Vine-Shoot Waste Aqueous Extracts for Re-use in Agriculture

Article pubs.acs.org/JAFC

Vine-Shoot Waste Aqueous Extracts for Re-use in Agriculture Obtained by Different Extraction Techniques: Phenolic, Volatile, and Mineral Compounds Rosario Sánchez-Gómez, Amaya Zalacain, Gonzalo L. Alonso, and M. Rosario Salinas* Cátedra de Quı ́mica Agrı ́cola, E.T.S.I. Agrónomos y Montes, Universidad de Castilla-La Mancha, E-02071 Albacete, Spain ABSTRACT: Vine-shoots are an important waste in all viticulture areas that should be re-used with innovative applications. The aim of this work was to produce Airén waste vine-shoot aqueous extracts by four solid−liquid extraction techniques such as conventional solid−liquid extraction (CSLE), solid−liquid dynamic extraction (SLDE-Naviglio), microwave extraction (ME), and pressurized solvent extraction (PSE). Their chemical composition was studied in terms of phenolic, volatile, and mineral compounds. The highest concentrated extracts corresponded to CSLE and SLDE-Naviglio, independent of the conditions tested. The CSLE extracts had the highest flavanols, phenolic acids, and stilbenes contents. The volatile composition, quantified for first time in this work, shows that furanic compounds were the most abundant. All extracts showed an interesting mineral content, which may be assimilated by plants. These results show the agricultural potential of Airén vine-shoot waste aqueous extracts to be used as grape biostimulants and/or foliar fertilizer. KEYWORDS: Airén vine-shoot wastes, aqueous extracts, minerals, phenolics, volatiles

■

INTRODUCTION

units (namely, trans-p-coumaroyl, coniferyl, and sinapyl units), characterized by a phenolic structure. The lignin degradation process releases phenolic compounds of low molecular weight, alcohols, aldehydes, ketones, or acids. The hydrolysis of carbohydrate derivatives together with their Maillard products may also release many furanic compounds. These are the main reasons most grape canes and vine-shoots have been characterized as a potential source of phenols, which may be summarized by the presence of an important stilbene fraction,11,12 phenolic acids, and flavanols.13,14 The aroma profiling of some vine-shoots was also studied by Delgado de la Torre et al.,15 although only at a qualitative level. Even with such interesting chemical characterization, vine-shoots are still left for degradation or burned, so different approaches should be sought. Recent studies have demonstrated that grapevines foliarly treated with aqueous oak extracts are able to modulate the phenolic and aroma composition of the grapes and their resulting wines.16−18 For this reason such extracts have been described as biostimulants.19 Similar grapevine applications could be tried with vine-shoot waste extracts, as both vegetable materials have a similar chemical composition. Vine-shoot mineral composition was evaluated by Ç etin et al.,14 in some Turkish cultivars, showing important concentrations of K, P, Ca, Fe, Mg, and Zn for use as food supplements. Vine-shoots from Spanish cultivars (La Rioja)10 showed that the most abundant minerals were N, S, Al, K, and Ca, suggesting that these residues could be used as fertilizers as such minerals are essential nutrients for plants. The qualitative and quantitative mineral content of vine-shoots are soil and

Optimization of food processing based on the reduction of wastes has become a mandatory standard within the most developed countries. The European Union in Directive 2008/ 98/EC1 stated that “waste prevention should be the first priority of waste management, and that re-use and material recycling should be preferred to energy recovery from waste”. According to the previous statement, one of the biggest challenges for wine-producing regions is to create alternatives for processing the vast amount of grape waste generated during harvest season. In Spain, viticulture is one of the most important agricultural activities as it is the country with the largest surface in the world dedicated to vineyards (approximately 1.1 million hectares). The Castilla-La Mancha region is the largest Spanish area (440,033 ha)2 and the most abundant Vitis vinifera cultivar is Airén, which represents 47% of this local vineyard with 209,035 ha.2 Innovative applications on grape waste skins re-use are already proposed.3,4 Another important grape waste is the vine-shoots, which average production was estimated at about 1,150,000 tons for 2013 in the Castilla-La Mancha region. Thus, the huge amount of vine-shoots produced every year has led to a growing interest in exploitation of this agricultural residue. Vine-shoots are traditionally left in the vineyard, sometimes used as organic fertilizer5 or as substrates for the mushroom industry.6 Recent research applications are related as a source for obtaining activated carbons for the wine industry,7 as a food additive,8 or even for the production of paper pulp.9 Their use based on its energy efficiency has also focused on obtaining solid biofuels.10 The composition of vine-shoots is characterized by two main fractions: holocellulose, the content of which is about 68%, and lignin, around 20%9 (dry weight). Lignin is a high molecular weight mass cross-linked polymer, which is built up by random oxidative coupling of three major C6−C3 phenylpropanoid © XXXX American Chemical Society

