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Characterisation of single-variety still ciders produced with dessert apples in the Italian Alps

2018; Wiley; Volume: 124; Issue: 4 Linguagem: Inglês

10.1002/jib.510

2050-0416

Giorgio Nicolini, Tomás Román, Silvia Carlin, M. Malacarne, Tiziana Nardin, Daniela Bertoldi, Roberto Larcher,

Biochemical and biochemical processes

Journal of the Institute of BrewingVolume 124, Issue 4 p. 457-466 Research articleFree Access Characterisation of single-variety still ciders produced with dessert apples in the Italian Alps Giorgio Nicolini, Giorgio Nicolini Fondazione Edmund Mach, Via E. Mach 1, 38010 San Michele all'Adige (TN), ItalySearch for more papers by this authorTomás Román, Corresponding Author Tomás Román tomas.roman@fmach.it orcid.org/0000-0002-4403-059X Fondazione Edmund Mach, Via E. Mach 1, 38010 San Michele all'Adige (TN), ItalyCorrespondence to: Tomás Román, Fondazione Edmund Mach, Via E. Mach 1, 38010 San Michele all'Adige (TN), Italy. E-mail: tomas.roman@fmach.itSearch for more papers by this authorSilvia Carlin, Silvia Carlin Fondazione Edmund Mach, Via E. Mach 1, 38010 San Michele all'Adige (TN), ItalySearch for more papers by this authorMario Malacarne, Mario Malacarne Fondazione Edmund Mach, Via E. Mach 1, 38010 San Michele all'Adige (TN), ItalySearch for more papers by this authorTiziana Nardin, Tiziana Nardin Fondazione Edmund Mach, Via E. Mach 1, 38010 San Michele all'Adige (TN), ItalySearch for more papers by this authorDaniela Bertoldi, Daniela Bertoldi Fondazione Edmund Mach, Via E. Mach 1, 38010 San Michele all'Adige (TN), ItalySearch for more papers by this authorRoberto Larcher, Roberto Larcher Fondazione Edmund Mach, Via E. Mach 1, 38010 San Michele all'Adige (TN), ItalySearch for more papers by this author Giorgio Nicolini, Giorgio Nicolini Fondazione Edmund Mach, Via E. Mach 1, 38010 San Michele all'Adige (TN), ItalySearch for more papers by this authorTomás Román, Corresponding Author Tomás Román tomas.roman@fmach.it orcid.org/0000-0002-4403-059X Fondazione Edmund Mach, Via E. Mach 1, 38010 San Michele all'Adige (TN), ItalyCorrespondence to: Tomás Román, Fondazione Edmund Mach, Via E. Mach 1, 38010 San Michele all'Adige (TN), Italy. E-mail: tomas.roman@fmach.itSearch for more papers by this authorSilvia Carlin, Silvia Carlin Fondazione Edmund Mach, Via E. Mach 1, 38010 San Michele all'Adige (TN), ItalySearch for more papers by this authorMario Malacarne, Mario Malacarne Fondazione Edmund Mach, Via E. Mach 1, 38010 San Michele all'Adige (TN), ItalySearch for more papers by this authorTiziana Nardin, Tiziana Nardin Fondazione Edmund Mach, Via E. Mach 1, 38010 San Michele all'Adige (TN), ItalySearch for more papers by this authorDaniela Bertoldi, Daniela Bertoldi Fondazione Edmund Mach, Via E. Mach 1, 38010 San Michele all'Adige (TN), ItalySearch for more papers by this authorRoberto Larcher, Roberto Larcher Fondazione Edmund Mach, Via E. Mach 1, 38010 San Michele all'Adige (TN), ItalySearch for more papers by this author First published: 08 August 2018 https://doi.org/10.1002/jib.510Citations: 14AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Abstract Apple cider is a traditional beverage in the Italian Alps, but little is reported about is composition. Accordingly, ciders produced with Golden Lasa, Braeburn, Granny Smith, Fuji, Reinette Champagne and Reinette Canada dessert apples were obtained on a semi-industrial scale using various fermentation options and Saccharomyces cerevisiae strains. A spectrum of compounds was analysed to better characterise the product: phosphate, chloride, nitrate, sulphate, total phenols, 52 