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Betacyanins in fruits from red-purple pitaya

Betacyanins in fruits from red-purple pitaya

Betacyanins in fruits from red-purple pitaya

Analytical,Nutritional and Clinical Methods Section

Betacyanins in fruits from red-purple pitaya,Hylocereus polyrhizus

(Weber)Britton &Rose

Florian C.Stintzing,Andreas Schieber,Reinhold Carle*

Institute of Food Technology,Section Plant Foodstu?Technology,Hohenheim University,Garbenstrasse 25,D-70599Stuttgart,Germany

Received 15May 2001;received in revised form 7September 2001;accepted 7September 2001

Abstract

The betalain pattern of Hylocereus polyrhizus (Weber)Britton &Rose is reported for the ?rst time and a highly practicable technique is described for the simultaneous isolation of pigment and mucilage from the mesocarp by extraction with water.Whereas betaxanthins were totally absent,10betacyanins could be separated by HPLC-PDA.For eight betacyanins the respective molecular masses could be obtained by positive ion electrospray mass spectrometry.Five of them were unequivocally assigned to bougainvillein-r-I,betanin,isobetanin,phyllocactin,and iso-phyllocactin.The remaining betacyanins were tentatively identi?ed as (60-O -3-hydroxy-3-methyl-glutaryl)-betanin,its C 15-stereoisomer,and (60-O -3-hydroxy-3–butyryl)-betanin,http://www.wendangku.net/doc/e0ffe0e8998fcc22bcd10dda.htmling the b -glucosidase assay,acylated structures could be distinguished from non-acylated betacyanins.Contrary to white-?eshed Hylocer-eus undatus (Haworth)Britton &Rose with a slightly pink mesocarp,H.polyrhizus most likely possesses the same set of betalain forming enzymes in both pulp and mesocarp as the betacyanin pattern was found to be similar.#2002Elsevier Science Ltd.All rights reserved.

Keywords:Pitaya;Hylocereus polyrhizus ;Betalain pigments;Natural food colorants

1.Introduction

Oblong shaped fruits of the genus Hylocereus (Berger)Britton &Rose originating from Latin America and known as red pitaya derive from climbing epiphytes belonging to the Cactaceae family.Due to Crassulacean Acid Metabolism (CAM),members of this family exhi-bit an extraordinarily high water-use e?ciency with low water requirements (Raveh,Nerd,&Mizrahi,1998;Winter &Smith,1996).An additional ecological feature was very recently pointed out with CAM plants responding to high CO 2atmospheric concentrations by increasing their biomass production (Drennan &Nobel,2000).Compared to the more common cactus pear (Opuntia sp.),the usually red peel from Hylocereus pos-sesses large scales instead of spines and its pulp only contains small digestible seeds (Raveh,Weiss,Nerd,&Mizrahi,1993).Due to self-incompatibility,cross-polli-nation is required and hand-pollination is still necessary to obtain fruits (Lichtenzveig,Abbo,Nerd,Tel-Zur,&

Mizrahi,2000;Mizrahi &Nerd,1999;Weiss,Nerd,&Mizrahi,1994).Pulp colour in Hylocereus fruits varies from white to red and purple (Nerd,Gutman,&Miz-rahi,1999).Producing a deep purple-coloured ?esh comparable to red beet (Stintzing,Schieber,&Carle,2000b)or amaranth (Cai,Sun,&Corke,1998),fruits from Hylocereus polyrhizus are highly appealing.Public concern about possible or proven harmful e?ects of arti?cial food colorants has increased the search for natural colour sources.Showing a stable appearance in the pH range from 3to 7,betalains have a great poten-tial in colouring a broad array of food.In this view,betacyanins from H.polyrhizus are most promising,not only as colouring agents but also in possessing anti-radical potential (Escribano,Pedren o,Garc?a-Car-mona,&Mun oz,1998;Pedren o &Escribano,2001).Very recently,ripening and postharvest behaviour of Hylocereus undatus (Haworth)Britton &Rose and H.polyrhizus were studied to determine the optimum date of harvest in relation to colour development of pulp and peel (Nerd et al.,1999).However,no data were given about the pigment pattern of H.polyrhizus .Both the juice from the pulp and the aqueous extract of the deep-coloured mesocarp provide a hitherto little known

0308-8146/02/$-see front matter #2002Elsevier Science Ltd.All rights reserved.P I I :S 0308-8146(01)00374-

*Corresponding author.Tel.:+49-711-459-2314;fax:+49-711-459-4110.

E-mail address:carle@uni-hohenheim.de (R.Carle).