CALBO, A. G.

ISHII, G.

SILVA, J. L. O. da

English

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FOL3305oInfluence of Wasabi( Eutrema wasabi Maxim. ) Powder and L-AscorbicAci,d on Browning of Le-bt..gce_GenSholEHIILaboratory of postharvest physiology,NIVOT,Mie,JapanA.Gimenez lcalbo and J.L.Oliveira da ~ilva--EMBRAPA / CNPH , Brasilia DF , Brazil Inf!uence af wasabi '"1990 FL-3305i1IIIIIIIillllilllllllll!l! 111I1 I1I1I11I11 1111111111 1111111111 II!II 11111111CNPH-7129-1INTRODUCTIONBrowning of cut surfaces and injured regions is one of themo~t important deterioration symptoms of lettuce. However,itis difficult to control the browning in horticultural products.Unoxidized phenolic compounds,such as chlorogenic acid and cate-chins,are usually present in a small amount in healty tissue andin many cases are newly produced in injured tissue( I ). Thoseare enzymaticaily oxidized by polyphenol oxidase to 'form quioneswhicr easily react with nitrogen compounds-to produce coloredsubstances.Recent report (2) showed that browning of shredded cabbagewas inhibited by isothior::yanates."The ob'ective of this paper was to investigate whether W~ sabisolution cantaining L-ascorbic acid could inhibit browningIo~lettuce or noto -,, ,MATERIALS AND METHODSSample preparation :' Lettuce ( Lactura sativa L. ) was obt;ainedfrom CEASA in Brasilia on 24th,of April. Five healthy samples( 357±58g FW/ sample ) of lettuce were chosen,and their midribsBrasília-1990-weretaken with a knife from green leaves. The midribs were cutinto lem segments. Fifty g~ams of them was used to test of"browning ,and another fifty grams served ·as a controloPreparation of Wasabi suspended solution Five ml of 10 mML-ascorbic acid was added to one gram of Wasabi (San-Maru indust-ria e comércio LTDA.) powder,and well mixed.Evaluation of browning in lettuce: . 'For a control,the exeised50 gram of midribs was plaeed and sealed in a 500ml flask afteraddition of 5ml of 10mM L-aseorbie aeid,then held for 20 hours·at room temperature( around 22°C). For a treatment,Sml ofWasabi solution was applied to the flask with the exeised midribs.This treated sample was also held at room temperature for.20 hours.After treatment,the eolour of the midribs was evaluated by visualobservation and a portable speetroradiometer ( LI-1800,LI-COR INC.).Visual observation: The browning of their eut ends waseva\uated by 4 grades as shown in Table 1.CIE Chromatieity coordinates: The reflectanee of sample at\300~8S0nm was seanned ,and the chromatieity eoordinates (X,Y,Z,x,y,u;v' ) were ealeulated by LI-l800. For this measurement,each sample was homogenized for 3min in 50ml of ethanol,and chlo-rophyll was removed by a total of 200ml of ethanol using a glassfilter. The residue was placed and spread into a Petri plate.After dryingover one night at room temperature,the chromatieitywas determined.After holdingfor 20 hours atroom temperature,each sample gas was taken fromthe sealed flask by I ml of syringes for injection into GC.RESULTS AND DlSCUSSlONThebrowning of mid~ibs in lettuc~ was inhibited by addition.~-of Wasabi so1ution containing L-ascorbic acid (Table 1). Thisphenomenon was confirmed by visual observation and ClE chromaticity.Respiration and ethylene production rates of,the excisedmidribs were clearly lower in Wasabi solution than those in controloThis result was consistent with a preliminary experimento AIsothe browning of the excised mandioca. ( Manhiot utilissima wasinhibited by this material in another testoThe browning inhibition mechanism is unknown at present time.It is well-known fact that Wasabi powder contains sinigrin andmyrosinase,and that the enzymatic reaction betweenthem is pro-moted by L-ascorbic acid and water. One hypothesi~ canobe sugg-.ested as follows Al1yisothiocyanate(AlTC) ,which is enzymatic-ally produced by hydrolysis of sinigrin,may be a key compound.tosolve this mechanism. AITC has an àctive chemical structurethat ~eacts easily with other compounds such as the SH-group ofproteins. Therefore,the enzymes which are related to the brown-ing of polyphenol compounds and formation ofethylene may becomeinactive by AlTC. A further investigation will be required tosolve this problem.REFERENCES-1.Ke,D and Sa1tveit,Jr.M.E.1988.Plant Phy~iol.,88:l136.2.Yano,M.,Saijo,R.and Ota,Y.1986.J.Japanese Soc.Hort.Sci.,55:194.Table 1. Effect of Wasabi powder and L-ascorbic acid on thebrowning ,C1H~and COaproduction rates af cut surface of midribs. .....•.. - .in lettuce. 'Respiration EthyleneT.reatment mi.co, /kg/hr )UCl.H.f. /kg/hrBrowningVisual CIE(chromaticity)y x yControl 28 0.63 +++ .1796E06 .3407 .3543Wasabi + 7L-ascorbic acid0.24 .1827E06 .3539 .3620,NOTE : Visual observation of browning was done 20 hr aftertreatment. +++ i severe;++;medium,+islight ,-i non,respectively.A d)1~t r ~Jll~"J ?iJ t" *75 ~ 'L L- )'1; dJ*) 1f / /j{; ~ ~l-t§/) A,6: -C (11 ho: /J L. _O{ive;rd'o{~ S í1va:1.'. /"t=*-p,,' ,7t,'., ;"lv1: t4 t:t~~;J >~-ttOJ1f ~ -l L5;Z 0;0 ~;b1C ,~O) I? (,:-(1:I *~t~\.,.M~. i~t': =0) pij Jt >-~l~:,/ ~) Z t~~t1Jt~dj I p~IL tr J->cl}'~E:*~1~~1t~7-tft';W~%'[ l- rÀ:J/t-·t">l~>t:~~ ~, flJ9l/:frL ~ t9J-t~~(~)~1JD L1 1.?\~P*tt~I\"K o lrfíZ '('o \ 1fti~i$~J1\ I f;-) ~ r ~ .L4-1.-),- li $ t ,-t)l<i~-lIJt O) iri'l1~-Ikt.,

Influence of wasabi (Eutrema wasabi maxim.) powder and L-ascorbic acid on browning of lettuce.

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Influence of wasabi (Eutrema wasabi maxim.) powder and L-ascorbic acid on browning of lettuce.

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