AOAC 996.06 Fat in Food鱼油的检测方法1

鱼油的检测方法

41.1.28A

AOAC Of fi cial Method 996.06

Fat(Total,Saturated,andUnsat

urated)in Foods

Hydrolytic Ex trac tion Gas Chro mato graphic Method

First Ac tion 1996Revised2001

(Ap pli ca

ble to de ter mi na tion of fat in foods.)Cau tion:Bo ron tri fluor ide may be fa tal if in haled.

See Ta bles 996.06A–C for the re sults of the interlaboratory study

sup port ing ac cep tance of the method.

A.Principle

Fat and fatty ac ids are ex tracted from food by hydrolytic meth ods(acidic hy dro ly sis for most prod ucts, al ka line hy dro ly sis for dairyprod ucts, and com bi na tion for cheese). Pyrogallic acid is added to

minimiz

eoxidativedegradationoffattyacidsduringanalysis.Triglyceride, triundecanoin (C11:0), is added as in ter nal stan dard. Fatis ex tracted into ether, then meth yl ated to fatty acid methyl es ters(FAMEs) us ing BF3 in meth a nol. FAMEs are quan ti ta tively mea sured by cap il lary gas chro ma tog ra phy (GC) against C11:0in ter nal stan dard.To tal fat is cal cu lated as sum of in di vid ual fatty ac ids ex pressed astriglyceride equiv a lents. Sat u rated and monounsaturated fats are

cal cu lated as sum of re spec tive fatty ac ids. Monounsaturated fatin cludes only cis form.

B. Ap pa ra tus(a)Gas chromatograph.—Withhydrogenflameionizationde tec tor, cap il lary col umn, split mode in jec tor, oven tem per aturepro gram ming suf fi cient to im ple ment a hold-ramp-hold se quence.Op er ating con di tions: tem per ature (°C): in jec tor, 225; de tec tor, 285;

ini tial temp, 100 (hold 4 min); ramp, 3°C/min; fi nal temp 240; hold

15 min; car rier gas, he lium; flow rate, 0.75 mL/min; lin ear ve loc ity,18 cm/s; split ra (b) Cap il ltio, 200:1.

ary col umn.—Sep ar ating the FAME pair of ad ja centpeaks of C18:3 and C20:1 and the FAME trio of ad ja cent peaks of C22:1,C20:3, and C20:4 with a res o lu tion of 1.0 or greater. SP2560 100 m ´0.25 mm with 0.20 mm film is suit able.(c) Mojonnier flasks.(d) Stop pers.—Syn thetic rub ber or cork.(e) Mojonnier cen tri fuge bas ket.(f) Hengar mi cro boil ing gran ules.(g) Baskets.—Alu mi num and plas tic.(h) Shaker wa ter bath.—Main taining 70°–80°C.(i) Steam bath.—Sup porting com mon glass ware.

(j) Wa ter bath.—With ni tro gen stream sup ply, main tain ing 40°±5°C.

(k) Wrist ac tion shaker.—De signed for Mojonnier cen tri fugebas kets.

(l) Mojonnier mo tor driven cen tri fuge.—Optional;maintaining600 rpm.

(m) Gravityconvectionoven.—Main taining 100°± 2°C.(n) Vortexmixer.(o)Gas dis per sion tubes.—25 mm, po ros ity “A,” ex tra coarse,175 mm.

(p) Three-dram vi als.—About 11 mL.

(q) Phe no lic closed top caps.—With poly vi nyl liner, to fit vi als.(r) Teflon/siliconesepta.—To fit vi als.

C. Re agents

(a) Pyrogallic acid.

(b) Hy dro chlo ric acid250 mL 12M HCl to 110 mL H .—12 and 8.3M. To make 8.3M HCl, add2O. Mix well. Store at roomtemperature(20°–25°C).

(c)Am mo nium hy d

rox ide.—58% (w/w).(d) Diethylether.—Pu rity ap pro pri ate for fat ex trac tion.(e) Petroleumether.—An hy drous.(f) Eth anol.—95% (v/v).(g) Toluene.—Nanograde.(h)Chlo ro form.(i) So dium sul fate.—An hy drous.(j) Borontrifluoride re from com mer cially avail agent.—7% BF3 (w/w) in meth a nol, made

