The fatty acid composition of grapefruit seed oil

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Authors Teles, Francisco Franco Feitosa, 1941-

Publisher The University of Arizona.

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THE FATTY ACID COMPOSITION

OF GRAPEFRUIT SEED OIL

by

Fran c isco Franco F e ito sa Teles

A T hesis Submitted to th e F aculty of the

COMMITTEE ON AGRICULTURAL BIOCHEMISTRY AND NUTRITION

In P artia l Fulfillm ent of the Requirements For the D egree of

MASTER OF SCIENCE

In the G raduate College

THE UNIVERSITY. OF ARIZONA

1 9 7 1

STATEMENT BY AUTHOR

This th e s i s has been subm itted in partia l fu lfillm ent of r e ­quirem ents for an advanced degree a t The U niversity of Arizona and is d ep o s ited in the U niversity Library to be made av a ila b le to borrowers under ru les of the Library.

Brief quo ta tions from th is th e s i s are a llow able w ithout sp e c ia l p e rm is s io n , provided tha t accu ra te acknow ledgm ent of source is m a d e . R equests for perm ission for ex tended quota tion from or reproduction of th is m anuscrip t in whole or in part may be granted by the head of the major departm ent or the Dean of the G raduate C ollege when in his ju d g ­ment the proposed use of the m ateria l is in the in te re s ts of s c h o la r ­sh ip . In a ll o ther in s ta n c e s , h o w ev e r , perm ission m ust be obtained from the au thor.

SIGNED:

APPROVAL BY THESIS DIRECTOR

This th e s is has been approved on the da te shown below:

L xJ . W arren Stull

"ofessor of Dairy and Food S c ien cesa te

ACKNOWLEDGMENTS

< '

The author w ish e s to ex p re ss h is s ince re ap p rec ia t io n to the

following members of The U niversity of A rizona, T u c s o n , Arizona:

Dr. J . W arren S tu l l , P ro fesso r of Dairy and Food S c ie n c e s , for

h is adv ice throughout th is s tu d y . I am s in c e re ly g ra te fu l for his p a t ien t

unders tand ing and a s s i s ta n c e ex tended to me in the p repara tion of the

m anusc rip t . Dr. G erald H. S to tt , H e a d , D epartm ent of D airy and Food

S c ie n c e s , D r. W illiam H. Brown, A sso c ia te P rofessor of Dairy and Food

S c ien ces and Dr. Thomas N. W e g n e r , A ss is ta n t P ro fe sso r , D epartm ent

Of D airy and Food S c ie n c e s .

G ratitude is ex tended to Dr. W illiam J. P i s to r , for h is help

and encouraging w o rd s .

A ppreciation is a lso ex tended to Dr. W illiam G. M atlock, Campus

coord inator of the U n ivers ity of A rizo n a /U n iv ers ity of G ear a C o n trac t .

Dr. Ralph L. P r ic e , A ss is ta n t P ro fesso r , is thanked for the

donation of fruit sam ples and for h is help during a portion of my s tu d y .

I w an t to thank a ll my co lle a g u e s w hose help en ab led me to

com plete th is s tu d y .

S p ec ia l recogn it ion is g iven to my w i f e , E n e id a , w hose

p a t ie n c e and unders tand ing made th is work p o s s ib le .

TABLE OF CONTENTS< ■

Page

LIST OF TABLES . ........................................................ v

ABSTRACT ................... v i

INTRODUCTION . . . . . ............................. 1

LITERATURE REVIEW................................ 3

H is to r i c ' ................ .... . .................................... 3B o t a n i c ................................... 4G rapefruit Seed Oil . . . . A '..................... 5Oil P rocess ing . ........................................ 8Importance of H arvesting Time ........................................ 9Seed Com position . ........................ 11

Fatty Acids .................... 13

MATERIALS AND M E T H O D S ................................ . . ' . .....................................15

S a m p le s ............................................................................................ 15Sample C o l l e c t i o n ........................................ 16Seed P r e p a r a t i o n ........................................................ . 17Oil E x t r a c t io n ................................................................................ 17M ethyl Esters Preparation . ..................................... 17G as-L iqu id Chromatography . . . . . . . ......................................... 18

RESULTS AND DISCUSSION . . . . . . . . . . . . . . . . . . . . . . 19

CONCLUSIONS ........................... 37

. LITERATURE C I T E D ...................................................... 38

HST OF TABLES

Table Page

1. Fatty Acid C om position of Burgher Grapefruit Seed OilRelated to H arvest D ate . . . ................................................ 20

2. Fatty Acid Com position of C handler Grapefruit SeedOil Related to H arvest D a t e ............................................ 21

3. Fatty Acid C om position of Yuma Yellow Grapefruit SeedOil Related to H arvest D ate . ........................ 22

4. Fatty Acid C om position of Yuma Pink Grapefruit SeedOil Related to H arvest D a t e .................................... 23

5 . Fatty Acid Com position of U. of A. G rapefruit SeedOil Related to H arvest D a t e ........................................ . . 24

6. Average C ontent of Saturated and U nsa tu ra ted Fatty Acidsof A rizona 's Grapefruit Seed O i l s ................................ 28

7 . Total Lipids , Petroleum Ether Extract and Ind iv idual AirDried Seed W eight of Burgher G r a p e f r u i t ......................... . 30

8. Total L ip ids , Petroleum Ether Extract and Ind iv idual AirDried Seed W eigh t of C hand le r G r a p e f r u i t ........................ 31

9. Total Lipids , Petroleum Ether Extract and Ind iv idual Air, Dried Seed W eight of Yuma Yellow G r a p e f r u i t .................... 32

10. Total Lipids , Petroleum Ether E x t ra c t , and Ind iv idua lAir Dried Seed W eight of Yuma Pink G r a p e f r u i t ................ 33

11. Total Lipids , Petroleum Ether E x trac t , and Ind iv idua l AirDried Seed W eight of U. of A. G ra p e f ru i t . 34

12. The Average C on ten t of Total Extrac tab le Lipid, PetroleumEther Extract and Their Ratios . ........................................ . 35

v

ABSTRACT

Seeds from five Arizona g ra p e f ru i t , C itrus p a ra d is i (Macf.)

v a r ie t ie s were an a ly zed by gas liquid chromatography for fa tty ac id

com position . Three M aricopa county groves (Burgher, U. of A. , and

Chandler) and two in the Yuma area (Yuma Pink and Yuma Yellow) were

u sed as sou rces of g rapefru it . Fruit were p icked a t approxim ately

2 w eek in te rv a ls during the 1969-70 growing s e a so n .

Six fa tty a c id s including m y ris t ic , p a lm itic , s t e a r i c , o le ic ,

l in o le ic , and l in o len ic w ere m easu red . There w as such a s im ila r ity

be tw een a ll sam ples th a t ne ith e r varie ty nor h arvesting time could be

d is t in g u ish e d on th e b a s is of seed fa tty ac id a n a ly s is .

The Arizona grapefruit seed oil an a lyzed in th is s tudy had an

average of 65% u n sa tu ra ted and 35% sa tu ra te d fa tty a c id s . The air

dried s e e d s conta ined approxim ately 30% to ta l ex trac t ab le l ip id s of

w hich 25% w as petroleum ether so lu b le .

I

INTRODUCTION

The average y ie ld of se e d s from g ra p e fru i t , C itrus parad is i

(M acf . ) , is about 4 .7 per c en t of w et seed conta in ing 55 to 60 per cen t

m o is tu re , b a sed on the w eigh t of the whole fruit (16). According

to the same authority the a ir dried se e d s con ta in 28 to 35 per cen t

o i l , a ty p ic a l a n a ly s is being g iven as 3 0 .3 per cen t e th e r ex trac t from

seed con ta in ing 11.9 per c en t m oisture . Seeds from two v a r ie t ie s

grown in the W e s t Ind ies were found to con ta in from 41 to 53 per cen t

o i l . In th e s e s e e d s , one-fou rth of the w eight w as hull and th re e -fo u r th s

w as kernel (3).

The se e d s of grapefruit and other c itrus fruits are r ich in oil

and although the proportion of seed to fru it is s m a l l , the tonnage a v a i l ­

ab le as a byproduct of the c itrus fruit p ro cess in g industry is co n s id e r­

a b le . M ethods for s e p a ra t in g , drying and milling the s e e d have been

developed and com m ercial production of c itrus seed o i ls has become

large enough to be e x p re sse d in terms of ta n k -c a rs per month (3).

