Thermal Bleaching of Red Algal Pigment in Shucked Oysters · and 60 ( lor 1'\. 20. anu 25 minutes...
4
6.347 metric tons of ne ttin g and rope worth $10 million . Tabl es 16 a nd 17 pr ov ide a dditi onal sta ti stics o n Kor ea's exports of fis h ery product s to different countries. for different commodities. during the pe riod 1961-72 . SUMMARY It is always difficult to project th e future direction of a na ti on fis heries. H oweve r . in th e case of the Rep ublic of Kor ea . it is quite poss ibl e that the Korean s may me et or exceed the ir targets during th e coming yea rs . The se goa ls we re out lin ed by th e Director Genera l of the ROK Office of Fis he ri es. Kim Dong Soo . In Oct o ber 1972 : ' The nation 's fisheries producti o n is pr ojec ted a t 1 mi lli o n metric tons a nd a nnu al exports of ma rine prod- ucts at $350 million by 1976. As a res ult. the na ti on is anticipated to rank the fifth in the world in terms of fis he ri es pr od uction a nd th e firs t in te rm s of annual exports of marine Whether or not th es e projecti ons are reached. it is c ertain that th e Republic of Korea will become better able to serve th e needs of the na ti on in fishing and it is also certa in that Korean fishermen will be recognized through out th e wor ld as ambiti ous and skilled fi she rmen. ·Office of Fisheri es. Plcto rwl K oreall Fi shen ', Republic of Korea. 1972. . MFR Paper 1098. From Mann e Flshenes Rev ie w. Vol . 36, No. II, No vember 1974 . Copie s o f th iS paper , In limited numbers , are available from 083, Te c hn i cal Information Division, Env ironmental SCience Information Center, NOAA , Washington, DC 20235 . MFR PAPER 1099 Abnormal red color can be removed from oysters by heat treatment. Thermal Bleaching of Red Algal Pigment in Shucked Oysters V. G. BURRELL , JR . ABSTRACT-A technique for decoloring oysters ex h ibiting " red liquor " due to ingesting algal pigment is described . The abnormal color was per- manently removed by holding the oysters at 55°C for 25 minutes in the aeration tanks . Heat treatment did not noticeably affect the taste or keep- ing quality of the oyster meat and is fea sible using e quipm ent commonly found in most Chesap eake Bay shucking hou ses . INTRODUCTION "Red liqu or" in s hu cked oy ter s has been a c hr o ni c problem for pack- ers (Beaven. 1964: Burr e ll . 1 97 1: Hunt er. 1910: Lear. 1958: Lear and Manning. 1957: and Sieling. 1971) . Plant pigm ents. deri ved from algae on which the oys ter has been fee din g. co ns titut e a principal ca use of this co loration (Lea r. 1958). The co lo r is often not no ticeable when the oysters are s hucked a nd pack ed but may de- ve lo p seve ral da ys aft er packi ng. when oys ter s are held at temperatures ju st a bove freezing. or immediate ly a ft er fr oze n oysters h ave th awed. The wholesomeness a nd fl a vor of such oysters is in no wa y impaired . but cust omer rejection often ca uses se ri ous financia l losses to packers (Ne l son. 1948) . Oysters feed on the al gae ca u sing r ed co lo r o nl y abo ut two weeks out of each year . Such al gae are usua ll y pre s- ent before oysters cease to feed in the fall a nd are a pr ob lem for on ly a wee k or two in s huck ed oys ters. H owever. during some years the pigment appar- ently is retain ed in the intestinal tract of oys ters from fall to the following sp ring (Lear. 1 95 8). Thus. "red" oys- ters can be a pr ob l em to shucking houses for th e ent ire seaso n. Se rious o utbr eaks of red liqu o r in oys ters 19 Formerl y a member of the sta ff of the Virg ini a I nstitute of Mar ine SCience, Gloucester Point, VA 23062, V. G. Burrell , Jr . is now assoc i ated with the Ma rine Resources Research In stitute , P .O. B ox 12559, Charle ston , SC 29412. This pape r is Contri but ion No . 633 from the Virginia Institu te of Marin e Sc ience and Con tribu- tion No. 20 from the South Car olina Marine Res ources Cent er . appear to follow an extended warm fa ll (Nel so n. 1948). A me tho d of eliminating red pig- mentati on fr om shucked oysters would be adv ant ageou s to the oyster Indus try . For a bleaching techniqu e to be of value to th e industry , I) the tr('ated product mu st h ave all the attributes of fresh oysters in appearance, taste. and k ee pin g qua li ty, 2) cost of lab or and equipment to process oysters must be minimal. and 3) yield after processing sho uld not be greatly reduced. The pu rpose of this study was to de t ermine the feasibility of therma l bleac hi ng, employing laboratory and fie ld tests. LA BORATORY TESTS Objective Laboratory tests were und ertaken to dete rmin e the le ngth of tim e oys ters mu st be held at a specific te mp era tur e to d eco lor red algal pigment. A t em- perature- time regime least affe ctin g
Transcript of Thermal Bleaching of Red Algal Pigment in Shucked Oysters · and 60 ( lor 1'\. 20. anu 25 minutes...