Received: August 18, 2014 Revised: October 15, 2014 Accepted: October 22, 2014

A

dx.doi.org/10.1021/jf503929v | J. Agric. Food Chem. XXXX, XXX, XXX−XXX

Journal of Agricultural and Food Chemistry

Article

at 100 °C. The extraction time was set at 15, 30, and 60 min (CSLE15, CSLE-30, and CSLE-60, respectively). SLDE-Naviglio. A dynamic solid−liquid extraction was carried out using a Naviglio Extractor (FT 110, Armfield, UK) following the Naviglio methodology.27 The Naviglio extraction is based on a suction effect generated by a compression of water, used as extracting solvent, on solids at room temperature (25−27 °C) and a pressure of 8 bar, followed by immediate decompression at atmospheric pressure. Two hundred grams of ground vine-shoot wastes was placed inside the extraction chamber, and 1.1 L of water was added as a solvent. The conditions tested for compound extraction were as follows: 20 extractive cycles of 6.5 min (5 min in the static phase and 1.5 min in the dynamic phase; SLDE-Naviglio-6.5), 8 min (5 min in the static phase and 3 min in the dynamic phase; SLDE-Naviglio-8), and 12 min (9 min in the static phase and 3 min in the dynamic phase; SLDENaviglio-12) each. ME. Microwave extraction was carried out with a NEOS apparatus (Milestone, Italy). Fifty grams of ground vine-shoot waste samples was placed into the reactor with 250 mL of water at 100 °C. The extraction program was set at 600 W (held for 5, 10, and 15 min; ME-5, ME-10, ME-15, respectively). A rotating microwave diffuser ensured homogeneous microwave distribution throughout the plasma-coated PTFE cavity. The temperature was monitored by an external IR sensor. PSE. Twenty grams of ground vine-shoot wastes was placed into each cell (four cells) with 100 mL of water and extracted using a pressurized extractor (Speed Extractor BUCHI E-914, Barcelona, Spain). The extractor parameters were set at temperature of 30 °C (T1) and 100 °C (T2), pressure of 50 bar (P1) and 100 bar (P2), three cycles (heat up, 1 min; hold (10, 15, 30 min), and discharge (9 min) named PSE-time, pressure, temperature (PSE-10P1T1, PSE-10P1T2, PSE-10P2T1, PSE-10P2T2, PSE-15P1T1, PSE-15P1T2, PSE-15P2T1, PSE-15P2T2, PSE-30P1T1, PSE-30P1T2, PSE-30P2T1, PSE-30P2T2). After the discharge of the last cycle, the extraction cells were flushed with water for 3 min and with N2 gas for 5 min. All extracts were filtered through a PVDF Durapore filter of 0.45 μm (Millipore, Bedford, MA, USA). Extract Analysis. Extracts general parameters such as °Brix, pH, and total phenol index (TPI, measured at 280 nm by means of an UV−vis spectrophotometer Lambda 25 (PerkinElmer, Norwalk, CT, USA) were determined. Determination of Phenolic Compounds by HPLC-DAD-MS. This method was based on Pardo-Garcı ́a et al.’s19 work, but the gradient condition was slightly modified to improve the resolution of new standards. The HPLC grade solvents used were water/formic acid/ acetonitrile (97.5:1.5:1 v/v/v) as solvent A and acetonitrile/formic acid/solvent A (78.5:1.5:20 v/v/v) as solvent B. The elution gradient was set up for solvent B as 0 min, 5%; 2 min, 10%; 4 min, 14%; 9 min, 14%; 37 min, 18.5%; 35 min, 20%; 50 min, 25%; 55 min, 50%; 60 min, 5%; and 65 min, 5%. The loop volume was 20 μL. Phenolic acid, stilbene, and flavanol detections were carried out with the DAD by comparison with the corresponding UV−vis spectra and retention time of their pure standards in the chromatogram. Acids trans-caftaric and trans-p-coutaric were not available, so they were identified with the molecular ion and the spectral parameters, which were very close to their analogous trans-caffeic and trans-p-coumaric acids. Compounds were quantified and identified at different wavelengths: (+)-catechin, (−)-epicatechin, gallic acid, protocatechuic acid, pyrogallol, and syringic acid at 280 nm; ellagic, ferulic, and vanillic acids at 256 nm; trans-caffeic acid, trans-caftaric acid, and sinapaldehyde at 324 nm; trans-resveratrol, piceid (t-resveratrol-3glucoside), trans-p-coumaric acid, and trans-p-coutaric acid at 308 nm. Quantification was based on calibration curves of the respective standards (Sigma-Aldrich, Steinheim, Germany) at five different concentrations (0.70−175 mg/L) (R2 > 0.97). All analyses were made in duplicate. Determination of Volatile Compounds by HS-SBSE-GC-MS. Volatiles were extracted by means of headspace stir bar sorptive extraction (HS-SBSE) according to Pardo-Garcia et al.’s32 method. The volatile analysis was performed using an automated thermal