There are no pub lished reports of the c h a ra c te r is t ic s of

Arizona grapefru it s e e d o i l . W ith the p o s s ib i l i ty of in c re a se d in te re s t

in grapefru it seed o i l , there appeared to be an advan tage in studying the

s e a so n a l and v a r ie ta l d iffe rences of A rizona 's seed oil p o te n t ia l .

Furtherm ore, th e advent of improved gas chrom atographic p rocedures for

1 '

2

the q u a li ta t iv e and q u an ti ta t iv e determ ina tions of fa tty a c id s has

g rea tly fa c i l i ta te d a s tudy of th is ty p e . In th is w o rk , the s e a s o n a l and

v a r ie ta l d iffe ren ces in the fa tty ac id com position of five A rizona 's

g rapefru it s e e d o ils were s tu d ied .

/

LITERATURE REVIEW

H is to ric

G rapefruit , C itrus pa rad is i (M acf .) , is a n a tiv e of

M a la y s ia and P o ly n e s ia . It was in troduced into J a m a ic a , where it

becam e of im portance com m ercially and w as grown e x te n s iv e ly (4).

Grapefruit may have come into e x is te n c e as a mutant or seed lin g in the

W e s t I n d ie s , perhaps from se e d in troduced by Shaddock. C ap ta in

° S h addock , an E ast Indian s e a c a p ta in , is c red ited w ith bringing seed of

the shaddock (pummelo) to the W est In d ie s .

The e x ac t d e ta i ls of the in troduction of the pomelo (grapefruit)

into Florida are un k n o w n . In all p ro b a b i l i ty , it w as brought to Florida

to g e th e r with o ther members of the genus by the S p a n ia rd s , w h o , under

the lead e rsh ip of Ponce de L eon , f irs t landed upon the c o a s t of Florida

in th e y ea r 1513. It is known th a t Don P h il l ip s , a S pan ish noblem an,

s e t t le d in Florida in about 1809. He brought grapefru it s e e d s with him

and p lan ted them . W ith the t re e s ob ta ined from th e se s e e d s , and w ith

o thef t r e e s , he s e t out a c itrus grove a t th a t point and brought it in to

bearing (10).

3

Botanic

In a rev iew w hich d i s c u s s e s the chem ical com position of a

na tu ra l p lan t p ro d u c t , it is d e s irab le to iden tify as a c cu ra te ly as

p o ss ib le th is p a r t ic u la r fruit under d i s c u s s io n . G rapefruit be longs to

the Rue Fam ily—R u ta c e a e . The Rue family in c lu d es about 100 genera

and 900 s p e c ie s of herbs , shrubs , and t re e s , most of w hich require

tro p ica l or sub trop ica l c lim a tes but some of w hich ex tend into tem perate

re g io n s . The developm ent of oil g lands con ta in ing fragrant e s s e n t ia l oil

in l e a v e s , fruits , or o ther parts of the p lan ts is c h a ra c te r is t ic of the

fam ily . Some of the members, of the family are fam iliar ornam ental

p l a n t s , but the m ost u se fu l and w ell known members are th e c itru s fru it

t r e e s , where grapefru it is a s p e c ia l iz e d form or v ar ie ty (3) . Unfor­

tu n a te ly , there is a lack of agreem ent among taxonom ists about the

exac t b o tan ica l nom enclature of c i tru s s p e c ie s , and the m atte r is

further com plica ted by the e x is te n c e of many m utants , hybrids , and

ho rticu ltu ra l v a r ie t ie s (12).

It has been commonly a c c e p te d , but not e s t a b l i s h e d , that

g ra p e f ru i t , C itrus pa rad is i (M acf. ) , is a sport from the shaddock or

pummelo. C itrus grand is (Linn.) O sb e c k , b ecau se of the resem blance of

the tw o. It is p o ss ib le however th a t th e two may not be re la ted or th a t

the grapefru it may be a na tu ra l c ross be tw een shaddock and orange (8).

Although there is some d isag reem en t, in 1938, Harold Hume (10)

referred to C itrus paradis 1 (M acf.) (parad is i of p a rad ise or g a rd e n s ) .

C om m erc ia lly , the fruit i s known a s g rapefru it . This ap p e lla t io n w as

given b e c a u se th e fruit is so frequently borne in g ra p e - l ik e c lu s te rs

or from th ree or four to a dozen and a h a lf .

Grapefruit Seed Oil

One of the e a r l ie s t re fe ren ces to grapefruit seed o il as a

com m ercial product w as th a t of Jam ieson (11) who in 1932 reported

both so lven t ex trac ted and Anderson ex p e lle r o il sam ples fa tty acid

c o n ten t , iodine number and other chem ica l and p h y s ica l c h a r a c te r i s t i c s .

He s ta te d th a t Jam ieson , Baughman and G ertler Oil and Fat Ind. ,

‘ 7, 181 (1930) . found th a t the a ir dried seed con ta ined 30 per cen t o il .

The e x p re sse d oil gave the following c h a r a c te r i s t i c s : sp e c i f ic gravity

at 25°C 0 .9170 ; re frac tive index 1 .4700 ; iodine no . (Hanus) 106 .3 ;

s ap o n if ica t io n va lue 194 .1 ; ac id va lue 2 .5 ; a ce ty l v a lu e 7 .7 ; u n sa p o n i-

fiab le m atter 0.7%; sa tu ra ted ac id s 28.60%; u n sa tu ra ted a c id s 68.50% .

The oil con ta ined the following p e rcen tag es of fa tty a c id s : o le ic 1 9 .6 6 ,

l in o le ic 48 .84 ; palm itic 1 9 .2 , s te a r ic 7 .2 5 , and l ig n o cer ic 0 .1 6 .

The so lven t ex trac ted meal w as exam ined w ith the fo llow ing

percen tage com position reported: m oisture 9 .7 ; a sh 3 .8 ; fa t 4 .3 ,

prote in 2 1 .4 ; crude f iber 22 .0 ; and n i tro g en -free ex trac t 3 8 .8 (11).

The b i t te rn e s s of the crude grapefru it seed oil appeared

in i t ia l ly to p reclude i ts u se in anything but soap m anufacture s ince a

fe a s ib le method for the rem oval of th is t a s t e was not a v a i la b le . By

1940, h o w ev e r , N olle and von Loeseck (16) reported procedures for the

com m ercial production of grapefru it seed o il including e x p re s s io n ,

b le a c h in g , and w intering of the oil in Florida and poin ted out further

th a t th e extrem ely b it te r crude oil could be e a s i ly re fined to a bland

ta s t in g product (5). In 1938-39 , the production of c i tru s s e e d oil in

Florida was only 45 to n s , and it w as es tim a ted th a t approxim ately

2 ,000 tons to ta l could have been recovered (6).

Approximately 40 tons of g rapefru it crude oil were produced

annually in 1940 when a po ten tia l of a lm ost 2 ,000 tons w as s t i l l

th e o re t ic a l ly a v a i la b le . In te re s t in production of grapefru it seed oil in

the su b seq u en t 20 y ea rs a lm ost d isa p p e a re d un til recen tly when public

. a t ten tio n w as c a l led to the p o ss ib le th e ra p e u tic u s e fu ln e s s of having a

h igher proportion of u n sa tu ra ted fa ts in the d ie t as is fu rn ished by some

v eg e tab le o ils (5). In 1954, M. J. W . K esterson , ch em is t at the

C itrus Experiment S ta tion , Lake Alfred, Florida d ec la re d th a t one h a r­

v e s t in g s e a so n can produce about 5 ,000 tons of c itrus seed oil (9). In

the l a s t few years , annual production has in c re a se d to about 1 ,500

to n s . On the b a s is of boxes of seedy fru its p ro c e s s e d , it is es tim ated

th a t a th e o re t ic a l p o ten t ia l as high as 14,720 tons of s e e d oil could have

been removed in the 1961-62 s e a so n (6). According to the U. S. D. A. Agri­

cu ltu ra l Handbook, 1968 (19), how ever, i t has been e s tim a te d th a t if a l l the

se e d s from c i t ru s -p ro c e s s in g p lan ts in Florida alone were u sed for the

ex trac tion of oil around 4 or 5 th ousand tons of oil cou ld be ob ta ined

a n n u a l ly . Only a sm all f rac tion of the s e e d s are so u s e d , as most of

them are dried with th e w a s te cannery pee l and rag to produce dried

c itrus pulp for s to ck feed .