6.347 metric tons of netting and rope worth $ 10 million .
Tables 16 and 17 prov ide additi o na l sta ti stics o n Korea's exports of fis hery products to different countries. for different commodities. during th e period 1961-72 .
SUMMARY
It is a lways difficult to project the future direction of a na ti o n fis heries. However . in th e case of the Republic of Ko rea . it is quite poss ibl e
that th e Koreans may meet o r exceed th eir ta rgets during th e coming yea rs . These goa ls we re out lined by th e Director Genera l o f the ROK Office of Fisheri es . Kim Do ng Soo . In
Oct o ber 1972 :
'The nation 's fisheries producti o n is projected a t 1 mi lli o n metric to ns a nd a nnu a l exports of ma rine products a t $350 million by 1976. As a result. the na ti o n is anti c ipa ted to rank the fifth in the world in terms of fis heri es producti o n a nd
the firs t in te rms of an nua l exports of marine product s . "~
Whether o r not th ese projecti o ns are reached. it is certain that the Republic of Korea will become bette r able to serve the needs of the na ti on in fishing a nd it is a lso certa in that Korean fishermen will be recognized through out th e wor ld as ambiti ous and skill ed fi shermen.
·Office of F isheries. Plctorwl K o reall Fi sh en ', Republic of Korea. 1972. .
MFR Paper 1098. From Manne Flshenes Review . Vol . 36, No . II, November 1974. Copies o f th iS paper , In limited numbers , are available from 083, Te c hn ical Information Division, Environmental SCience Information Center, NOAA , Washington, DC 20235 .
MFR PAPER 1099
Abnormal red color can be removed from oysters by heat treatment.
Thermal Bleaching of Red Algal Pigment in Shucked Oysters
V. G . BURRELL, JR .
ABSTRACT-A technique for decoloring oysters exhibiting " red liquor" due to ingesting algal pigment is described . The abnormal color was permanently removed by holding the oysters at 55 ° C for 25 minutes in the aeration tanks . Heat treatment did not noticeably affect the taste or keeping quality o f the oyster meat and is feasible using equipm ent commonly found in most Chesapeake Bay shucking houses .
INTRODUCTION
" Red liquo r" in shucked oy ters has been a chroni c problem for packers (Beaven. 1964: Burrell . 197 1: Hunter . 1910: Lear. 1958: Lear a nd Manning. 1957: a nd Sielin g. 1971) . Plant pigments. deri ved from a lgae o n which the oyste r has been feedin g . constitut e a principal cause of thi s colo rati o n (Lear . 1958). The co lo r is often not noticeable when the oys te rs are shucked and packed but may deve lop several da ys after packi ng . when oys ters a re held a t temperatures just above freezing. o r immediate ly aft er frozen oysters have th awed . T he
wholesomeness a nd fl a vor of such oysters is in no wa y impaired . but customer rejection often causes se ri ous financia l losses to packers (Ne lson. 1948) .
