LI M UX hi pht trin, nhu cu n ung ca con ngi cng thay i theo. Ngi tiu dng by gi khng cn quan nim n no, n nh xa na m iu h quan tm nht hin nay l thc phm m h dng c m bo cht lng hay khng? Mt trong nhng thay i ln trong cch ch bin thc phm ca ngi tiu dng hin nay l h t b thi quen dng m ng vt, c bit l m heo ch bin mn n v n cha nhiu cholesterol gy nh hng sc khe. V vy, ngun cht bo c chit xut t thc vt c ngi tiu dng ch hn. Ngy nay, vic s dng du thc vt trong ch bin tr nn rt ph bin. C nhiu loi du thc vt xut hin trn th trng nh: du u nnh, du hng dng, du vng, du gc,v.v V mt pht minh mi ra i gp phn vo danh mc du thc vt m t lu con ngi b qun, l du thc vt c chit xut t qu b. V trong b hm lng lipit rt cao, cao hn nhiu so vi cc loi khc. Ngoi ra, trong b cn cha nhiu vitamin v khong cht bao gm canxi, st, ng, magi, phtpho, kali, natri, km mangan v selen. V th, b cn c s dng vo nhiu mc ch khc nhau nh n qu ti, ch bin nhiu mn n ngon v c bit b c s dng rt nhiu trong m phm cho vic chm sc sc p. ti: Xc nh hm lng lipit trong qu b s cung cp cho chng ta nhiu thng tin v cy b, cng nh cc c tnh c li m qu b mang li cho sc khe con ngi. c bit ti ny s i su phn tch thnh phn lipit trong b v cch xc nh hm lng lipit trong qu b New Zealand.

1

Phn 1: TNG QUAN1.1. Gi tr kinh tTrong cc loi cy nhit i v nhit i, b ng vo bng th 5 theo thng k ca FAO (1977). Tng sn lng th gii l 1.221.000 tn, tp trung cc nc chu M v mt tiu th, cc nc pht trin c nhu cu ngy cng tng i vi mt hng ngy cng quen thuc ny. Thnh phn dinh dng ca tri b cao hn nhiu loi cy khc, nht l v mt calo, protein, cc cht mui khong; b l thc phm l tng cho ngi b bnh tiu ng. Hm lng cc cht du thc vt trong qu b rt cao (3-30%) v c th con ngi c th hp th n 92,8%. Bng : So snh mt s tri cy v mt cht lng (trong 100g phn n c). Nc Protein Lipid ng VitB1 Loi tri Calo (g) B 102 79 (g) 1,1 (g) 6,1 (g) 13,2 (mg) 0,05 (mg) 8 (mg) 38 (mg) 12

VitC

Phosphor Calci

Xoi

70

79,9 0,9

0,1

18,5

0,01

13

4

u

45

87,1 0,5

0,1

11,8

0,03

73

24

Cam

40

88,6 0,8

0,2

9,9

0,07

43

23

21

Mc d thnh phn dinh dng ca tri b rt cao so vi nhiu loi tri cy khc, nhng do mi pht trin trong thi gian gn y, nn sn lng b cha cao,

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nng sut bnh qun ch t 4-10 tn, ngay c nhng vn cy thm canh California.

1.2. c im thc vt v sinh l1.2.1. c im thc vtCy to c xp vo loi cy xanh l quanh nm, nhng vi ging c tnh rng l mt phn hoc rng ht khi cy tr hoa, nhng c tnh ny ch c tnh cch tm thi v sau chi non li pht sinh ngay. Trn a s ging l gi ch rng dn trong mt thi gian kh di vo ma xun nn cy lc no cng xanh l. L lc cn non thng c lng mn, mu hi hoc mu ng nhng n khi trng thnh, l c mu xanh lng v di. Chiu di l rt thay i t hnh thun n hnh dao. Chp l thng bn nhn nhng c vi ging chp l hi trn. Mi v ca l thng ch c trng cho loi Persea drymifolia Cham.et Schect. Khi v ngi c mi hi. Hoa c mu xanh nht, hoc xanh vng, thng pht sinh thnh chm trn on cui cnh qu. Khi hoa n, hoa c ng knh 12-14mm. Hoa c 12 nh, nhng ch c 9 nh hot ng, mi nh mang 4 ti phn. Hoa ch c mt nhy v mt tm b cha mt tiu non. a s cc b phn ca hoa c lng mn. Qu b c trng lng v hnh dng khc nhau ty ging: trn, trng, qu l, thun... Trng lng thay i t 60-150g, c ging qu rt to nng n 1,5 kg. Trn thng trng nhng ging qu b hoc qu ln u t c a chung. Qu c ba phn r rt: v tht v ht. B dy v cu to ca v thay i ty ging. Qu ca nhng ging thuc chng Mexico thng c v mng v lng, chng Guatemala v Antilles thng c v dy hn. C ging qu v sn si, c ging v lng v i khi c s g. Mu sc ca v qu bin ng t mu xanh sng, mu xanh nht, xanh vng, hoc tm n tm sm khi qu chn.

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Tht qu thng c mu vng kem, vng b, hoc mu vng sng, c ging cho tht qu c mu vng xanh st phn v qu. Tht qu c hm lng du bo rt cao so vi cc loi qu khc. Ht c 2 lp v la bao bc, gm c hai t dip hnh bn cu. Gia hai t dip c phi ht nm v pha cung qu, v khi ht ny mm, cy mm s mc thng t di ln theo trc thng ng ca ht. Mt ngoi t dip (ni nh) trn lng hoc sn si ty theo ging v hnh dng cng bin ng kh nhiu. T l gia v, tht v ht ca qu cng ty thuc nhiu vo ging; chng hn nh ging Lula, ht chim n 25% trng lng qu.

1.2.2. c im sinh l ca hoa bMc d hoa mang tnh cht lng tnh, nhng c im th phn ty thuc vo hot ng sinh l ca nh v nhy. Qua nhiu nghin cu hin tng n hoa v th phn c J.A.Samson (1980) quan st ghi nhn s th phn ca hoa b mang tnh tp giao. Cn c vo thi gian hot ng ca nh v nhy, cc tc gi chia b ra thnh 2 nhm: - Nhm A: hoa n ln 1 vo bui sng; nhy chn nhng nh cha tung phn; tip theo l thi k hoa cp li; hoa n ln 2 vo bui tra ngy hm sau; nh chn tung phn nhng nhy khng cn kh nng th phn na. Khong cch thi gian gia 2 ln n hoa ca mt hoa ko di trn 24 gi. - Nhm B: c c im n hoa ngc li: hoa n mt ln vo bui chiu; nhy chn sn sng n phn; tip theo l thi gian hoa cp li khong di 24 gi; hoa n ln 2 vo bui sng hm sau; nh chn v tung phn. Nh th hai nhm A v B c c tnh b sung s th phn cho nhau cy u qu tt. Nghin cu v ng dng tp tnh n hoa ca cc ging l yu t quyt nh vic trng b c hiu qu kinh t.

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Hin ti cha c ti liu phn loi ging, nhng vi tc gi phn chia mt s ging nh sau: - Nhm A: gm cc ging: Mexicola, Puebla, Jalna, Gottfried, Taylor, Queen, Dickinson, Waldin, Simmonds, Collinson, Wagner, Taft, Lula, Dunedin.... - Nhm B: gm cc ging: Wilslowson, Nabal, Pollock, Trap, Fuerte, Mc Donald, Schmidt, Tonnage, Linda, Hardy... Trong mt s ging c kh nng t th phn gm: Hass, Trap, Lula, Waldin, Taylor, Fuerte, nhng trng ring r nhng ging ny thng khng th cho nng sut cao c.

1.3. c tnh sinh thi ca cy bCy b c rt nhiu ging thuc cc chng khc nhau nn khng th nu nn c im sinh thi ni chung.

1.3.1. Nhit Nh trnh by, cy b c ngun gc cc x nhit i Trung M, phn b cao di 1.000 - 2.700 m. y cc ging thuc chng Guatemala, Mexico c th chu c nhit t -20 0 n -60 0C, cc ging Antilles ch chu c nhit khong 0 0C. Ti Lt, nhit tuyt i thp rt him khi t mc 0-10 0C, nn cc ging Antilles km chu rt nht cng chu c, do vn nhit thp i vi cy b khng quan trng lm. Vn t ra l nh hng ca nhit qu cao i vi s chng chu ca ging v vn phm cht biu hin hm lng du trong qu. Nh th mi ging c yu cu v nhit khc nhau. Chng hn nh ging Booth 7 bt u rng tri khi nhit xung n 3 0C. Tuy nhin, ngi ta tm chia cc ging b ra thnh 5 nhm cn c vo sc khng lnh nh sau:5

- Nhm chu lnh rt gii: c Lula, Taylor... - Nhm chu lnh gii: c Nabal, Hall, Tonnage... - Nhm chu lnh kh: Booth 8, Monroe, Wagner, Choquette... - Nhm chu lnh km: Booth 7, Waldin, Hickson, Collinson, linda... - Nhm chu lnh rt km: Pollock, Trap...

1.3.2. m Lng ma ti thch cho c nm l 1.000 - 1.500mm. Khi b ra hoa, nu gp tri ma dm, m khng kh qu cao, hoa s rng nhiu. Do , b cn c mt ma kh mt ra hoa u qu tt. Ma nhiu vo ma qu chn cng lm gim cht lng qu, hm lng du khng cao.