able 14% BF3

so lu tion. Pre pare in the hood.(k) Diethylether–petroleumethermixture.—1 + 1 (v/v).(l) Triglyceride in ter nal stan dardso lu tion.—C11:0-triun decanoin;5.00 mg/mL in CHCl3. Ac cu rately weigh 2.50 g C11:0-triundecanoininto 500 mL vol um et ric flask. Add ca 400 mL CHCl3 and mix un tildis solved. Di lute to vol ume with CHCl3. In vert flask at least10additionaltimes.Triglycerideinternalstandardsolutionissta ble up to 1 month when stored in re frig er a tor (2°–8°C).(m)Fatty acid methyl est ers (FAMEs) stan dardsolutions.—(1) Mixed FAMEs stan dard so lu tion.—Referencemix ture con tain ing se ries of FAMEs, in clud ing C18:1cis and trans(avail able as GLC-85 from Nu Chek Prep, Ely USA, or equiv a lent). To pre pare mixed FAMEs stan sian, MN 56028,

dard so lu tion,

break top of glass vial, open, and care fully trans fer con tents to

3-dram glass vial. Wash orig i nal vial with hex ane to en surecom p

lete trans fer and add washings to 3-dram glass vial. Di lute to ca 3 mL with hex ane.

(2) C11:0 stan dardso lu tion.—C11:0-Undecanoic methyles ter in hex FAME ane. Use only in prep a rstan dard so la tion of in di vid ual FAMEu tions, (3).To pre pare C11:0 FAME stan dard so lu tion,break top of glass vial open and care fully trans fer con tents to 50 mLvol u met ric flask. Wash orig i nal vial with hex ane to en sure com pletetrans fer and add washings to 50 mL vol u met ric flask. Di lute tovol ume with hex ane. C11:0 FAME stan dard so lu tion is sta ble up to1 week when stored at 0°C.(3)In di vidual FAME stan dardso lu tions.—Stan dard so lu tions ofeach of fol low ing FAMEs: C4:0-tetranoic methyl es ter,C6:0-hexanoic methyl es ter, C8:0-octanoic methyl es ter,C10:0-decanoic methyl es ter, C12:0-dodecanoic methyl es ter,C13:0-tridecanoic methyl es ter, C14:0-tetradecanoic methyl es ter,C14:1-9-tetradecenoic methyl es ter, C15:0-pentadecanoic methylester,C15:1-10-pentadecenoic methyl es ter, C16:0-hexadecanoicmethyl est er, C16:1-9-hexadecenoic methyl es ter,C17:0-heptadecanoic methyl es ter, C17:1-10-heptadecenoic methylester,C18:0-octadecanoic methyl es ter, C18:1-9-octadecenoic methylester,C18:2-9,12-octadecadienoic methyl es ter,C18:3-9,12,15-octadecatrienoic methyl es ter, C20:0-eicosanoic methylester,C20:1-8-eicosenoic methyl es ter, C20:2-11,14-eicosadienoicmethyl es ter, C20:3-11,14,17-eicosatrienoic methyl es ter, andC22:0-docosanoic methyl es ter. Pre pare in di vid ual FAME stan dardso lu tions as fol lows: Break top of glass vial open and care fullytrans fer con tents to 3-dram glass vial. Wash orig i nal vial with hex aneto en sure com plete trans fer and add washings to 3-dram glass vial.Add 1.0 mL C11:0 FAME stan dard so lu tion, (2), di lute to to tal vol umeof ca 3.0 mL with hex ane. In di vid ual FAME stan dard so lu tions aresta ble up to 1 week when stored in re frig er a tor (2°–8°C).ã 2005 AOAC IN TER NA TIONAL

鱼油的检测方法

aProduct

x, % 1.9646.311.2 26.513.3 3.92 21.9 1.46

No. of labs/ outliers

—10/210/2——10/110/1—

sr0.2080.860.3540.5400.9290.0871.11 0.131

sR0.2602.370.5414.171.950.1461.82 0.222

r

b

R

c

RSDr, %10.6 1.853.142.047.002.225.068.98

RSDR, %13.3 5.124.8015.8 14.7 3.748.3215.2

HorRat3.692.281.736.475.431.153.314.03

Wheat-based ce realPeanutbutterFish sticksParmesancheeseChocolatecake(baked)Fruit snackGround beef

Blind du pli cates.b

r = 2.8 ´ sr.c

R = 2.8 ´ sR.