For our pu rp o se , one should n o tice th a t in F lo rida , c itrus se e d

oil is produced from a mixture of predom inantly grapefru it and sm alle r

q u an ti t ie s of orange s e e d s (6). Crude c itrus seed o i ls are in genera l

su i ta b le for the u su a l nonedib le u s e s to w hich sem i-d ry ing o ils are pu t.

They include soap m aking, su lfonation for d e te rg e n ts , and th e p rep a ra ­

tion of fa tty ac id d e r iv a t iv e s . G rapefruit s e e d oil has found some

commercial ap p lica t io n in th e trea tm en t of te x t i le s and Feather (19).

The flavor of a refined c itru s seed oil re sem b les g rea tly th a t .

of o live o i l , for w h ich i t some tim es has been s u b s t i tu te d . I t is pale

y e llow in co lor, co n s id e red w holesom e and w ell su ited for food and has

been u sed m ost s u c c e s s fu l ly as a cooking oil and s a la d o i l . In addition,

c itrus seed oil can be hydrogenated to becom e a bu tter su b s t i tu te or

cooking fa t . Somewhat s im ila r ly , i t can be brominated to secu re a h igh

sp e c if ic gravity oil (approximately 1 .3 0 ) , w hich may be u se d by the

beverage industry to a d ju s t the d e n s i ty of flavoring o ils added to

b e v e ra g e s . Brominated c itrus seed oil is com petitive w ith other

brominated o ils , such as ap rico t kernel seed oil and se sam e oil (6).

Oil P rocess ing

C itrus se e d s are ob ta ined from citrus p ro cess in g p la n ts ,

where large q u an ti t ie s of fruit have been co l le c te d and u t i l iz e d

primarily for ju ice or s e c t io n s p ro d u c tio n . The se e d s are obta ined

in tim ate ly mixed w ith rag and pulp but s e p a ra te from the p e e l . Separa­

t ion of see d s from the rag and pulp may be accom plished in sev e ra l

w a y s , but th e d iff icu lty of so doing is one of the ch ie f d e te rren ts to

in c re a se d production of s e e d o i l . Separa tion may be accom plished

w ith a p ad d le - ty p e f in ish e r or s im ilar equ ipm ent. Another procedure is

to lime the mixture of seed and w et pu lp , as in the p repara tion o f dried

c itrus fe e d , and dry in ro tary d r ie rs . The see d s can th en be se p a ra ted

from the dried pulp by sc reen in g and winnowing (19).

Dried s e e d s from w hich the hu lls may or may not be removed

are p a s se d through c rack ing ro l l s , and the oil is e x trac ted in screw

ex p e lle rs of the type commonly u sed in preparing c o t to n see d and tung

o i l s . These m achines produce a p re ss cake w ith an oil con ten t ranging

from 14 to 16%. The oil con ten t of the p re ss cake can be further

reduced in th e s e m achines but a t th e ex p en se of h ea t dam age to the o i l .

More modern m achines have been deve loped th a t w ill reduce the r e s id u a l

o il to 7 percen t w ithout h ea t d a m a g e , but th e se m ach ines are not y e t

(1968) in genera l u s e . Solvent ex trac tio n would reduce the re s id u a l oil

even fu r th e r , but so far as is known th is has not been a ttem pted com­

m ercia lly (19).

The e x p re s se d oil is tran sfe rred into tanks w here it is allow ed to

s e t t le briefly and then pumped through f il te rs and into s to rage ta n k s ,

where it undergoes a f ina l s e t t l in g before further p ro c e ss in g . S ubse­

quent trea tm en t of oil depends on the u se for w hich i t is d e s t in e d . For

ed ib le purposes i t is a lk a l i re f in ed . This trea tm en t rem oves the b i t te r

p rinc ip le and free fa tty a c id s . The lo s s e s in th is s te p u su a lly do not

exceed 2%. The b land , neu tra l o il r e su l t in g may th e n be hydrogenated .

for u se in shorten ing p repara tions or, if n e c e s s a ry , may be w in te r ized

if in tended for a s a la d oil or liquid sh o rten in g . This la t te r trea tm en t is

= accom plished by ch illing until the h igher melting g ly ce r id es C rysta llize

and th en removing them in a f i l te r p re s s . Crude grapefru it seed oil

w ill so lid ify around -1 2 °C to -1 0 °C (19).

Importance of H arvesting Time

In the g rea t m ajority of p lan ts o il s torage ta k e s p lace in the

s e e d in o i l - s to r in g - p la n t - f r u i t s . The conditions for the form ation,

developm ent and ripen ing of the s e e d s are determ ined by the nature and

s truc tu re of the fruit t i s s u e s . Rapid s y n th e s is of o il occu rs not only in

the s e e d s of the o i l - s to r in g p lan ts (sunflow er, f lax , hem p, poppy, e t c . )

but in the s e e d s of th e g rea t m ajority of o ther p lan ts (17 j .

Samuel F ra se r , in 1924 (4) poin ted out th a t C a lifo rn ia is at a

d isad v a n ta g e in com peting w ith F lorida in the e a s te rn m arkets on

accoun t of the g rea te r ex p en se of ra i l t ran sp o r ta t io n and the time of y ea r

10

at w hich th e ir crop m a tu re s . C alifo rn ia grapefru it is co n s id e red a sum ­

mer fruit w hile in Florida it is a .w in te r and spring fru it . To m eet th is

s itu a tio n C alifo rn ia is planning to r a is e m ateria lly the s tandard of i ts

product and to supply the e a s te rn m arkets during la te summer and early

f a l l when there is l i t t le Florida fru it . The M arsh s e e d le s s is the v a r ie ty

w hich has been ch o sen by the C a lifo rn ia in d u s try . This is a f la t t e n e d ,

th in - s k in n e d , j u i c y , s e e d le s s var ie ty w hich beg ins to r ipen in May (4).

The same au thority sa id th a t th e p ickers should h a rv es t g rap e ­

fruit for s iz e , b e c a u se the demand in the fa ll and early w in ter is for

la rger s i z e s . Medium s iz e s are in l e s s demand and sm all s iz e s are

at a d isc o u n t . Toward the la t te r end of the s e a s o n cond it ions are

r e v e rse d . The la rge s iz e s are at a d isc o u n t , many buyers prefer medium

s iz e and sm all f ru it . The y ie ld and the grow ers ' income can be

in c re a se d by ca te r in g (4).

B esides th is market problem th e re are the p h y s io lo g ic a l ones

concerned w ith the fru it i t s e l f such as : "If ripe fruit is le f t on the t r e e ,

the se e d s are apt to sp rou t and the fru its lo se flavor, but in s to rage

the ac id con ten t of the fruit d e c re a se s and the b i t te r p r inc ip le breaks

dow n, w hile the su g ar con ten t appears to be u n a ffec ted , so tha t the

f lavor is improved. Fruit h a rv es ted in February or M arch may be held

for shipm ent in May to Ju ly . In F lo rida , harvesting p roceeds from

November to August. Some fruit may be on t re es throughout the

y ea r (4). "

. ' 11

A com parison of the percen tage of seed in the d ifferen t

v a r ie t ie s of orange and grapefru it during the normal p ro c e ss in g period

w as made by R. H endrickson and J. W . K e s te rso n , in 1965 (6). They

found th a t in the. la te r s ta g e s of m atura tion the percen tag e of seed s by

weight in c itrus is markedly in fluenced by fruit m a tu r i ty . Fruit weight

in c re a se s during th is period a t a g rea te r ra te than seed w eigh t and

brings about a c o n s ta n tly d e c re a s in g percen tage of seed w eigh t in the

f ru i t . In many in s ta n c e s there w as a lso a sm alle r number of developed

seed in the fruit p icked a t the end of the s e a s o n . Although there were

some i n c o n s i s t e n c i e s , the se e d s of a l l c i tru s v a r ie t ie s d e c re a se d in

m oisture con ten t as th ey m a tu re . P ercen tage of oil in dried c itrus s e e d s

is var iab le and depends upon m a tu r i ty . H ighest oil co n ten t u sua lly

co inc ided w ith the optimum m aturity need ed for p ro c e ss in g (6).

