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FN2232 > topic9 fat > Flashcards

topic9 fat Flashcards

1
Q

Fat

A

Caloric value
Functional ingredient
Taste
Mouthfeel
Triglycerides
Insoluble, non-polar, lower density

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2
Q

nutritive value of fat

A

9 kcal/g
Essential fatty acids (linoleic and linolenic)
Antioxidants (Vitamin E, Vitamin C)
Fat soluble vitamins (A, D, E, K)
Brain, nerve, retinal cells(eye health)
Hormones

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3
Q

linoleic fatty acid / linolenic fatty acid?

A

linoleic: omega-6
linolenic: omega-3

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4
Q

classification of fat

A

solid/ liquid
saturated/ unsaturated: monounsaturated, polyunsaturated

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5
Q

food trend shift

A

low fat –> low carb

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6
Q

what’s saturated fat?

A

only single bonds in fat structure

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7
Q

what’s unsaturated fat?

A

double bonds exist in fat structure,
one double bond —> monounsaturated

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8
Q

being a solid fat under room temperature

A

plastic fats

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9
Q

being a liquid fat under room tempuature

A

oils

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10
Q

how could fatty acids attract with each other to form crystals as it cools

A

van der Waal forces

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11
Q

Yes or no? Symmetrical and similar carbon length will form more readily

A

yes

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12
Q

3 main forms of fat crystal

A

alpha, beta-prime, beta

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13
Q

what kind of fat crystal is milk fat?

A

Heterogeneous fatty acids(3种都有) – beta prime(mainly)

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14
Q

what kind of fat crystal is lard?

A

Homogenous fatty acids – beta —> more crystals

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15
Q

how is the melting point of fat affected??

A

前提：more attraction between molecules, higher the melting point
so: 1.type of fat, 2.form, 3.length of the fatty acids

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16
Q

type of fat and melting point?

A

liquid fat —> lower melting point
solid fat —> higher MP

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17
Q

length of fat and melting point

A

longer chain, higher melting point

18
Q

form of fat and melting point

A

Asymmetrical fats have a lower MP —> kink in structure, lower energy needed

19
Q

what is the smoke point of fat

A

Temperature at which smoke comes from the fat surface when heated, Indicates thermal stability when in contact with air

20
Q

what determines the smoke point

A

Dependent on ease of hydrolysis to glycerol and % of free glycerol

21
Q

what is the smoke coming out from fat when overheating?

A

glycerol(甘油)—>Acrolein丙烯醛

22
Q

why is acrolein bad?

A

Mucous membrane irritant

23
Q

what is the flash point of fat?

A

Temperature of volatiles being ignited – cannot sustain
combustion被点燃的挥发物温度-不能维持燃烧

24
Q

what is fire point?

A

Temperature of volatiles sustaining combustion

25
Q

apply of high smoke oil?

A

For deep fry

26
Q

Plasticity of solid fats

A

Does not undergo permanent change in shape until a stress or
force has been applied, Beta prime crystals = smooth and creamy

27
Q

what would happen if combine liquid fat and soild fat together?

A

Composed of liquid and crystal portions allows flexibility, would lead to grow mold

28
Q

Processing - Refining

A

Settling - separates oil from water, protein, phospholipids, carbs
Degumming - removes gums and phospholipids from crude oilNeutralization - remove FFA with NaOH & residual phospholipids, improves colourBleaching - remove colour (chlorophyll), trace metals, oxidation productsWinterization - improves clarity, crystals filteredDeodorization - steam distillation under low pressure to remove volatile compounds沉淀-从水、蛋白质、磷脂、碳水化合物中分离油脱胶-去除原油中的树胶和磷脂中和-去除FFA与NaOH和残余磷脂，改善颜色漂白-去除颜色(叶绿素)，微量金属，氧化产物防寒-提高透明度，晶体过滤除臭-在低压下蒸汽蒸馏去除挥发性化合物

29
Q

Processing - Hydrogenation

A

Adding hydrogen to points of unsaturation in fatty acid to become saturated
Change liquid oils into solids or plasticsIncreases oils thermal and oxidative stability
Used for shortenings for desirable shortening power
Partial hydrogenation causes trans fatty acids - not permittedH2 bubbled through liquid oil in presence of nickel catalyst which speeds up the reaction (traditional oil hydrogenation)
在脂肪酸的不饱和点加入氢使其饱和把液体油变成固体或塑料提高油的热稳定性和氧化稳定性用于起酥油，以获得理想的起酥油力部分氢化会产生反式脂肪酸——不允许氢气在镍催化剂的作用下通过液体油产生气泡，加速了反应(传统的油加氢)。

30
Q

Processing - Interesterification加工-互化

A

Fatty acid addition or rearrangement on glycerol backbone by chemical or enzymatic process, creating a ‘new’ triglycerideBonds broken on FA and re-esterified on same glycerol (intra) or different glycerol (inter)Does not change the FA but rather rearranges them Ex. ShorteningProce脂肪酸通过化学或酶的过程在甘油主链上的加成或重排，产生“新的”甘油三酯FA上的键断裂并在同一甘油(内)或不同甘油(间)上重新酯化。不改变足总，而是重新安排它们例缩短流程

31
Q

Processing - Fractionation分馏

A

Separate triglycerides by difference in melting point, solubility and volatility

32
Q

Processing - Additives添加剂

A

Protect quality and prolong storageAntioxidants - reduce oxidation (BHA, BHT.
Lecithin - emulsifier
Citric acid - metal chelating agent to inhibit oxidative rancidity
Polyglycerol esters - modify and inhibit crystallization保护品质，延长储存时间抗氧化剂-减少氧化(BHA, BHT等)卵磷脂-乳化剂柠檬酸-金属螯合剂抑制氧化酸败聚甘油酯-修饰和抑制结晶

33
Q

Sources – Animal fats (Rendering取出：extracting animal fat)

A

By-product of meat processing Heat or steam

34
Q

what is tallow

A

Cattle and sheep - Deodorized or undeodorized for flavour
use for Biofuels, soap/detergent

35
Q

what is lard

A

fat rendered from pig

36
Q

what is lard used for?

A

Flavour, shortening power (pie crusts)
White grease

37
Q

poultry fat

A

Added in foods for flavor (chicken soup)
Commonly used in pet food industry

38
Q

examples of marine oils

A

Fish, fish liver, krill, squid, seal, algae, etc

39
Q

structure of marine oils

A

long polyunsaturated fatty acids, Less stable – susceptible to oxidation

40
Q

nutritive value of marine oil

A

High in vitamin A and D, Source of EPA, DHA, ARA

41
Q

best source for marine oil?

A

Algae can be easily grown, sustainable

42
Q
A

FN2232 (13 decks)

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