functional group (‐CO.OH); characteristic of carboxylic acids. καρβοξυλικόs 10. Catalyze (v): To bring about the catalysis of a chemical reaction. 11. Cellulose: The main polysaccharide in living plants, forming the skeletal structure of the plant cell wall; κυτταρίνη 12. Glucose :A simple monosaccharide sugar, which is a principal source of energy for most living things. γλυκόζη 13. coagulation (n): the act or process of making a substance (usually a liquid) thicker by adding another substance to it called a coagulant or thickener;Coagulate (v): clotting, thicken, congeal / coagulant (adj) ≠ anticoagulant(opp.) 14. Compose (v) : to form the substance of : constitute <composed of many ingredients>composition (n) ;Component(n) 15. Compound (n): a substance that consists of two or more different substances or chemical elements (ένωση) 16. Concentration (n) concentrate (v) 17. a concentrate (n): a liquid or substance from which unnecessary substances such as water have been removed in order to increase its effect 18. Consumer (n): products buyer; Consume (v): use up (power, amount, energy, fuel, time etc) (καταναλώνω); consumption(n) 19. Content (n): the part of sth which consists of a particular substance, ingredient etc ; contain (v): have as content; include substance or mass 20. Convert to(v): alter; change shg to sthg different; conversion(n); convertible(adj) 21. Covalent: (chemistry) containing or characterized by a covalent bond: ομοιοπολικος 22. Demands (n, plural): needs 23. Denaturation (biochemistry) The change of folding structure of a protein (and thus of physical properties) caused by heating, changes in pH, or exposure to certain chemicals. μετουσίωση 24. Dextrose: naturally‐occurring form of glucose δεξτρόζη 25. Dietary (adj): Of or relating to the diet. 26. Digestion (ν): The process, in the gastrointestinal tract, by which food is converted into substances that can be utilized by the body. 27. Distribution (n): Distribute (v): to divide among several or many a : to spread out so as to cover something : scatter b : to give out or deliver especially to members of a group <distribute newspapers> <distribute leaflets> 28. Dissolve (v) : to separate into component parts : disintegrate : a. to cause to pass into solution <dissolve sugar in water> b : melt, liquefy :To melt, change into a fluid 29. Efficient (adj): effective/ does the job well; Efficiency (n): effectiveness, competence; doing the job successfully and quickly; Efficiently (adv) 30. Empirical(adj): Relying upon or derived from observation or experiment ; verifiable by means of scientific experimentation 31. Emulsion(n): a substance composed from the combination of two liquids ; emulsify (v); emulsification (n); Emulsifier (n): A substance that helps to combine two liquids, esp. a water‐
based liquid and oil (γαλακτοματοποιητής) 32. Essential (adj): of the utmost importance: basic, indispensable, and necessary 33. Ester bonds: (organic chemistry) A compound most often formed by the condensation of an alcohol and an acid, with elimination of water. It contains the functional group carbon‐oxygen double bond joined via carbon to another oxygen atom. 34. Evaluation(n): An assessment or a summary of a particular situation. Εκτίμηση, αξιολόγηση, αποτίμηση 35. Excess (n): state of surpassing limits; exceed (v); excessive (adj) 36. Flavor (n): The characteristic (sensory) quality of something; a substance used to produce a taste; flavor(v): to add a substance to food to improve its taste 37. Fuel (n): Substance that provides nourishment for a living organism; food. 38. Function (v,n): the role or purpose for which sth is used; the way in which sth works or operates esp., the way in which a part of the body or a machine works (λειτουργώ); functional (adj): how useful sth is (λειτουργικός, χρήσιμος,) 39. Harvest(n,v): συγκομιδή, θερίζω 40. Inhibit (v): to hinder; to restrain ( αναστέλλω) 41. Influence (v): to have an effect on the condition or development of sthg ; influence (n) 42. Instance (n): an event; one occurance of sthg 43. Insoluble (adj): a substance that cannot be dissolved 44. Insulator (n): a material that helps to maintain temperature (usually heat in or out); insulate (v); insulation (n) 45. Intake(n): The quantity taken in; as, the intake of air. 46. Intestine (n): bowel; gut; έντερο 47. Link (+to): join, connect, attach to 48. Make up(phr. Vb) : compose, constitute, form 49. Metabolism(n): All the chemical reactions that take place in a living organism, comprising both anabolism and catabolism. 50. Nitrogen: άζωτο 51. occur (v): happen 52. Oxidase`: biochemistry) Any of many enzymes which catalyze oxidation reactions, especially ones using molecular oxygen. οξειδάση 53. Oxidation : A chemical reaction that increases the oxygen content of a compound. οξίδωση 54. Peptide :class of organic compounds πεπτίδιο 55. Pigment(n): any color in plant or animal cells; A dry colorant, usually an insoluble powder 56. Primary (adj): chief, main; extremely important 57. Preservative(n): A chemical added to foodstuffs to prevent oxidation, fermentation or other deterioration, usually by inhibiting the growth of bacteria; preserve(v); preservation(n) 58. Processing (n): 59. Process (n): progress: something going on : a continuing natural or biological activity or function; a series of actions or operations that lead to an end; <Breathing and the circulation of blood are life processes> process(v) 60. Property‐ies(n): the characteristics or qualities associated with chemical elements 61. requirement (n): a condition needed for sthg to happen Require (v): want, need, demand / 62. Saliva (n): σίελος 63. Saturate (v): to cause a substance to become inert by chemical combination with all that it can hold; to become penetrated or soaked 64. Slice (n): thin, broad piece cut off 65. stabilize (v): to make steady or permanent ; Stabilization (n): normalization; make steady / 66. Starch (n): άμυλλο 67. Solid (adj): chemistry: fundamental state of matter; large, massive 68. Structure(n): The overall form or organization of something. δομή 69. Solvent (n): Substance, generally a liquid, capable of dissolving another substance. 