Seed Com position

C itrus seed o ils are semi drying o ils w hich resem ble co tto n ­

seed oil in the nature and d is tr ibu tion of the probable component

g ly ce r id es (12). I t can be. d is t in g u ish e d from the o th e r s , how ever, by

the ab sen ce or p re sen ce of ce r ta in fa tty ac id s or by the proportional

d iffe rences in fa tty ac id conten t (6).

A tw o -y e a r survey of the oil co n ten t of the dried se e d s of

P ineapple oranges and D uncan grapefruit e s ta b lish e d average s e a so n a l

v a lu es of 38% and 34%, r e sp e c t iv e ly . Although the oil co n ten t of th e se

12

se e d s did not vary w id e ly , there w as a tendency for maximum oil

con ten t to occur when the fruit had reach ed the genera lly a ccep ted

m atu r i ty . During the 1965-66 c i tru s s e a s o n , many problems a s s o c ia te d

w ith th e com m ercial production of c i tru s seed o ils w ere in v e s t ig a te d .|

I t w as shown th a t (a) prolonged wet s e e d s to rage s e r io u s ly in c reased

the free fatty acid co n ten t of the expe lled o i l , (b) the w a te r con ten t of

c o l le c te d w et se e d s varied from 5 6% to 71%, (c) improved f in ish ing

tech n iq u es could low er drying c o s ts and d e c re a se the fixed color of the

s e e d o i l , (d) drained w a s te liquid from w et seed s to rage bins had a

b io log ica l oxygen demand of from 11,000 ppm to 20 ,000 ppm, and (e)

co n secu tiv e t a n k -c a r lo ts of c itru s seed o il were m ost s im ila r .

In v e s t ig a t io n s of the prote in con ten t of s e e d s and other

com ponents of dried c itru s pulp has s ta b l ish e d average v a lu e s of 16% in

the s e e d s , 9.4% in the rag and pulp f rac t io n , and 6.2% in th e f la v ed o -

a lbedo portion . Removal of se e d s from dried c itrus pulp d ec re a se d the

protein conten t 8% to 15% w ith seedy v a r ie t ie s , but only 3% w ith the

l e s s seed y c itrus fruit (7).

The seedy v a r ie t ie s were no ted to have approxim ate ly the same

number of see d s per fruit w ith a trend toward a fewer number of seed s as

full or over-m atu rity w as reached (5). The range in dry so lid s con ten t

of the com ponents of grapefruit and shaddock w as: ju ic e 8 to 12%,

13

a lbedo 15 to 22%, f lavedo 19 to 29%, rag and pulp 12 to 18%, s e e d s

30 to 68 p e rcen t (8).

Seedy v a r ie t ie s of c itrus fruit such as se e d lin g and Pineapple

oranges and D uncan grapefru it con ta in about 3.5% s e e d s , w h ic h in tu rn

con ta in from 55 to 60% m oisture and about 15% o il . The a v e ra g e '

com position of a ir -d r ied c i tru s se e d s , com piled from v ar io u s pub lished

d a t a , is as fo llow s: a sh 2 .4 8 to 3 .5 7%, crude fiber 5 .4 1 to 17.79% ,

crude pro te in 6 .9 4 to 15 .94% , e ther e x trac t 21 .88 to 34 .44% , non-

.n itrogenous su b s ta n c e s 22 .21 to 44 .63% , and w ate r 6 .8 2 to 11 .86

p e rcen t (19). R. H endrickson and J. W . K esterson (6) s t a t e d , h o w ev e r ,

th a t percen tage of o il in dried c itrus se e d s is v a r iab le and depends

upon m a tu r i ty . T y p ica lly , the dried D uncan (grapefruit) s e e d s variedX

from 2 9 .2 p e rcen t to 37 .3 percen t o i l .

Fatty Acids

Early work by M atlack in 1929 (14) and in 1940 (15), had

shown th a t the p ee l and the endocarp of oranges co n ta in lip id m ateria l

made up of o le ic , l in o le ic , l in o le n ic , p a lm itic , and s te a r ic ac ids as

g ly ce r id es and probably a lso s te ro ls (12). By an a lo g y , the seed s

should con ta in a t l e a s t the same q u a l i ta t iv e com position,, and th is

su p p o sit io n was proved by Dunn, H ild itch and Rileg (2) who made an

in v es t ig a t io n in 1948, on sam ples from W e s t Indian g rapefru its and

found the following com position:

14

Variety F oste r M arsh

C o n s t i tu en t

Oil C onten t (%)£■ 43 41

Satura ted ac id s : - p e rcen t of to ta l -M y ris tic 0 .8 1 .2Palm itic 28 .9 27 .5S tearic 2 .1 2 .9

U nsa tu ra ted ac id s :O le ic 25 .1 21.1

. L inole ic 3 6 .6 39 .3Linolenic 5 .9 5 .9

(a) Percent by w eight of a ir dried seed s

Later in 1961, H endrickson ,and K esterson (5) doing the same

determ ina tion w ith grapefru it from Florida found th a t a ty p ic a l a n a ly s is .

of a Florida grapefru it s e e d oil could be expec ted to have the five fatty

a c i d s , p a lm i t ic , s t e a r i c , o le ic , l in o le ic , and l in o len ic in the following

p roportions : 35, 3 . 5 , 21, 36, 4 .5% , r e sp e c t iv e ly . This is cons id e rab ly

d ifferen t from the ea r l ie r pub lished a n a ly s e s (11) w here in the

o lder more d iff icu lt e s te r f ra c tio n and lead s a l t procedure had to be u s e d .

In 1965, the same au th o rit ie s (6) s ta te d th a t grapefru it s e e d

oil is com posed of the following fa tty ac id s : palm itic 34%, s te a r ic

3 .4% , o le ic 22%, l in o le ic 37%, l in o len ic 4 .6% . This a n a ly s is draws

a tten tio n to the point th a t c itrus seed oil has been c la s s i f ie d as a

l in o len ic ac id oil and by o thers as one th a t is r ich in both o le ic and

l in o le ic a c i d s .

MATERIALS AND METHODS

Sam ples

Samples of grapefru it from w hich seed s w ere ob ta ined for

a n a ly s is were c o l le c te d from the following sou rces :

1. Burgher Grove (Maricopa C ounty , A rizona): Burgher g rap e ­

fru it , C itrus parad is i (M acf .) cu lt ivar Burgher, are t r a d i - '

t io n a l ly h a rv es ted very l a t e , som etim es as la te as May or

Ju n e . Because of th e ir la te m aturity they are very sour and

b i t te r during the regu la r h arvesting s e a so n (December).

2. C handler H eights (Sposito) (Maricopa C ounty , Arizona):

C handler g rapefru it . C itrus p a rad is i (M acf.) cu lt ivar

C h an d le r , is h a rv es ted e a r l y , as soon as the Brix-acid

ra tio is le g a l , or before (sometimes in Novem ber). I t is

u su a lly quite sw ee t if a llow ed to m a tu re .

3 . Yuma Yellow (Yuma C o u n ty , Arizona): C itrus parad is i

(M acf.) cu lt iv a r Yuma Yellow , was grown at The U niversity

of Arizona Yuma Experim ental Farm on C itrus m acrophyla

ro o ts to c k . H arvest is accom plished th roughout the w in te r .

This is a M arsh grapefru it as are a ll the M aricopa County

grapefru it ana lyzed in th is w o rk .

15

16

4. Yuma Pink (Yuma C o u n ty , Arizona): C itrus p a rad is i (M acf.)

cu l t iv a r Yuma Pink, a red or pink grapefru it (not M a rsh ) ,

grown at The U n ivers ity of Arizona Yuma Experim ental '

Farm on C itrus macrophyla ro o ts to c k , i s h a rv es ted th rough­

out the w in ter u su a lly a l i t t le e a r l ie r than M aricopa County

grapefru it b e c a u se of the h igher average environm ental

tem perature in Yuma. They are a l i t t le sw ee te r and the

Brix-acid ra tio is a l i t t le h igher than th a t of Yuma Yellow.

5. U niversity of Arizona (M aricopa C ounty , Arizona):

U. of A. g rapefru it . C itrus p a rad is i (M acf.) c u l t iv a r U . of

A . , is grown at The U n ivers ity of Arizona Experim ental

Farm in M e sa . It is u su a lly medium in s w e e tn e s s and

ac id ity and is h a rv es ted in la te Decem ber or throughout

January.

