This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and

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1 This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier s archiving and manuscript policies are encouraged to visit:

2 Available online at LWT - Food Science and Technology 41 (2008) 2064e Evolution of aroma compounds in sparkling ciders Roberto Rodríguez Madrera*, Ana García Hevia, Noemí Palacios García, Belén Suárez Valles Area de Tecnología de los Alimentos, Servicio Regional de Investigación y Desarrollo Agroalimentario (SERIDA), Villaviciosa, Asturias, Spain Received 8 June 2007; received in revised form 17 December 2007; accepted 18 December 2007 Abstract This paper reports the influence of yeast strain and aging time on the volatile composition of sparkling cider made according to the traditional method. Two sparkling ciders were obtained from the same base cider using a selected cider yeast strain (Saccharomyces bayanus) and a commercial wine yeast strain (Saccharomyces cerevisiae). Analysis of volatile compounds (alcohols, esters and carbonylic compounds) were performed every 3 months, from 3 to 15 months. The analysis of variance revealed that the majority of differences between sparkling ciders are due to the aging time. Acetaldehyde and acetoin decrease with time, while higher alcohols, ethyl acetate, ethyl lactate and ethyl octanoate significantly increase during aging in contact with lees. The concentrations of methanol, 2-phenyletanhol, ethyl lactate and ethyl octanoate were higher in the cider made with the selected yeast strain (S. bayanus). Ó 2008 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved. Keywords: Cider; Yeast; Aging time; Volatile compounds 1. Introduction The production of cider and sparkling cider is an important economic resource in European regions where apple cultivars are viable. There are several similarities between the procedures employed in cider making, although differences exist which confer on each product its peculiar characteristics (Lea, 1995). Cider making is one of the most important food and drinks industries in the region of Asturias (Suárez & Picinelli, 2001). A sparkling cider made according to the traditional method characterized by a secondary fermentation in the bottle has recently been protected by the European Designation of Origin Sidra de Asturias (EEC Commission Regulation No. 2154/2005). These sprakling ciders must have an alcoholic strength higher than 5% (v/v), a volatile acidity lower than 2 g/l of acetic acid, a total sulfur dioxide content below 200 mg/l and an overpressure in bottle higher than 3 atm. Moreover, these ciders will be designated as dry when their content in sugars is lower than 20 g/l, semi-dry between 30 and 50 g/l and sweet between 50 and 80 g/l. * Corresponding author. Tel.: þ ; fax: þ address: rrodriguez@serida.org (R.R. Madrera). The quality of sparkling wines has been related to several factors, namely: raw material, yeast strains, aging time on lees and fining treatments (Andrés-Lacueva, Gallart, Lopez- Tamames, & Lamuela-Raventos, 1996; Andrés-Lacueva, Lamuela-Raventós, Buxaderas, & de la Torre Boronat, 1997; Barcenilla, Martín- Alvarez, Vian, & González, 2003; Charpentier & Feulliat, 1992; Hidalgo et al., 2004; Marchal, Chaboche, Douillard & Jeiandet, 2002; Marchal, Sinet, & Maujean, 1993; Martínez-Rodríguez & Polo, 2003; Pozo-Bayón, Pueyo, Martín- Alvarez, Martínez-Rodríguez, & Polo, 2003). During the autolysis process, yeasts release different compounds into the extracellular medium that enhance the sensorial characteristics of the final products (Feuillat & Charpentier, 1982; Fornairon-Bonnefond, Camarasa, Moutounet, & Salmón, 2002; Leroy, Charpentier, Duteurtre, Feuillat, & Charpentier, 1990). The main changes consist of variations in polysaccharides, the nitrogen fraction and aromatic compounds (Fleet, 2003; Lubbers, Dibourdier, & Villetaz, 1994; Lubbers, Voiley, Charpentier, & Feuillat, 1993; Martínez- Rodríguez, Carrascosa, Martín- Alvarez, Moreno-Arribas, & Polo, 2002; Moreno-Arribas, Pueyo, Nieto, Martín-Alvarez, & Polo, 2000; Moreno-Arribas, Pueyo, & Polo, 1996). In this respect, some authors have studied the influence of several /$34.00 Ó 2008 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved. doi: /j.lwt