Oysters feed o n the a lgae causing red co lo r o nl y about two weeks out o f each year . Suc h a lgae are usua ll y present before oys te rs cease to feed in th e fall and are a problem for on ly a week o r two in shucked oysters . However. during some years th e pi gment apparentl y is re ta ined in th e intesti nal tract of oyste rs from fall to the following sp ring (Lear. 195 8). T hus. "red" oysters can be a prob lem to shuc kin g houses for the ent ire season . Seri ous outbreaks of red liquo r in oysters
19
Formerly a member of the sta ff of the Virg inia Institute of Marine SCience , Gloucester Point, VA 23062, V. G. Burrell , Jr . is now assoc iated with the Marine Resources Research Institute , P.O. Box 12559, Charleston , SC 29412. This paper is Contribution No . 633 from the Virginia Institu te of Marine Sc ience and Contribution No . 20 from the South Carolina Marine Resources Center .
appear to follow an extended warm fa ll (Nelson . 1948).
A method of eliminating red pigmentati o n from shucked oysters would be advant ageous to the oyster Indus try . For a bleaching technique to be of valu e to the industry , I) the tr('ated product must have all the attributes of fresh oysters in appearance, taste. and keeping q ua li ty, 2) cost of labor and equipment to process oysters must be minimal. and 3) yield after processing should not be greatly reduced.
T he purpose of this study was to determine the feasibility of therma l bleachi ng, employing laboratory and fie ld tests .
LABORATORY TESTS
Objective
Laboratory tests we re undert aken to determine the length of time oysters must be held a t a specific tempe rature to deco lo r red a lgal pigm ent. A temperature-time regime least affecting
t he appeara nce. tas te. a nu J.. cerln g qual ities of 0) ~ t e r~ wa~ \o ugh t
to t a l 0 1 I ') ulilcre nt reglm e n\ Pn o r to
hea tin g . o \ \ te r gut c~' nt enh a nu Ircc liq uo r In th e ca n ""cle In\ r ec tcu m lcro~co rl ca ll ) to e~ t ah l l~ h th a t colo ra ti on \.\ a~ not uu e t~l \ ca~t ~'r hac tcr la I he rH \.\a~ u~cu t~, ucterml ne I re~ hn c\\
hecau~c th l ~ cn t cn~'n I ~ a r r lleu h) m lill ar) rurcha\cr~ anu \lgnillLant quan tl tle~ 01 Irn/cn o\~ t er~ In\oheu
Methods and Materials
Pint conta in ers of reu 0\ ~tcr\ . ~,h
talneu from a local \hucJ..lng hou~e .
were he lu at Internal t emrerature~ 0 1 40. 45 . 50.55 . and 60 ( lor 1'\ . 20. anu 25 minutes In \\ater hath\ . lor a
Table 1 -Treated oYlte" trozen and thaw ed att er Ihree daYI
Temperature · C Appearance pH Be lo re Trea tm ent ---------------------------------
40 40 40 45 45 45 50 50 50 55 55 55 60 60 60