varietal dependents, so such composition can be associated with the so-called “terroir character” of their vineyards and their wines. There are a number of solid−liquid extraction (SLE) techniques used for the extraction of phenolic compounds from different vegetable waste materials, most of them using organic solvents (mainly ethanol), high temperatures (up to 240 °C), and long extraction times (up to 1 h) to exhaust the materials.20−22 However, such long extraction times can cause the generation of artifact compounds, and the use of organic solvents limits the search for new applications, due to their negative environmental impact and other human health issues. SLE procedures may be assisted by other parameters such as as ultrasound (UAE),23 pressure (PSE),13,24 or the use of supercritical fluids25 among others. Nowadays there is a trend that encourages the use of free environmental techniques to enhance sustainability; it is the socalled “green chemistry”. Such techniques are developed to reduce and/or eliminate the use of organic solvents, and the use of water as extractant should be preferred. As well, the resulting aqueous extracts will have the advantage of being exempt from certification based on their vegetal origin,26 although the compounds’ concentration in such extracts may be lower than when other techniques are used as the exhaustion of the vegetable material does not take place. Other SLE techniques that may be in agreement with this new green postulated may be based on the Naviglio principle27,28 or on microwave extraction (ME).29,30 Whereas the Naviglio solid−liquid extraction technique is carried out at room temperature and compression/decompression times are modified, ME uses higher temperatures but shorter extraction times. Extraction techniques to get aromatic plant extracts are very limited, except for essential oil production.31 Delgado de la Torre et al.15 have only refereed vine-shoot aroma description where ethanolic water mixtures at 220 °C for 60 min were the selected extraction conditions. Volatile phenols and furanic derivates were described in the previous work as the main components in vine-shoots, the same compounds found in oak aqueous extracts with biostimulant properties.18 Consequently, the aim of this work was to compare Airén vine-shoot waste aqueous extracts produced by four solid− liquid extraction techniques (conventional solid−liquid extraction (CSLE), solid−liquid dynamic extraction (SLDE-Naviglio), solvent free microwave extraction (ME), and pressurized solvent extraction (PSE) and to study their chemical composition in terms of phenolic, volatile, and mineral valuable compounds as they may have agricultural applications such as plant biostimulants or foliar fertilizers.

■

MATERIALS AND METHODS

Vine-Shoot Samples. One hundred kilograms of Airén white V. vinifera vine-shoot wastes was sampled in D.O. Mancha, located in the Castilla-La Mancha Spanish region, 4 months after the harvest of 2013, by randomized selection. Samples were dried for 72 h at room temperature until a final humidity of 6.5% (gwater/100 g of sample). Dry vine-shoot wastes were ground by using a hammer miller (LARUS Impianti, Skid Sinte 1000, Zamora, Spain) to get a homogeneous 40 mesh sieve sampling. Samples were kept under vacuum until their use at room temperature (25−27 °C). Vine-Shoot Extraction Procedures. All vine-shoot waste aqueous extracts were submitted twice for each extraction technique and condition tested. CSLE. Fifty grams of ground Airén vine-shoot waste samples was extracted with 250 mL of boiling water, and then the solution was kept B