Sample C o llec t io n

Fruit were p icked a t approxim ately 2 w eek in te rv a ls during the

1969-70 growing s e a s o n . The th ree M aricopa County groves were

ch o sen as exh ib iting very b i t te r (Burgher— la te h a rv e s t in g ) , medium

(U. of A .— la te h a rv es tin g ) , and sw ee t (Chandler— early harvesting)

c h a ra c te r is t ic s . In ad d it io n , two Yuma v a r ie t ie s were a ls o ch o sen . Ten

grapefru it were p icked a t random each t im e , the se e d s w ere removed and

s to red in p la s t ic bags at - 5 ° C . for about s ix months prior to a n a ly s is .

Seed Prepara t ion

After reach ing room tem p e ra tu re , approximate ly ten s e ed s from

e ach "varie ty" were s e le c te d a t random and w ashed with d i s t i l l e d wate r

followed by spraying with 3 to 5 ml. of ace tone to a s s i s t in the removal

of w a te r . The seed's were air dr ied overnight at room temperature and

then weighed.

'Oil Extract ion

The oil w a s ex trac ted by p lacing the s e e d s in a high speed

mixing b lender , us ing a 500 ml. jar ,for 10 minutes with 100 ml. of

ch loroform:methanol , 2:1 so lven t mixture (18).

The ex t rac t was f il tered through f il ter paper (S. and S.

No. 489, b lack band) and.dried under n i trogen atmosphere a t 50°C. and

weighed a s to ta l l ip id (TL)., The ex t rac ted l ipid mate r ia l w as w ash ed

with four 5 ml. portions of petroleum e th e r , dr ied under reduced

p ressure at 45°C . and then weighed to obta in the petroleum ether

ex t rac ted mater ia l (PE).

Methyl Esters. Preparat ion

In preparat ion for methyla t ion approximate ly 0 .2 ml. of oil was

dr ied under vacuum at 45 C . for 60 m inu tes . The fatty ac id methyl

e s te r s were prepared by t ransm ethy la t ion , us ing sodium methoxide (13).

The methyl e s te r s were ex t rac ted in hexane (1), and s to red under

refr igera tion unti l ana lyzed by g a s - l iq u id -c h ro m a to g ra p h y .

18

G as-L iqu id Chromatography

A Perkin-Elmer Model 800 gas chrom atograph , equipped with

dua l flame ion iza t ion d e tec to r , two 6 f t . x 1 /8 in . s t a i n l e s s s tee l

columns packed with 15% die thyl g lycol su c c in a te (DEGS) on a 60/80

m esh Chromosorb W , and a pr int ing in tegra tor , was u s e d . Argon at

15 ps i of p ressu re w as u se d as th e ,c a r r ie r g a s . ■ The column temperature

w as 17 0 ° C . Sample s iz e w as about 0 ,5 u l . The e s t e r s were ident i f ied

by comparison with s tandard compounds and chromatograms (5). Peak

a reas were measured by the printing in tegra to r and e x p re s s e d as a

. percen tage of to ta l fa tty ac ids .

RESULTS AND DISCUSSION

Grapefrui t s eed o i ls of the Arizona va r ie t ie s an a ly zed in th is

s tudy conta ined predominant ly s ix fat ty ac ids (Tables 1, 2, 3, 4, and

5). The sa tu ra ted ac ids were m y r i s t i c , palmit ic and s t e a r i c , and the

u nsa tu ra ted ones were o le i c , l i n o l e i c , and l ino len ic .

The content of myris t ic ac id ranged from 0.46% (Yuma Yellow)

to 0 .81% (Chandler) . The p re sen ce of myris t ic ac id in grapefrui t seed

oil was reported by Dunn e t a l . (2) in 1948 who made an in ves t iga t ion

on samples from W e s t Indian grapefruit and found r e su l t s from 0.8%

(Foster grapefruit) to 1.2% (M arsh) . This somewhat different r e su l t is

p o ss ib ly exp la ined by the fact that th o se authors used the older e s t e r -

f ract ion and lead s a l t procedure on the determination (5).

The palmitic ac id va lues found var ied from 28.33% (Chandler) to

32.37% (U. of A . ) . These r e su l t s agree with th o se of Dunn et a l . (2)

who found from 27.5% to 28.9% in W e s t Indian grapefrui t s e e d oil and

by Hendrickson and Kesterson (5) who reported a range in palmit ic ac id

content from 20 to 39%, when analyz ing F lor ida 's grapefru i t s eed oi l .

The same au thor i t ies (6) s ta ted in 19 65 th a t a typ ica l con ten t was 34%

palmit ic ac id in F lor ida 's g rape f ru i t . The re su l t s d iffer somewhat from

tha t found by J a m ie s o n , Baughman and Gentler , in 1930 (in 11) who

reported 19.2% palmit ic ac id in grapefruit s eed oi l .

.

20

TABLE 1 . Fatty Acid C o m p o s it io n o f Burgher G rapefruit S e e d O ilR ela ted to H arvest D ate

HarvestDate

Fat ty Acids (%)M yris t ic Palmitic Stear ic Oleic Linoleic Linolenic

0 9 /0 8 /6 9 0. 79 34 .73 1.25 19.97 40. 74 2 .50

0 9 /2 2 /6 9 0 .3 4 31 .04 1. 85 22 .64 39 .68 4 .4 2

1 0 /0 4 /6 9 0 .29 32 .03 0 .87 24 .04 40 .1 6 2 .5 8

1 0 /1 8 /6 9 1.21 32 .24 2.71 20 .95 37 .24 5 .63

1 1 /05 /69 0 .6 7 33 . 70 1 .67 21.63 40 .19 2 .1 3 .

1 2 /1 3 /6 9 0 .5 0 34 .32 1 .48 20.53 40 .93 2 .47

0 1 /1 9 /7 0 0 .3 8 31 .36 2.19 22.21 41 .00 2 .84

0 2 /0 2 /7 0 0 .40 28 .08 3 .80 19.65 36 .93 4 .9 7

03/0 2/70 0 .85 28.75 4 .0 2 20.83 38 .03 7 .51

0 3 /3 0 /7 0 0 .53 28.93 5 .0 8 20 .24 38 .6 4 6 .57

X 0.59 31 .52 2 .49 21.27 39 .35 4 .7 8

Tota l Saturated: 34.50%

T otal U nsaturated: 6 5 . 40%

99 . 9 0 %

21

TABLE 2 . Fatty Acid C o m p o s it io n of C han d ler G rapefruit S eed O ilR ela ted to H a rv est D ate

HarvestDate

Fat ty Acids (%)M yris t ic Palmitic Stear ic Oleic Linoleic Linolenic

0 9 /0 8 /6 9 0 ,5 2 32.39 3 .5 6 19.36 39 .13 5 .0 2

0 9 /2 2 /6 9 0 .4 4 29.11 5 .3 0 24 .64 37.91 2 .60

1 0 /0 4 /6 9 0 .4 4 28.00 4 .4 7 21 .16 34 .80 11 .12

1 0 /1 8 /6 9 0 .49 22 .66 3 .35 29 .54 33 .89 10.07

1 1 /0 3 /6 9 0 .70 27.70 6 .27 23 .66 36 .07 5 .60

1 2 /1 3 /6 9 1 .08 27 .05 4 .61 21.41 36.23 9 .6 1

0 1 /0 5 /7 0 0 .57 29 .68 4 .29 22.29 37 .22 5 .9 5

0 1 /1 9 /7 0 2.27 28 .98 4 .2 4 21.19 3 7 .90 5 .4 2

0 2 /1 6 /7 0 0 .7 8 ' 29.02 3 .71 20.95 35 .33 10.19

0 3 /1 5 /7 0 0 .87 27 .74 3 .9 0 21 .42 36 .9 8 9 .0 8

X 0.81 28.23 4 .3 7 22 .56 36 .5 4 7 .4 6 .

Total Saturated: 33.41%

T otal U nsatu rated : 66 . 56%

99 . 9 7 %

2.2

Table 3 . Fatty Acid C o m p o s it io n o f Yuma Y e llo w G rapefruit S eed O ilR elated to H arvest D ate

HarvestDate

Fatty Acids (%)M yris t ic Palmitic Stearic Oleic Linoleic Linolenlc

10 /1 3 /6 9 0 .40 29. 65 5 .05 24.11 37 .62 3 .17 .