1.3.3. GiCy b c g dn, chng gi yu nn vn trng cy che chn gi c tc dng hn ch gy ng thi gim tc bc thot hi nc vo ma ra qu (ma kh) cy khng b rng tri. Gi cn lm tri c st ln nhau, c st vi l, cnh gy ra bnh sinh l lm gim gi tr tri b.

1.3.4. t ai C th trng b trn nhiu loi t khc nhau: t st pha ct, t pha st, t thtnng. Nhng vn c bit cn lu l t phi thng thong, d thot nc, giu cht hu c. Lp t thng thong thot thy phi su t nht l 90 cm. t c mch nc ngm thp su t nht l 2m, v trong thi k u sinh trng, r b n cn, cy vn pht trin tt nhng cng v sau, b r n cng su, gp t ng thy, r pht sinh nm Phytophthora lm cht cy.

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1.4. K thut trng b Khong cch trng: tu theo chng v ging i vi chng Antilles v nhng ging lai, c th trng khong cch kh tha: 8x8m hoc 10x10m. Vn xen canh: vo nhng nm bt u trng b, khi cy b to tn cha rng, c th trng xen rau u nhng khng nn trng c chua, khoai ty v nm Verticilium c th lan truyn cho cy b. Bin php gi m: giai on cn nh, b r b n cn, cho nn vn ti gi m v ph gc l cn thit b khng b cht do nng kh vo ma nng; nht l i vi nhng vn b trng bng cy ghp. Tt nht nn ti phun v khng nn ti m vo gc. Bn phn: Tu tui ca cy giai on cy cn nh c th bn theo cng thc N - P2O5 - K2O vi t l 1-1-1. cy ln nn tng t l K2O v N ln theo t l 2-1-2. Trc khi trng v trong nhng nm u, nht thit phi bn phn chung hoai 10-20 tn/ha. Vn to tn: Tin hnh t nh i vi nhng ging cy cao to dng cy khng cao qu 6m v cnh to u v cc pha. Vic ct xn cnh kh, cnh vt cng phi thc hin sau ma thu hoch gip cy sinh trng bnh thng v ngn nga khng cho su bnh lan trn.

Trng cy chn gi: thn cnh b rt dn, d gy, nn vn trng cychn gi rt quan trng. Thng dng cy dng liu: (Casuarina equisetifolia) trng dy cch hng b ba 6m che gi v gip cho t

1.5 . Phng tr su hi1.5.1. SuTrn b c nhiu loi su hi: - Su cun l (Gracilaria percicae Busk): bm thng trng trn l mi ra, trng n thnh su v ln dn ln theo l, nhng thng thng nht l su nh t7

cun l li lm t. Su di khong 10mm, xanh v c nhng ln ngang khng r rt. Trng thnh, su lm nhng trong cc t l, nm yn 5-7 ngy ri v ha. Dng cc loi thuc tr su ni hp phun dit tr. Nu c iu kin, trc khi phun thuc, nn g b cc t l do su cun li tng thm hiu lc ca thuc. - Su cn l: c rt nhiu loi, c hai loi c nh danh l Seirarctia echo v Feltia subterrania F. Su n tri l lm cht cy con v lm gim sc tng trng cy ln. C th tm thy su trn l, trn cnh hoc v thn cy. Ban ngy, su n np di gc cy, m n b ra ph hi. - Ry bng (Pseudococcus citri Risse): ry thng xut hin vo ma ma, chch ht nha l v t non, qu non lm cy gim sc tng trng.

1.5.2. Bnh L i tng bo v thc vt quan trng trn cy b, gm cc bnh hi sau:- Bnh thi r: do nm Phytophthora cinnamoni gy ra, nhng chn t c thu cp cao, nm xm nhp lm h r chnh (r cc), sau nm lan trn ph hu c b r lm cy cht ri. Cy b bnh c tn l x xc, l i sang mu xanh nht ri rng. Cnh cht dn t ngn xung thn chnh. - Cch phng: Chn ging ghp v gc ghp chng chu bnh. Khng dng ht ging b nhim bnh v vn m ging phi tun th cc bin php phng chng bnh pht sinh v lan trn. - Trng b trn cc loi t c kt cu ti xp, tng t canh tc su, rt nc nhanh khi ma. -Tuyt i khng dng nc t nhng vn b b bnh ti. - Phi ty u nng c k cng. - Pht hin kp thi nhng vt thi trn thn, co sch v qut sulfate ng - vi c. Khi cy cht v bnh, nn o v hu b bnh khng lan trn. - Bnh m l (Cerocospora purpurea): bnh hi l v tri, nm bnh xut hin8

ri rc trn l c hnh dng v kch thc gn ging nhau, hnh c gc cnh hoc hi trn, mu nu. Nhng m ny cng c th lin kt li vi nhau thnh nhng mng. Trn tri bnh to nn nhng mt li c 5mm, c mu nu nht n nu m. Tri b bnh mt gi tr. Bnh tn ti trn l gi pht tn khi c iu kin thch hp. - Bnh kh cnh (Colletotrichum cloeosporiodes): nm xm nhp vo trn cnh thng lm cnh kh cht. Trn tri gi, gn chn, nm thng xm nhp vo nhng ch do tri c st hoc b thng tch hoc do cng trng chch ht, n v qu, lm cho tri b nhn (thng l phn cui tri). - Bnh ho r: (Verticillium albo - atrum): cy b nhim nm thng t nhin b ho l trn mt phn cy hoc khp cy. L b cht rt nhanh, i thnh vng nhng l kh rng. Nu lt v ca cnh hoc r cy cht s thy nhng ng sc mu nu phn tip gip v v g. Sau thi gian vi thng, mm non pht sinh tr li trn nhng nhnh cha cht v trong vng mt hoc hai nm, cy s sng tr li bnh thng v khng cn triu chng g c. Nm tn ti trong t v gy bnh cho nhiu loi thc vt bt c tui no. Cy bnh c th cht lun hoc sng tr li, i vi nhng cy b bnh mt phn th phn bnh khng th cho tri trong vng mt hoc hai nm. Thng p dng cc bin php phng tr nh sau: - Dng thuc ha hc. - Ct xn k khi cy va c triu chng bnh, sau khi cy b bnh phc hi, ct b nhng nhnh nh, cht. - Khng dng cnh thp ca nhng cy b bnh, nn dng gc ghp l nhng ging thuc chng Mexico. - Khng nn xen canh hoc lun canh b vi cc cy h c,... - Khng trng cy trn t km thng thong, m thp v ng thu.

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1.6. Thu hoch v ch binCy m ht bt u c tri sau khi trng c 5 hoc 7 nm. Cy thp bt u cho tri bi sau khi trng 1 n 2 nm, nhng khng nn duy tr thu hoch qu nhng nm u (3 nm tr li); n nm th 4 ch mt s tri tng xng vi hnh vc ca cy; v nm th 5 khi tim lc cy cho nng sut th khng ta b tri na m ch p dng cho nhng ging c khuynh hng ra tri qu sc. Sau khi cy tr hoa c t 6 -12 thng th tri chn, thi gian ny tu theo ging. Nng sut cng bin thin rt nhiu theo ging, nhng nng sut bnh qun thng 8-20 tn/ha. Vic tin hnh thu hoch, thi im hi tri s nh hng rt nhiu n phm cht cng nh iu kin bo qun, vn chuyn. Thng thng da vo mu sc ca da, nhng Califorlia, ngi ta gim nh hm lng du trong cm. Tri b c th bo qun lnh hoc nhit thng. Thng thng cc ging b c th bo qun lnh nhit 7 C, nhng nhng ging thuc chng Antilles phi c bo qun nhit cao hn 12 C. Tri b c s dng bng nhiu cch, cch gin d nht l n vi ng, sa hoc mui tiu. Tri b cn c dng nh mn rau salade hoc trn vi rau dip, u, c chua, tng t... Tri b cn c ct ra trn vo canh n khi cn nng rt ngon. Tri b khng th lu hoc ng hp c, tuy nhin ngi ta cn dng tri b lm kem. Trong k ngh, du tri b c dng lm x phng ho hng v cc loi m phm cao cp. Tri b tuy rt bo nhng l mt trong rt t loi tri cy khng c cholesterol; cht bo trong tri b l loi cht bo n khng bo ha rt tt cho c th lm gim hm lng cholesterol. Tri b l loi tri cy cha hm lng protein cao nht so vi cc loi qu khc, gn tng ng vi sa.

10

Tri b c ti 14 loi vitamin v rt nhiu khong cht nh canxi, kali, natri, km, mangan, ng, st, magi, pht pho v selen. Cc loi vitamin A, E, D trong tri b l cht chng oxy ha tuyt vi, ngn nga cc gc t do. V vy, n gip tng cng kh nng chng ung th nh ung th v, ung th ming, ung thu thn. N cng rt tt cho mt, chng c thy tinh th. Vi tnh cht ny, tri b cng gip chng lo ha da, gip duy tr ln da sn chc. Hm lng Folate cao trong tri b gip tri tim khe mnh, gim thiu ti a cc cn t qu. Ngoi ra, vi hm lng mui thp, nhiu kali, nhiu cht x, tri b cng rt tt cho ngi cao huyt p. Trong cng ngh lm p, ngi ta s dng du tri b ti to v gi m ln da, bo v da khng b kh n v tng kh nng n hi ca da.