Conlrol
Temperature C
40 40 40
45 45 45
50 50 50
55 55 55
60 60 60
Control
15 20 25 15 20 25 15 20 25 15 20 25 15 20 25
ContrOl
red red red red red red red
clear clear clear Glear clear clear clear clear clear
64 64 6 4 6 4 64 64 64 64 64 64 6 4 64 6 4 64 64 6 4
64 6 4 64 64 64 64 64 65 64 6 4 64 65 6 4 6 4 65 64
Table 2.-5torage ot tre ated oYl te " In dry r.trlger. tlon . t 3·6 C
T me In M inutes
15 20 25
15 20 25
15 20 25
15 20 25
15 20 25
5 days
pH Appearance pH
63 red 62 6 4 red 62 64 red 6 1
65 red 62 6 4 clear 6 1 64 red 62
64 red 63 6 4 clear 62 6 4 clear 6 2
63 clear 6 1 65 clear 6 3 6 4 cle ar 63
6 4 cle ar 6 2 6 .3 cle ar 6 1 64 cl ear 6 2
6 .3 cle ar 62
10 days 15 days
A ppearance p H Appea rance
red 57 red red 56 red red 5 ired
red 56 red red 58 red red 58 rpd
red 58 red clear 56 red red 57 red
cle ar 57 cl ear clear 5 8 c lear cl ear 5 7 c lear
clear 5 7 c lear clea r 5 8 c lear clear 5 6 clear
cl ear 5 7 clear
In th e reu o\\ te r rro hle m go to thl ~
1l1a rJ.. et O\d J.. dn u Il ege r (1<)')7)
fo unu th a t rH wa\ too van a ble to be u\eu a\ ..I te\t 0 1 Ire\hne\\ In commerLld ll\ \loreu o)\te r\ hu t th a t rH UIU UeCrCd\e ~ 1 (l\.\ 1\ In \ toreu o,\ te r\ rh e r H \.\..1\ uetermlneu hy homogeni/ ing o\\ter meat\ In a hlenue r anu te\t lng \.\I t h a Heckman 11,uel ~~ ~ rH me ter hel ore anu al ter t rLat ml:nt In rerlieate te~h r H \.\a\ a\erageu aceorulng to
I--. Inne\ (11.)71) .
I dCh treatment \.\d\ drrlieu to ten rl nh 01 0\ ~t er~ One rl nt I rom edch treatment regimen \.\d\ Iro/en anu
thd\\CU . a~ th" " the ~ure~t meth"d III der11on\tratlng red rlgment Ii It 1\ \tJlI rrc\ent In o\\ter~ (Tahle I) -\
~ec,'nu gn1ur ~ I -+" rlnh (J Irom each regimen ) \\a~ \t,'red under Uf"}
rclngcratll'n "I 1-0 ( . the third grour ~ll I.)() (0 rlnh Irom edeh regimen ) \\a~ held I n cru~heu Ice n ahlc~ 2 and 1)
lhe latter t\\I' gr')Ur~ \\ere tL .... teu c\er) '\ da)\ It,r aprearance . td te . ,mell . and p H tor I" and J() ua\ ~
rC\rcLtl\ el\ \ I\ual l,h cnalllln\ v.ere madc to
uetermlne II reu Lnillr \\ a~ pre,>ent and 11 treateu n\ ~ter~ v. ere \ 1~lht~ dilterent fnlm ~)\.,tcr\ nlll recel\ Ing heat treatment \.\n or more rav. o)\ter trllm edLh Lontalner \\ere eaten at the pre~cnoeu Intenal~ to note ta\te change. Ii am . \\ Ith \to rage lime metl \\a~
aho noteu at each Intenal
ontroh of un o lmeu . tre h 0) ters (ootal neu In a n area tree from problems \\ It h red 0) \ters) \\ e re stored u nuer \ lm Jl a r cond iti o ns to compare J.. eeplng q ua liti es of treateu \\I th un treated 0) ter
Tab le 3.-0y.te" held In Ice In a cold room at temperature. of 0-2 C atter he.t tr .. tm.nt .
