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Food Chemistry 1 > 2. TG nomenclature + Fat sources + Processing > Flashcards

2. TG nomenclature + Fat sources + Processing Flashcards

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1
Q

Simple glyceride? vs mixed glyceride

A

glycerol + 3 FA that are the same
- mixed = more than 1 type of FA

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2
Q

Palmitostearolinolein?

A

glycerol + palmitic acid + stearic acid + linoleic acid
OR glyceryl-1-palmitate-2-stearate-3-linoleate

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3
Q

Is there a Simple way to identify individual TG? explanation

A

No! necessary to release FA from TG by hydrolizing ester linkages that attach them to glycerol backbone

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4
Q

4 steps for analysis of FA composition?

A
  1. saponify fat –> react with NaOH to release FA
  2. methylate FA to convert them to volatile FA methyl esters (FAMES) + separate FAMEs by gas chromatography (25-100m)
  3. identify peaks in GC against known FAME standards and measure peak areas
  4. employ results of GC analysis to calculate overall FA composition
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5
Q

what type of FA exit last in gas chromatography?

A

long chain and long double bonds exit last

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6
Q

what is a common internal standard for FAMEs gas chromatography?

A

odd-numbered FA like methyl heptadecanoate

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7
Q

which fat sources tend to be oils? (2)

A

plant and marine sources

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8
Q

in plant seeds, TG are used as source of E for ______________

A

germination

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9
Q

common primary plant sources of edible oils in North America (4)

A

soybean, rapeseed (Canola), corn and peanut

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10
Q

Non-edible oils from plant sources (2) used for what?

A

castor oil and linseed (flax) oil
- traditionally used for industrial pain and chemical plasticizer purposes
- today, linseed (flax) oil transformed to edible linola

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11
Q

How are animal fat sources (lard) produced? (2 ways)

A
  • from trimmings and carcasses of cattle, hogs and sheep –> boil until fat starts to melt + float to top –> cool and scoop out
  • OR fat separated from milk of ruminants/cows
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12
Q

Fish sources –> sat or unsat?
- good for frying?

A
  • highly unsaturated
  • unstable for frying
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13
Q

7 major groups of fats and oils (determined by gas chromatography)

A
  1. milkfat group
  2. lauric acid group
  3. oleic-linoleic group
  4. linolenic group
  5. animal fat depot group
  6. marine oil group
  7. erucic acid group
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14
Q

short chain FA are responsible for a _________ odor when released from TG by __________

A
  • bad rancid-like odor
  • lipolysis
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15
Q

water in oil emulsion vs oil in water emulsion –> which one is milk vs butter?

A
  • water in oil: water = minor vs oil = major –> butter
  • oil in water: oil = minor vs water = major –> milk
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16
Q

is palm oil part of lauric group?

A

No! palm oil = highly unsaturated!
VS palm kernel oil (from palm oilseeds) part of lauric group

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17
Q

History of oleic-linoleic acid group –> partial hydrogenation of oils in this group (4 parts)
1. started when bc of what?
2. resulted in what?
3. concerns when? –> result?
4. consequence
5. solution ish

A
  1. partial hydrogenation first used in food industry in 1911 bc excess of cottonseed oil
  2. resulted in cis to trans –> not same chemical structure as naturally occurring trans (ie in milk)
  3. concerns about how human body metabolize trans fat in 1990s –> margarines lost status of “healthy alternative” (since it didn’t have sat. fat)
  4. over years, partially hydrogenated oil banned in canada and us
  5. solution ish: switch to fully hydrogenated oils –> no double bonds
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18
Q

Polymerization capability is present in all (sat or unsat) oils but those containing high levels of ___________ acid are particularly reactive

A
  • unsat
  • linolenic
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19
Q

GS2U VS GS3

A
  • GS2U = 2 sat + 1 unsat
  • GS3 = 3 sat
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20
Q

Which oils high in oleic vs linoleic vs linolenic vs Sat?

A
  • Oleic: almond, hazelnut, olive, canola
  • Linoleic: walnut, hemp, soybean, sunflower, corn, safflower
  • Linolenic: flax, hemp, (walnut, canola)
  • sat: coconut, butter, palm oil
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21
Q

GRAPH:
- Fats and FA into 2 branches?
- one of these branches into 2 branches
- one of the previous branches into 2 branches

A
  • Sat fats: animal fats, butter, lard, coconut and palm oil
  • Unsat fats –> poly unsat vs monounsat
  • monounsat = omega 9 –> olive oil, avocado, peanuts, almonds
  • poly unsat –> omega 3 + omega 6
  • omega 3: fish + shellfish (EPA and DHA), flaxseed, soybean, walnut, rapeseed/canola (alpha linolenic acid)
  • omega 6: corn, safflower, sunflower
22
Q

First step of food processing to make oils? then what? which aids what?

A

crush oilseed –> then give the crush a heat treatment which aids in knocking out enzymes that can cause deteriorative reactions (lipolysis and autoxidation)

23
Q

TIssue ___________ (ie crushing of oilseeds) exposes lipids to ________, _________ and other reactive agents like ________ such that multitude of reactions can occur

A
  • tissue disruption
  • enzymes, oxygen and metals
24
Q

2 main enzymes that cause deteriorative reactions in fats and oils. catalyse which reaction?

A
  • lipase –> lipolysis
  • lipoxygenase: autoxidation
25
Q

what is lipolysis?