mineral elements and 16 volatile compounds. Tristimulus chromatic parameters were measured before and after accelerated ageing and correlated with total phenol concentration. The elemental composition was compared with that of French ciders, revealing significant differences. Yeast related differences were found for several aroma compounds and 4-ethylcatechol. Apple variety and processing contributed to the differences in methanol content. This work provides the first compositional data of Italian Alps ciders. © 2018 The Institute of Brewing & Distilling Introduction In the context of alcoholic beverages made from fruits other than grapes, apple cider has a leading position worldwide and has seen increasing demand in non-traditional countries, as well as in the Far East 1. Italian cider has also experienced commercial growth with sales rising to 33,000 L in 2016 and an expected volume of 43,000 L by 2021 2. Indeed, numerous producers are exploring ancient traditions and fermentation procedures for the production of cider 3-5. Traditionally, apple cider production and consumption were based in northern areas of Europe and America where the Vitis vinifera wine grape was unlikely to grow. This fermentative transformation of the apple was, a means of obtaining an alcoholic beverage for drinking or calvados distillation, and also making use of apples with sub-optimal compositional and microbiology for direct consumption. The traditional classification of varieties into cider apples and dessert apples is largely based on the higher acidity of the former. Nevertheless, sweeter dessert apples can also be used to produce cider. However they are harvested from the tree and not from the ground, and are in optimal condition in terms of soundness and microbiological quality 6. Further these apples have lower levels of toxins, e.g. patuline 7, minimising problems in terms of dessert apple production 8. The literature includes reports regarding dessert varieties used for cider making, including Fuji apples 8-10, Ralls 11, Lietuvas Pepins, Auksis, Remo, Merry Gold and others 12, 13, Crispin and McIntosh 14 and Šampion, Idared and Gloster 15. Even though cider production is traditional in the coldest areas of the Italian Alps, there are few reports of the composition of this beverage. Accordingly the aim of this work was to investigate a spectrum of chemical characteristics of single-variety still apple ciders produced on semi-industrial scale with different dessert cultivars, focussing on basic composition, inorganic anions, mineral elements, total phenols, colour and aroma compounds. Materials and methods Apple cultivars and processing Fresh sound apples of six dessert varieties cultivated in the Trentino Alto Adige region (North Eastern Italy) were used: Golden Lasa, Braeburn, Granny Smith, Fuji and Reinette de Champagne, grown in a single plot in the Adige Valley, and Reinette du Canada from the Non Valley. Golden Lasa, Braeburn, Granny Smith and Fuji were processed in triplicate according to the following semi-industrial scale process, similar to that used for clear fruit juice fermentation (referred to as white-processed). Milling and supplementation with 30 mg/kg sulphur dioxide and 30 mg/kg ascorbic acid, addition of 20 mg/kg pectolytic enzyme (Novoclairzym; Novo Nordisk A/S, Bagsværd, Kobenhavn, Denmark). Maceration (15 h at 12°C) with pressing, settling (24 h at 4°C) and devatting. Clear juice fermentation was conducted by separately adding three Saccharomyces cerevisiae yeast strains: Fermicru LS2 (Oenobrands SAS, Montferrier-sur-Lez, France), Zymaflore VL1 (Laffort Oenologie, Bordeaux, France) and RM1515 (E. Mach Foundation collection) known to be a high vinylphenol producer 16. All were inoculated at 5 ×106 cells/mL. The juice was fermented to dryness in demijohn at 18–20°C – appropriate for apple juice fermentation 17 – without any assimilable nitrogen supplementation; the cider was devatted, sulphited, stored cold (3°C × 4 months) to avoid malolactic fermentation, and bottled after sterile filtration (0.45 μm). Reinette du Canada and Reinette de Champagne ciders were fermented according to the above protocol but using only the LS2 yeast strain. In addition, one cider was produced by fermenting a Golden Lasa apple mash in a similar way to the production of fruit wine in presence of pomaces (referred to as red-processed), and a mix of nearly exhausted pomace of all the varieties (coded ‘mix’) was also fermented with the sameprocess, using the LS2 yeast strain for both. Yeast inoculum and supplementations were as described above. After send days contact with pomace together with submerging the mash cap twice a day, at 18–25°C before pressing and the cider was settled, devatted, supplemented and treated as in the white-processed cider. Chemical analysis Basic composition Soluble solids (°Brix), titratable acidity (g/L, as malic acid), pH, alcohol (% vol), reducing sugars after inversion (g/L), volatile acidity (g/L, as acetic acid), free and total sulphur dioxide (mg/L) and citric acid (mg/L) were measured according to the International Organization of Vine and Wine (OIV) 18. Assimilable nitrogen was calculated as the sum of ammonia nitrogen and alpha nitrogen of each amino acid, measured using ion exchange chromatography 19. Lactic acid (g/L) was analysed using HPLC on a Waters LC1 module (Millford, MA, USA), equipped with a UV–vis detector at 210 nm and an Aminex HPX-87H column (300 × 7.8 mm) from Bio-Rad (Hercules, CA, USA), maintained at 65°C; the eluent was H2SO4 (4 mM). Sulphate (expressed as K2SO4, mg/L), chloride (NaCl, mg/L), phosphate (PO43−, mg/L), nitrate (NO3−, mg/L) and malic acid (g/L) concentrations were measured using ionic chromatography 20, after sample filtration (0.22 μm). A DX-120 chromatograph working in suppressed ion conductivity was used, controlled by Peaknet software 5.1 and equipped with PAX-100 column, AG 10 pre-column and AS 40 autosampler (Dionex, Sunnyvale, CA, USA). Polyphenols and colour Total phenols [mg/L, (+) catechin] were determined according to Di Stefano and Guidoni 21, after separation through a Sep-Pak C18 cartridge. Colour as absorbance at 420 nm was measured one month after bottling, and again after accelerated oxidative ageing 22. Colour was also assessed using tristimulus L*C*h colour space, using a CT 310 Chroma Meter (Minolta, Osaka, Japan), a 20 mm optical path length cell and the ‘Standard C’ light source 23. Mineral elements Elemental analysis was performed in the ciders from Trentino, with the exception of the Reinette Canada sample, and in 10 French commercial ciders from Brittany, Normandy and Cornwall available on the market in Bordeaux. The concentrations of 22 elements (Al, As, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, Sn, Sr, V, Rb and Zn) were measured using inductively coupled plasma–optical emission spectrometry (ICP-OES), while that of further 30 elements (Ag, Au, Be, Cd, Ce, Cs, Dy, Er, Eu, Ga, Gd, Hf, Ho, Ir, La, Lu, Nd, Pb, Pr, Pt, Ru, Sb, Sm, Te, Th, Tl, Tm, U, Y, Yb) was determined with ICP–mass spectrometry (MS). For ICP-OES analysis, an Optima 3300 Dual View optical spectrometer was used, equipped with cyclonic spray chamber and AS90 autosampler, controlled by ICP WinLab 1.42 software (Perkin Elmer, Norwalk, CT, USA). The