1 1 /1 0 /6 9 0 .3 7 29 .03 5 .9 2 22.51 3 8 .3 8 • 3 .79

1 1 /2 4 /6 9 0 .13 32 .08 . 2. 68 23 .56 37 .43 4 .1 2

1 2 /0 8 /6 9 0 .3 6 , 33.03 3 .26 21 .76 38 .1 8 3 .41

1 2 /2 2 /6 9 0 .43 31 .84 3 .47 22.20 39 .42 2 .6 4

0 1 /0 5 /7 0 0 .42 28 .60 3.71 22.19 37 .23 7.85

0 1 /1 9 /7 0 0 .5 4 29 .92 2.70 22.60 36.73 7 .51

0 2 /0 2 /7 0 . 0.41, 28 .64 3 .09 21 .66 36 .26 8.93

0 2 /2 3 /7 0 1 .00 28. 60 3V.89 21 .76 38 .95 5 .8 0

0 3 /1 6 /7 0 0.49 28.93 3 .03 21 .74 3 8 .3 8 7 .43

X 0 .4 6 30 .03 3 .6 8 22.41 37 .96 5 .4 6

Total Saturated: 34.17%

T otal U nsaturated : 65 . 83%

99 . 9 0 %

23

Table 4 . Fatty Acid C o m p o s it io n of Yuma Pink Grapefruit. S eed O ilR ela ted to H arvest D ate

HarvestDate

Fatty Acids (%)M yris t ic Palmit ic Stear ici Oleic Linoleic Linolenic

1 0 /1 3 /6 9 0 .45 27.79 5 .03 .22.44 33 .83 10.46

11 /1 0 /6 9 0 .42 27.60 5 .95 21.53 36 .65 7 .85

1 1 /2 4 /6 9 0 .5 2 25 .77 4 .3 5 21 .34 38 .1 4 9 .8 8

1 2 /0 8 /6 9 0 .7 2 37 .92 3 .0 4 17.85 35 .13 5 .3 4 ,

1 2 /22 /69 0 .2 7 28.69 5 . 63 21 .78 35 .96 7.63

0 1 /0 5 /7 0 0 .49 26 .54 3 .4 0 22 .08 40 .13 7 .36

0 1 /1 9 /7 0 0 .7 0 22 .70 4 .5 8 25 .72 35 .02 11.08

0 2 /0 2 /7 0 1.79 26 .24 3.51 22.73 3 8 .40 7 .33

0 2 /2 3 /7 0 1.65 32 .35 5 .0 2 19.05 36 .09 5. 83

0 3 /1 6 /7 0 0 .4 8 28 .17 4 .45 21.30 34 .88 10.78

X 0 .75 28 .38 4 .49 21 .58 36 .42 8 .37

Total Saturated: 33.62%

T otal U nsaturated: 6 6 . 37%

9 9 . 9 9 %

24

T ab le 5 . Fatty Acid C o m p o s it io n of U . o f A, Grapefruit S eed O ilR ela ted to H arvest D a te . ' .

H arves tDate

Fatty Acids (%)M yris t ic Palmit ic S tear ic Ole ic Linoleic Linolenic

0 9 /0 8 /6 9 0 .89 29.15 2 .89 21.32 40 .0 2 5 .74

1 0 /0 4 /6 9 0 .35 32.59 2 .73 22 .88 37. 88 3 .5 7

11 /0 3 /6 9 0 .57 35 .30 2 .19 22.01 38 .21 1.71

11 /1 5 /6 9 0 .56 32 .51 2 .57 23.09 37 .92 3 .35

0 1 /0 5 /7 0 0 .31 32 .69 2 .43 21.70 39. 84 3 .03

0 1 /1 9 /7 0 0 .36 31 .84 1. 87 20.73 39 .62 5 .5 8

0 2 /0 2 /7 0 0 .43 31 .35 2 .61 21.90 39 .6 7 4 .05

0 2 /1 6 /7 0 0 .51 31 .24 3 .4 3 22.38 37 .99 4 .4 6

0 3 /0 2 /7 0 0 .4 8 32.95 2 .64 20 .58 39 .61 3 .8 7

0 3 /3 0 /7 0 0 .63 34 .06 2.03 20.60 3 7 . 5 8 5 .10

X 0.51 32 .37 2 .54 21.72 38 .83 4 .0 5 .

Total Saturated: 35.42%

T otal U nsaturated : 6 4 . 60%

1 0 0 . 02%

25

Stearic ac id was d e te c ted in proportions from 2.49% (Burgher)

to 4.49% (Yuma Pink) . These r e su l t s genera l ly agree with those pub- h

l i sh ed by Hendrickson and Kesterson (5) (2 .2 to 5%) and with th o se of

the same authors in 1965 (6) who reported an average of 3 .4% s tea r ic

ac id in F lor ida 's grapefrui t s e e d o i l . The re su l t s found by Dunn et a l .

(2) were somewhat lower (2.2 and 2.9%) in s tea r ic ac id in W e s t Indian

grapefruit s e e d s / e s p e c i a l l y when compared with the 7.25% reported

by Jamieson in 1932 (11).

The seed oil ana lyzed in th is work showed no d e tec ta b le

a rach id ic ac id . This ac id w as included in the a n a ly s is of Dunn et a l .

(2) in 1948, in W e s t Indian g r a p e f ru i t s , and in pe rcen tag es of 0 .6 and

2 . 1 , r e s p e c t i v e l y , for Fos te r and Marsh grapefruit s e e d o i l .

In the unsa tu ra ted fatty ac id g ro u p , the o le ic ac id content

found in th is s tudy compared c lo se ly to tha t reported in other w o rk . The

per cen t o le ic ac id in the v a r ie t ie s ana lyzed in th is r e s e a r c h ranged from

21,27 (Burgher) to 22 .56 (Chandler) . These va lues can be re la ted to a

1932 report by Jamieson (11) showing 19.66% o le ic a c i d , one by Dunn

e t a l . (2) giving 21.1% and 25.1%, and lev e ls found by Hendrickson and

Kesterson in var ious reports (5, 6, 7, and 8) of 21 .22 to 27%. The

ra ther c lo se agreement in the va lues found and reported for ole ic ac id i s .

of in te re s t as the s epa ra t ion of th is component from s te a r i c and l ino le ic

ac id s is one measure of column performance in the GLC an a ly t ica l

procedure (6).

26

Values for l ino le ic ac id ranged from 36.42% (Yuma Pink) to

39.35% (Burgher). Comparing th is 'component with the other fat ty ac id s

ana lyzed in th is w o r k , l ino le ic ac id appears in the h ig h e s t concentra t ion.

These v a lu es confirm ones by Dunn e t a l . (2) who reported 3 6.6% and

39 .3% , and by Hendr ickson and K es te r so n , who found 35%, 36 and 38%

in 1961 (5), and 37% in 1965 (6) working with Florida grapefrui t

v a r i e t i e s . The h ig h es t r e su l t was found by Jamieson et a l . in 1930 (in 11)

who reported 48.84% l ino le ic ac id from the i r a n a ly s i s .

F in a l ly , small amounts of l ino len ic ac id were d e te c te d . In

th is work, it var ied 4 .05% (U. of A.) to 8.37% (Yuma Pink). In the

l i te ra tu re c i t e d , v a lues reported were 0 .16% (11), 3%, 4 .5% , 5.1% (5),

4.6% (6) and 5.9% (2). These var ia t ions are unders tandab le bec a u se of

the re la t ive ly s m a l l , broad peak recorded in the GLC procedure for

th is component.

In the Burgher grapefrui t s eed there was a t e n d e n c y for l ino len ic

acid to in c rease in concentra t ion in th ree a n a ly se s of sam ples from

February to March (4 .9 7 , 6 .57 and 7 .51%, respec t ive ly ) with r e su l t s a l l

above the average percen tage (4 .78) . The same phenomena occurred

with Chandler (10.19 and 9.08%) where in the average pe rcen tage of th i s

ac id was 7 .4 6 , and with Yuma Yellow (8 .9 3 , 5 . 80 and 7 .43) , the

average va lue being 5 .4 6 .

