International Dairy Journal 15 (2005) 579–584 www.elsevier.com/locate/idairyj
Preliminary observations of ﬂavonoid glycosides from the vegetable coagulant Cynara L. in protected designation of origin cheeses
L.B. Roseiroa,Ã, D. Vialab, J.M. Besleb, A. Carnatc, D. Fraissec, J.M. Chezalc, J.L. Lamaisonc
b a ´strias La ´cteas (UIL)-DTIA– INETI, Lisboa, Portugal Unidade deIndu ´ Unite de Recherches sur les Herbivores, INRA, Clermont Ferrand-Theix, France c Faculty of Pharmacy, Clermont Ferrand, France
Received 9 April 2004; accepted 8 July 2004
Abstract Aqueous extracts of Cynara cardunculus L. (cardoon) ﬂowers have been used for centuries as vegetable coagulants for traditional cheesemaking in the Iberian Peninsula. However, the full chemical composition ofthe extract that is added to the milk has never been studied. In this study we investigated the phenolic components of the aqueous extracts from cardoon ﬂowers and their detection in cheese. Analysis by HPLC-diode array detection (HPLC-DAD) revealed the presence of one ﬂavonoid-7-glycoside (isorhoifolin) and the aglycones apigenin and luteolin. Another major ﬂavonoid-7-glycoside(apigenin-7-O-glucuronide) was also identiﬁed and its structure elucidated by 13C-NMR. This represents the ﬁrst report of these compounds in the aqueous extract of cardoon ﬂowers. These compounds were also found in cheese curd made using this coagulant but were not present in the original milk, leading to the suggestion that these phenolic compounds could be used as authentication markers for cheeses made usingcardoon extracts as the coagulant. r 2005 Elsevier Ltd. All rights reserved.
Keywords: Vegetable coagulant; Cynara spp; Authentication of cheese; PDO cheeses; Flavonoids
1. Introduction The occurrence of phenolic compounds in milk and dairy products may be the consequence of several factors, such as the consumption of particular fodder crops by cows or their deliberate addition as speciﬁc ﬂavouringor functional ingredients (O’Connell & Fox, 2001). However, for the manufacture of some traditional ewes’ milk cheeses, such as some Spanish cheeses and the Portuguese varieties Serra da Estrela, Castelo ´ Branco, Azeitao, Evora, Niza and Serpa [that have ˜ protected designations of origin (PDO)] the use of an
ÃCorresponding author. Tel.: +351 217127112; fax:+351 217127162. E-mail address:firstname.lastname@example.org (L.B. Roseiro).
aqueous extract of ﬂowers from cardoon (Cynara spp.) as a coagulant is compulsory. Aqueous extracts from cardoon ﬂowers have been used for centuries as coagulants in traditional ewes’ milk cheesemaking in the Iberian Peninsula. This extract is prepared in different ways by traditional cheesemakers (Roseiro, Barbosa, Ames, & Wilbey, 2003), but normallythe cut, air-dried ﬂowers are soaked in water at room temperature, then ﬁltered through a cloth and the solution obtained is added to the milk (Fig. 1). Coagulation usually occurs within 30–60 min. This may therefore introduce into the milk, and hence into the cheese, a certain amount of phenolic compounds originating from the vegetable coagulant used. Some studies on the chemical compositions ofdifferent parts of Cynara spp. have been reported (Roseiro et al., 2003). The driving force behind those
0958-6946/$ - see front matter r 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.idairyj.2004.07.027
ARTICLE IN PRESS
580 L.B. Roseiro et al. / International Dairy Journal 15 (2005) 579–584
Cardoon flowers aqueous extract
Cardoon extract (Rel. Area% = 2.37) Cardoon extract +Apigenin std. (Rel. Area% = 34.31)
350 Cardoon extract (Rel. Area% = 10.52) Cardoon extract + Isorhoifolin std. (Rel. Area% = 17.37) 250 150
50 0.0 15.0 30.0 45.0
Retention time (min)
Fig. 1. HPLC separations of aqueous extract from cardoon ﬂowers: (a) peaks (1) isorhoifolin, (2) unidentiﬁed...