operating conditions are reported in Larcher and Nicolini 24. Single element and multi-element standards were purchased from Merck (Darmstadt, Germany), with the exception of Sn, which was purchased from Baker (Deventer, The Netherlands). In order to correct matrix effects and drift, yttrium (100 μg/L; Merck) was used as internal standard. For ICP-MS analysis, a HP 4500 mass spectrometer (Hewlett-Packard, Corvallis, OR, USA) was used, equipped with Fassel torch, Babington nebulizer, Scott-type spray chamber, ASX 500 autosampler (CETAC Technologies Inc., Omaha, NB, USA) and HP-4500 Chemstation software. Cider (5 mL) was added to 0.1 mL of ‘Suprapure’ nitric acid (68%; Carlo Erba Reagenti, Rodano, Italy) and Milli-Q water to arrive at a final volume of 10 mL. In order to correct drift and matrix effects, a solution of Sc, Rh and Tb was used as internal standard (Plasma Emission Standard ICP; Aristar, BDH Laboratory Supplies, Lutterworth, UK). Three multi-element calibration standards from Agilent Technologies and one from Aristar (ICP-MS Calibration Standard 4) were used in various concentrations for external quantification. Further details are reported in Nicolini et al. 25. Aroma volatiles Methanol, higher alcohols, acetaldehyde and ethyl acetate were analysed using a GC/FID with Carbopack C packed column 26, 27. Hexanol and the main aroma compounds, responsible for fruity and floral notes, were analysed using GC/MS after headspace solid-phase microextraction (HS-SPME). HS-SPME was carried out following a previous method 28, with minor modifications. Cider (5 mL) was added to a 20 mL glass headspace vial, together with 1.5 g sodium chloride, spiked with 50 μL of alcoholic solution of 2-octanol at 2.13 mg/L, and stirred in a water bath (10 min at 30°C). A polydimethylsiloxane-coated fibre (100 μm; Supelco, Bellafonte, PA, USA) was placed in the sample headspace and stirred (40 min), before insertion for gas chromatographic analysis. This was done using an Autosystem XL single quadrupole gas chromatograph, coupled with a Turbo-Mass Gold mass spectrometer (Perkin Elmer, Boston, MA, USA) equipped with an INNOWax (PEG) fused-silica capillary column (30 m length, 0.25 mm internal diameter, 0.25 μm film thickness; Agilent Technologies, Palo Alto, CA, USA). Helium was used as the carrier gas at a flow rate of 1.2 mL/min. The temperature of the transfer line was 220°C. The electron energy was 70 eV, and the source temperature 150°C. All the tests were carried out in full scan mode. Quantification of the aroma compounds was using 2-octanol as internal standard. Relative peak areas to 2-octanol for each standard were plotted against the actual concentration to obtain standard curves 29. Ethyl and vinyl phenols were analysed using high-performance liquid chromatography–coulometric electrochemical array detection (HPLC-ECD) according to Larcher et al. 30. Statistical analysis The following STATISTICA v. 8.0 (StatSoft Inc., Tulsa, OK) procedures were used: Anova, Tukey's HSD test, and the Mann–Whitney U-test. Results and discussion Juice composition The basic composition of the six single variety juices is shown in Table 1. Varietal differences in total acidity and pH were of significance owing to their higher pH, Granny Smith and Fuji in particular could be at higher risk of contamination by wild yeasts and bacteria, both during fermentation and after bottling. Yeast assimilable nitrogen (YAN) values were at three levels: the highest were Golden Lasa, Reinette du Canada and Reinette de Champagne; Braeburn in the middle; and the lowest with Granny Smith and Fuji. In contrast to YAN in grape juice 31, the lowest YAN values