0.5822.410.9911.512.600.2443.11 0.367

0.7286.641.5111.7 5.46 0.4095.10 0.622

Yogurt

D. Ex trac tion of Fat

(b) Dairy produ cts.—Ac cu rately weigh ground andho mog e nized test por tion (con tain ing ca 100–200 mg fat) intola bsi ble.eled Mojonnier flask. Force ma te rial into flask as far as pos Add ca 100 mg pyrogallic acid, C(a), and 2.00 mL triglycerideinternalstandardsolution,C(l).Add a few boil ing gran ules to flask.Add 2.0 mL eth a nol and mix well un til en tire test por tion is inso lu tion. Add 4.0 mL H2O and mix well. Add 2.0 mL NH4OH, C(c),and mix well. Place flask into bas ket in shak ing wa ter bath at70°–80°C set at mod er ate ag i ta tion speed. Main tain 10 min. Mixcon tents of flask on Vor tex mixer ev ery 5 min to in cor po rateparticulates ad her ing to sides of flask into so lu tion. Af ter di ges tion,re move flask from wa ter bath and add a few drops ofphenolphthalein. Keep so lu tion ba sic (pink) with ad di tion ofam mo nium hy drox ide. Add enough eth anol to fill bot tom res er voirof flask and mix gently.(c) Cheese.—Ac cu rately weigh ground and ho mog enized testpor tion (con tain ing ca 100–200 mg fat) into la beled Mojonnierflask. Force ma te rial into flask as far as pos si ble. Add ca 100 mgpyrogallic acid, C(a), and 2.00 mL triglyceride in ter nal stan dardso lu tion, C(l). Add a few boil ing gran ules to flask. Add 2.0 mLeth a nol and mix well un til en tire test por tion is in so lu tion. Add4.0 mL H2O and mix well. Add 2.0 mL NH4OH, C(c), and mix well.

Finely grind and ho mog e nize test sam ples prior to ex trac tion of fat.[Note:stion, it may be With ma trixes of un known com po i necessarytoanalyzetestportionwithoutadditionofinternalstan dard to en sure against in ter fer ences. Should in ter fer ing peak befound, the area of C11 in ter nal stan dard peak must be cor rectedbe fore per form ing cal cu la tions. Use 2.0 mL chlo ro form in stead ofin ter nal stan dard so lu tion.]

(a) Foods ex clud ing dairy produ cts and cheese.—Accuratelyweigh ground and ho mog e nized test por tion (con tain ing ca100–200 mg fat) into la beled Mojonnier flask. Force ma te rial into

flask as far as pos si ble. Add ca 100 mg pyrogallic acid, C(a), and2.00 mL triglyceride in ter nal stan dard so lu tion, C(l). Add a fewboil ing gran a nol and mix well un tilules to flask. Add 2.0 mL eth en tire test por tion is in so lu tion. Add 10.0 mL 8.3M HCl and mixwell. Place flask into bas ket in shak ing wa ter bath at 70°–80°C set atmod er ate ag i ta tion speed. Main tain 40 min. Mix con tents of flask onVor tex mixer ev ery 10 min to in cor po rate particulates ad her ing tosides of flask into so lu tion. Af ter di ges tion, re move flask from bathand al low to cool to room tem per a ture (20°–25°C). Add enougheth a nol to fill bot tom res er voir of flask and mix gently.

Table 996.06B. Interlaboratory study results for de ter mi na tion of sat ur ated fat in food stuffs by hydrolytic ex trac tion—gas chro ma tog ra phy Product

a

x, %0.4938.723.00 17.4 3.561.27 9.98 0.986

No. of labs/ outliers

10/010/110/1——10/210/1—

sr 0.03910.2570.2230.3110.171 0.02420.6360.119

sR 0.05221.81 0.5722.46 0.304 0.03621.39 0.170

r

b

R

c

RSDr, % 7.92 2.95 7.44 1.79 4.81 1.90 6.3812.1

RSDR, %10.620.719.114.1 8.55 2.8313.917.2

HorRat2.397.185.645.422.590.744.924.30

Wheat-based ce realPeanutbutterFish sticksParmesancheeseChocolatecake(baked)Fruit snackGround beef

Blind du pli cates.b

r = 2.8 ´ sr.c

R = 2.8 ´ sR.

0.1090.7200.6240.8710.479 0.06781.78 0.333

0.1465.071.60 6.89 0.8510.1013.89 0.476

Yogurt

ã 2005 AOAC IN TER NA TIONAL

鱼油的检测方法

gas chro ma tog ra phyProduct

a

x, % 0.28022.3 1.836.433.791.088.88 0.345

No. of labs/

outliers

—10/2—10/1

sr 0.03200.4110.1650.271

sR 0.05601.11 0.3131.09

r

b

R

c

RSDr, %11.4 1.84

RSDR, %20.0 4.9617.1 33.5 67.7 22.0 15.1

HorRat4.141.984.695.6310.25 17.16 7.653.23

Wheat-based ce realPeanutbutterFish sticksParmesancheeseChocolatecake(baked)Fruit snackGround beef

Blind du pli cates.b

r = 2.8 ´ sr.c

R = 2.8 ´ sR.