3 R.R. Madrera et al. / LWT - Food Science and Technology 41 (2008) 2064e factors influencing the presence of volatiles in Spanish sparkling wines (Francioli, Guerra, López-Tamames, Guadayo, & Caixach, 1999; Francioli, Torrens, Riu-Aumatell, López- Tamames, & Buxaderas, 2003; Hidalgo et al, 2004; Pozo- Bayón et al., 2003; Riu-Aumatell, Bosch-Fusté, López-Tamames, & Buxaderas, 2006; Ubeda & Briones, 2000). The relationships between analytical foam parameters, sensory assessment and the chemical composition of sparkling ciders have been analyzed. Foamability and foam stability time have been found to be significantly influenced by yeast strain and aging time, while sensory attributes improved with maturation time (Picinelli Lobo, Fernandez Tascon, Rodriguez Madrera, & Suarez Valles, 2005). Likewise, the amino acid composition of sparkling ciders has been studied as a function of two factors: the second fermentation yeast strain and aging time in the bottle (Suárez Valles, Palacios Garcia, Rodriguez Madrera, & Picinelli Lobo, 2005). To the best of our knowledge, however, there is no information available on the changes in volatile composition that occur during yeast autolysis in the making of sparkling cider by the traditional method. In the present study, two sparkling ciders were made from the same base cider using two different yeast strains under industrial conditions. The aim of the present research work was to study the influence of the yeast strain and aging time on the evolution of volatile compounds in sparkling cider. 2. Materials and methods 2.1. Cider making Apple juice was obtained using an automatic hydraulic Bucher-Guyer press from a mixture of apples belonging to the Denominación de Origen Sidra de Asturias. The apple juice (20,000 L) was fermented in a steel tank in the El Gaitero S.A. cellars. After spontaneous alcoholic and malolactic fermentations, the base cider was run off from the lees, matured two months and finally clarified and sterilized by cross-flow filtration using 0.22 mm ceramic membranes from Millipore (Bedford, MA). Sparkling ciders were made from the same base cider according to the traditional method. The base cider had an alcoholic proof of 5.9% (v/v), 1.05 g/l acetic acid volatile acidity, 3.25 g/l sulfuric acid total acidity, ph 3.74, dry extract 23 g/l and free and total sulfur dioxide contents of <10 and 60 mg/l, respectively. Sucrose (20 g/l) and bentonite (3 g/hl) were added to the base cider prior to inoculation with the selected yeasts ( cfu/ml). One half was inoculated with a local cider strain from the Region of Asturias (C6, Saccharomyces bayanus), belonging to the SERIDA collection of pure cultures and the other half was inoculated with a commercial yeast (Levuline CHP, Oeno France, France) recommended for sparkling wine making (Saccharomyces cerevisiae). The inoculated ciders were bottled and left in a horizontal position at 13e15 C. The second fermentation finished in 21 days, reaching a final pressure in the bottle of 7 bars. Once this process had finished, the maturation of ciders on lees for 15 months started. Sampling was every 3 months until disgorgement at 15 months. The final product was obtained by restoring the lost volume with the same cider Reagents and standards Standards used were of analytical quality, of at least 97% purity and were purchased from Sigma-Fluka-Aldrich (Madrid, Spain), Merck (Darmstadt, Germany) and Panreac (Barcelona, Spain). The standard working solutions were prepared by dilution of individual compounds in an ethanol/water mixture (5/95). Ethanol (HPLC quality) was purchased from Panreac (Barcelona, Spain) and ultra pure water was obtained from a Milli-Q system from Millipore (Milford, MA, USA). All standards were injected in triplicate Chromatographic analysis Major volatile compounds Acetaldehyde, ethyl acetate, methanol, 1-propanol, 2- methyl-1-propanol (isobutanol), 1-butanol, amyl alcohols (2- methyl-1-butanol þ 3-methyl-1-butanol), 3-hydroxybutanone (acetoin), ethyl lactate and 2-phenylethanol were analyzed on a Hewlett-Packard model 5890 series II gas chromatograph (Agilent Technologies, PaloAlto, CA, USA) equipped with a flame ionization detector (FID) and an FFAP semicapillary column ( mm i.d.; phase thickness, 1.0 mm) supplied by Tecknokroma (Barcelona, Spain). Injection was carried out in splitless mode (1 min) employing