in these apple juices is adequate for fermentation. Indeed, assimilable nitrogen of 140–150 mg/L for Saccharomyces has been defined for grape juice 32-34, whereas 70 and 120 mg/L are sufficient for apple juice fermentation 35, 36. Nevertheless, with poor nitrogen availability, there is the risk of higher production of sulphur compounds responsible for off-odours such as hydrogen sulphide 37, 38 and 3-methylthio-1-propanol 39, 40, even though for the latter that ranges from 200 to 3000 μg/L 10, 41 in cider. A different correlation with YAN has been reported in skin-contact fermentations 42. Table 1. Basic composition of juice Braeburn Granny Smith Fuji Golden Lasa Reinette Champagne Reinette Canada Soluble solids (°Brix) 13.3 12.6 13.5 12.1 11.8 14.2 pH 3.28 3.53 3.59 3.17 3.04 3.19 Titratable acidity (g/L) 5.72 4.56 3.13 6.88 8.13 7.41 Reducing sugars after inversion (g/L) 117 102 125 99 106 119 Yeast assimilable nitrogen (mg/L) 123 67 70 195 187 190 Basic composition of ciders Still cider composition is shown in Table 2. As a consequence of the grape wine-like protocol, here fermentation time (7–10 days) was shorter than reported by Villière et al. 43, from about 30 to 280 days. The alcohol content ranged between 5.92 and 7.68% abv while the residual sugar was between 1.8 and 5.6 g/L, a range included in the ‘dry’ category as applied to sparkling wine 44. The pH values ranged between 3.11 and 3.61, the highest belonging to Fuji and Golden Lasa, while the red-processed products had intermediate values. The overall microbiological management of fermentation was satisfactory, as proved by the low volatile acidity values, with the exception of one sample (red-fermented Golden Lasa), and by the low concentration of lactic acid (≤0.20 mg/L) in all white-processed ciders, while red processing increased lactic acid production. Citric acid, which increases during fermentation 45, 46, was higher in white-processed ciders, as is common in white wine 47 compared with unsupplemented red wine, in which citric acid is usually metabolised by lactic bacteria 48. Table 2. Basic parameters and concentration of organic acids and inorganic anions in ciders Apple variety Braeburn Granny Smith Fuji Golden Lasa Golden Lasa Reinette Champagne Reinette Canada Mix Processing white white white white red white white red No. of samples 3 3 3 3 1 1 1 1 Alcohol (% vol) 7.32 6.53 7.68 6.44 6.54 5.92 6.38 6.82 Reducing (g/L) 2.3 1.8 1.9 2.7 4.2 1.9 1.9 5.6 pH 3.38 3.33 3.61 3.47 3.37 3.11 3.19 3.3 Titratable acidity (g/L) 6.43 7.26 4.26 5.83 6.97 8.67 8.67 6.43 Volatile acidity (g/L) 0.11 0.10 0.15 0.10 0.94 0.07 0.10 0.13 Free SO2 (mg/L) 15 15 13 9 17 14 15 15 Total SO2 (mg/L) 126 121 112 112 109 111 110 106 Citric acid (mg/L) 150 140 129 107 80 80 100 69 Lactic acid (g/L) 0.11 0.10 0.09 0.08 2.14 0.07 0.20 0.66 Malic acid (g/L) 4.94 5.10 5.26 5.63 1.89 6.71 5.81 3.29 Chloride (mg/L, NaCl) 21.3 23.8 26.0 30.9 466 45.7 91.9 319 Phosphate (mg/L, PO43−) 119 103 87 76 190 101 334 97 Nitrate (mg/L, NO3−) 6.8 6.8 5.6 5.8 5.5 3.7 5.0 8.1 Sulphate (mg/L, K2SO4) 144 146 145 149 109 215 251 121 As regards inorganic anions, chloride was markedly different in white- and red-processed ciders, ranging from 21.3 to 91.9 and from 319 to 466 mg/L, respectively. Nitrate ranged from 3.7 to 8.1 mg/L and sulphate from 109 to 251 mg/L. As regards phosphate concentration, this ranged from 76 to 190 mg/L in the ciders obtained from apples cultivated in the Adige Valley, with the highest value for red-processed cider. The maximum concentration (334 mg/L) was observed in white-processed Reinette Canada sampled in the Non Valley, suggesting the possible