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Foodchem2 - midterm 2 > food flavors > Flashcards

food flavors Flashcards

1
Q

what are the three components to flavors?

A

smell taste mouthfeel

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2
Q

Define food flavor

A

the sensation produced by food in the mouth and nose

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3
Q

to what is due the sweet taste?

A

due to electromagnetic elements of organic molecules (like nitrogen and oxygen).

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4
Q

which optical isomer of the amino acid is sweet ? the D or L?

A

D isomer is sweet while L is bitter

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5
Q

how are the high fructose corn syrup are made

A

HFCS : the amylase are used to break the starch into mixture of monosaccharides abd then the enzyme glucose isomerase is used to convert the glucose into fructose.

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6
Q

what is maltodextrin?

A

it is the breakdown products of carbohydrates

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7
Q

what are the criteria for selecting alternate sweetners?

A
  1. cariogenicity 2. sweetness equivalent 3. solubility and viscosity 4. hygroscopicity 5. heat of solution 6. laxative effect 7. cost
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8
Q

what are the only two polyol that are not hygroscopic?

A

mannitol and isomalt

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9
Q

why polyol produces the higest cooling effect

A

xylitol

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10
Q

explain the cooling effect observed with certain polyols

A

The sweetners will need heat energy (from the saliva) to be able to be dissolved. When they absorb the heat, they can leave a cooling sensation in the mouth and so it gives a cooling effet that is not desirable. It could be desirable is some kind of products.

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11
Q

___ and __have laxative effect – because they are incompletely digested and slowly absorbed

A

Polyols and polydextrose

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12
Q

Rate these polyol in relative sweetness order : maltitol mannitol polydextrose isomalt sorbitol xylitol

A

xylitol > maltitol > mannitol > sorbitol > isomalt > polydextrose (xylophone monopolise mon super incroyable passetemps)

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13
Q

T or F : xylitol is as sweet as sugar

A

true

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14
Q

Does xylitol have an after taste

A

no

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15
Q

what are the technical characteristics of xylitol?

A

-high thermal stability; -high microbiological stability; -inhibits many food-spoilage organisms; -does not react with amino acids; -moderate hygroscopicity

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16
Q

In general, the ___-amino acids tend to be sweet & the ___-isomers are bitter; some exceptions are ___ which has an insipid taste and ___ which is sweet and the amino acid ___

A

D L D-Ala L-Ala glycine (no D and L)

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17
Q

To what sugar do we compare the others on the relative sweetness scale

A

compare to sucrose

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18
Q

What is the relative sweetness scale?

A

Relative sweetness. is defined as “the ratio of concentrations of substances. matching in sweetness” (12), and it is used to calculate the. concentration of an alternative sweetener that produces. sweetness equivalent to that of sucrose.

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19
Q

name the natural sweeteners seen in class (3)

A
  1. miraculin 2. thaumatin 3. stevia
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20
Q

name the alternate sweetener : a glycoprotein from berries found in West Africa. The fruit of this plant is commonly referred to as the miracle fruit. Has the unusual property of tasting intensely sweet only in the presence of acids.

A

miraculin

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21
Q

name the alternate sweetener : a mixture of sweet-tasting proteins found in the African fruit known as katemfe. It is about 1,500-2,500x sweeter than sucrose.

A

thaumatin

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22
Q

name the alternate sweetener : a shrub found in the tropical and sub-tropical zones of the Americas. Active compound is steviol glycoside

A

stevia

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23
Q

name the alternate sweetener : the methyl ester of the dipeptide, L-aspartyl-L-phenylalanine; about 200x sweeter than sugar; approved in early 1980’s for use as table-top sweetener, in dry beverage mixes, and in foods that are not heat processed;

A

aspartame

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24
Q

name the alternate sweetener : - It is K-salt of methyl-oxathiazine-dioxide; about 200x sweeter than sugar; more stable than other synthetic sweeteners; and sweet taste is clean and does not linger;

A

acesulfame K

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25
Q

name the alternate sweetener : trichloro derivative of glucose-fructose; ~600x sweeter than sucrose. More stable than sugar, and appears to be very suitable for several

A

sucralose

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26
Q

T or F : aspartame can be used in baked goods

A

false it is heat labile

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27
Q

T or F : the acesulfame K can be used in hot beverages

A

true

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28
Q

what is the general structure of sucralose

A

trichloro derviative of sucrose

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29
Q

Which alternate sugar is this

A

aspartame

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30
Q

which alternate sugar is this

A
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31
Q

which alternate sugar is this

A

sucralose (3 cl on the sucrose molecule)

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32
Q

name the alternate sweetener : :- a derivative of the dipeptide L-a-aspartyl-alaninamide. It is about 2,000-3,000x sweeter than sucrose

A

alitame

33
Q

which alternate sugar is this?

A

alitame

34
Q

is alitame stable to heat?

A

yes ( it is the advantage over aspartame in food application)

35
Q

which alternate sweetener is this ? : (Na or Ca salts - ~200-400x sweeter than sucrose);

A

saccharin

36
Q

cyclamate : intestinal bacteria can convert them in ____

A

cyclohexyl amine

37
Q

why is there a controversy around the cyclamates

A

because intestinal bacteria can convert it into cyclohexylamine which is a carcinogen

38
Q

To what is due the sour taste?