helium as carrier gas at 10 ml/min. The temperature gradient was as follow: 40 C isotherm for 5 min, followed by a linear increase of 4 C/ min until 60 C. This temperature was then raised to 220 C at a rate of 10 C/min. Injector and detector temperatures were 240 C and 275 C, respectively. The microfiltered samples were directly injected into the chromatograph (1 ml). Samples were analyzed in duplicate Minor volatile compounds Methyl acetate, 3-methyl-1-butyl acetate (isoamyl acetate), hexyl acetate, ethyl butyrate, ethyl 3-methylbutyrate, ethyl hexanoate and ethyl octanoate were analyzed by gas chromatography and the purge and trap technique, as described by Rodriguez Madrera, Palacios García, García Hevia, and Suárez Valles (2005). A Tekmar 3100 Purge and Trap Concentrator equipment provided with a Teklink 3000 software (version 2.02) to control the headspace sampling was used. The trap employed was a Tenax (polymer of 2,6-diphenyl-pphenylene oxide) supplied by Agilent Technologies (Palo Alto, CA, USA). Five milliliters of sample were introduced into the vessel and purged at 20 C during 30 min with helium at 50 ml/min. The trap was at room temperature while purging and then risen up to 230 C for desorption during 10 min. A bake time of 20 min (230 C) was established for cleaning up the trap between analyses. The transfer line temperature was 300 C. The separations were carried out on a FFAP capillary column ( mm i.d.; phase thickness,

4 2066 R.R. Madrera et al. / LWT - Food Science and Technology 41 (2008) 2064e mm) supplied from Tecknokroma (Barcelona, Spain). Chromatographic conditions were as follows: oven temperature, initial isotherm at 40 C (5 min), raised up to 220 Cat a rate of 3.0 C/min, and final isotherm of 220 C (5 min); injector and detector temperature 250 C; carrier gas, He at 1.5 ml/min; injection volume 1 ml. Split ratio 1/10. Samples were analyzed in duplicate Statistical analysis Two-way analysis of variance (ANOVA) was performed to detect significant differences in the analyte concentrations depending on the main factors studied (aging time and yeast strain), the interaction and the within error terms being pooled. Furthermore, when differences were statistically significant for aging, Duncan s test for mean comparisons was used. SPSS for Windows (version 11.5) was used for data processing. 3. Results and discussion Table 1 summarizes the concentrations of major and minor volatile compounds in sparkling ciders according to yeast strains and aging time. Results from two-way ANOVA and Duncan s test are also shown in Table 1. The results obtained revealed that the concentration of methanol and 1-propanol was only significantly influenced by yeast strain, whereas 1-butanol, ethyl butyrate and hexyl Table 1 Volatile compounds in sparkling ciders and results of the two-way ANOVA and Duncan s test a Factor effect Aging time (months) Time Yeast Acetaldehyde b *** ns Levuline 26.41bc 27.26c 25.02b 25.5b 21.15a C c 26.95c 24.46b 24.35b 23.54a Ethyl acetate b *** ns Levuline 71.8a 72.03a 82.16c 75.91b d C a 75.01b 76.08bc 79.52c d Methanol b ns *** Levuline C propanol b ns *** Levuline C methyl-1-propanol b * ns Levuline 49.37a 48.84a 49.52a 48.64a 54.12b C a 47.91a 47.84a 48.22a 53.19b 1-butanol b ns ns Levuline C Amyl alcohols b *** ns Levuline ab ab b a c C a a a a b Acetoin b *** ** Levuline 7.02bc 7.15c 6.65b 7bc 3.93a C6 7.74c 6.76b 6.83b 7.5c 4.3a Ethyl lactate b *** ** Levuline a ab 199.2b c d C a ab b c d 2-phenylethanol b * * Levuline 49.35ab 42.7a 44.52ab 41.05a 52.44b C a 48.62a 48.15a 48.11a 59.64b Methyl acetate c * * Levuline b a b b ab C d a b d c Ethyl butyrate c ns ns Levuline C Ethyl 3-methylbutyrate c ** ** Levuline 84.37c 66.36a 75.35b 73.75b 76.18b C c 63.1a 69.18b 68.22ab 72.23bc 3-Methylbutyl acetate c * ns Levuline c 647.2b ab b b C b a 739.8a a 720.4a Ethyl hexanoate c * ns Levuline c a 298.6b a ab C6 318b a ab 264.1a ab Hexyl acetate c ns ns Levuline C Ethyl octanoate c *** ns Levuline a a a b c C bc 151.8a ab bc c *: Significant at the 0.1 significance level; **: significant at the 0.05 confidence level; ***: significant at the 0.01 significance level. a Results are the mean of two determinations. Mean values with different letters indicate significant differences at the 5% significance level. b expressed in mg/l. c expressed in mg/l.