0.08961.15

0.1573.11

0.462 0.7591.16 0.1272.60 0.0621

0.8763.053.562.065.49 0.152

9.02

4.2010.94.1710.5 6.42

17.0 —10/2—10/1

0.413 0.04530.930 0.0222

1.27 0.7341.96 0.0542

Yogurt

Place flask into bas ket in shak ing wa ter bath at 70°–80°C set atmod er ate ag i ta tion speed. Main tain 20 min. Mix con tents of flask onVor tex mixer ev ery 10 min to in cor po rate particulates ad her ing tosides of flask into so lu tion. Add 10.0 mL 12M HCl and place flaskinto boil ing steam bath and main tain 20 min. Mix flask con tentsev ery 10 min us ing Vor tex mixer. Re move flask from steam bath and al low to cool to room tem per a ture (20°–25°C). Add enough eth a nolto flask to fill bot tom res er voir and mix gently.(d) Extraction.—Add 25 mL di ethyl ether to Mojonnier flaskfrom (a), (b), or (c). Stop per flask and place in cen tri fuge bas ket.

Place bas ket in wrist ac tion shaker, se cur ing flask in shaker withrub ber tub ing. Shake flask 5 min. Rinse stop per into flask with

ether–pediethyltroleumethermixture,C(k). Add 25 mLpe tro leum ether, stop per flask, and shake 5 min. Cen tri fuge flask(in bas ket) 5 min at 600 rpm. (Note: If cen tri fuge is not avail able,al low con tents to set at least 1 h un til up per layer is clear.) Rinsestop per into flask with di ethyl ether–pe tro leum ether mix ture.De cant ether (top) layer into 150 mL beaker and care fully rinse lipof flask into beaker with di ethyl ether–pe tro leum ether mix ture.Slowly evap or ate ether on steam bath, us ing ni tro gen stream to aidinevaporation.Residueremaininginbeakercontainsextractedfat.

E. Methylation F.GCDetermination

Rel a tive re ten tion times (vs FAME of triglyceride in ter nalstan dard so lu tion) and re sponse fac tors of in di vid ual FAMEs can beob tained by GC anal ysis of in di vid ual FAME stan dard so lu tions anddard so mixed FAME stan lu tion. In ject ca 2 mL each of in di vid ualFAME stan dard so lu tions and 2 mL of mixed FAMEs stan dardso lu tion. Use mixed FAMEs stan dard so lu tion to op ti mizechro mato graphic re sponse be fore in ject ing any test so lu tions. Af terall chro mato graphic con di tions have been op ti mized, in ject testso lu tions from E.

G.Calculations

To tal fat is the sum of fatty ac ids from all sources, ex pressed astriglycerides.Expressingmeasuredfattyacidsastriglyceridesrequiresmathematicalequivalentofcondensingeachfattyacidwith glyc erol. For ev ery 3 fatty acid mol e cules, 1 glyc erol(HOCH2CHOHCH2OH) is re quired. Es sen tially, 2 meth y lenegroups and 1 methine group are added to ev ery 3 fatty ac ids.Cal cu late re ten tion times for each FAME in in di vid ual FAMEsstan dard so lu tions, C(m)(3), by sub tract ing re ten tion time of C11:0peak from re ten tion time of fatty acid peak. Use these re ten tiontimes to iden tify FAMEs in mixed FAMEs stan dard so lu tion. Usead di tional FAME so lu tions (from the same sup plier) whennecessaryforcompleteFAMEidentityverification.