Treatment Temperature · C
40 40 40
45 45 45
50 50 50
55 55 55
60 60 60
Cont ro l
5 days Ti me In
Minutes Appearance
15 red 20 red 25 red
15 red 20 red 25 red
15 red 20 c lear 25 c lear
15 c lear 20 clear 25 clear
15 cle ar 20 cle ar 25 cl ear
clear
10 days 15 days
pH Appearance pH Appearance
64 red 64 red 6 5 red 64 red 6.5 red 64 red
64 red 64 red 6 .5 red 65 red 64 red 6 .4 red
6 .5 red 64 red 64 red 64 clear 6 4 red 6 4 red
6 4 cl ear 6 4 clea r 6 4 clear 6 4 clea r 6.5 cle ar 64 c lear
65 clea r 6 4 cl ear 64 c lea r 6.4 clear 64 c lear 6.4 clear
6.4 clear 6.4 clear
20
20 days
pH Appearance
62 red 62 red 62 red
62 red 6 3 red 61 red
61 red 62 clear 6 .3 red
6 2 c lear 6 2 clear 6 2 c lear
6 2 c lear 6.2 c lear 6 2 clear
6.2 clear
pH
62 61 61
62 62 61
62 62 62
6 2 62 6 1
61 6 2 6 2
6 2
25 days
Appearance pH
red 62 red 61 red 62
red 61 red 61 red 61
red 61 clear 62 red 62
c lear 6 2 c lear 61 c lear 61
cl ea r 61 cl ear 6.2 clear 61
clear 61
30 days
Appearance pH
red 6 1 red 61 red 61
red 6 0 red 60 red 6 1
red 61 clear 6 2 red 61
cl ear 62 c lear 61 cl ear 61
c lear 60 clear 61 clear 60
clear 61
Results of Laboratory Tests
(h I~r h~.tI~d III () ( rcm.lIlle 1 1l(l11~l:dh" Ild ( I .Ibl" I .lIlll
{)11~' plill III 111" C hC.lled II IIlI
11.111\ IO~1 r.:d IlI"I, .dlilllll·il lire
IlIrnl:d .tller IrCI:/III' .111.1 Ih.1 ~III' .In I
Upoll ,Im,l .~' ( I "hk, I, _ .lI1d I f{ cd
ulIIH \\ ,,' Ilhl .lIld did nol Idllrn ,111 ... '1
Ilel:/lll' ,llld Ih.l\\ln· In <1\ IC" he.llcd
1<1 "() ( Ilir Illllle Ih.11l rlllnUI.:
hUI Ihe C,,11l1 r.:llIl Ill'll "'"1"~ Ill' I,ll .Iel' ( r dhl _, .tnd 'I \11 11\ I ... ·r
Ill'oJl'd .tl <i<i ( .tnd 110 ( III I Inl
plgll1ellldlloll ,1lld did Ihll 11:).!.t11l II
,lIll:r Ileoin/;! .t nd I h.I\~ Ill!;! IIr dll II Ill! ,IIlr,I/;!1: III lip III ,() da\' (Llhl.:, I,
~ .lnd \ I
Il p H l.h,lnge \lccun cd 1/11l11edl,llc'
h .Iller heal Ire,lIl11enl . hUI dunn!!
hl1lh ,1111 J/;!e In ILe Jnd dn rdn!!er,l'
111111 Ihe p H dnlpped III h(llh clllllr"I,
.Ind Irealed ""Ier, .II Ihe 'dille IoJle
( I Jhle, 2 dlld \ I I here" oJ' 11\1 \ I\udl
e\ IdcIlC': 'lich .I, ,hrrnh.Jge 1'1 ~urled
ll1anlle edge, 1(1 Indlc"tc IhJI 1'"ler,
had becn he,lled . lllhef Ih"n Ihe I""
\II led cl,l"r I 1,1\ Of 1,1 !l"tcf, held In
ICC hegdn I" delenl'f"le .. nL!.r ir!,!hl
odnf de\.:lop.:d In hOlh le,1 \" ,1':1\ Jnd
cl,nlfol, ,II 2" dd'" bUI n':llhel \\efl'
'Plllkd .. I \0 da" i)elerl(lf,llll'n III
n,l\llr and de\ell'pmenl I'! .r ,irghl
OJ"f I'CClIfrl'd .11 l'i dol"~ 111 ,1\,1':1\
Tabl ~ - 0,'' r. "elel
o
Illln
() lh.11
\l·r.II'Ir
• 0\1 . 01
~ .11 ~t 1 c.tIll 1'1111 r~ nl ,II r
,ul'l'll u l Ir"1 1 II, 1,'llll'lIl "I Ih~ 1,111
FIELD TESTS
Objectives
One lll->l ...... If\~ ",I' I,) lkl~rlllllll: II
II " k"'lbl~ III he.ll 11\ I,'r II'I .1
,ulfl<:Il'1l1 111l1~ In .lel,III,11l 1.111 prIOr