5 R.R. Madrera et al. / LWT - Food Science and Technology 41 (2008) 2064e acetate were not influenced by either of the two factors considered. In this respect, some authors reported these compounds as typical aromas in apple juice and apples (Brown, Buchanan, & Hicks, 1996; López, Lavilla, Recasens, Riba, & Vendrell, 1998; Su & Wiley, 1998). Methanol is cleaved from pectins and its concentrations depend on several factors such as raw material (varieties, ripening) and enological practices. However, significant differences were detected for the yeast strain factor in agreement with some reports (Cabranes, Mangas, & Blanco, 1997; Vilanova et al., 2000). This fact shows that the production of methanol is linked to the pectolytic activity of yeast. As regards 1-propanol, its mean content in the ciders made with the wine strain (Levuline) was mg/l, and mg/l in the ciders obtained with the cider strain. The aging time factor had a significant influence on acetaldehyde, ethyl acetate, isobutanol, amyl alcohols, isoamyl acetate, ethyl hexanoate and ethyl octanoate contents. Levels of isoamyl acetate, ethyl hexanoate and ethyl octanoate decreased after 3 months (Fig. 1a). This decrease is attributed to esterases released by the yeast into the liquid medium or the adsorption of esters to the yeast cell walls (Fraile, Garrilo, & Ancín, 2000; Lafon-Lafourcade, Geneix, & Ribéreau-Gayón, 1984). The levels of ethyl hexanoate and isoamyl acetate remain constant from 6 to 15 months, whereas the concentration of ethyl octanoate increased after the ninth month of aging in the bottle. Acetaldehyde and ethyl acetate evolved in opposing ways, showing significant differences. The former compound decreased throughout maturation time, while the latter seems to be formed during aging by esterification between acetic acid and ethanol (Fig. 1b). Amyl alcohols and isobutanol, on the other hand, showed a major increase (10e16%) after 12 months. This fact could be explained by the significant increase detected in the amino acid contents in the sparkling ciders after 11 months in the bottle (Suárez Valles et al., 2005). The levels of acetoin, ethyl lactate, 2-phenylethanol, methyl acetate and ethyl 3-methylbutyrate were significantly influenced by the yeast strain used in the second fermentation and aging time in the bottle (Table 1). At 3 months, the selected cider yeast (C6) produced higher concentrations of acetoin, ethyl lactate and 2-phenylethanol than the wine yeast (Levuline). Likewise, an increase in ethyl lactate, 2-phenylethanol, methyl acetate and ethyl 3-methylbutyrate were observed between 6 and 15 months, whereas acetoin decreased throughout the aging period. During alcoholic fermentation it is generally assumed that the yeasts of the genus Saccharomyces produce acetoin from non detectable amounts to 12 mg/l and that its contents decline presumably as a result of reduction to 2,3-butanediol (Romano & Suzzi, 1996; Suárez Valles, Pando Bedri~nana, Fernández Tascón, González García, & Rodríguez Madrera, 2005). The higher ethyl lactate and 2- phenylethanol contents found in the sparkling ciders made with the cider strain (S. bayanus) are in good agreement with previous reports (Antonelli, Castellari, Zambonelli, & a concentration (mg/l) b concentration (mg/l) Aging time (months) Isoamyl acetate (Levuline) Isoamyl acetate (C6) Ethyl hexanoate (Levuline) Ethyl hexanoate (C6) Ethyl octanoate (Levuline) Ethyl octanoate (C6) Acetaldehyde (Levuline) Acetaldehyde (C6) Ethyl acetate (Levuline) Ethyl acetate (C6) Isobutanol (Levuline) Isobutanol (C6) Amyl alcohols (Levuline) Amyl alcohols (C6) Aging time (months) Fig. 1. Evolution of (a) minor and (b) major volatile compounds during aging of sparkling ciders made with Levuline (wine commercial yeast) and C6 (cider selected yeast) strains.

6 2068 R.R. Madrera et al. / LWT - Food Science and Technology 41 (2008) 2064e2069 Canacini, 1999; Masneuf, Hansen, Groth, Piskur, & Dubourdieu, 1998; Querol, Fernández-Espinar, del Olmo, & Barrio, 2003). In general terms, the changes in the contents of the volatile compounds analyzed in these ciders during aging with yeast were similar to those observed in sparkling wines aged 9 months after tirage (Hidalgo et al, 2004). In disagreement with a previous report (Pozo-Bayón et al, 2003), the results showed that both aging time and yeast strain have a major influence on the volatile composition of sparkling ciders. A greater increase in the concentration of some compounds in ciders occurred near the end of the sampling period (15 months), being especially evident for higher alcohols, ethyl acetate, ethyl lactate and ethyl octanoate. The enrichment of ciders with ethyl octanoate is worth noting, which is in discrepancy with results reported elsewhere (Francioli et al, 1999, 2003). Yeast autolysis is a continuous and prolonged process and the results obtained could depend on the period of time studied and external factors, such as temperature and composition of the medium (Fornairon-Bonnefond et al., 2002). In this respect, the lower ethanol content in cider compared to wines could modify the simultaneous degradation and synthesis of volatile compounds (Migue-Gordillo, Iglesias, & Exposito, 1990). In summary, both of the factors studied, yeast strain and aging time, affected the concentration of volatile compounds in cider through distinct synthesis and degradation routes. Furthermore, the differences with regards to other bibliographical data could be explained on the basis of different enological practices. Acknowledgements We thank the CICYT for funding this project (CICYT- AGL ) and the enterprise El Gaitero, S.A. (Villaviciosa, Asturias) for financial support for this work and for N.P.G. 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