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Phn 2 NI DUNG2.1. Thnh phn cht bo v axit bo ca b2.1.1. Lipid trong bLipid l thnh phn quan trng nht ca qu b. N bao gm 60-80% cc cht kh ca mesocarp, cc phn n c ca qu, v c nh hng ti hng v trong qu b. Ngoi ra, lipid ca mesocarp (% cht kh tng s) cn c s dng xc nh s trng thnh qu b. Mc tiu chnh ca vic trnh by y l xc nh nh hng ca thi gian trong ma v khu vc ang pht trin trn ni dung lipid v thnh phn ca New Zealand b 'Hass. Ngy by ln gia thng Chn, 1998 v Thng T, 1999 qu t hai vn cy n tri (mt trong Te Puke v mt min Bc ) c thu hoch v phn tch cht kh, hm lng lipid v thnh phn acid bo. nh gi vn kh c thc hin bng cch s dng cc phng php thng mi v tng s cht bo c chit xut t cc m lnh bng cch s dng mt sa i ca Bligh v k thut Dyer. Sau , cc thnh phn acid bo ca lipid c xc nh bng cch phn tch sc k kh. Cht kh trung bnh tng trong thi gian (thng chn-Thng T). Hm lng cht kh trong b Te Puke tng t 24,6% n 36,4%, trong khi min Bc tng t 24,1% n 32,3% so vi cng k. Hm lng lipit tng t 17,2% n 31,3% (tc l bng 82%) trong Te Puke v t 16,4% ln 26,7% (62%) min Bc ( t thng Chn n thng T.) Chng ti xc nhn rng c mt mi tng quan cao gia tng s cht bo v hm lng cht kh trong qu b. Trong nghin cu ny, b Te Puke lun cho thy hm lng lipid cao hn (v hm lng cht kh) so vi min Bc. Ti c hai vng, cc axit bo khng bo ha n c li oleic acid l acid bo ch yu tch ly. Tuy nhin, b t Te Puke cho thy mc axit oleic cao hn so vi b12

min Bc . T quan im sc khe v dinh dng cho thy, t l ca (axit oleic v palmitoleic) khng bo ha n bo ha axit bo (palmitic acid) v khng bo ha a (linoleic v linolenic acid) axit bo bo ha c tm thy trong qu b NZ c th so snh vi du liu Mt trong nhng yu t nh hng n cht lng qu l thi gian thu hoch. Ch thu hoch b trng thnh t cht lng tt (Lewis, 1978). Bn cnh nhng vn ca s trng thnh , mt kha cnh quan trng l cht lng ca b vo cui ma v. Vi mt ngnh cng nghip pht trin xut khu b, New Zealand cn tip tc nghin cu xem xt s thay i cc thnh phn ca qu( lipit v cc thnh phn khc trong b) theo ma v khu vc trng. Lipid l mt trong nhng tnh nng phn bit ca qu b. Cc loi cht bo xy ra trong b bao gm tri-, di-v mono-glycerides. Trong tri cy trng thnh, khong 85% cc cht bo l cht bo trung tnh (Platt-Aloia v Thomson, 1981) v thng c coi l ngun d tr cung cp cacbon v nng lng (v d nh ht ging ny mm). Cc glycerides khc ch yu l cht bo c trong cu trc mng t bo, ni chng tn ti nh l mt bilayer lipid (Stumpf v Conn, 1987). Lipit kt cu c mt trong cc m vi s lng tng i nh v do tiu th nh mt phn ca qu. Nhiu ngi trong s cc thnh phn ca cu trc cht bo trong thc phm s c a vo cc lipid cu trc trong c th ca ngi tiu dng (Enser, 1995). Ngoi ra, nhng qu b cn non khng c glyxerit, cc hp cht ang hin din trong cht bo b v nhng thnh phn c cha hng v v cc vitamin dinh dng quan trng. Cc cht bo trung tnh c mt trong cc t bo mesocarp du b hoc idioblasts (Schroeder, 1953, PlattAloia et al, 1983.). Cc cht bo lu tr c cc cht bo trung tnh c trong qu b mesocarp t bo cht bo hoc idioblasts (Schroeder, 1953, Platt-Aloia et al, 1983.). Hn 85% cc cht bo trong qu b l triacylglycerol (Platt-Aloia v Thomson, 1981). Cc cht bo c tng hp ch trong thi gian tng trng v trng thnh ca cc qu trn cy v khng tng hp trong thi gian lu tr v chn qu (Platt-Aloia13

v Thomson, 1981; Luza et al, 1990.). Cc idioblasts c phn bit bng kch thc ln v thnh t bo phc tp ba lp (Platt-Aloia et al., 1983 v Kaiser v cng s, 1992.). Dolendo (1966) bo co rng cc t bo lipit c lin kt vi nhau bi cc cht pectin. Nh vy, mc d tng s lipid ca qu l cao ti thi im thu hoch. Trong qu trnh lm mm gim mc este ha ca pectin th mi t bo v giai on khc nhau mc ni lng ca cc t bo cng khc nhau,ngoi ra cc t bo cng c th d dng b v, dn n vic xut hin ca lipid. Trong tri cy trng thnh cc t bo ny c ng knh khong 60 m, (Kaiser v cng s, 1992;. Werman v Neeman, 1987). Ross et al. (1993) khi nghin cu s hin din ca protein oleosins trong b v ht liu thy rng ch cha khong 1% trn trng lng ti (Biale v Young, 1969). Lipid v thnh phn ca b b nh hng bi nhiu yu t nh ngun gc , v tr ca qu trn cy (Hatton v cng s, 1957) (Schroeder, 1987), mc trng thnh ca qu (Davenport v Ellis, 1959; Mazliak, 1965a ), iu kin mi trng (lng ma, nhit ) (Kaiser v Wolstenholme, nm 1994; Kruger v Claassens, 1996a, 1996b; Mc Onie v Wolstenholme, 1982) v x l sau thu hoch (khng kh cha thnh phn) (Mazliak,1965b).

2.1.2. Axit bo bo ha v axit bo khng bo haLipid l nhng hp cht ha hc c cha mt hoc nhiu axit bo. Axt bo l cc axit hu c v c cu to ch yu l cc nguyn t carbon v hydro. Cc chui ngn axit hu c, c t hn mi nguyn t carbon, tt c u tan trong nc. Tuy nhin, cc axit bo chui di t ha tan trong nc do kch thc ca chui hydrocarbon di. Cc axit bo tm thy trong cc mesocarp b l chui di, vi 16 nguyn t cacbon tr ln (Kikuta v Erickson, 1968). C ba loi chnh ca axit bo: bo ha, khng bo ha n v khng bo ha a. Mt acid bo bo ha c s lng ti a l mt dy cc nguyn t hydro gn lin vi nguyn t carbon. Mt s cc axit bo b mt mt i nguyn t hir gia cc phn t carbon c gi l "axit bo khng bo ha n". Axit bo m

14

b thiu nhiu hn mt cp ca cc nguyn t hydro c gi l " axit bo khng bo ha a" (Mayfield, 1994). Cc thut ng vit tt thng thng cho cc axt bo cho thy hai con s; chiu di ca chui v s lng cc lin kt i. V d, "18:02" ch mt acid bo ca 18 nguyn t carbon v 2 lin kt i nh acid linoleic. Tng t, mt acid bo bo ha, nh acid palmitic s c hin th l "16:00". Thng thng (S) axit bo bo ha c tm thy trong thc phm ngun gc ng vt, trong khi axit bo khng bo ha n (M) v cc axit bo khng bo ha a (P) l ch yu c tm thy trong thc phm ngun gc thc vt. Triacylglycerol c th cha nhiu axit bo, mc d trong b ch c nm hoc su nguyn t ny. y l nhng acid bo bo ha acid palmitic (16:00) v axit stearic (18: 0), cc axit bo khng bo ha n oleic acid (18:01) v acid palmitoleic (16:01) v cc axit linoleic acid bo khng bo ha a (18 : 2) v acid linolenic (18:03). Oleic acid l cc acid bo ch yu, chim gn 60% tng s cht bo (Mazliak, 1965a; Kikuta v Erickson, 1968; Luza et al, 1990.). Nhn chung, s kt hp ca cc axit bo trong phn triacylglycerol xc nh cc c tnh vt l v dinh dng ca lipid ny. Cho n nay nhng thay i trong cu trc acid bo cha c nghin cu New Zealand

2.2. Tm quan trng ca Lipid trong b2.2.1. Ch tiu trng thnh, hm lng cht kh v thnh phn lipid tng s.Tng s lipid trong b l c s cho cc thng s xc nh s trng thnh, cc tham s c s dng ph bin nht cho cc ngnh cng nghip thng mi th gii l phn trm trng lng kh ca qu. V hm lng cht kh tng quan vi hm lng lipit c trong qu v l phng php va ph bin va tin li nn c nhiu quc gia p dng trong vic nh gi s trng thnh ca qu (Stahl,1933; Biale v Young, 1969; Appleman, 1969; Kikuta v Erickson, 1968; Lee v cng s, 1983;. Ranney et al, 1992).. N c ch ra rng phn trm lipid (trn mt trng lng ti) v phn trm m l i ng vi s thay i15

ca mt gi tr khng i. V d i vi b, Swarts 'Hass' (1976 trch dn bi Kruger et al., 1995) tm thy gi tr khng i l 87,8%. Tng t nh vy, Kruger et al. (1995) thy n c khong 86,5%, trong khi Hopkirk (1989) v Pearson (1975) thy n c khong 88% v 91% tng ng. Mt mi quan h gia lipid v nc cho php cc cht bo c th tnh t hm lng nc. C rt t nghin cu kim tra cht bo b New Zealand. Lawes (1980) chng minh mi quan h gia lipid v m cho cy trng Fuerte v Zutano v phn tch cc thnh phn acid bo ca cc loi tri cy Hass. Hopkirk (1989) o lng mc lipid trong qu 'Hass trong sut bn ma lin tip 1981-1985, v mi quan h gia hm lng lipid v s thnh thc ca qu. Cc nghin cu thy rng khi ma thu hoch t thng chn-thng hai hm lng cht kh ca b t Kaitaia ( min Bc xa) tng t khong 31% n 35%, trong khi hm lng lipid tng t khong 18% n 23%. Trong thi gian ny, mesocarp ca b t Vnh Plenty cht kh tng t 28% n 36% v lipid tng t 16% n 23%. Tuy nhin do s bin i cc cht trong qu ln ,ng thi hm lng lipit v hm lng cht kh t l thun vi thi gian sinh trng ca qu. V th, Hopkirk a ra kt lun c mt mi quan h mnh m gia vt cht kh v hm lng lipid v iu ny cn b nh hng ca tng vng.