III P,ILh.II1\.! 111 <:,111' III I'tlier I, dClI,l,r
,dg.tl plCI1l~nh "hlLh l.!U ~ rc\1 ~\ll,'r.t
II(ln \ -ec(lnd 1,l->jl'LII\l' \~." II kl~r
111111.: ,helllril "I hL.!1 Irl'lllll I \,I,'r
Methods and Materials
O',I.:r 1I,ul II. : • ...Id Il I ' cr~
l'k<:l~d Irl'll1 b,lldl~ 1)11'\ ler 11,'''11
II' h,J\ ~ fcd plCIl1~1l1 .tilhLlLJ 'h ",h'r
mlghl 11111 h~ .rI'P,trcnl I hi \\" dcler
I11ln.: I 1->\ 111 pClllng Ihl' CIII ,'I II rn
hl'id .. 1 \./1 <. lInder dn 1.:111/;!l'I.tlll'n "I u,p,:cll'l (I\\I ... 'f
Conclusions on Laboratory Tests
I re,h c"nlll'd ,1\ ,Ief, h.:.II.:d I"
<iT1d htl !llf I" mlnUle 111,1 r.:d
Cl"11I.IIILln c.llI,ed b, a'!,!,tI plCI11.:nh
1,1,1':, ,lppe,lf,lnl.': ,Ind 111.:11 \~.:r.: nl'l
"d\cI\ch .lllcl.ll'd b\ Ihc'l' Ile,lIlll.:nl
1 hl\ Illdle,lIcd Ih.1I Il'lllpCr,I IUfe In
Ih" gCllel,t! I"ngc \\I'uld he he I II'f
111111,,1 IIl'i I le,1\ T Imc "I ICl11p.:r.llull'
hll\\':\el Illichl [C4Ulle ,1111 ... ' IUrlhl'f
':'PCrlIllCI1I.11lll n 'Incl' . In 1.lh 11.11111\
Ic I III11C r,:cllldeJ \\ .1' Ih ... ' I'lIll d
Ih.11 Ihc Cenl ... ·r 1'1 Ihl I', lef In Ihl:
C.I n \\ ':1,' h l'id .11 d," If ul II: m I'll .!l1I r e
1 h,' .:r .111 III 1,'1' Ihl:
1"!!ll," pl:J ...... , 1<
hl':Jll'd \\ Jll'r 111.1\
Ih n PI
e"I11': IHII11 l'\ cr.t! .He.l' 11l ... ludlll
UPl'lr ( he ,lp.:.1 ... ' B.n R.IPI.lho1l1n
RI\,r . 1','IIII11.IC RI\cr .JIld I lUI l.ln,1
B.lIChc' ,,! Ihe e ,,, ICf
4U,JIlIII\ Ifl'l11 Itl 10 _I)
I->I1Ih ,1 ,1Ild,lfd und 'ekLI
Ihrel',"'urlh
.1
c • .. .. • •
Tabl e 5.-0 ysters held in c rushed Ic e In a cold room ma lnta ne d at 0-2 C after he.t tr •• lmenl In an •• r.tor pH la a me." of all repllcet .. Re pl ic ates .t 55 C Include d pint and gallon cana ----
Treatment o days 5 days 10 days ~a.p 20 dal's - 25 days 30 day. Wothoul heal Temperature t rp.8 1menl
°C Appearance pH Appearance pH Appearance pH AppearanCe pH Appear ncp pH A pPQ,HanCe PH AppPMilnce pH Iroll-n dnd Ihaw p.d
50 clear 64 red 63 83'; r"d 17'; cl~ ( 53 clear 64 25 r; red 63 25 r~ r d 63 lOr, red 6 J 10(~ (Pld 62 lOr;. r~d 6 1 lor; red 6 1
75 r ; clear 75", clear 90 r , cleM or~ cle r 62 O't cl "' 1 90'; Clfl;jf 6 t 01"-; ",d 10'f clAa r 55 clear 64 clear 64
Control clear 64 clear 63
'No further tests
s ho weJ nO ob" IOU\ color \\ hen pl acl' J in storage (Tabk, -I anJ ~) II o f th ese oys t er~ JC\l' lo[leJ reJ col,lr upon storage. Thosl' ral\cJ lO ~ 1 ( f(lr 2~
minutes \\erc ell'ar \\. h l'n placl'J In
storagc. but lo-(,(,r( J l'\l' lo [l l'J rl'J color. IAlth larger o) ,I l'r'l mo,t (Iftl'n shOWing co lor. Oyster, , ubJl'l'tl'J to 55 ° C for 25 m inut es JIJ nOl Jl' .:lop red colorat io n In ~ t oragl' up ((I 10 days. Oysll'r from th e ,aml' halch In each In lance abo\e. not ha\lng received heat t reatmenl. ... holAl'J rl'J color when frozcn anJ IhalAl'J In l' ( .