(a)Calculateresponsefactor(Ri) for each fatty acid i as fol lows:

Ri=

PsiW

´C11:0

PsC11:0Wi

Dis solve ex tracted fat res i due in 2–3 mL chlo ro form and 2–3 mL

di ethyl ether. Trans fer mix ture to 3 dram glass vial and thenevap or ate to dry ness in 40°C wa ter bath un der ni tro gen stream. Add2.0 mL 7% BF3 re agent, C(j), and 1.0 mL to lu ene, C(g). Seal vialwith screwcap top con tain ing Tef lon/sil i cone sep tum. Heat vial inoven 45 min at 100°C. Gently shake vial ca ev ery 10 min. (Note:Evap ora tion of liq uid from vi als in di cates in ad equate seals; if thisoc curs, dis card so lu tion and re peat the en tire pro ce dure.) Al low vialto cool to room tem per a ture (20°–25°C). Add 5.0 mL H2O, 1.0 mLhex ane, and ca 1.0 g Na2SO4, C(i). Cap vial and shake 1 min. Al lowlay ers to sep ar ate and then care fully trans fer top layer to an other vial con tain ing ca 1.0 g Na2SO4. (Note: Top layer con tains FAMEsin clud ing FAME of triglyceride in ter nal stan dard so lu tion.)In ject FAMEs onto GC col umn or trans fer to autosampler vial forGC anal ysis.

where Psi = peak area of in di vid ual fatty acid in mixed FAMEsstan dard so lu tion; PsC 11:0 = peak area of C11:0 fatty acid in mixedFAMEs stan dard so lu tion; WC11:0 = weight of in ter nal stan dard inmixed FAMEs stan dard so lu tion; and Wi = weight of in di vid ualFAME in mixed FAMEs stan dard so lu tion.(Note: Peaks of known iden tity with known rel a tive re ten tiontimes are listed in Ta ble 996.06D. When peaks of un known iden tityare ob served dur ing the chro mato graphic run, at tempt to iden tifysuch peaks us ing MS, FTIR, etc. Peaks of unkown iden tity shouldnot be in cluded in the sum ma tion when quan ti fy ing fat in the testportion.)

ã 2005 AOAC IN TER NA TIONAL

鱼油的检测方法

Ta ble 996.06D. Re ten tion time of fatty ac ids and methyl es ter (FAME)

Relativeretention

times

4:0 Bu tyric10.490.466:0 Caproic12.360.548:0 Caprylic15.690.6810:0 Capric20.390.89

11:0 Undecanoic22.991.00

12:0 Lauric13:0 Tridecanoic25.581.1128.151.2214:0Myristic30.651.3314:1 Myristoleic32.631.4214:1 trans-Myristelaidic32.011.3915:0 Pentadecanoic33.041.4415:1 Pentadecenoic34.981.5216:0 Palmitic35.411.5416:1 trans-Palmitelaidic36.391.5816:1 Palmitoleic36.881.6017:0 Margaric37.541.6317:1 Margaroleic38.921.6918:0 Stearic39.781.7318:1 trans 6-Petroselenic40.501.7618:1 trans-Elaidic40.611.7718:1 trans 11-Vaccenic40.721.7718:1 Petroselenic40.901.7818:1 Oleic40.991.7818:1 Vaccenic41.181.7918:1 Octadecenoic41.541.8118:2 trans-Linolelaidic41.6918:2 trans 9-Linolelaidic1.81

42.111.8318:2 trans 12-Linolelaidic42.531.8518:2 Linoleic42.871.8620:0 Arachidic43.751.9018:3 g-Linolenic44.251.92

20:1 Eicosenic cis 544.421.93

20:1 Eicosenic trans 1144.45

1.9320:1 Eicosenic cis 844.671.9420:1 Eicosenic cis 1144.821.9520:1 Eicosenic cis 1344.991.9618:3 Linolenic45.021.9618:2Linoleic—conjugated45.351.9718:2Linoleic—conjugated45.401.9721:0 Heneicosanoic45.691.9918:2Linoleic—conjugated46.182.0118:4 Octadectetraenoic46.392.0220:2 Eicosadienoic46.652.0322:0 Behenic47.462.0620:3 g-Eicosatrienoic47.942.0922:1 Cetoleic48.272.1022:1 Erucic48.502.1120:3 Eicosatrienoic48.682.1220:4 Arachidonic48.942.1323:0 Tricosanoic49.222.1422:2 Docosadienoic50.172.1824:0 Lignoceric50.792.2120:5 Eicosapentaenoic50.962.2224:1 Nervonic51.922.2622:3 Docosatrienoic51.982.2622:4 Docosatetraenoioc52.282.2722:5 Docosapentaenoic54.752.38ã 2005 AOAC IN TER NA TIONAL

Table996.06E.Factors(flentsTG) for con ver sion of FAMEs to

tryglicerideequivaFatty acidFa

b

Tri/FAME (F)

4:0 Bu tyric0.86270.98686:0 Caproic0.89230.98978:0 Caprylic0.91140.991510:0 Capric0.92470.992811:0 Undecanoic0.93000.993312:0 Lauric0.93460.993713:0 Tridecanoic0.93860.994114:0Myristic

