2. TG nomenclature + Fat sources + Processing
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Simple glyceride? vs mixed glyceride
glycerol + 3 FA that are the same - mixed = more than 1 type of FA
Palmitostearolinolein?
glycerol + palmitic acid + stearic acid + linoleic acid OR glyceryl-1-palmitate-2-stearate-3-linoleate
Is there a Simple way to identify individual TG? explanation
No! necessary to release FA from TG by hydrolizing ester linkages that attach them to glycerol backbone
4 steps for analysis of FA composition?
• saponify fat –> react with NaOH to release FA • methylate FA to convert them to volatile FA methyl esters (FAMES) + separate FAMEs by gas chromatography (25-100m) • identify peaks in GC against known FAME standards and measure peak areas • employ results of GC analysis to calculate overall FA composition
what type of FA exit last in gas chromatography?
long chain and long double bonds exit last
what is a common internal standard for FAMEs gas chromatography?
odd-numbered FA like methyl heptadecanoate
which fat sources tend to be oils? (2)
plant and marine sources
in plant seeds, TG are used as source of E for ______________
germination
common primary plant sources of edible oils in North America (4)
soybean, rapeseed (Canola), corn and peanut
Non-edible oils from plant sources (2) used for what?
castor oil and linseed (flax) oil - traditionally used for industrial pain and chemical plasticizer purposes - today, linseed (flax) oil transformed to edible linola
How are animal fat sources (lard) produced? (2 ways)
• 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
Fish sources –> sat or unsat? - good for frying?
• highly unsaturated • unstable for frying
7 major groups of fats and oils (determined by gas chromatography)
• milkfat group • lauric acid group • oleic-linoleic group • linolenic group • animal fat depot group • marine oil group • erucic acid group
short chain FA are responsible for a _________ odor when released from TG by __________
• bad rancid-like odor • lipolysis
water in oil emulsion vs oil in water emulsion –> which one is milk vs butter?
• water in oil: water = minor vs oil = major –> butter • oil in water: oil = minor vs water = major –> milk
is palm oil part of lauric group?
No! palm oil = highly unsaturated! VS palm kernel oil (from palm oilseeds) part of lauric group
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
• partial hydrogenation first used in food industry in 1911 bc excess of cottonseed oil • resulted in cis to trans –> not same chemical structure as naturally occurring trans (ie in milk) • concerns about how human body metabolize trans fat in 1990s –> margarines lost status of “healthy alternative” (since it didn’t have sat. fat) • over years, partially hydrogenated oil banned in canada and us • solution ish: switch to fully hydrogenated oils –> no double bonds
Polymerization capability is present in all (sat or unsat) oils but those containing high levels of ___________ acid are particularly reactive
• unsat • linolenic
GS2U VS GS3
• GS2U = 2 sat + 1 unsat • GS3 = 3 sat
Which oils high in oleic vs linoleic vs linolenic vs Sat?
• Oleic: almond, hazelnut, olive, canola • Linoleic: walnut, hemp, soybean, sunflower, corn, safflower • Linolenic: flax, hemp, (walnut, canola) • sat: coconut, butter, palm oil
GRAPH: - Fats and FA into 2 branches? - one of these branches into 2 branches - one of the previous branches into 2 branches
• 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
First step of food processing to make oils? then what? which aids what?
crush oilseed –> then give the crush a heat treatment which aids in knocking out enzymes that can cause deteriorative reactions (lipolysis and autoxidation)
TIssue ___________ (ie crushing of oilseeds) exposes lipids to ________, _________ and other reactive agents like ________ such that multitude of reactions can occur
• tissue disruption • enzymes, oxygen and metals
2 main enzymes that cause deteriorative reactions in fats and oils. catalyse which reaction?
• lipase –> lipolysis • lipoxygenase: autoxidation