so r ( and 92 rr 01 thl' can .... rl'~pl'C
tivel, Keeping quallt) a ... ml'ill>ureu by depreSSIOn of pH of I reateJ 0) 'I tl'f'> and controls <;howed no dlfkrencl' (Table 4 and 5).
Gallon container<; k.ept as v.el l a ... pint containers (Table 5). Appearance in all instances wa the ame In lrea led as in untreated oysters Ta tc t ~ t s
by the author indicated no dl ffe ren e with time in treated and untrea led oysters. The reaction of reCIpien t of test oyster was In e .. ery In tan e favorable with no greater acceptability for control oyster. Again a ligh t odor developed in both control and treated oysters held in a household refrigerator at 15 days. a nd at 25 days in those held in ice at 0-2 °C, H eat treatment time reduced to 23 mi nut es at 55°C by adding crushed ice to the aerato r fo r coo lin g purposes was sufficient to decol o ri ze the red p igment.
CONCLUSION
O ysters may be he ld a t 55° C for 23 to 25 minu tes during the aeration process in a shucking house to decolorize red pigments derived fro m a lgal food of oysters. A te mpe rature o f 53 °C during th e aeratio n process is su ffic ient fo r small oys te rs (sta n d a rds); ho wever , grading by m ost shucke rs is not strict enough to pre-
clear 6 J cl ar 63 cleM 62 clear 63 clear 6J cln r 6J
-----
\l'n t ,Pille I,lrgc (,ekL I) ll\\ler\ Iror11 gl' tt tng In l,1 nc.trh L'\ef\ h.t ILh . I he re
forl'. thc lo\\cr tem[le rJ l llrl' " nll l rellahk
I\ J\Jn lagl" III hl'a l IrCd ll11ent III ll, ... Il'r, 10 Jl'uIlllr Ingc'Il'J rl'd [l l.tn t
[llgmcnh .HL I) )\ tl'r' url' nIl Illngl'r ,uhJCLt III
l'U,lOmcr rl'Jl'Ltllln Jue III a p[ll'arancl'
2) Trl:all'J ,l\'lla, hil\l' Ih c '.Jme \ hl'11 Ilk a' Un l rl'atl'J 0\ \l l'r,
3) either ta,ll' nor a [l [lcaruncl' (olh.:r Ihan Ill" 0 1 rcJ Cllillri " aitl'rl'J
-I) hl' [lroCC\ mJ\ hl' Lafrtl'J IIUt u~lng l'\I~lIng e4ulpml'nt
Thl' main JI\aJ\ antagl' nl th" pr\lCl'~\ 1\ thl' nl'l'J I lr ,Inct tlJhl'rcncL' III
Ilml' anJ lem[ll'raIUrl' . f h" rL"qulrL"'ciO"'l' ,upen 1,"1n thrllughoul Ihl' trl'illment empl'r.Jt u re, hlghl'r thJn th'hC prl'\cnheJ mil\ Jl'naturl' thl' [lnltl'ln'> In t hl' q\lCr a nJ Incrl'J"'l' th l' Jillicul t) In coolin g (l" Il'r III pal' !.. lng lempera tu rc
Ith ough thl \ t rl'alml'n l h il ... bl'l'n effcct l\e In Jeg radlng Ihl' rl' J [ll gml'nt In 0) te r from man) arl'a~ Jun ng the wint ers of 1971 a nJ 1972. It ma~