0.94210.994514:1 Tetradecenenoic0.94170.994415:0 Pentadecanoic0.94530.994815:1 Pentadecenoic0.94490.994716:0 Palmitic0.94810.995016:1 Hexadecenoic0.94770.995017:0 Margaric0.95070.995317:1 Margaroleic0.95030.995218:0 Stearic0.95300.995518:1 Octadecenoic0.95270.995518:2 Octadecdieoic0.95240.995418:3 Linolenic

0.95200.995418:4 Octadectetraenoic0.95170.995420:0 Arachidic0.95700.995920:1 Eicosenic0.95680.995920:2 Eicosadienoic0.95650.995820:3 Eicosatrienoic0.95620.995820:4 Arachidonic0.95600.995820:5 Eicosapentaenoic0.95570.995821:0 Heneicosanoic0.9588

0.996122:0 Behenic0.96040.996222:1 Docosaenoic0.96020.996222:2 Docosadienoic0.96000.996222:3 Docosatrienoic0.95980.996122:4 Docosatetraenoic0.95950.996122:5 Docosapentaenoic0.95930.996122:6 Docosahexaenoic0.95900.996123:0 Tricosanoic0.96200.996424:0 Lignoceric0.99630.996524:1 Nervonic

0.9632

0.9965

aFAi is the con ver sion fac tor for con ver sion of FAMEs to cor re spond ing fatty ac ids.

b

FTgi is the con ver sion fac tor for con ver sion of FAMEs to tri glyc er ides forin di vid ual fatty ac ids.

(b) Cal cu late amount of in di vid ual (tri glyc er ides) (WTG) in testportion as fol lows:

W10067.

FAMEi =

Pti´WtC11:0´PtC11:0´Ri

WTGi = WFAMEi ´ fTGi

鱼油的检测方法

where Pti = peak area of fatty acid i in test por tion; WtC11:0 = weightof C11:0 in ter nal stan dard added to test por tion, g; 1.0067 =con ver sion of in ter nal stan dard from triglyceride to FAME; PtC11:0 = peak area of C11:0 in ter nal stan dard in test por tion; and fTGi =con ver sion fac tor for FAMEs to tri glyc er ides for in di vid ual fattyacids(see Ta ble 996.06E).(Note: If pro ce dure is fol lowed ex actly, WtC11:0 should be0.010 g.)(c) Cal cu late amount of to tal fat in test portion (sum of all fattyac ids; ex pressed as tri glyc er ides [in clud ing cis and trans forms ofmonounsaturated ac ids]) as fol lows:

To tal fat, % = ( åWDTG/Wtest por tion)

where Wtest portion = weight of test por tion, g.(d) Cal cu late weight of each fatty acid (Wi) as fol lows:

Wi = WFAMEi ´ fFAi

where fFAi = con ver sion fac tors for con ver sion of FAMEs to theircor re spond ing fatty ac ids (see Ta ble 996.06E).(e) Cal cu late per cent of sat ur ated fat in test portion (w/w;ex pressed as sat ur ated fatty ac ids; sum of C4:0, C6:0, C8:0, etc.) asfol lows:

Sat ur ated fat, % = (åsaturated Wi/Wtest por tion) ´ 100%(f) Cal cu late amount of monounsaturated fat in test sam ple (w/w; ex pressed as sum of only cis form of monounsaturated fatty ac ids[C16:1, C17:1, C18:1 cis, C20:1, etc.]) as fol lows:

Monounsaturated fat, % =

(åmonounsaturated Wi/Wtest por tion) ´ 100%

Poly un sat urated fat, % =

(åpolyunsaturated Wi/Wtest por tion) ´ 100%

(Note: Test sam ples con tain ing hy dro ge nated fat will yieldcomplicatedchromatograms due to large num ber of iso mersformed dur ing hy dro ge na tion pro cess. One gen eral in di ca tion ofhy dro ge na tion is pres ence of C18:1trans peak(s). For hy dro ge natedfat chromatograms, use the fol low ing guide lines to cal cu late FAMEpeak ar eas: trans peaks elute prior to cis, there fore, in clude all peaks betweenC18:1cis and C18:2 cis,cis in cal cu la tion of C18:2 peak area.Of ten C18:1trans “peak” con sists of broad se ries of peaks [due topo si tional iso mers from hy dro ge na tion]; in clude all of these in C18:1trans peak area.)

References:.ã 2005 AOAC IN TER NA TIONAL

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