2.2.2. Thng mi khai thc du biu ng ch l hm lng lipit trong qu b cao hn nhiu so vi cc loi tri cy khc. Trong thc t, tt c cc loi tri cy, ch c liu (Olea Europea) v du c tri cy (Eleaeis guineensis) l c hm lng lipit bng vi b m thi (Lewis, 1978). iu ny khuyn khch cc nh sn xut khai thc b trch xut cc cht bo. Du b cn c s dng rng ri trong m phm do tnh cht ca n nh l mt cht chng oxy ha t nhin v kh nng xm nhp vo da (Tng ng vi lanolin). Hn na, v thnh phn du b cha nhiu axit oleic cao nn c th c qung co l lm gim cholesterol. Nh vy trong tng lai, ngnh cng nghip chit xut du b c th l mt ngnh cng nghip pht trin New Zealand.

16

2.2.3. Hng v v mi i ca qu bKaiser et al. (1992) bo co rng cc thnh phn lipid trong qu b, cung cp mt kt cu c o v hng v hp dn cho qu. Sau khi thu hoch, b chn v mm, tht b mm cn ty thuc vo lng cht bo trong qu ti thi im thu hoch. Nn nh rng cc cht bo trung tnh ca b ch c tng hp trong qu trnh tng trng v pht trin trn cy v khng qua qu trnh bo qun hoc lm chn (Platt-Aloia v Thomson, 1981). S khc bit v hm lng du ca cy liu c quan st cc khu vc khc nhau, v s khc bit v s lng trong cc hp cht hng v cng c quan st (Lercker et al, 1973;. Montedoro et al, 1978.). Do , b New Zealand c mt hng v c trng m c th c s dng sn xut. Tuy nhin, trong ngnh cng nghip sn xut b New Zealand vn v mi i c xem l mi e da. Vn ca mi i s khng c xem xt trong bi ny, nhng cc mi quan h ca cc axit bo cho s pht trin ca hng v v mt hng v trong qu b s c nghin cu k lng v n l tiu chun nh gi cht lng sn phm.

2.2.4. Tn thng lnh v cc kha cnh khcLipid l mt thnh phn chnh ca ch n ung ca con ngi, ng gp ln n 40% lng calo trong ch n ca cc nc pht trin (Enser, 1995). Trong nhiu nm,nhng cht dinh dng c ngi tiu dng tiu th cao nh vy c t cu hi, c bit l tiu th ca mt t l cao ca axit bo bo ha (S) (cholesterol, thc y cc axit bo) v t l thp hn ca cc axit bo khng bo ha (U), c bit axit bo khng bo ha n (M) (cholesterol-gim axit bo) (WHO, 1982; COMA, 1984). Axit bo khng bo ha a v khng bo ha n axit bo khng thc y s hnh thnh ca ng mch, tc nghn mch mu (hin tng ny c gi l x va ng mch v gy ra bnh tim mch vnh (CHD)) v thng do cch axit bo bo ha gy ra (Mayfield, 1994). Tuy nhin theo cc bo co gn y cho rng ch n giu axit bo khng bo ha cng c th lm tng cholesterol v do lm tng nguy c CHD. V cng c nhiu kin cho rng cc axit bo khng bo ha n l h tr trong vic phng chng s tch t cholesterol trong ng mch ch (Howard v Savage, 1994). Do , t l ch 17

n ung ca cc axit bo khng bo ha a bo ha axit bo (P: S) c th khng cn thch hp (Ulbricht v Southgate, 1991). Slater v cng s. (1975) bo co cho 'Hass' b mt P trung bnh: S t l 0,75 t thng chn-Thng Mi Mt. Kt qu dinh dng ch ra rng ch n giu axit bo khng bo ha n (trong oleic acid c cc acid bo cho n nay ch iu tra) c th c li hn cho sc khe trong kh nng chng x va ng mch (Christakis, 1980). Lm lnh thng tch nhy ca cc nguyn liu thc vt c lin quan vi t l axit bo bo ha (S) cho cc axit cha bo ha (U) bo trong mng t bo (Lyon, 1973; Wang, 1982; Eaks, 1990). Lipid l mt phn quan trng ca mng t bo v ang tch cc tham gia vo qu trnh trao i mng. T l axit bo cha bo ha vi cc axt bo bo ha trong glycerolipids mng t bo ca qu b c th b nh hng bi nhit mi trng xung quanh trong qu trnh pht trin cy n qu (Moreton, 1988 c trch dn ca Kaiser v Wolstenholme, 1994). Cc hot ng ca mng t bo c th b nh hng bi nht ca pha lipid ca n. Khng ging nh cc axit bo bo ha, axit bo khng no thng l cht lng nhit thp.Do gia tng nhit s lm tng tnh lu mng (Stryer,1988). V vy, b c trng trong iu kin lnh c xu hng tch t nhiu axit bo khng bo ha trong khi pht trin hn so vi b c trng trong iu kin m.

2.3. o lipid v axit bo trong b 2.3.1. Xc nh hm lng LipidXc nh hm lng lipid rt tn thi gian v tn km vi mt lot cc k thut c s dng cho n nay. Refractometric: phng php ch s (RI) c pht trin bi Leslie v Christie (1929) s dng du Halowax nh mt dung mi (monochloronaphtalene), chnh thc c s dng o lng phn trm ca tng s lipid trong b California. Tuy nhin, cc kt qu khng ging nhau do b nh hng bi nhit , v tn nhiu chi ph. Phng php ny c xem l bt tin cho ngi trng. Phng php RI cng cho kt qu chnh xc khi kim tra tri cy chn v c bit tm ra mt cht nghi ng gy ung th (Lee,1981). Soxhlet l k thut s dng te du kh18

(khng phn cc dung mi) l phng php tiu chun phn tch hm lng lipid trong thc phm. Trong khai thc Soxhlet m c sy kh trc y, do ko di thi gian nh gi. Phng php ny c th mt n 12 gi v h thng t ng thng ch chy tm mu ti mt thi gian. Nh vy, k thut ny c coi l qu chm c s dng nh mt bi kim tra thng xuyn cho ngnh cng nghip. Mt s phng php chit xut lipid c pht trin cho sn phm ng vt c s dng xc nh tng s cht bo trong qu b vi thnh cng tng i. y l trng hp vi cc phng php c pht trin bi Folch et al. (1957) v Bligh v Dyer (1959). Tuy nhin, mu c kch thc v khi lng dung mi ln, v thi gian tin hnh di l nhng yu t bt lin trong qu trnh xc nh hm lng lipit trong qu.

2.3.2. Xc nh thnh phn axit boSc k kh hin nay l k thut tiu chun phn tch chi tit cc acid bo (nh l methyl este ca axit bo) thnh phn trong qu b (Mazliak, 1965a; Kikuta v Erickson, 1968; Eaks nm 1990;. Luza v cng s, 1990; Kaiser v Wolstenholme, 1994 ; Inoue v Tateishi, 1995). Trong bi ny, cc thnh phn acid bo ca cht bo chit xut s c xc nh bng kh sc k phn tch ca cc este axit bo methyl. Kt qu sc k kh cng s hin th thi gian trong ma m cht lng dinh dng (v thnh phn acid bo) ca qu t mc ti a. Nhng kt qu ny c tm quan trng v chng c th c s dng so snh b New Zealand vi b t cc nc khc mc dinh dng. B l mt loi qu m thnh phn c trng ca n c th thay i ph thuc vo ging cy trng, thi gian trong ma v mi trng. Mc tiu chnh ca bi ny l xc nh nh hng ca thi gian trong ma v a im trng nh hng n hm lng v thnh phn lipid trong b New Zealand. iu ny s gip nng dn trong vic la chn tri cy vi mong mun t tng s hm lng lipid cao nht. Hn na,cc thng tin lien quan v cht bo b New Zealand s rt hu ch.

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2.4 . Tin hnh th nghim2.4.1. a im thu hochQu b (Persea americana cv 'Hass.) c ly t hai vn cy n tri (mt nm min Bc v mt Te Puke), c la chn trn c s cc iu kin kh hu khc nhau. min Bc th kh hu m (ti Awanui t ti Lt. S. 35 03 '; Long 173 16'). Te Puke th kh hu mt hn( Vnh Plenty Te Puke, t ti Lat.S. 37 47 '; Long. 176 20').

2.4.2. c im cy bTrn 2010 nm tui cy b 'Hass ", cm t 10-20 cy n qu cc gc phn t ng-Bc ca cy cao 1-2 m, c gn th trong c vn cy n tri. Ti thi im gn th, dataloggers Sapac (Sapac TempRecord, Argus distributers Ltd, Auckland) c t trong cc tn cy (c che bi mt container nha) ng nhp nhit khng kh mi gi.

