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Food Chemistry

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Answer 50 questions in 15 minutes.
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Match each statement with the correct term.
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This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. At what pH is benzoic acid most effective?
The speed of a molecule is proportional to the surrounding voltage gradient.
Emulsoids
Pectin Esterase
pH 3-5

2. What happens to chlorophyll on heating?
Pheophytin forms
RNA transcribed to DNA
Sodium chloride reduces foam stability and sucrose improves foam stability.
RNA transcribed to DNA

3. Name three nonpolar polar - and charged amino acids.
Nonpolar: (Valine - Alanine - Leucine - Isoleucine - Proline)Polar: (Glycine - Serine - Cystein - Threonine - Tyrosine)Charged: (Lysine - Arginine - Histidine - Aspartic Acid - Glutamic Acid)
It explodes
Bright green
Yellow

4. What two enzymes degrade pectic substances?
Pectin methylesterase & polygalacturonase
Phospholipids - water - sulfur compounds - soaps - partial glycerol esters - carbon dioxide - and mineral acids.
Primary-amino acid sequence. Secondary-alpha-helix - beta sheet. Tertiary-one complete protein chain with cross bonds linking it together. Quaternary-four separate protein chains assembled as one.
Pheophytin forms

5. What are two common reducing agents that break disulfide bonds in proteins?
.05 M HCL
Orange Juice
2-mercaptoethanol (2-ME) - dithiothreitol (DDT)
Daminozide

6. Which of the following examples of browning is enzymatic in nature? 1. Browning of sugars as a result of heating 2. Browning of freshly cut surfaces of fruits and vegetables 3. Browning of bread during toasting 4. Browning of potato chips
Browning of freshly cut surfaces of fruits and vegetables.
Gossypol (it is removed during the oil refining process)
Covalent (strongest) and Hydrophobic (Weakest)
Fatty acid composition - free fatty acids versus the corresponding glycerols - oxygen concentration - temperature - surface area - moisture - pro-oxidants - antioxidants

7. An emulsifier with a high hydrophilic-lipophilic balance (HLB) value would promote which type of emulsion: oil in water or water in oil?
Oil in Water
.05
Molarity is moles of substance per liter solution. Molality is moles of substance per kg solvent. Normality is equivalents of substance per liter solution.
Polyphenols

8. Name the two components that comprise the relaxing factor in muscle fibers.
Olive Green
Troponins and Tropomyosin
It allows the conversion of liquid oils into semisolid or plastic fats and it improves the oxidative stability of the fat.
Water

9. Is a disaccharide
An enzyme that converts hydrogen peroxide to water plus oxygen.
Orange Juice
Sucrose
Daminozide

10. To which of the following four basic tastes are humans most sensitive? A) Bitter B) Sweet C) Sour D) Salty
It allows the conversion of liquid oils into semisolid or plastic fats and it improves the oxidative stability of the fat.
Bitter
Decreased solubility - altered water-binding capacity - loss of biological activity - increased susceptibility to attack by proteases - increased intrinsic viscosity - inability to crystallize.
Polyphenoloxidase

11. What are the limiting amino acids in corn - potato - and green peas?
Carmelization and Maillard
Corn- Lysine - Potato-Methionine - Green Peas-Methionine
Blue pigment in flowers
The speed of a molecule is proportional to the surrounding voltage gradient.

12. What does Reichert-Meissert Number measure?
Smoother - less acid and less bitter chocolate flavor - darker color - and improved solubility (elevated pH enhances sugar-amino browning reactions and polymerization of flavonoids).
Primary butyric acid also caproic acid.
Nucleation or crystal formation and crystal growth.
Emulsoids

13. What are the three main steps in the autooxidation of lipids?
Corn- Lysine - Potato-Methionine - Green Peas-Methionine
Initiation - Propagation - Termination
Lycopenes
Pheophytin forms

14. What kinds of food emulsions are? (1) Butter (2) Mayonnaise(3) Milk
Lipase - lipoxygenase - catalase - chlorophylase - peroxidase - pectinase - protease - ascorbic acid oxidase - alkaline phosphotase.
Phenophylin
Butter= water in oil Mayonnaise= oil in water Milk= oil in water
Degradation of protein and production of acid from sugar at the same time.