In the same period (February and March) there w as a t rend for

palmit ic ac id con ten t to be lower in Burgher (28.08 to 28.93%) and Yuma

Yellow (28.60 to 38.93%) than the a v e rag e , 31 .52 and 30 .03%,

r e sp e c t iv e ly . A s im ila r r e la t ionsh ip is s e e n in the o le ic ac id com posi­

t ion during the same period (February and March) in the two v ar ie t ie s

c i t e d , Burgher (19 .60% to 20 . 83%) and Yuma Yellow (21. 66% to 21. 76%)

where the r e sp e c t iv e averages for th e s e de termina tions were 21.27% and

22.41%. This observa t ion was a l so found in Chandler grapefru i t , when

the o le ic ac id con ten t var ied from 20.95% to 21.42%, in February and

M arch , r e s p e c t iv e ly , and its average percen tage w as 2 2 .5 6 . These are

only s l igh t d i f f e re n c es , however , which are not s t r ic t ly d i s t in c t iv e for

harves t ing t ime or v a r ie ty , in the fruit examined in th is study. This a l so

agrees with Hendrickson and Kesterson (5) who found th a t there was a

remarkable s im ilar i ty between all samples such tha t ne i the r var ie ty nor

maturity could be d is t in g u ish e d on the b a s i s of fatty ac id an a ly s is alone.

Comparing the to ta l s a tu ra ted and unsa tu ra ted fa t ty ac ids as

averages of all samples (Table 6) there is only a s l igh t v a r ia t ion around

the mean, (+1.19 and -0 .81% in the sa tu ra ted and +0 .08 and -1 .15% in

the unsa tu ra ted o n es ) . This further corroborates the con ten t ion tha t a l l

va r ie t ie s of Arizona grapefrui t ana lyzed seed oils h a v e fa t ty acid

composit ion extremely a l ik e , al though Chandler and Yuma Pink have

a s l igh t ly higher unsa tu ra ted acid content (66.56 and 66.37%) ,

r e s p e c t iv e ly , when compared with Yuma Yellow (65.83%), Burgher

(65.40%) and U . of A. (64.60%). These r e su l t s show th a t Arizona 's

grapefruit seed o i ls , have an unsa tu ra ted fat ty ac id con ten t

28

Table 6. Average Conten t of Satura ted and Urisaturated Fatty Acids of Arizona 's Grapefruit Seed Oils

VarietyFat ty Acids (%)

Satura ted Un sa tu ra ted

Chandler 33.41 ' 66 .56

Yuma Pink 33 .62 66 .37

Yuma Yellow 34.17 65.83

Burgher 34 .50 65.40

U. of A. 35 .4 2 64.60

X 34 .22 65.75

Variation around the mean (X):

Satura ted +1.19% Unsatura ted : +0.08%

-0 .81% -1 .15%

29

approximate ly tw ice tha t of the sa tu ra ted a c id s . One may cons ide r i t

as an oil of medium unsa tu ra t ion conta in ing (65%). u n sa tu ra ted fat ty

ac ids as compared with a lower con ten t (16%) in coconu t oil and a

higher one (81%) of s e sa m e seed oil (11).

Since the ex t rac t ion procedure len t i t s e l f to obse rva t ions on

oil content of the grapefruit s e e d , th e s e d e te rm in a t io n s are included

in the re su l t s ' (T a b le s 7, 8, 9, 10, and 11). There w as some r e l a t i o n .

be tween dr ied s e e d weight and y ie ld of to ta l l ip id s . The to ta l l ipids

content var ied from 14.80 to 37.90% in Burgher; 25 .60 to 36.40% in

° Chandler ; 11.59% to 40 . 02% in Yuma Yellow; 15 .44 to 34.13%, in

. Yuma P in k , and 27.11 to 32.62% in U. of A. grapefrui t . Those re su l t s

are not g rea t ly dif ferent than those found in the l i t e r a t u r e , where

Hendrickson and Kesterson (6) found 29.2% to 37.3% oil in F lor ida 's

Duncan g rap e f ru i t . The same au thor i t ies re fer to a l ipid content of

35% in the same var ie ty suprac i ted in a la te r report (8) and the

U. S. D. A. (19), r eg is te red a l ipid con ten t of 21.84% to 39.44% oil

from ai r dr ied grapefruit s e e d s . Comparing to ta l l ip ids and petroleum

eh te r ex t rac t there w as a rat io of 1 .20 in the Yuma Pink and Chandler

va r ie t ie s , 1 .15 and 1 .18 for U. of A. and Yuma Yellow v a r ie t ie s ,

and 1 .24 for Burgher, r e sp ec t iv e ly (Table 12).

There was a higher l ipid con ten t in the v a r i e t i e s cons ide red to

be ear ly harves t ing (Chandler and Yuma Pink) around Decem ber and January.

30

Table 7 . T ota l L ip id s , Petroleum Ether Extract and In d iv id u a l Air D riedS e e d W e ig h t o f Burgher Grapefruit

Harve s t Date

Dried Seed . Weight

: „ JgL_. .

Total E x t r a c t a b l e .Lipid

.......... (%)____

Petroleum Ether Extract

(%)

0 9 /0 8 /6 9 0 .2000 14 .80 10.00

0 9 /2 2 /6 9 0.1810 18.00 15.00

10 /0 4 /6 9 0.2321 20.40 17.00

10 /1 8 /6 9 , 0 .1920 26 .30 20.00

1 1 /0 5 /6 9 0 .1425 26 .60 22.00

1 2 /13 /69 0 .1626 36 .80 30 .80

0 1 /1 9 /7 0 0.1479 37 .40 30 .90

0 2 /0 2 /7 0 0 .1627 37 .50 31 .50

0 3 /0 2 /7 0 0 .1624 33 .80 27.50

0 3 /3 0 /7 0 0 .1584 35 .40 2 6 .9 0 .

X 0 .17417 28 .70 23 .16

31

Table 8. T ota l Lipids , Petroleum Ether Extract and In d iv id u a l Air D riedS eed W eig h t o f C handler Grapefruit

HarvestDate

Dried Seed W eight

............... (g)..............

Total Extractable Lipid

...................... (%).......

Petroleum Ether Extract

(%)

0 9 /0 8 /6 9 0 .0949 25 .60 21.30

0 9 /2 2 /6 9 0 .1605 26.30 21.60

10 /0 4 /6 9 0 .1801 29 .20 24.50

10 /1 8 /6 9 0 .1958 30 .80 26.40

1 1 /0 3 /6 9 0.1735 34 .80 30 .00

12 /13 /69 0 .1775 34 .70 28.90

0 1 /0 5 /7 0 0 .1716 36. 40 31 .10

0 1 /1 9 /7 0 0 .1985 34 .40 29.10

0 2 /1 6 /7 0 0.1889 34 .60 29.20

0 3 /1 5 /7 0 0.1765 . 33 .00 23.70

X 0 .17178 31 .98 26.57

32

T able 9 . T ota l L ip id s , Petroleum Ether Extract and In d iv id u a l Air D riedS eed W e ig h t o f Yuma Y ello w Grapefruit

HarvestDate

Dried Seed W eight

.. ... (g)

Total Extractable Lipid

(%)

Petroleum Ether Extract

(%)

10 /1 3 /6 9 0 .1438 32 .68 27.40

1 1 /1 0 /6 9 0 .1542 3 4 .4 4 29 .28

1 1 /2 4 /6 9 0 .1456 32 .77 24.23

1 2 /0 8 /6 9 0 .1677 36 .05 30 .77

12 /2 2 /6 9 0 .1564 40 .0 2 34 .23

0 1 /0 5 /7 0 0 .1562 22 .00 19 .44

0 1 /1 9 /7 0 0 .1872 23 .34 20 .68

0 2 /0 2 /7 0 0 .1433 17 .84 14.69

0 2 /2 3 /7 0 0.0851 11 .59 9 .99

0 3 /1 6 /7 0 0 .1648 15 .92 13.73

X 0.15143 26 .46 22.44

T able 10 . T otal L ip id s , Petroleum Ether E xtract, and In d iv id u a l AirD ried S eed W eig h t o f Yuma Pink. Grapefruit

H arves tDate

Dried Seed W eight .

(g).............

Total Extractable Lipid

..._ _ ..._ ...(%) .............. .

Petroleum Ether Extract .