2.4.3 Thi gian thu hochTri cy c thu hoch trn by ln gia thng 9 nm 1998 (bt u vo ma thu hoch) n thng t nm 1999. Nhng v thu hoch bao gm cc ma thu hoch chnh New Zealand. T mi cy, hai qu ln nht c la chn, mt cho o lng cht kh / lipid, v mt xc nh gim trng lng. Cc khay tri cy nh gi cht kh / lipid c gi trong mt ti nha vi 3 l nh gim thiu s mt nc trong khi vn chuyn. Qu mu xanh l cy v khng hin th mu tm / mu en gy ra bi nh sng mt tri qu nhiu. B c thu hoch vo sng sm ( trnh mt nc) v vn chuyn qua m bng chuyn pht nhanh khi n phng th nghim trong vng 30 gi sau thu hoch.

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2.4.4. Kt qu nh giKhi n phng th nghim, tri cy c cn v o cng bng cch s dng Anderson Firmometer. -Vt cht kh S c bn khay, mi khay cha nm qu b v c a n ni kim tra. C hai loi kim tra cht kh, hai ni thc hin. -Hm lng cht kh: y l phng php thng c s dng trong ngnh cng nghip. Mt phn qu (thi lt theo chiu dc) c bc v, lp mng bao ph ht c loi b. Mt mu c 20 gram v sy kh trong thi gian 36 gi ti 60 C (cho n khi trng lng khng i) v em i cn li. -Plug kh c vn Mt plug t phn xch o ca tri cy tng c chp bng cch s dng mt su c na ng (ng knh 5mm ni b) v ct theo chiu dc. Cc phch cm c sy kh trong mt nguy c cho 36 gi ti 60 C (cho n khi trng lng khng i) sau khi h c ti cn nng. -Chun b mu cho trch Tng Lipid i vi vic xc nh tng nng lipid mt plug th hai, tip gip vi cc plug a cho cht kh, c ly t tri cy mi. Cc phch cm c thi lt mng (khong 5mm ng knh, chiu rng 0,5-1,0 mm), sau cn nng trong ng nghim tared KMax knh. Mi ml dung dch cloroform-methanol (1:1 v / v) c thm vo mi ng, sau c vortexed cho 10 giy m bo rng lt c hon ton m mnh trong cc dung mi. Cc homogenates ni cn li nhit phng trong 36 gi vi thnh thong lc. Sau thi gian ny cc lt m c r rng v b chm xung y ca ng (cc nc trong m c thay th bng methanol trong). Cc mu ny sau c lu tr -20 C cho n khi cn thit nh lng lipid khai thc v phn tch acid bo.21

2.4.5. cng v gim trng lng-Gim trng lng i vi mt s v thu hoch, gim trng lng thng xy ra trong thi gian 14 ngy sau khi chn 15 C. -nh gi cng cng tri cy c xc nh bng cch s dng mt Firmometer Anderson nh c m t bi Woolf et al., (1997). Firmometer Cc bin php khng c cung cp bi tri cy mt lc nn ca mt trng lng 300g thng qua mt nt li ng knh 17mm trong khong thi gian 10 giy. Kt qu (mm chuyn) c nhn vi 10 cung cp cho cc gi tr Firmometer. Ngay sau khi thu hoch gi tr Firmometer thng 10-15, ty thuc vo thi gian ca ma v. Cc Firmometer c th t gi tr ti a l 110 nh tri cy mm.

2.4.6. Xc nh nh lng Lipid tng sK thut ny c s dng nh lng hm lng lipid trong cc mu l mt sa i ca phng php Bligh v Dyer (1959) khai thc tng s lipid. Lipid c trch xut vi mt hn hp ca methanol, chloroform v nc = v 1:1:0.9 / v / v. Sau ly tm trn v ngn gn trit , hai lp c tch ra hon ton. Cc lp thp hn ch yu l chloroform v cha cc cht bo t cc m ban u, trong khi cc lp pha trn bao gm methanol v nc. V vy, khi cc lp chloroform c phn lp, th thu c cht bo. n gin v thun tin, chng ti tin hnh lm th nghim c th chit xut cht bo tng s t lt mng mesocarp vo chloroform / methanol m khng cn n homogenisation. Tuy nhin, mc d lt mesocarp chn c trch xut y , lt cha chn (cng) cc m hnh nh khng (Ph lc 1). V vy, cc phng php khc nhau ca tng s cht bo chit xut t mesocarp cng vo chloroform / methanol c th nghim.

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Kt qu cho thy rng khi s dng b cng cha chn, nghin bng cch s dng mt my xay sinh t (Polytron) t c hiu qu khai thc lipid cao nht (xem ph lc 1 cho kt qu cho thy chit lipid bng cch s dng ba phng php khc nhau). Ngoi ra, hm lng lipid ca b khng thay i trong qu trnh chn t khi thu hoch (ngy 0) thng qua chn ( 15 C) cho n khi t c chn mm, c th n c (ngy th 8 sau khi thu hoch) nh trc y bo co ca Platt-Aloia v Thomson (1981) v Luza et al. (1990) (xem ph lc 1 cho kt qu). Nhng kh khn trong vic chit xut lipit vi hm lng cao c th l do cc thnh t bo ba tng phc tp xung quanh idioblasts. Phng php ny c hp l ha m khng c kh khn ln v c s dng cho cc mu ly trong sut ma v. Trong khi cc th nghim khai thc trn c thc hin, cc mu thu thp c thi mng, cn nng v ngm trong 10 ml methanol chloroform v c bo qun -20 C cho n khi t yu cu. Cc k thut s dng phn tch cc mu b nh sau: Cc mu ct c ng lnh trong methanol-chloroform tan trong t nht mt gi nhit phng. 5 ml (1:1 v / v) chloroform / methanol, cc mu c ng nht bng cch s dng mt Polytron (m hnh CH-6010 Kinematica Kriens-Lu, PT 10-35 cm, ng knh u. 1,5 cm., Vi mt iu khin tc nhanh) trong khong 30 giy. yn trong 15 pht cc mu c vortexed v ngay lp tc c lc qua Miracloth. Cc m tri cy cn li trong giy lc c ra sch vi 5 ml dung dch methanol chloroform v p sut c p dng bng cch p m bo ti a phc hi dung mi. Mi ml nc lc c cha trong ng nghim KMax, 4,2 ml 1% v / v NaCl gii php b sung v sau ly tm (2500 vng / pht trong 30 giy). Cc dung dch mui c b sung cho cc phn vng, v n ng t l nc trong h thng. H thng cui cng nn cha chloroform: methanol: nc trong 1:1:0.9 t l hnh thnh h thng hai pha. Hn hp b chn ng mnh v ly tm cho php tch tt hn v lm r cc lp lipid c cha chloroform, sau c23

ht bng ng tim thy tinh. Mt lng nh ca lp chloroform c b li pha sau trnh loi b cc lp methanol-nc. Hn hp cn li c ti chit xut bng cch thm 2,5 mlte du kh (im si 40-60 C) vortexed v ly tm. Cc lipid c cha lp ether du kh c ht v kt hp vi chit chloroform u tin. Cc dung mi c bc hi 40 C theo mt dng lin tc ca nit oxy t do ( ngn chn qu trnh oxy ha ca cc axit bo c trong mu) cho mt trng lng khng i. Trng lng ca cc phn lipid kh c ghi li.Ngoi ra, phng php Soxhlet s dng te du kh c thc hin bng tay v kt qu ca hai phng php ging nhau.

2.4.7. Phn tch Acid bo ca LipidChuyn i Triglycerides Ester axit bo Methyl (FAME) Cc cht bo nng ngay lp tc resuspended trong 5 ml chloroform v c lu tr ti -20 C. xc nh thnh phn acid bo ca n, mt 50 L subsample ca-lipid chloroform-in c iu tr vi 100 L l 0,5 metoxit natri N trong methanol (chun b vi mt gii php ca dimethoxypropane v methanol (95:5, v / v)). Ester ca acid bo thnh acid bo este methyl (FAME) c hon tt sau khi ng nhit phng trong vng 15 pht. Sulfuric acid (400 L ca 0,125 N) c b sung v acid bo methyl este thu hi 7,5 ml ether du kh (im si 60-80 C).

2.4.8. Phn tch sc k khMt L ca methyl este acid bo trong te du kh c bm vo cc sc k kh (Hewlett Packard 5890A m hnh), c trang b mt Supelco hp nht s silica ct mao dn 11484-02A, ca hng s 2-4019 (30 mx 0.25mm x 0,2 m ID phim Mfg) v ion ho ngn la pht hin (r sot). Nhit l 100 C ban u, sau tng 15 C / pht n 190 C v c t chc ti 190 C trong 25 pht. Phun v my pht hin nhit c ti 200 v 220 C tng ng. Kh vn chuyn c nit, chy ti 22 cm / giy. i vi nghin cu ny, mt thnh phn acid bo thm, Stearic acid methyl ester (18:00) c thm vo mi mu nh mt tiu chun ni b ngay lp tc trc khi tim. Cc phn ng pht hin c24

hiu chnh vi mt hn hp acid bo methyl ester tiu chun (c cung cp bi Sigma-Aldrich) c cha cc axit bo c nm thng xy ra nng ng k trong qu b, palmitic acid (16:00), palmitoleic acid (16:01) oleic acid (18:01), linoleic acid (18:02), linolenic acid (18:03) v axit stearic (18: 0). Cc nh ni acid bo trong cc mu lipid c xc nh bng cch so snh vi thi gian lu gi ca cc axit bo trong hn hp tiu chun, v s tin tnh bng t l phn trm ca tng s lipid.