15. What is the Peroxide Value a measure of?
Lipase - lipoxygenase - catalase - chlorophylase - peroxidase - pectinase - protease - ascorbic acid oxidase - alkaline phosphotase.
V=IR and P=VI or I x I x are
Primary-amino acid sequence. Secondary-alpha-helix - beta sheet. Tertiary-one complete protein chain with cross bonds linking it together. Quaternary-four separate protein chains assembled as one.
Fat Oxidation

16. What are the primary secondary - tertiary - and quaternary structures?
Primary-amino acid sequence. Secondary-alpha-helix - beta sheet. Tertiary-one complete protein chain with cross bonds linking it together. Quaternary-four separate protein chains assembled as one.
Polyphenol Oxidase
Sweet - Salty - Sour - and Bitter
Polyphenol Oxidase

17. What is the protein efficiency ratio (PER) of casein?
Fat Oxidation
2.5
Gossypol (it is removed during the oil refining process)
Oil in Water

18. Which of these foods is not appropriate to this list? A) Salami B) Yogurt C) Orange Juice D) Beer
Two aldehydes
Osmosis
Orange Juice
Lipid oxidation

19. Name the strongest biochemical bond and the weakest biochemical bond.
Chlocophyllide does not have a phytoltail
Covalent (strongest) and Hydrophobic (Weakest)
ERH=100 x Aw
Lycopenes

20. What are two common reducing agents that break disulfide bonds in proteins?
Polyphenol Oxidase
Chitin
2-mercaptoethanol (2-ME) - dithiothreitol (DDT)
Initiation - Propagation - and Termination

21. What are the fructose contents in commercial HFCS products.
45% - 52% - 90%
Troponins and Tropomyosin
Solid phases of the same chemical composition that differ by crystalline structure - but yield identical liquid phases upon melting.
Racemic Mixture

22. What are colloids that are stabilized by a layer of solvation called?
Emulsoids
.05 M HCL
Whole Milk
Capsaicin

23. What metabolic disorder prevents conversion of phenulalanine to tyrosine by normal metabolic pathways?
Fatty Acid and Alcohol
Phenylketonuria
Fat Oxidation
Fatty Acid (Ester linked) to Fatty Alcohol

24. What name is given to the small circular DNA molecules that carry genetic information independently of the main bacterial chromosome?
Plasmids
.05 M HCL
Water
Daminozide

25. How do sodium chloride and sucrose affect foam stability?
Polyphenols
Acetoin
Pheophytin forms
Sodium chloride reduces foam stability and sucrose improves foam stability.

26. How many carbon atoms and how many double bonds are there in arachidonic acid?
Linoleic Acid
Pheophytin forms
20 carbons and 4 double bonds
Pheophytia does not have magnesium in porphyrin ring.

27. What are soluble polymers of anhydro-galacturonic acid and its esters called?
Acids - Alkalis - Metals - Organic Solvents - and Aqueous Solutions of Organic Solvents
Pheophytia does not have magnesium in porphyrin ring.
Fatty Acid and Alcohol
Pectins

28. Name three non-nutritive sweeteners approved for use in USA?
Two aldehydes
Acsulfame-K - Saccharin - Cyclamate - Aspartame
45% - 52% - 90%
Primary-amino acid sequence. Secondary-alpha-helix - beta sheet. Tertiary-one complete protein chain with cross bonds linking it together. Quaternary-four separate protein chains assembled as one.

29. Name one way foam stability can be assessed.
The degree of liquid drainage or foam collapse (foam reduction) after a given time - the time for total or half-drainage (or half-reduction in volume) - or the time before drainage starts.
Polyphenol Oxidase
Tryptophan
Monosodium Glutamate

30. Name two main gluten proteins.
Gliadins and Glutenins
Water
14
Phospholipids - water - sulfur compounds - soaps - partial glycerol esters - carbon dioxide - and mineral acids.

31. Name two non-enzymatic browning reactions.
Carmelization and Maillard
Pheophytia does not have magnesium in porphyrin ring.
It explodes
Polyphenol Oxidase

32. What is the enzyme responsible for browning in apples and lettuce?
For proteins: SDA-PAGE. For DNA & RNA: Agarose gel.
Polyphenol Oxidase
Pectin methyl esterase or galacturonase
Negative log of the hydrogen concentration (mol/l).

