A study of the nonvolatile fraction of extracts fro
m vine shoots obtained by superheated ethanol-water
mixtures is presented. The influence of the te
mperature, extraction ti
me, and percentage ofethanol on extraction was investigated by a
multivariate experi
mental design to
maxi
mize the yieldof total phenolic co
mpounds,
measured by using the Folin-Ciocalteu
method. The best values foundfor these variables were 80% (v/v) ethanol, 240
![](/i<font color=)
mages/entities/deg.gif">C, and 60
min. Under these conditions, the effectof pH was also investigated, and a strong i
mprove
ment of yield was observed by decreasing the pH.The extracts were subject to liquid-liquid extraction with
n-hexane. The re
maining polar phase wasdried in a rotary evaporator and then reconstituted in 10
mL of water. The insoluble residue wasdissolved in 10
mL of
methanol. Both fractions (aqueous and
methanolic) were analyzed by HPLC,and the differences in co
mposition according to the extraction conditions were studied. Co
mpoundsusually present in co
mmercial wood extracts were identified (
mainly benzoic and hydroxycinna
micacids and aldehydes); the
most abundant were quantified, and the stability of the identified phenolicfa
milies under different extraction conditions was also investigated. Finally, the superiority of thesuperheated liquid extraction over conventional solid-liquid extraction was de
monstrated.