not wo r!.. fr ail reJ a lga l pl g me nl\ Inge ted b) 0, ters an d o th e r b(\ a h e~
ACKNOWLEDGMENTS
peclal lh a n!.. a re du e H ogg O~ te r Compan y. 0 k. O y te r o mpa n). a nd Virgini a eafood . Inc .. fo r th e
CI(liH 60 Clpar 60 92'1 red er ,. CI~:H
clp-i." 6 1 Cle It 60 1000 clp.ar
U'l' 0 1 Ih elr e4ul[l nle nl ,mJ p ro\ IJlng o\\ ler, lo r Ih " \ luJ , tl nJ lo \ l r 1 rll 1\ "> e .. il ooJ ,. Inc. v. ho [l r<l\l J eJ Ihe In:lIer 'UppII L",>
1 dnl gril ldul lO D r, J D nJrL v. , I) 0 11. I 0 Per !.. ln\. ilnJ \ 1 r D ">
H il\en (II lhL \ Ir 'Inlil In\ l llUtc 0 1 \I ilrlnL Lienee Ipr Ihe lr hel [ll ul CrJllcl\n1 anJ aJ\ Ice
I hl\ \luJ\ lA d' \u [l[lorleJ h~ Ihe e .. 1 Jrilnl P ro/rilnl (I I Ihl' :-" allPnill Le,lnlC anJ \ lnHl [lhcrJc .\ Jmlnl\lra-
l inn \11 lhL DC[l M lnlCn l II I llmmerce. onlr.JLI '. umhcr 1-1hfU2
11'1711
LITERATURE CITED B I\en (, I~ -I ("n,01<nl on Ihl."
,~\.urrt:n\"'l· .JnJ n..1lurt: III I..tn •. un ('pc III i.:lllnr.JlIOn In I) ler ...... J.I Kc (Jur I n 1 l nI\ \l u h~ B,,,I I ~h Rd ' . , p
Hurrell \ (, I~~ I fJ ,n k c"lor .. llI)n ,n ""t~r, \ ~ I n'l \I ~r \1 ~r R<","ur Inl Bull 1"1(, ~
lI unl"r A I~~n poll...tRl' In n~ 'h."r I~. ~4 r
pIn k 't:~'1 c~U Ing Der -\ g'" Bull
"- Inn,,\. (- ( I~' -\ \cr .. gc (lr fll" .. n p H Prog f- "h-( ult "~,
I Colr [) \\ . 19' I urlhcr n'u ,h"lIh h ~ol"r ~llun ,tUU lt c\C~r,,1 C.W '" lor reu ,ulor .. t",n \l d T, de " .l ler ' e", 14 II
I c .. r D \\ . .ln d J H \ \annl ng 19'~ . Iud) ul red , he ll fi h co lo r.ltion Inltl.lled l d T,de" atc r ' e", 13(9) 1-2
..... e l o n . T C 19-1 O )\ter I!.I\ tng ulT red-d l ~ h JU I<: e "hen CUI pro \ e e , ce ll enl lood T ra de Rer 99 O)'ler In I ' o rth m J r
0 \ .1 1. . . .l nd E. ' earc h o n h a ndling e rn oy,le r, P roc 4 14 -150
le llng. F . \\- 19 I o r 0 ) Sler e xpl a tn ed Fi s h \\- dd!. dmln
Fl eger ) 95 Re-a nd rroce tng ,oulh 'a t I h e llfi h soc
H armle", colo rauo n Comme r FI h e "' . l d . 4(2 )' 1-2
MFR Paper 1099. From M ari ne Fisheries ReView , Vol. 36. No II , November 1974 . Co p ies of th iS paper. In limited numbers , are availab le form 083, Technica l Info rmaCion DIViSion. EnVironmental Science InformaCion Center , NOAA , Washln9ton. DC 20235.
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