33. Name 3 physical agents capable of denaturing proteins.
Fat Oxidation
Heat - Cold Mechanical Treatments - Hyrdostatic Pressure - Irradiation - and Interfaces
Negative log of the hydrogen concentration (mol/l).
Pectins

34. What are 3 mesomorphic structures associated with lipids in the liquid state?
Egg white proteins - the globin part of hemoglobin - bovine serum albumin - gelatin - whey proteins - casein micelles - B-casein - wheat proteins - soy proteins - and some protein hydrolyzates.
Oil in Water
Linoleic Acid
Lamellar; Hexagonal I - II; Cubic

35. What are the only phenols approved for use in the microbiological preservation of foods?
The speed of a molecule is proportional to the surrounding voltage gradient.
Tryptophan
Sodium chloride reduces foam stability and sucrose improves foam stability.
Parabens

36. What is the winterization process for an oil?
Cooling the oil and filtering of the solids formed so that long chained saturated fats do not crystallize at low temperatures.
Decreased solubility - altered water-binding capacity - loss of biological activity - increased susceptibility to attack by proteases - increased intrinsic viscosity - inability to crystallize.
Emulsification
Emulsoids

37. What are colloids that are stabilized by a layer of solvation called?
14
Olive Green
pH below positive charge; pH at no charge; pH above negative charge
Emulsoids

38. What metabolic end product does the Voges-Proskauer test detect?
Acetoin
HLB (hydrophilic-lipophilic balance); a low value (3-6) promotes water in oil emulsions and a high value (8-18) promotes oil in water emulsions.
V=IR and P=VI or I x I x are
Gliadins and Glutenins

39. How do sodium chloride and sucrose affect foam stability?
Sodium chloride reduces foam stability and sucrose improves foam stability.
Fatty acid composition - free fatty acids versus the corresponding glycerols - oxygen concentration - temperature - surface area - moisture - pro-oxidants - antioxidants
Yes
Cooling the oil and filtering of the solids formed so that long chained saturated fats do not crystallize at low temperatures.

40. What enzyme is most responsible for browning bananas?
Yes
Decreased solubility - altered water-binding capacity - loss of biological activity - increased susceptibility to attack by proteases - increased intrinsic viscosity - inability to crystallize.
Polyphenol Oxidase
An enzyme that converts hydrogen peroxide to water plus oxygen.

41. How does ERH relate to water activity?
ERH=100 x Aw
The degree of liquid drainage or foam collapse (foam reduction) after a given time - the time for total or half-drainage (or half-reduction in volume) - or the time before drainage starts.
Onions ( or leeks)
Smoother - less acid and less bitter chocolate flavor - darker color - and improved solubility (elevated pH enhances sugar-amino browning reactions and polymerization of flavonoids).

42. Name a commonly used household chemical leavening agent and the gas it generates.
Sodium bicarbonate generates CO2
Carmelization and Maillard
Tryptophan
Initiation - Propagation - Termination

43. Are sorbitol and mannitol sweet?
Yes
Non-protein nitrogen
Fatty acid composition - free fatty acids versus the corresponding glycerols - oxygen concentration - temperature - surface area - moisture - pro-oxidants - antioxidants
45% - 52% - 90%

44. In genetics What is conjugation?
Cis
Polyphenol Oxidase
NaCl (it dissociated to a 2M solution)
DNA transferred by cell to cell contact (bacterial sex).

45. What degradative enzyme causes browning in apples - pears - bananas - and peaches?
Polyphenoloxidase
Four
Temperature - Water Content and Activity - Extremes of pH - Chemicals - Alterations of Substrates - Alterations of Products - Preprocessing Controls
14

46. At low water activity What is the main deteriorative concern?
2-mercaptoethanol (2-ME) - dithiothreitol (DDT)
Arachidonic Acid
Smoother - less acid and less bitter chocolate flavor - darker color - and improved solubility (elevated pH enhances sugar-amino browning reactions and polymerization of flavonoids).
Lipid oxidation

47. If oxygen attacks an unsaturated fatty acids at the double bond What is the resultant product?
Browning of freshly cut surfaces of fruits and vegetables.
2.5
Emulsification
Two aldehydes

48. Name two enzymes that are involved in softening fruits.
Glycosides of anthocyanidins
Gossypol (it is removed during the oil refining process)
Primary butyric acid also caproic acid.
Pectin Esterase - Polygalacturonase - Pectin Layase

49. What is Carboxy-methyl cellulose often used for?
Initiation - Propagation - and Termination
Thickener in foods
Lipid oxidation
NaCl (it dissociated to a 2M solution)

50. In the enzyme Taq Polymerase What does Taq stand for?
Polyphenols
DNA transferred by cell to cell contact (bacterial sex).
Thermus Aqauticus
D: None of the above