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Flashcards in Food Chemistry Deck (259)
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1

Would a more hydrophilic substance have a higher or lower HLB than a hydrophobic substance?

Higher

2

Within what range of its pK is a buffering agent is effective?

Plus or minus 1 pH unit

3

Why do triglycerides normally soften slowly and don't have sharp melting points?

Triglycerides can contain up to three different fatty acids and each fatty acid will have a different melting point.

4

Why do seed proteins like soy protein have a high isoelectric point?

Most of the glutamic and aspartic acid residues are amidated

5

Which sugar alcohol has the same sweetness as sucrose?

Xylitol

6

Which of the following solution would exhibit the lowest aw? Which the highest? a) 1 M NaCl b) 1 M glycerol c) 1 M glucose d) 1 M sucrose e) 1 M CaCl2

Lowest – 1 M sucrose, Highest – 1 M CaCl2

7

Which of the following gums should not be included in a formulation of a product, which does not require heating? Locust bean gum, Guar gum, Xanthan gum, or Gum Arabic

locust bean gum

8

Which of the following are emulsifying salts for use in processing cheese? sodium tartrate, sodium chloride, potassium chloride, all of the above

sodium tartrate (a)

9

Which is more viscous: high DE or low DE corn syrup?

Low DE

10

Which has a higher melting point: oleic or palmitic?

Palmitic

11

Which fatty acid would be expected to have the highest iodine value- linoleic, oleic, or linolenic?

Linolenic (18:3 - has more unsaturation) (oleic has 1 double bond, linoleic has 2 double bonds)

12

Which amino acids may form dehydroalanine?

Cysteine, cystine, serine, P-serine

13

Where is banana oil obtained from?

Trick question? No oil in bananas?

14

Where does isoamylase and pullinase attack on a starch molecule?

Breaks the alpha-1,6 bond between 2 glucose molecules

15

When hydrogen peroxide is added, a positive catalase test shows the formation of what?

Oxygen

16

When alpha-amylase attacks starch, what products are formed?

Alpha-amylase hydrolyzes alpha 1,4 glycosidic bonds producing glucose, maltose, and dextrins

17

What vitamin is a 6-carbon compound with a structure very similar to glucose?

Vitamin C (ascorbic acid)

18

What type of secondary protein structure is most prevalent in β-lactoglobulin?

β-sheet

19

What type of pectin will form gels if the pH is below 3.6?

High methoxyl pectin

20

What type of pectin interacts with divalent cations to form gels?

Low methoxyl pectin

21

What type of gum as three main fractions based upon increasing sulfate ester content, known as kappa, iota, and lambda?

Carrageenans

22

What two sugars comprise lactose?

Glucose and galactose

23

What term is given to strongly hydrophillic macromolecular materials that dissolve or disperse in water producing a thickening or viscosifying effect?

Hydrocolloids

24

What term describes the spontaneous loss of fluid from a food gel?

Syneresis

25

What term describes the ability of a fat to exist in multiple crystal forms?

Polymorphorism

26

What results from the hydrolysis of a specific Phe105-Met106 bond in kappa casein?

Destabilization of the casein micelles (cheese curd formation)

27

What protein is responsible for transferring iron from the intestine to the blood stream?

Transferrin

28

What non-nutritive protein is a major component of connective tissue?

Collagen

29

What molecule is a polymer of α-D-galacturonic acid that is produced commercially by extraction of citrus fruits and apples and is used to make jelly?

Pectin

30

What method, often used in protein analysis, aids a researcher in determining the relative percentages of alpha-helix and beta-sheets in a single protein?

Circular Dichroism (CD)