involvement of soil and/or manure treatments. The highest anionic concentration observed – in particular in the case of chloride – for red-processed ciders compared with white cider agrees with the results observed in grape must and wine from Trentino 20. To the best of our knowledge, data are not available in the literature regarding the inorganic anion composition of unsupplemented apple cider. Phenols and colour The total phenols in bottled cider (Fig. 1) ranged approximately from 200 to 500 mg/L, with Fuji, Braeburn, Golden Lasa, Reinette de Champagne, Granny Smith and Reinette du Canada in order of increasing concentration. This ranking agrees with that measured in apple extracts by Vrhovsek et al. 49 for fruit collected in the same geographical area used in this study. As expected, the presence of pulp in the case of red-processed Golden Lasa caused an increase in total phenols (+36.5%) compared with cider obtained from clear juice of the same variety. The phenol content in the Reinette du Canada white-processed cider is similar to that of the red-processed Golden Lasa cider, confirming the phenol richness of the first variety. Figure 1Open in figure viewerPowerPoint Mean, maximum and minimum values for total phenols (a) and colour (b; 1 cm optical path length) in white- (left) and red-processed (right) bottled cider (G, Golden Lasa; R., Reinette; Champ., Champagne; mix, blended pomace of different varieties). Colour at 420 nm, measured a few days after bottling in order to permit stabilisation of the final SO2 supplementation, ranged between 0.090 and 0.169 without any apparent relationship with total phenol content. Some white-processed cider – i.e. Reinette du Canada, Golden Lasa and Fuji – showed a colour intensity within the range for red-processed cider whereas closer correlations of chromatic parameters with total phenols, all with R2 values >0.70, appeared after the accelerated ageing (Fig. 2). These ageing conditions resulted in increasing absorbance at 420 nm, in agreement with higher phenol content, indicating a shift towards a deeper yellow colour; moreover, it resulted in a marked drop in luminance, and a shift in hue and chroma towards a more saturated yellow-reddish colour. Figure 2Open in figure viewerPowerPoint Correlation of chromatic parameters with total phenols in cider shortly after bottling (control) and accelerated ageing. [Colour figure can be viewed at wileyonlinelibrary.com] Mineral elements The concentration of 26 elements (Al, B, Ba, Ca, Ce, Cr, Cs, Cu, Fe, Ga, K, La, Li, Mg, Mn, Na, Ni, Pb, Rb, Sb, Sn, Sr, Tl, U, Y and Zn) was above the respective limits of quantification (LOQ) in all of the 25 ciders analysed (Table 3). Considering the usually non-normal concentration of most elements and the unequal number of samples from Trentino (N = 15) and France (N = 10), a non-parametric statistical approach was used 50 to evaluate possible differences between geographical origin. According to the Mann–Whitney U-test, the experimental ciders from Trentino had significantly lower concentrations of Al, Ca, Ce, Cr, Fe, La, Li, Mn, Na, Ni, Sr and Y, but higher concentrations of B, K, Mg, Pb, Sn, Tl and Zn. Besides the natural contribution of soil and dust deposited on the apple skin, the higher concentrations of B, Pb, Sn and Zn in experimental ciders could be linked to the absence of any apple washing treatment and supplementation with adsorbent agents for settling and stabilisation 51-53; other reasons are likely to be pesticides or boron containing leaf treatments to encourage pollination applied to dessert apples. In all cases, the concentration of each element was far below the