70. Solute (n): Any substance that is dissolved in a liquid solvent to create a solution 71. Soluble (adj): able to be dissolved; Capable of dissolving in a liquid. 72. Substance (n): a solid, powder or liquid with particular properties 73. substitute (n) : To use in place of something else, with the same function ;Substitute(v): To use in place of something else, with the same function. A replacement or stand‐in for something that achieves a similar result or purpose. (Αναπληρώνω αποκαθιστώ αντικαθιστώ) 74. Sucrose: a disaccharide σακχαρόζη 75. Sulfur: A chemical element ( symbol S) with an atomic number of 16 θείο 76. Texture (n): The feel of a surface or a fabric; the smoothness, roughness, softness, etc. of something. 77. Tissue (n): a group of cells in an animal or plant that are similar to each other and that have the same function 78. Utilization (n): χρησιμοποίηση utilize(v) 79. Volume (n): the amount of space that an object takes or occupies FOOD CHEMISTRY‐ READING COMPREHENSION A. Read the following statements and answer whether they are true or false according to the text. Correct the false statements. 1. Food chemists are concerned with where food products are processed, prepared, and distributed. T/F? 2. Basic food chemistry deals with all food components. T/F? 3. Plant photosynthesis produces carbohydrates. T/F? 4. Carbohydrates are used as energy by plants and animals. T/F? 5. What does ‘address consumer demands’ mean? (line 5, p. 1) 6. From lines 5‐6 we understand that some substitutes may alter the taste and texture of food. T/F? 7. Cholesterol is a type of lipid. T/F? 8. All cells need protein to build up their structure and function. T/F? 9. Amino acids serve as the polymers to make peptides and proteins. T/F? 10. Amylase brakes down starch found in saliva. T/F? 11. Antioxidants are often used as preservatives. T/F? 12. Carbohydrates make up approximately the 3/3 of the dry mass of all the plant life on earth. T/F? 13. Casein is an amino acid from milk. T/F? 14. Coagulation is the transformation of a liquid into another liquid. T/F? 15. The denaturation of protein results in the loss of its biological activity. T/F? 16. Digestion begins in the mouth with the breaking down of starch. T/F? 17. The enzymatic browning is a biochemical process in which fruit and vegetable tissues become brown when they are exposed to oxygen. T/F? 18. Enzymes are active in high concentrations. T/F? 19. Ester bonds are formed between fatty acids and glycerol atoms. T/F? 20. Fatty acids are the building blocks of fats and are found in all cells of the human body. T/F? 21. Glycerol is the building block of fatty acid molecules. T/F ? 22. Glucose is a complex sugar. T/F? 23. Glucose is about twice as sweet as table sugar. T/F? 24. Fats cannot be solved in water. T/F? 25. Sugar can be solved in water unless more volume is added that water can dissolve. T/F? 26. Lecithin is a solvent. T/F? 27. Lipids are molecules mostly found in fatty acids and glucose. T/F? 28. Lipids are the most effective source of energy in live organisms. T/F? 29. Cholesterol is found everywhere. T/F? 30. Melanin occurs in plants and animals. T/F? 31. Peptides are long chains of amino acids, T/F? 32. During the process of photosynthesis plants use water and oxygen to produce carbon dioxide. T/F? 33. Polyphenol oxidase is an enzyme which contains copper. T/F? 34. Polysaturated are called the fatty acids that have many single bonds. T/F? 35. Muscle, hair and skin are examples of protein. T/F? 36. Cheese contains the enzyme rennin. T/F? 37. The crystallized form of a solid fat is called shortening. T/F? 38. Vegetable oils come from plants like beans. T/F? 39. Vegetable oils are a source of unsaturated fats. T/F? 40. Organic are considered only living things containing carbon. T/F? B. Answer the following questions according to the text. 1. What does food science deal with? 2. What does ‘evaluation and utilization of food’ mean? (lines 1‐2, p. 1) 3. What do food chemists work with? 4. Where are carbohydrates found? 5. Why are they called “carbohydrates”? 6. Which types of carbohydrates are included in food? 7. What does “thermal insulator” mean? 8. Why should most people try to limit the amount of dietary they take? 9. Where do fats and oils come from? 10. What do we use lipids for? 11. How many amino acids are found in the body? 12. In what sense are proteins “essential” for us? 13. What is the native state of proteins? 14. What is “denaturation” and what causes it? 15. How many amino acids are found in the body? 16. What is an antioxidant? 17. What happens with the smaller food molecules with digestion? 18. What is digestion? 19. What is emulsion? 20. What is the most common emulsion? 21. Why are emulsions important? 22. What is the influence of hormones? 23. How many types of lipids are there? 24. What is cholesterol used for? 25. What do plants do with “extra” sugar produced by photosynthesis? 26. What is a polymer? 27. What is also called phenolase? 28. What is the function of phenolase? 29. What is the composition of proteins? 30. What are called “solutes”? 31. What are called “solvents”? 32. What is starch and where is it found? 33. What is triacylglycerol?