2.5 Kt qu th nghim.2.5.1. cng v gim trng lng ca qu bTrong sut ma v, qu b ti Te Puke c trng lng trung bnh l 252,1 g v gi tr trung bnh l 14,3 Firmometer, trong khi b ti min Bc c trng lng trung bnh 261,7 g v gi tr trung bnh l 13,9 Firmometer. B min Bc v Te Puke thu hoch trong thng mi mt khong 2,7% v 3,8% trng lng ca qu trong thi gian 14 ngy lm chn 15 C. T l gim trng lng trong qu trnh chn l tng i n nh, tng ng vi khong 0,2% / ngy i vi min Bc v 0,3% / ngy i vi Te Puke. S khc bit trong vic gim trng lng c th l do s khc bit v kch c qu t cc vn cy n tri.

2.5.2. Hm lng cht kh v LipidCht kh trung bnh tng trong thi gian trng. Hm lng cht kh trong b ca Te Puke tng t 24,6% n 36,4%, trong khi min Bc tng t 24,1% n 32,3% so vi cng k. Cng vi cc k thut thng mi tiu chun xc nh cht kh, chng ti cng kim tra vic s dng mt mu cm n nh. Chng ti tm thy mt s tng quan gia kt qu t cc cht kh thng mi v th nghim cm cht kh (R2 = 0,92), Ph lc 2. Vic xc nh vn cm kh nhanh hn ng k so vi cc k thut doanh, thng mi kh, tuy nhin, c nhiu bin i trong cc kt qu thu c.25

Cc vn v t l hm lng cht kh v hm lng lipid trong ma cho tri cy t hai khu vc c v trong hnh 1. Trong thi gian nghin cu, cht kh gi tr cao hn cho Te Puke hn so vi min Bc xa. Mc d t l cht kh trong c vn cy n tri bt u ti mt gi tr tng t vo thng Chn ( 24%), cht kh tri cy Te Puke tng vi tc nhanh hn ca tri cy Far North. i vi tri cy Te Puke, cht kh ni dung tng ln nhanh chng t Thng chn (24,6%) n nh im vo gia thng (35,2%), ni n chng li v sau cho thy mt xu hng tng nh trong thng ba v thng t. i vi min Bc, cho thy cht kh tng nhanh t 24,1% trong thng Chn ti mt nh cao 33,5% vo cui thng hai, gn mt thng sau hn Te Puke, v sau gim nh 32,4% trong thng t. Tng s lipid (% trng lng ti) c o trong thng Chn l trn trung bnh 17,2% trong Te Puke v 16,4% min Bc . Hm lng Lipid ca b Te Puke vn cao hn so vi ma, tng nhanh n nh cao 29,6% trong thng mt v sau tng t t n 31,3% trong thng t. Min Bc cho thy mt s gia tng nhanh chng n mt nh cao 26,7% trong thng Ba, hai thng sau Te Puke, v khong 26% trong thng t. Tng s lipid min Bc l nhng gi tr tng ng hm lng cht kh ca qu b (phn trm cht kh t nh im vo thng Hai v phn trm cht bo t nh im vo thng Ba). Mi quan h gia lipid v hm lng cht kh trong b t hai khu vc c th hin trong hnh 2. Phn tch hi quy tuyn tnh gia vt cht kh v lipid phn trm tng s phn trm cho thy rng c mt mi quan h cht ch gia cc yu t ny trong tri cy t c hai a im. Cc mi tng quan dn n mt R2 cho Te Puke ca 0,99, v l 0,9 i vi Bc Vin. Ngoi ra, tng s cht bo v lng nc ca tri cy cho tng khu vc vn lin tc thng qua cc ma gii vo khong 94% cho Te Puke v 93% i vi min Bc. Phn tch cc cht bo chit xut bng sc k kh tng t cho thy thnh phn acid bo cho c khu vc. Axit bo c xc nh bng cch s dng cc tiu chun thng mi cho thy cht bo c ch yu bao gm oleic (18:01),26

palmitic (16:00), linoleic (18:02), acid palmitoleic (16:01) v linolenic (18:03). Cc acid oleic khng bo ha n l acid bo c nhiu nht c hai vng. Ti Te Puke, oleic acid (18:01) nng tng t 67% trong thng Chn n 71% ca tng s cht bo trong thng Mi. N sau gim dn v cui cng plateaued ti 62% trong thng t (hnh3a). Acid palmitic (16:00) l acid bo th hai phong ph, cn li tng i n nh mc khong 15% tng s lipid. Nng acid linoleic (18:02) vn khng i mc 11% cho n khong thng Ging khi n t t tng ln n 15% trong thng t. Nng acid palmitoleic (16:01) vn tng i n nh mc khong 6% trong khi linolenic acid (18:03) tng nh t 0% trong thng Chn ln 1,4% trong thng Ba v sau gim xung 0,9% thng qua thng t. min Bc, oleic acid cng tng nh t 62% ca tng s cht bo trong thng Chn n 63% vo thng sau n gim t t v plateaued ti 57% thng qua thng ba v thng t (hnh 3b). Nh trong Te Puke, acid palmitic (16:00) l acid bo quan trng th hai hin ti v vn tng i n nh mc khong 18%. Linoleic acid (18:02), vn tng i n nh mc khong 13% cho n thng mt khi n tng nh n 16% trong thng t. Palmitoleic acid (16:01) vn tng i n nh mc khong 6% cho n gia thng ni m n cho thy mt s gia tng cht t 9% vo cui thng Hai. Linolenic acid (18:03) tng nh t 0% trong thng Chn ti 1,2% trong thng Ba, ni n plateaued. Ngy acid oleic trung bnh (18:01) cp c 10% thp hn min min Bc (60%) so vi nm Te Puke (66%), trong khi palmitoleic acid (16:01) l 17% cao hn min Bc xa (7%) so vi nm Te Puke (6%). Acid palmitic (16:00) l 20% cao hn trong tri cy t min Bc Far (18%) so vi nm Te Puke (15%). Linoleic acid (18:02) l 17% cao hn min Bc Vin (14%) so vi nm Te Puke (12%). Trong c hai khu vc, linolenic acid (18:03) trung bnh khng thay i trong hu ht ma gii vo khong 0,8%.

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Phn 3 THO LUNChng ti xc nhn mi quan h cht ch gia hm lng lipid v cht kh trong qu b c bo co ca b NZ bi Lawes (1980) v Hopkirk (1989), v trong cc nghin cu nc ngoi bi Stahl (1933), Biale v Young (1969) , Appleman (1969), Kikuta v Erickson (1968), Lee et al., (1983), v Ranney et al. (1992). Nh vy, Te Puke v min Bc, hm lng nc lin tc gim, hm lng lipid tng (R2 = 0,96) trong thi gian nh gi. Cc phng trnh tng quan tnh trong hnh 2 c ngha l chng ta c th d on t l cht bo trong qu ti mt t l phn trm cho mt vn kh hoc ngc l ( vng Te Puke c chnh xc cao hn min Bc). So vi cc bo co trc y xc nh cht bo trong qu b, ti u ha k thut cung cp nhng li th nh kch thc mu nh, chi ph hot ng thp, n gin, chnh xc v xc nh tng i nhanh (c bit i vi s lng ln cc mu). K thut mi ny c th trch xut bnh qun 5% cht bo hn so vi khai thc s dng k thut Soxhlet. Lewis et al. (1978) cng chng minh rng cc dung mi phn cc nh chloroform / methanol, chit xut cht bo trung bnh 5-8% cao hn so vi phng php Soxhlet (bng cch s dng te du kh). H cho rng methanol chloroform , pht hnh mt s cht bo protein, c th l phospholipid v glycolipids. Trong nghin cu ny c k thut c tm thy s c tch cc tng quan (R2 = 0,7), nhng n c khuyn co rng hai k thut c so snh hn na bng cch s dng cc k thut Soxhlet t nht hai ln trong ma v. Hm lng lipid khc nhau do cc phng php khai thc v iu kin chm sc khc nhau. Do cn c tin hnh kho st nhiu khu vc khc nhau a ra kt qu chnh xc. Nhn chung, hai giai on ca s tch t cht bo c th phn bit. Giai on u tng nhanh chng nng , xy ra t thng t cho n thng Ging Te Puke, v t thng chn n thng Ba min Bc , giai on th hai hm lng lipit tng chm . Eaks (1990) bo co rng mt l do cho s st gim hm lng cht bo sau ngy (tng ng Nam bn cu) c th l tng hp lipid lm chm li hay dng li nhng b vn cn tng trng lng. Ngoi ra, hm lng lipit tng28