A

due to the H+ ions from acids.

39
Q

[H+] determines _____, not the ____

A

degree of sourness

total acidity

40
Q

what are the factors that will influence the sour taste of a food

A
  1. the nature of acid (strong / weak)
  2. buffering capacity
  3. presence of other compounds
41
Q

___ acid will give a more sour taste

A

stronger, since they will ionize into H+ more extensibily.

42
Q

t or f : the total acidity influences the sourness

A

false, the sourness is due to the H+ ions and not the total acidity

43
Q

t or f : acids enhance the action of natural anti-oxidants

A

true

44
Q

what is the salty taste due to ?

A

salt ions like Na+, K+, Cl- etc

45
Q

The salty taste depends on __

A

the size of the ions

46
Q

small ions taste ___ salty

A

more

47
Q

large ions will taste ___

A

bitter

48
Q

true of false ; all ions will give a salty taste

A

false, larger ions have a bitter taste

49
Q

what are the function of salt (NaCl)

A
  1. reduce Aw (microbial activity)
  2. impart flavors and bost food consumption
  3. digestive stimulant
50
Q

to what is due the bitter taste in foods ?

A

to the various organic and inorganic compounds

51
Q

what are the three classes of bitter compounds?

A
  1. alklaoids
  2. glycoides
  3. amino acids peptides
52
Q

define alkaloids

A

a class of compounds that yields a bitter taste because of their nitrogenous composition.

53
Q

quinine, caffeine and theobromine are exmaple of ___ compounds

A

alkaloids

54
Q

what is the difference in structure between theobromide and caffeine

A

theobromide has 2 methyl groups attached to 2 of the 4 nitrogen while in cafeine there is three methyl group attached to 4 of the nitrogen.

55
Q

What are glycosides?

A

aglycones esterifed with various sugars, e.g., are naringin, hesperidin, coniferin, and sinigrin.

56
Q

which glycoside are we refering to : ofound predominantly in grapefruit and bitter orange; it is one of the most bitter substances known;

A

naringin

57
Q

name the glycoside we are refering to : Found in sweet orange and several other citrus fruits; yields rutinose and the aglycone hesperetin on hydrolysis.

A

hesperidin

58
Q

Which glycoside are we refering to : in conifer wood, it produces glucose and coniferyl alcohol on hydrolysis - which may subsequently be oxidized to vanillin;

A

coniferin

59
Q

which glycoside are we referring to : in black mustard seed, it yields glucose and allyl isothiocyanate on hydrolysis

A

sinigrin

60
Q

what is the aglycone of hesperidin nad the sugar

A

sugar : glucose
aglycone : hesperetin

61
Q

what is the sugar part and the aglycone part of sinigrin?

A

sugar : glucose
Aglycone : isothiocyanate

62
Q

what is the sugar part and the aglycone part of coniferin?

A

aglycone : conniferryl alcohol
sugar : glucose

63
Q

what are the bitter glycoside we saw in class ?

A
  1. naringin
  2. hesperidin
  3. coniferin
  4. sinigrin
64
Q

Sub-threshold levels of__ reduces sourness in foods

A

salt

65
Q

Sub-threshold levels of ____enhances saltiness in foods

A

acid

66
Q

oSub-threshold levels of ___ reduces saltiness in foods.

A

sugars

67
Q

name the flavor enhancer we saw in class

A
  1. MSG
  2. Nucleotides
  3. Maltol
68
Q

What are the flavor enhancer that we have seen in class?

A

MSG
Nucleotides (IMP and GMP)
Maltol

69
Q

What are the three componennts of mouthfeel?

A
  1. Pain
  2. Temperature
  3. Tactile sensations
70
Q

what are the two methods of sensory evaluation of foods?

A
  1. peference testing
  2. difference testing
71
Q

what are the three methods comonly used in the preference testing?

A
  1. paired comparison test
  2. hedonic scale
  3. ranking test
72
Q

name the test : the panelist are presented with two products and they need to pick the one that they prefer. Simple paired comparision test.

A

simple paired comparision test

73
Q

name the test : test this is an extension of the simple paired comparison test in the sense that the panel is able to quantify the degree of difference – ex A is 20 % sweeter then B and so on. So you don’t only say the number 1 is preferred by me.

A

Scheffé paired comparision

74
Q

name this test : In this approach, 3 or more products are compared with each other for particular attributes. Ex for A B and C, you would compare A-B, A-C and B-C and you say the one that is your preferred product..

A

multiple paired comparison test

75
Q

name this test : you are ask to select the odd one from a set of 3 products in which two are the same.

A

triangle test

76
Q

name this test : a variation of the triangle test. There is 3 items, and there is one of the three that is a reference, and you need to select the one that is similar to the reference. So 2 of the 3 items are identical and you need to state the one that is 1- identifical and 2 – different

A

duo trio test

77
Q

what are the different test we use in difference testing?

A

simple paired comparison test
scheffé paired comparison
multiple comparison
triangle test
duo-trio test
ranking test

78
Q

Solubility can influence ___, ___ and ____ of the product;

A

mouthfeel, texture & onset of sweetness perception

79
Q
A

Foodchem2 - midterm 2 (3 decks)

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