limit set for ciders 54, 55. No significant differences relating to yeast strain were found as regards the final elemental concentration using Anova and Tukey's test. Table 3. Mineral element composition in cider and significance in the Mann–Witney U-test ICP LOQ Trentino (N = 15) France (N = 10) U-test technique (μg/L) min median max min median max p-level Aluminium Al (mg/L) OES 0.004 0.153 0.252 0.787 0.208 0.494 1.030 ** Boron B (mg/L) OES 0.05 2.02 3.28 4.31 1.71 1.92 2.50 *** Barium Ba (mg/L) OES 0.017 0.05 0.07 0.43 0.01 0.03 0.20 n.s. Calcium Ca (mg/L) OES 0.065 38.2 46.5 72.5 41.3 105.1 161.0 ** Cerium Ce (μg/L) MS 0.06 0.18 0.27 1.12 0.16 2.17 5.69 * Chromium Cr (μg/L) OES 0.6 9.90 11.10 12.70 4.70 15.75 29.80 * Cesium Cs (μg/L) MS 0.01 0.58 2.42 6.90 0.66 1.34 8.83 n.s. Copper Cu (mg/L) OES 0.002 0.04 0.09 0.52 0.03 0.06 0.11 n.s. Iron Fe (mg/L) OES 0.006 0.45 0.68 2.80 0.70 1.22 3.41 ** Gallium Ga (μg/L) MS 0.12 4.40 6.50 37.30 1.20 3.55 24.60 n.s. Potassium K (mg/L) OES 6 976 1150 1450 835 881 1160 *** Lanthanium La (μg/L) MS 0.02 0.03 0.07 0.47 0.05 1.04 2.71 ** Lithium Li (μg/L) OES 0.2 1.0 3.0 4.0 1.0 16.5 55.0 ** Magnesium Mg (mg/L) OES 0.04 33.8 43.7 65.9 24.8 30.2 32.5 *** Manganese Mn (mg/L) OES 0.001 0.120 0.243 0.418 0.171 0.350 0.557 * Sodium Na (mg/L) OES 0.09 2.44 3.66 4.69 11.8 33.1 233.0 *** Nickel Ni (μg/L) OES 4.8 4.8 7.0 9.0 6.0 9.0 12.0 ** Lead Pb (μg/L) MS 0.18 11.5 24.2 56.1 1.4 5.8 13.4 *** Rubidium Rb (mg/L) OES 0.003 0.74 3.09 7.14 1.40 1.67 5.62 n.s. Antimony Sb (μg/L) MS 0.24 0.40 0.60 0.90 0.24 0.55 1.30 n.s. Tin Sn (μg/L) OES 27.4 51.0 68.0 88.0 36.0 45.0 55.0 *** Strontium Sr (mg/L) OES 0.001 0.035 0.049 0.242 0.029 0.088 0.185 * Thallium Tl (μg/L) MS 0.10 0.10 0.30 0.70 0.10 0.10 0.20 ** Uranium U (μg/L) MS 0.02 0.02 0.10 0.60 0.02 0.25 0.80 n.s. Yttrium Y (μg/L) MS 0.02 0.06 0.12 1.46 0.19 0.92 1.98 ** Zinc Zn (mg/L) OES 0.001 0.037 0.313 0.767 0.026 0.040 0.106 ** p < * 0.05, ** 0.01 and *** 0.001. ICP, Inductively coupled plasma; OES, optical emission spectrometry; MS, mass spectrometry; n.s., not significant. Sixteen elements were found in some samples only (Table 4), generally with a higher frequency or concentration in French ciders. The main difference between geographical origins concerned vanadium whose concentration was about 30 times higher in French ciders. This could be related to differences in the two areas in terms of certain characteristics (in particular, organic matter and iron oxide soil content) and the parent material, for example the vanadium richer soil resulting from mafic rock and shale, as well as the amount and composition of phosphate fertilisers used. Moreover, pollution could contribute, for example through vanadium rich industrial waste from steelworks and coal and oil fuelled power stations, as well as magnetite and bauxite mining activities, in the light of the higher concentrations of iron and aluminium in French ciders 56, 57. Table 4. Concentration (μg/L) of mineral elements in cider ICP LOQ Trentino (N = 15) France (N = 10) technique (μg/L) N > LOQ median max N > LOQ median max Arsenic As OES 12 0 1 14 Beryllium Be MS 0.06 7 0.09 0.61 9 0.24 0.59 Cobalt Co OES 1.8 0 8 4.0 5.0 Dysprosium Dy MS 0.04 2 0.23 0.34 7 0.25 0.44 Erbium Er MS 0.04 1 0.15 0.15 7 0.13 0.24 Europium Eu MS 0.02 0 5 0.07 0.13 Gadolinium Gd MS 0.04 1 0.22 0.33 7 0.32 0.54 Hafnium Hf MS 0.15 2 0.80 1.40 4 0.5 0.8 Holmium Ho MS 0.04 0 3 0.07 0.08 Molybdenum Mo OES 3.4 7 4.0 5.0 4 6.5 10 Neodymium Nd MS 0.14 2 0.35 0.50 9 1.4 2.8 Praseodymium Pr MS 0.04 2 0.10 0.13 7 0.43 0.7 Samarium Sm MS 0.03 2 0.12 0.19 7 0.3 0.52 Thorium Th MS 0.6 1 1.0 1 1.0 Vanadium Va OES 