cao vo cui ma min Bc c th l do s thay i nhit kh hu. Kaiser et al., (1992) cho rng cht bo c th c respired do nhit cao nh vy, lm chm s tng hp ca n. Orchard nhit cc h s trong thi gian ny (Ph lc 3) cho thy nhit ti a ca hai khu vc tng t nhau, nhng Te Puke c nhit trung bnh thp hn . Kt qu l b min Bc c th mt nhiu thi gian t c s trng thnh v nguyn nhn c th la do iu kin kh hu. Ti min Bc nhit trung bnh cao hn so vi khu vc Te Puke. Tuy nhin, b t Te Puke lun cho thy hm lng cht kh v hm lng lipit cao hn. Lawes (1980) tm thy gi tr tng t hm lng lipid (19,5% vo u thng mi mt v 22,9% gia thng) trong khi min Bc (19,5% v cui thng Mi 23% vo gia thng mt.) Tuy nhin, Lawes ch nghin cu t mt khu vc New Zealand (Gisborne) v ch hai ln trong ma v. Ngc li, Hopkirk (1989) tm thy gi tr cao hn ca hm lng cht kh v hm lng lipid cho b t Kaitaia ( min Bc) hn so vi b t Vnh Plenty. Trong Kaitaia, hm lng cht kh tng t 31% n 35% v cht bo tng t 18% n 23% t thng chn n thng Hai. Trong Vnh Plenty, cht kh tng t 28% n 36%, trong khi cht bo tng t 16% n 23%. Hopkirk ng vi kt qu ca Kaiser v Wolstenholme (1994) Nam Phi ngi cng c tm thy hm lng lipid cao hn trong b t cc vng c kh hu m hn so vi t cc vng c kh hu mt. Ni chung, nhit ca khu vc trng khng phi l yu t duy nht nh hng n s trng thnh ca tri b. Do tip tc nghin cu, bao gm c b t khu vc nhiu hn v nhiu vn cy n tri trong mt khu vc, l cn thit nh gi cc yu t khc nhau m c th nh hng n s trng thnh ca qu. Tng ca cht bo v lng nc vn tng i n nh cho tng khu vc trong thi gian sinh trng (thng Chn n thng T). iu ny ng rng tc gia tng t l cht bo l ging nh t l gim hm lng nc trong qu. Mc d c th c mt s thay i nh gia cc vng trng v ging cy trng, khng thay i ny cng c bo co trc khi vo nghin cu nc ngoi (Pearson, 1975; Swarts, 1976;. Kruger v cng s, 1995) v ti New Zealand bi Lawes (1980). Hopkirk (1989) cng ngh mi quan h ny, tuy nhin phng php29

tip cn ca nghin cu l, do mi quan h cht ch gia hm lng kh v hm lng lipid, cc cht bo khng i. Mc d Stahl (1933) cho rng hm lng nc c th thay i vi lng ma. Oleic acid bo chnh l acid c tng hp nh tryglicerides trong m mesocarp ca qu. V vy, vic tng tng lipid ch yu l do s tng hp ca axit oleic. Cc kt qu ny ph hp vi Eaks (1990). Trong nghin cu ny nm axit bo xy ra vi s lng ng k oleic (18:01), palmitic (16:00), linoleic (18:02), palmitoleic (16:01) v acid linolenic (18:03). Nhng axit bo cng c xc nh trong s lng tng t cho mt phn ca giai on trng thnh ti California bi Eaks (1990), Chile do et al Luza., (1990), Nam Phi ca Kaiser v Wolstenholme (1994), v ti Nht Bn bi Inoue v Tateishi (1995) axit oleic, cc cholesterol tng ln 10% min Bc so vi Te Puke. Ngoi ra, acid palmitic min Bc cao hn Te Puke l 20%. Tnh trung bnh, tng cc monounsaturates li (oleic v palmitoleic acid) o c khong 7,5% cao hn trong b t Te Puke (72%) hn so vi b t min Bc (67%). hiu ng tng t ca kh hu i vi cc axit bo c tm thy bi Kaiser v Wolstenholme (1994) trong nghin cu ca h. H tm thy oleic acid c khong 20% thp hn cc vng m hn trong cc vng mt, acid palmitic l 16% cao hn cc vng m hn trong cc vng mt, v tng ca monounsaturates c khong 10% cao hn cc vng mt m hn trong vng m hn. Tuy nhin, min Bc b c hm lng axit oleic khng bo ha n cao hn b Te Puke . Cc cp ca axit oleic (60%) v acid palmitoleic (7%) so vi nhng thun li ca du liu ngh (56 - 83% axit oleic v 0,3-3,5% acid palmitoleic) (IOOC, 1984 bng tm tt bng Kiritsakis, 1990 ). Cc tnh cht dinh dng ca du liu l thc phm gim cholesterol cng c bit n v c th hin bng cc ch s thp ca cc bnh mch vnh nhng nc c mc tiu th cao ca du liu (Andrikopolous, 1989). Ngoi ra, khng bo ha a t l bo ho (P: S) c xut nh l mt ch tiu, bin php khuyn khch ch n ung c bnh tim mch vnh hay khng (c gi l ch s ca atherogenecity). Trong thi gian nghin cu (thng chn-thng t) P: S khc nhau 0,7-1 trong c hai khu vc. C th thy rng t l tng vi k hn thanh ton. Tuy nhin, trung bnh cho ma 30

c hai trang web l nh nhau, cho Te Puke 0,9 v 0,8 i vi min Bc. Ti California et al Slater, (1975) bo co cho 'Hass' b trung bnh P: t l 0,75 S t thng chn-thng mi mt (tng ng Nam bn cu). Du liu P: S t l l trong khong 0,14-1,19 ty thuc vo khu vc ang pht trin (IOOC, 1984 bng tm tt bng Kiritsakis, 1990). Tuy nhin, din bin gn y trong dinh dng bo co li ch sc khe tt hn t mt t l cao, ch n ung khng bo ha n (c bit l oleic acid) axit bo bo ha (M: S) hn l t mt ch n ung vi mt P cao: S t l. V d i vi du liu M: S t l l trong khong 3,1-9,2 ph thuc vo khu vc ang pht trin. Chng ti tm thy mt M: S t l trung bnh l 4,7 i vi tri cy Te Puke, 3.8 cho min Bc .

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PHN 4 KT LUNTng s cht bo v hm lng cht kh trong qu b c mi quan h vi nhau. Trong thi k thu hoch, tri cy t Te Puke c hm lng lipid cao hn (v hm lng cht kh) so vi tri cy t min Bc. Ti c hai vng, cc axit bo khng bo ha n c li (oleic acid) l acid bo tng hp chnh. Tuy nhin, tri cy t Te Puke cho thy hm lng axit oleic cao hn so vi tri cy t min Bc. iu ny cho thy rng yu t nhit nh hng n vic tng hp v thnh phn ca cht bo trong qu. Ngoi ra, t l axit oleic v palmitoleic khng bo ha n bo ha axit bo palmitic acid v t l acid linoleic v linolenic axit bo khng bo ha a hai vng: min Bc v Te Puke gn bng vi du liu.

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Ti liu tham khoAndrikopolous, N. K. 1989. The tocopherol content of Greek olive oils. Journal of the Science of Food and Agriculture. 46, 503-509. Appleman, D. 1969. Personal Communication with Biale and Young 1969. In: The Biochemistry of Fruits and their products. Hulme, A.C (Ed) Academic Press, London, pp 1619.Barry, G. A.; Brown, B. I. and Baker, L.R. 1983. The use of lowresolution nuclear magnetic resonance for determining avocado maturity by oil content. Journal of Food Technology. 18. 401-410. Bligh, E.G and Dyer, W.J. 1959. A rapid method of total lipid extraction and purification. Canadian Journal of Biochemistry and Physiology, 37. 911-917.Biale, J.B and Young, R. E. 1969. The avocado pear In Biochemistry of fruits and their products Ed. Hulme. Bergh, B.; Kumamoto, J and Chen, P. 1989. Determining maturity in Whole avocados. California Avocado Society. Yearbook. 173-176.Christakis, G; Fordyce, M.K and Krtz, C. S. 1980. Th biological aspects of olive oil. Proceedings of the International Congress Biological Value of Olive oil, 3rd, Chanea Greece. Committee on Medical Aspects of Food Policy (COMA). 1984. Report on Health and Social Subjects No 28, HMSO, London. Dolendo, A. L.; Luh, B. S. and Pratt, H. K. 1966. Relation of fatty acids changes to respiration rate during ripening of avocado fruit. Journal of Food Science 31,(3), 332-336. Eaks, I. 1990. Change in the fatty acid composition of avocado fruit during ontogeny, cold storage and ripening. Tropical Fruit in International Trade. Acta Horticulturae 269: 141-151.Enser, M. 1995. Meat lipids. Developments in oils and fats. Edited by Hamilton, R. J. First ed. Blackie Academic & Professional.Folch, J; Lees, M. and Stanley, G.H.S. 1957. A simple method for the isolation and purification of total lipids from animal tissues. Journal of Biological Chemistry, 226. 497-509. Hatton, T.T.; Soule, M. Jr. and Popenoe, J. Effect of fruit position and weight on percentage of oil in Lula avocados in Florida. American Society for Horticultural Science, 69. 217-220. Hopkirk, G. 1989. Avocado Maturity Assessment. Division of Horticulture and Processing.33

DSIR. Howard, T. and Savage, G. 1994. The advantages of increasing olive oil in the diet. Nutritional Trends for the Future. Proceedings of a Continuing