_____ (%)

10 /1 3 /6 9 0 .2237 26.25 22.41

1 1 /1 0 /6 9 0 .2030 28.79 24 .48

1 1 /2 4 /6 9 0 .1946 31 .56 27.21

1 2 /0 8 /6 9 0 .1524 33 .4 2 26.55

12 /2 2 /6 9 0.2091 29 .60 24.17

0 1 /0 5 /7 0 0 .1236 30 .81 25 .82

0 1 /1 9 /7 0 0 .1714 34 .13 29 .34

0 2 /0 2 /7 0 0 .1233 29 .84 24.98

0 2 /2 3 /7 0 0.1221 3 3 .4 4 25 .84

0 3 /1 6 /7 0 0 .1514 15 .44 11.84

X 0.1674 29 .32 24 .26

34

Table 11 . T ota l Lipids-, Petroleum Ether E xtract, and In d iv id u a l AirD ried S eed W e ig h t o f U . o f A. Grapefruit

HarvestDate

Dried Seed W eight

...... (g)

Total Extractable Lipid

...................................... (%) ...................... . . .

Petroleum Ether Extract

(%)

0 9 /0 8 /6 9 0 .1143 27 .33 21 .07

1 0 /0 4 /6 9 0 .1659 31.01 25.70

11 /0 3 /6 9 0 .1770 29 .78 25 .55

11 /1 5 /6 9 0 .2003 29 .27 24 .74

0 1 /0 5 /7 0 0.2012 29 .56 24.11

0 1 /1 9 /7 0 0 .1793 29 .60 23 .64

0 2 /0 2 /7 0 0.1911 27 .11 21.63

0 2 /1 6 /7 0 0 .1658 32 .6 2 25 .48

0 3 /0 2 /7 0 0 .1862 29 .28 21 .78

0 3 /3 0 /7 0 0 .1650 28 .86 22 .27

X 0.1744 29 .44 25.59

35

Table 12. The Average Content of Total Extractable Lipid, Petroleum Ether Extract and Their Ratios

VarietyTotal Extrac table

Lipid (%) (TL)Petroleum Ether . Extract (%) (PE) TL/PE Ratio

Chandler 31 .98 26 .57 1 .20

IT. of A. 29 .44 25.59 1.15

Yuma Pink 29 .32 24.26 1.20

Burgher 28. 70 23 .16 1.24

Yuma Yellow 26.46 22 .44 1.18

36

The la te harves t ing v a r i e t i e s , h o w ev er , vary with the h ig h es t l ip id

content being from October to November (IT. of A . ) , December (Yuma

Yel low) , to January and February (Burgher). In th e se r e s u l t s the

maturi ty of fruits w as only ind irec t ly s tud ied but we agree with 1962

U. S. D . A. information (19) tha t not enough sam ples of c i t rus l ip ids

have been ana lyzed to show what va r ia t ions in composi t ion may be

ex p ec te d . Hendrickson and Kesterson (6) s ta te d tha t the percen tage

of oil in dried c i t rus s eed s is var iab le and depends upon fruit m a tu r i ty .

H ighes t oil content u su a l ly coincided, with the optimum maturi ty needed

for fruit p r o c e s s i n g . These same a u t h o r s , in 1967 (8), s ta ted tha t a

2- y e a r survey of the oil content of th e dried s e ed s of Duncan grapefruit

(Florida) had an average- s e a so n a l va lue of 34%. Although the oil

content of th e se s e e d s did not vary w id e ly , there w as a t e n d en cy for

maximum oil con ten t to occur when the fruit had reach ed the genera l ly

accep ted m a tu r i ty . It w as a l so shown th a t prolonged wet seed s to rage

se r ious ly in c re a se d the free fat ty ac id con ten t of the expe l led oi l .

CONCLUSIONS

1. Grapefruit s eed o i ls of the Arizona v a r i e t ie s ana lysed in

th is s tudy con ta in predominantly s ix fa t ty a c i d s . The sa tu ra ted ac ids

were m y r i s t i c , palmit ic and s t e a r i c , and the unsa tu ra ted ones were

o le i c , l in o le ic , and l i n o l e n i c .

2. There was a remarkable s im ilar i ty be tw een a l l samples

such th a t ne i ther var ie ty nor harves t ing time could be d is t in g u ish ed

on the b a s i s of fa t ty ac id a n a l y s i s .

3. Grapefruit s eed o i ls of the v a r ie t ie s ana ly zed in th is

s tudy had an average of 65% of unsa tu ra ted and 35% sa tu ra ted fatty

a c id s .

4. Air dr ied grapefrui t s e e d s con ta ined approximate ly 30%

to ta l ex t rac tab le l ip ids of which 25% were petroleum e the r s o lu b l e .

37

LITERATURE CITED

1. Brown, W . H. , J . W . Stul l , and G. H. S to t t , 1962. Fatty AcidComposi t ion of Milk . I . Effect of Roughage and Dietary Fat Journal of Dairy S c ien ce , 46; 191.

2. Dunn, H. C. , T. P. Hi ld i tch , and J. P. Rileg, 1948. TheComposi t ion of Seed Fats of W e s t Indian Citrus F ru i ts . J. Soc. Chem. Ind. (London), 67: 199.

3. Eckey, E. W . , 1954. Vegetable Fats and O i l s . AmericanChemical Soc ie ty , Monograph S e r ie s . Reinhold Publ ishing Co . , N. Y. , 548.

4. F ra se r , S. , 19 24. American F r u i t s . Orange Judd Publishing Co.I n c . , N. Y. , 664.

5 . H e n d r ic k so n , R. , and J. W . K es te rson , 1961. Grapefruit Seed, Oil . Florida State Agricultural Socie ty , 74; 219 .

6. , 1965 . By-Products of Florida Citrus . AgriculturalExperiment S ta t io n s , Univers i ty of F lo r id a , Bulletin 698: 44.

7. , 19 66. Seed Oils From Florida Cit rus F ru i t s . FloridaAgricultural Experiment S ta t ions , Annual Report: 239.

8. , 1967. N a r in g in , a Bitter Principle of Grapefrui t .Agricultural Experiment S ta t io n s , Univers i ty of F lo r id a , Techn ica l Bulletin 511 -A .

9. H o ran , J. , 1964. Margarine a Base d 'H ui l le Extra it e de Pepinsd'Agrumes. Car ibbean A gr icu l tu re , Puerto Rico, 3: 832.

10. Hume, H. H aro ld , 1938. The Cu l t iva t ion of C i t rus F r u i t s . TheM acM il lan Company, N. Y.

11. Jamieson , G. S . , 1932. Vegetable Fats and O i l s . AmericanChemical Socie ty , Monograph S e r i e s , The Chem ica l Cata log Company, Inc. , N. Y.

38

39

12. Kefford, J. F. , 1959. The Chemical Cons t i tuen ts of CitrusFru i ts . Advances in Food R esearch , Academic P re s s ,N. Y. , 9: 286.

13. Luddy, F. E. , R. A. Barford, and R. W . Riemenschneider , 1960.Direct Convers ion of Lipid Components to Their Fatty Acid Methyl E s t e r s . J. A. O. C . S . , 37: 447.

14. M a t la c k , M. B . , 1929. A Chemical Study of the Rind of •Cal i forn ian O r a n g e s . J. Am. Pharm. A s s o c . , 18: 24.

15. _________ , 1940. The Fatty C o n s t i tu en ts of Cal i forn ia ValenciaOrange Pulp. J. O rg . Chem. , 5: 504.

16. Nol te , A. J. , and H. W. von Loeseck, 1940. Grapefruit SeedO il , Manufacture and Physica l Propert ies . Ind. and Eng. C h e m . , 32: 144 .

17. Pantovich, V. E. , 1955. The Use of C ^ in Studies of thePhysiology of O i l -S to r ing-P lan t Fru i ts . Conference of the Academy of S c iences of the USSR on the Peacefu l U ses of Atomic Ene rgy , (in English t rans la t ion) : 155.

18. Stul l , J. W . , F. M. W hit ing , W. H. Brown, Mary Milbra th , andG. W. W are , 1968. Comparison of Extract ion Methods for Analysis of DDT, DDE, and DDD in Alfalfa Hay. J. of Dairy Sci . , Vol. 51: 1039.

19. U. S. D. A . , 1962. Chemis try and Technology of Citrus , Ci trusP roducts , and By-Products . Agriculture Handbook No. 98: 18, 60-61 .

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