A

hydrolysis of ester linkage btw glycerol backbone and FA in TG
- lipases are specific! ie: cut at FA 1 and 3

26
Q

while lipase enzyme is useful in certain _________________ of fats and oils, lipolysis is highly undesirable in _________ fats and oils

A
  • industrial applications
  • edible
27
Q

what does lipoxygenase catalyses? Be specific!

A

direct oxidation of polyunsaturated FA chains that contain a cis,cis-1,4-pentadiene group (ie linoleic or linolenic)

28
Q

Lipoxygenase enzymes are names according to what?

A

position of carbon atom that becomes oxidized (adds OOH)

29
Q

Hydroxyperoxyl group?

A

C -OOH

30
Q

hydroperoxy derivatives produced by __________-catalyzed oxidation are highly __________ and serve in living plants as _______ _____________ in various biosynthetic pathways

A

-lipoxygenase
- reactive
- reaction intermediates

31
Q

in ruptured plant tissues, hydroperoxy derivatives are chemically _________ species and rapidly break down to form _______ _________ ________ associated with _________ __________

A
  • unstable
  • volatile organic compounds
  • oxidative rancidity
32
Q

after crushing and heating, what are the 3 ways to extract oils?

A
  • hydraulic pressing
  • expelling
  • solvent extraction
33
Q

because animal/fish tissue contains high levels of ___________ (% vs oilseeds?), extraction with (hydrophobic or hydrophilic?) solvents is inefficient

A
  • moisture (60-80% vs 12% in oilseed)
  • hydrophobic solvents
34
Q

what process is used to extract lipids from meat and fish? what is it? (4 steps)

A

rendering –> ground meat/fish is placed into large pressurized vessel + heated with steam under pressure –> lipids melt and are released from tissue –> fat is skimmed off + oil is separated from water

35
Q

Following extraction of oil by expelling/solvent extraction, the residual press cake is _________ (removal of ?) and is usually sold as ?
- press cake may be further processed to obtain soybean protein for _______ _________

A
  • desolventized (removal of residual organic solvent)
  • sold as animal feed
  • human consumption
36
Q

why is the extracted oil dark brown?

A

due to lipid soluble pigments like carotenoids and chlorophyll (can accelerate autoxidation) and pheophytin

37
Q

what is contained in the particulate material of the extracted oil?
+ 5 other components

A
  • cellular debris comprised of mainly protein and carbohydrate
    1. FFA released from TG by action of plant’s lipase enzymes
    2. oxidative breakdown products formed by enzymatic action and attack by oxygen during crushing operation
    3. phospholipids (lecithins) naturally present in oil
    4. free and complexed metal ions (ie Mg2+ in chlorophyll)
    5. flavor components
38
Q

why does raw oil has to undergo variety of further processing steps to clean it up?

A

bc it contains constituents (FFA, oxidative breakdown products, lecithins, metal ions, flavor components) that detract oil from its functionality, palatability, stability and overall quality

39
Q

which processing steps does virgin olive oil go through? which steps are not used?

A
  • only goes through pressing
  • not bleached or steam stripped
40
Q

what does virgin in virgin olive oil mean?

A
  • processed by physical means
  • no chemical treatment
  • no heat!
41
Q

What does “refined” oil mean?
- cannot be contained in (2?)

A
  • chemically treated to neutralize strong tastes and acid content (from FFA)
  • extra-virgin and virgin olive oil
42
Q

olive pomace oil ? how?

A

oil extracted from the pomace (solid residue obtained from olive oil production process) using solvents (mostly hexane) and heat?

43
Q

How to test if virgin olive oil is mixed with refined olive oil? (2)

A
  • use color as indicator
  • look for chlorophyll concentration –> refined won’t have any
44
Q

What is interesterification used extensively for? (2)

A
  • remove graininess from lard
  • change characteristics of other fats and oils
45
Q

possible to produce artificial human milk?

A

yes by means of enzymatic interesterification reaction using sn-1,3 specific lipase as catalyst

46
Q

-hydrogenation reactions are proprietary. what does this mean?

A
  • recipe is a secret
47
Q

Interesterification also used for manufacture of ____________ used as ____________ –> excessive glycerol reacted with fat source to form _________________

A
  • monoglycerides –> emulsifiers
  • mono and diglycerides
48
Q

how can we replace cocoa fat/butter that have property of having sharp melting point at body temp?

A
  • can be imitated by proper mod of other fats and oils (using hydrogenation and interesterification) so that they can be used as extenders (reduce amount of more expensive cocoa butter needed)
49
Q

How did banning trans fat affect margarine/shortening production? Solution? (2)

A
  • only legal to have 100% hydrogenation = 100% saturated fats = hard as a rock because melting point was too high
    Solutions:
  • blend 100% sat fats from hydrogenation with oils until you get right consistency
  • interesterification
50
Q

what are 2 characteristics about FAs that need to be taken into account for graininess/texture/consistency of a fat/oil?

A
  • amount of saturated FA
  • where the FA is on the glycerol backbone
51
Q

what is an alternative to partial hydrogenation?

A
  • total hydrogenation of an oil + interesterification with its unhydrogenated counterpart –> won’t form trans
52
Q

products sold in Canada as chocolate cannot contain fats other than ____________. those containing ____________ are classified as candy

A
  • cocoa butter
  • cocoa butter equivalents (CBE)

Food Chemistry 1 (22 decks)

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