Education Seminar. Edited by Savage, G.P and Webster, G and Plows, E. Human, T. P. 1987. Oil as a by-product of avocado. South African Avocado Growers Association Yearbook, 10. 159-164. Inoue, H and Tateishi, A. 1995. Ripening and fatty acid composition of avocado fruit in Japan. Proceedings of the III World Avocado Congress. International Olive Oil Council (IOOC), 1984. International Trade Standards applying to olive oils and olive- residue oils. COI/T.15 NC No 1.Madrid Spain. Kaiser, C.; Smith, M. T and Wolstenholme, B.N. 1992. Overview of lipids in the avocado fruit, with particular reference to the Natal Midlands. South African Avocado Growers Association Yearbook. 15. 7882.Kaiser, C. and Wolstenholme, B.N. 1994. Aspects of delayed harvest of 'Hass' avocado (Persea americana Mill.) fruit in cool subtropical climate. I. Fruit lipid and fatty acid accumulation. Journal of Horticultural Science. 69, 3, 437-445. Kikuta. Y. and Erickson, L.C 1968. Seasonal changes of avocado lipids during fruit development and storage. California Avocado Society Yearbook, 52: 102-108. Kiritsakis, A. K. 1990. Olive Oil. American Oil Chemists Society. Champaign Illinois. Kruger, F.J.; Stassen, P.J.C and Snijders, B. 1995. A preliminary study on variation in the maturity parameters of avocados from the Kiepersol- Hazyview area. South African Avocado Growers Association Yearbook. 5, 74-77. Kruger, F.J. and Classens, V.E. 1996a. The Influence of rainfall and Irrigation on the maturity parameters of South African export avocados. South African Avocado Growers Association Yearbook. 19, 93-95. Kruger, F.J. and Classens, V.E. 1996b. Comparison of Export Avocado Maturation at Burgersahll during the 94 and 95 seasons. South African Avocado Growers Association Yearbook. 19, 105-108. Lahav, E and Kalmar, D. 1977. Water requirements of avocado in Israel II. Influence on Yield, Fruit growth and Oil content. Australian Journal of Agricultural Research, 28. 869-877. Lawes, G. S. 1980. Maturity and quality in avocados. The Orchardist of New Zealand. March, 63-64. Lee, S. K. 1981.34

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Yearbook. 65, 133-141. Lee, S.K, Young, R. E, Schiffman, P.M and Coggins, C.W, Jr. 1983. Maturity studies of avocado fruit based on picking dates and dry weight. Journal of the American Society for Horticultural Science, 108, (3) 390-394. Lercker, G. Capella, P. and Deserti, P. 1973. Volatile and aromatic compounds of extra virgin olive oils. Sci. Tecnh. Alim. 3, 299. Lesley B.E. and Christie, A. W. 1929. Use of the refractometric method in determination of oil in avocados. Industrial and Engineering Chemistry (Analytical Edition) 1:24 Lewis, C. 1978. The maturity of avocados- A general review. Journal of Science, Food and Agriculture 29. 857-866. Lewis, C, Morris, R. and OBrien, K. 1978. The oil content of avocado mesocarp. Journal of Science, Food and Agriculture. 29, 243-249. Luza, J.G.; Lizana, L.A. and Masson, L., 1990. Comparative lipids evolution during cold storage of three avocado cultivars. Acta Horticulturae 269, Tropical Fruit in International Trade. Lyon, J.M. 1973. Chilling injury in plants. Annual review of plants physiology. 24. 445-466. Mayfield, E. 1994. A consumers guide to fats. US. Food and Drug administration. Internet site. Mazliak, P. 1965a. Les lipides de l avocat. I. Composition en acides gras des diverses parties du fruit. Fruits 20: 49-57 Mazliak, P. 1965 b. Les lipides de l avocat. II. Variation de la composition en acides gras des lipides du pericarpe selon la composition de latmosphere autor des frutis en maturation. Fruits, 20: 117-120. McOnie, A. J and Wolstenholme B. N. 1982. Avocado fruit growth and maturity in two Natal localities. South African Avocado Growers Association Yearbook. 5, 74-77. Montedoro, G.; Bertuccioli, M.; and Anichini, F. 1978. Aroma analysis of virgin olive oil by head space volatiles and extraction techniques. In flavor of foods and beverages. Chemistry and Technology. Charalampous, G and G.35

Inglett Editors. Academic Press, NY. Moreton, R. S. 1988. Physiology of lipid accumulation yeasts. In: Single cell oil. (Moreton, R. S Ed.) Longman Scientific and Technical, Essex, England, 1-32.Pearson, D. 1975. Seasonal English market variation in the composition of South African and Israeli avocados. Journal of the Science of Food and Agriculture, 26, 207-213. Platt-Aloia, K. A. and Thomson, W.W. 1981. Ultrastructure of the mesocarp of mature avocado fruit and changes associated with ripening, Annals of Botany, 48, 451-465. Platt- Aloia, K. A.; Oross, J.W. and Thompson W.W. 1983. Ultrastructural study of the development of oil cells in the mesocarp of avocado fruit. Bot. Gaz 144. 49-55. Ranney, C.A.; Gillette, G.; Brydon, A; McIntyre, S.; Rivers, O.; Vasquez, C.A. and Wilson E. 1992. Physiological maturity and percent dry matter of California avocado. Proceedings of the Second World Avocado Congress. 379-385. Ross, J.H.E.; Sanchez, J; Millan, F. and Murphy, D .J. 1993. Differential presence of oleosins in oleogenic seed and mesocarp in olive (olea europea) and avocado (Persea americana). Plant Science, 93, 203-210. Rosenthal, I; Merin, U.; Popel, G. and Bernstein, S. 1985. An analytical assay for the determination of oil content in avocado. California Avocado Society. Yearbook, 133-136. Schroeder, C. A. 1953. Growth and development of the Fuerte avocado fruit. Journal of the American Society for Horticultural Science. Los Angeles. 61, 103-109. Schroeder, C.A. 1987. Physiological gradients in fleshy pericarp of avocado. South African Avocado Growers Association. Yearbook. 10. 32-34 Slater, G. G.; Shankman, S.; Shepherd, J. S.; and Alphin-Slater, R. B. 1975.36

Seasonal variation in the composition of California avocados. Journal Agricultural Food Chemistry, 23. (3). 468-474. Stahl, A. L. 1933. Changes in composition of Florida avocados in relation to maturity. Agricultural Experiment Station, Gainesville, Florida, May, Bulletin 259. Stryer, L. 1988. Introduction to biological membranes. In: Biochemistry, 3rd Edition. W. H. Freeman and Company, New York, USA, 283-312. Stumpf, P. K and Conn. E. E. 1987. The Biochemistry of Plants. Lipids: Structure and Function.Academic Press. Swarts, D.H. 1976. NPraktiese avokado-oliebepalingsmetode vir produsente. Citrus and Subtropical Fruit Journal. 511. 8-11.14. Ulbricht, T. L. V. and Southgate, D. A. 1991. Coronary heart disease: seven dietary factors. The Lancet, 338. 985-992. Vakis, N. J.; Gregoriou, C. and Papademetriou, M. 1985. Maturity and picking dates of avocados under Cyprus conditions. California Avocado Society, Yearbook. 81-88. Wang, C. Y. 1982. Physiological and biochemical responses of plants to chilling stress. HortScience 17(2). 173-186. Werman, M. J. and Neeman, I. 1987. Avocado oil production and chemical characteristics. Journal of American Oil Chemists Society. 64, 2. 229- 232. Woolf, A. B.; McLeod, D. L.; Burdon, J.N and White, A. 1997. Using the Anderson firmometer. HortResearch Client Report No 97/119. World Health Organization (WHO). 1982. Technical Report Series No 678, Geneva

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MC LCTrangLI M U ................................................................................................................... 1 Phn 1: TNG QUAN ...................................................................................................... 2 1.1. Gi tr kinh t ......................................................................................................... 2 1.2. c im thc vt v sinh l ................................................................................ 3 1.2.1. c im thc vt ........................................................................................ 3 1.2.2. c im sinh l ca hoa b .......................................................................... 4 1.3. c tnh sinh thi ca cy b ................................................................................ 5 1.3.1. Nhit ........................................................................................................... 5 1.3.2. m ............................................................................................................. 6 1.3.3. Gi .................................................................................................................. 6 1.3.4. t ai ............................................................................................................. 6 1.4. K thut trng b ................................................................................................... 7 1.5 . Phng tr su hi ................................................................................................. 7 1.5.1. Su .................................................................................................................. 7

1.5.2. Bnh.81.6. Thu hoch v ch bin ......................................................................................... 10 Phn 2 NI DUNG ......................................................................................................... 12 2.1. Thnh phn cht bo v axit bo ca b .............................................................. 12 2.1.1. Lipid trong b ............................................................................................... 12 2.1.2. Axit bo bo ha v axit bo khng bo ha ................................................ 14 2.2. Tm quan trng ca Lipid trong b ................................................................ 15 2.2.1. Ch tiu trng thnh, hm lng cht kh v thnh phn lipid tng s. ..... 15 2.2.3. Hng v v mi i ca qu b ..................................................................... 17 2.3. o lipid v axit bo trong b ............................................................................... 18 2.3.1. Xc nh hm lng Lipid ............................................................................ 18 2.3.2. Xc nh thnh phn axit bo ....................................................................... 19 2.4 . Tin hnh th nghim .......................................................................................... 20 2.4.1. a im thu hoch ....................................................................................... 20 2.4.2. c im cy b ........................................................................................... 20 2.4.3 Thi gian thu hoch ....................................................................................... 20 2.4.4. Kt qu nh gi ........................................................................................... 21 2.4.5. cng v gim trng lng ....................................................................... 22 2.4.6. Xc nh nh lng Lipid tng s ............................................................... 22 2.4.7. Phn tch Acid bo ca Lipid ........................................................................ 24 2.4.8. Phn tch sc k kh ...................................................................................... 24 2.5 Kt qu th nghim. ............................................................................................. 25 2.5.1. cng v gim trng lng ca qu b..................................................... 25 2.5.2. Hm lng cht kh v Lipid ....................................................................... 25 Phn 3 THO LUN ..................................................................................................... 28 PHN 4 KT LUN ...................................................................................................... 32 Ti liu tham kho .......................................................................................................... 33

38