0.8 2 4.5 6.0 8 123 179 Ytterbium Yb MS 0.06 1 0.10 5 0.1 0.3 It is noteworthy that arsenic was found in one sample. A similar level (15.3 μg/L) was found in commercial apple ciders sold in the USA 58. As arsenic concentration can decrease by about 75% during fermentation 59, it can be inferred that the juice's original concentration was about five times the limit (10 μg/L) that the US Food and Drug Administration 60 considers that can be achieved using good manufacturing practices to protect consumer health. The following elements were always found below the respective LOQ, reported in brackets: Ag (0.12 μg/L), Au (0.2 μg/L), Cd (0.2 μg/L), Ir (0.1 μg/L), Lu (0.05 μg/L), Pt (0.07 μg/L), Ru (0.12 μg/L), Te (0.05 μg/L) and Tm (0.03 μg/L). Volatile compounds Methanol, acetaldehyde, higher alcohols and esters The results of GC analysis of volatile compounds are shown in Table 5. The focus was on compounds responsible for well known sensory characteristics. The methanol concentration ranged from 219 to 810 mg/L, with an average level of 364 mg/L. The highest values were found in Reinette du Canada and in Golden Lasa ciders, particularly in the red-processed product, which almost doubled its methanol concentration as compared with the white-processed ones. These values are linked to the variety related pectin content and degree of methoxylation. Overall, the methanol concentration observed here was considerably higher than that measured – in the same winery and with the same devices – in 294 mono-variety red wines processed semi-industrially 61. In that survey, besides varietal differences, the overall mean of methanol in wine was 155 mg/L and no sample was above the OIV limit (300 mg/L) existing at that time for red wines, later set at 400 mg/L 62. Table 5. Volatile compounds in ciders produced with different apple varieties, yeast strains and processes Variety Fuji Braeburn Golden Lasa Granny Smith Reinette Champagne Reinette Canada Golden Lasa Yeast strain LS2 VL1 RM LS2 VL1 RM LS2 VL1 RM LS2 VL1 RM LS2 LS2 LS2 Processing W W W W W W W W W W W W W W R Methanol (mg/L) 225 227 219 256 238 255 443 447 468 394 372 372 292 440 810 Acetaldehyde (mg/L) 44 28 22 41 21 26 24 14 23 44 30 26 41 21 20 Higher alcohols 1-Hexanol (mg/L) 2.06 2.23 1.83 2.01 2.34 2.45 2.67 3.31 2.86 1.18 1.38 1.88 1.10 1.60 3.76 1-Propanol (mg/L) 29 20.5 18 29.5 19 19 71.5 39 38.5 20 13.5 12.5 19 56 65 2-Methyl-1-propanol (mg/L) 47 67 73 60 75 87 67.5 67 60 46.5 69 85.5 30.5 40.5 73 1-Butanol (mg/L) 12.5 13.5 12.5 9 8.5 9 18.5 19 20 1.5 1.5 1.5 19 4.5 20 2-Methyl-1-butanol (mg/L) 39 48 38.5 43 53 43 35.5 37.5 31.5 41.5 50 43.5 36 27.5 36.5 3-Methyl-1-butanol (mg/L) 174 207 152 196 233 190 140 144 112 190 217 190 141 130 129 2-Phenylethyl ethanol (mg/L) 27.7 20.5 21.7 19.4 19.3 21.5 16.2 18.8 13.1 13.0 17.8 30.8 4.6 55.0 15.0 Esters Ethyl acetate (mg/L) 12 10 14 9 15 11 5 13 15 5 5 9 10 5 106 Hexyl acetate (μg/L) 76 175 242 80 117 274 174 370 451 40 59 174 36 55 13 Isoamyl acetate (μg/L) 551 979 826 463 806 1188 610 1296 1359 79 350 724 161 540 255 2-Phenylethyl acetate (μg/L) 47 62 60 51 53 105 41 80 88 115 38 110 30 78 17 Ethyl hexanoate (μg/L) 144 137 97 102 92 118 93 106 136 37 66 98 90 78 86 Ethyl octanoate (μg/L) 199 267 159 136 180 166 132 224 149 67 96 144 103 100 147 Ethyl decanoate (μg/L) 60 46 48 44 57 38 10 44 30 19 14 27 38 8 13 W, Fermentation without pomace; R, fermentation with pomace; RM, RM1515 yeast strain. Overall, acetaldehyde averaged 28.1 mg/L, ranging from 13.5 to 43.5 mg/L. This compound plays a complex role in the sensory description of beverages 63 and is generally considered an off-flavour, reminiscent of green