C: Food Chemistry JFDS jfds˙1343 Dispatch: 9-2-2009 CE: PMS Journal MSP No. No. of pages: 6 PE: Marie 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 JFS C: Food Chemistry A Comparison of the Effect of Macerating Enzymes and Pulsed Electric Fields Technology on Phenolic Content and Color of Red Wine E. PU´ ERTOLAS, G. SALDA˜ NA, S. COND´ ON, I. ´ ALVAREZ, AND J. RASO ABSTRACT: The effect of the addition of 2 enzymatic preparations and the application of a pulsed electric fields treatment (PEF) on the phenolic content and color of Cabernet Sauvignon wine has been compared. The evolution of color intensity (CI), anthocyanic content (AC), and total polyphenol index (TPI) from crushing to 3 mo of aging in bottle was studied. The results demonstrated that both treatments promoted greater extraction of phenolic com- pounds, compared to the untreated wine. However, PEF technology was more effective. After 3 mo of storage, CI, AC, and TPI were 28%, 26%, and 11%, respectively, higher in PEF-wine than in control wine. By contrast, while both en- zymatic preparations increased the CI of the wine around 5%, only one of them increased the AC and TPI by 11% and 3%, respectively, in comparison with the control. After 3 mo of aging in bottle, the phenolic composition was also analyzed by high-performance liquid chromatography (HPLC). The content of nonanthocyanic families was higher in PEF-wine than in the rest of wines. In wines treated by enzymes, only an increase in phenolic acids and flavonols with respect to the control was detected. Practical Application: Pulsed electric fields is a novel food processing technology that poses a very promising future to the enological field, due to its capacity to improve the mass transfer phenomenon. The continuous development of this technology allows nowadays the application of treatments at semi-industrial scale. In this article, it has been demonstrated that the application of a PEF treatment to the grape pomace before maceration/fermentation is more effective, in terms of color intensity and phenolic content, than the addition of macerating enzymes. Keywords: color, macerating enzymes, phenolic compounds, pulsed electric fields (PEF), wine Introduction P henolic compounds are considered to be the most important components of red wine, due to their direct relationship with its color, astringency, bitterness, and susceptibility to oxidation re- actions (Glories 1984; Robichaud and Noble 1990). Furthermore, the well-known health beneficial effect of red wine is also attributed to these compounds (Frankel and others 1993; Nichenametla and others 2006). Grapes, especially grape skins, contain a large amount of differ- ent phenolic compounds that are partially extracted during wine- making. The envelopes of the grape skin cells, the cell wall and the cytoplasmatic membrane, are limiting barriers that prevent the release of phenols into the must during fermentation. The basic structure of the cell wall comprises 3 different layers and it is mainly composed of pectins, polysaccharides, cellulose, and hemicellu- lose. On the other hand, the cytoplasmatic membrane is a semiper- meable phospholipid bilayer that contains different molecules embedded, especially proteins. According to their disposition in the skin cell, phenols are classi- fied in cell-wall phenols, which are bounded to polysaccharides by hydrophobic interactions and hydrogen bonds, and non-cell-wall phenols, which are confined within the cell cytoplasm, basically in- side the cellular vacuoles (Pinelo and others 2006). MS 20090500 Submitted 6/2/2009, Accepted 8/2/2009. Authors are with Tec- nolog´ ıa de los Alimentos, Facultad de Veterinaria, Univ. de Zaragoza, c/ Miguel Servet, 177, 50013, Spain. Direct inquiries to author Raso (E-mail: jraso@unizar.es). Because of the significance of phenolic compounds in red wine, diverse enological techniques have been developed to enhance the extraction of these compounds during vinification (Sacchi and oth- ers 2005; Bautista-Ort´ ın and others 2007; Gambuti and others 2007; Baiano and others 2009). Since phenols are mainly located in grape Q1 skin cells, these techniques generally act by degrading or increasing the permeability of the cell envelopes (Amrani-Joutei and Glories 1995). In the last years, the employment of commercial macerating enzymes in the wineries has been generalized. These enzymatic preparations consist of pectinases and small quantities of other en- zymes, especially hemicellulases and cellulases. In principle, the hydrolysis of the structural molecules of the grape cell walls fa- cilitates the release of both cell-wall and non-cell-wall phenols (Mu ˜ noz and others 2004). However, contradictory results have been obtained concerning the ability of the macerating enzymes to im- prove wine color and phenolic content. Some researchers have reported an increase in color intensity and phenolic content at the end of fermentation (Pardo and others 1999; Gambuti and others 2007; Kelebek and others 2007). On the other hand, other researchers have obtained no effect and even a decrease in the an- thocyanic content or in the color of wines (Wightman and others 1997; Bautista-Ort´ ın and others 2005, 2007). Recently, it has been demonstrated that the application of a pulsed electric fields (PEF) treatment to the red grape pomace before the maceration/fermentation step increases the extrac- tion of phenolic compounds during the vinification of different grape varieties (L´ opez and others 2008, 2009). The application of microsecond-duration pulses of electric fields between 1 and C  2009 Institute of Food Technologists R  Vol. 00, Nr. 0, 2009—JOURNAL OF FOOD SCIENCE C1 doi: 10.1111/j.1750-3841.2009.01343.x Further reproduction without permission is prohibited