Article

Figure 1. Total composition, in terms of the main chemical families, for the aqueous vine-shoot waste extracts obtained under different extraction systems and conditions. ME, solvent-free microwave extraction (ME-5, 5 min; ME-10, 10 min; ME-15, 15 min); CSLE, conventional solid−liquid extraction (CSLE-15, 15 min; CSLE-30, 30 min; CSLE-60, 60 min); SLDE-Naviglio, solid−liquid dynamic extraction (SLDE-Naviglio-6.5, 5 min in the static phase and 1.5 min in the dynamic phase; SLDE-Naviglio-8, 5 min in the static phase and 3 min in the dynamic phase; SLDE-Naviglio-12, 9 min in the static phase and 3 min in the dynamic phase); PSE, pressurized solvent extraction (extraction temperature, 30 °C (T1) and 100 °C (T2); pressure, 50 (P1) and 100 bar (P2); cycles, 3 (heat up, 1 min, hold (10, 15, 30 min), and discharge (9 min) named PSE-time, pressure, temperature (PSE-10P1T1, PSE-10P1T2, PSE-10P2T1, PSE-10P2T2, PSE-15P1T1, PSE-15P1T2, PSE-15P2T1, PSE-15P2T2, PSE-30P1T1, PSE-30P1T2, PSE-30P2T1, PSE-30P2T2). °C/min, held for 5 min), raised to 150 °C (5 °C/min, held for 5 min), and then raised to 230 °C (10 °C/min, held for 5 min). The MS was operated in scan acquisition (27−300 u) with an ionization energy of 70 eV. The temperature of the MS transfer line was maintained at 230 °C. The identification of the compounds was performed using the NIST library and confirmed by comparison with the mass spectra and retention time of chromatographic standards. To avoid matrix interferences, the MS quantification was performed in the single ionmonitoring mode using characteristic m/z values. The standards employed to identify and quantify volatiles (GC-MS) were purchased from Sigma-Aldrich (Steinheim, Germany) (the numbers in parentheses indicate the m/z used for quantification): D-limonene (m/z 69), 1-hexanol (m/z 56), 3-hexen-1-ol (Z) (m/z 67), nonanal (m/z 57), 1-octen-3-ol (m/z 57), furfural (m/z 96), benzaldehyde (m/ z 106), linalool (m/z 71), linalyl acetate (m/z 93), 5-methylfurfural (m/z 110), 1-nonanol (m/z 56), α-terpineol (m/z 59), hexanoic acid (m/z 60), geranyl acetone (m/z 43), guaiacol (m/z 109), benzyl alcohol (m/z 108), trans/cis-whiskey lactones (m/z 99), 2-phenylethanol (m/z 91), β-ionone (m/z 177), octanoic acid (m/z 60), decanoic acid (m/z 60), and vanillin (m/z 151), together with the internal standards 3-methyl-1-pentanol and γ-hexalactone. Quantifica-

desorption unit (TDU, Gerstel, Mülheim and der Ruhr, Germany) mounted on an Agilent 7890A gas chromatograph system (GC) coupled to a quadrupole Agilent 5975C electron ionization mass spectrometric detector (Agilent Technologies, Palo Alto, CA, USA) equipped with a fused silica capillary column (BP21 stationary phase, 30-m length, 0.25 mm i.d., and 0.25 μm film thickness) (SGE, Ringwood, Australia). The carrier gas was helium with a constant column pressure of 20.75 psi. The stir bars were thermally desorbed in a stream of helium carrier gas at a flow rate of 75 mL/min with the TDU programmed from 40 to 295 °C (held 5 min) at a rate of 60 °C/min. The analytes were focused in a programmed temperature vaporizing injector (PTV) (CIS-4, Gerstel), containing a packed liner (20 mg tenax TA), held at 25 °C with Peltier cooling prior to injection. After desorption and focusing, the CIS-4 was programmed from 25 to 260 °C (held for 5 min) at 12 °C/s to transfer the trapped volatiles onto the analytical column. The TDU was operated in the splitless desorption mode, whereas the CIS-4 was operated in the PTV solvent vent mode (purge flow to split vent of 80 mL/min, vent 75 mL/min, and pressure 20.85 psi). The GC oven temperature was programmed to 40 °C (held for 2 min), raised to 80 °C (5 °C/min, held for 2 min), raised to 130 °C (10 C



Article

Figure 2. (a) Canonical discriminant analysis of the 21 vine-shoot waste aqueous extracts obtained by four extraction systems. (b) Standarized canonical coefficients of the main discriminant variables in functions 1 and 2 obtained for phenolic compounds, volatile compounds, and mineral composition data. ME, solvent-free microwave extraction (ME-5, 5 min; ME-10, 10 min; ME-15, 15 min); CSLE, conventional solid−liquid extraction (CSLE-15, 15 min; CSLE-30, 30 min; CSLE-60, 60 min); SLDE-Naviglio, solid−liquid dynamic extraction (SLDE-Naviglio-6.5, 5 min in the static phase and 1.5 min in the dynamic phase; SLDE-Naviglio-8, 5 min in the static phase and 3 min in the dynamic phase; SLDE-Naviglio-12, 9 min in the static phase and 3 min in the dynamic phase); PSE, pressurized solvent extraction (extraction temperature, 30 °C (T1) and 100 °C (T2); pressure, 50 (P1) and 100 bar (P2); cycles, 3 (heat up, 1 min, hold (10, 15, 30 min), and discharge (9 min) named PSE-time, pressure, temperature (PSE-10P1T1, PSE-10P1T2, PSE-10P2T1, PSE-10P2T2, PSE-15P1T1, PSE-15P1T2, PSE-15P2T1, PSE-15P2T2, PSE-30P1T1, PSE-30P1T2, PSE-30P2T1, PSE-30P2T2). tion was based on calibration curves of the respective standards at five different concentrations (2 μg/L−15 mg/L) (R2 > 0.97). All analyses were made in triplicate. Mineral Composition. Al, As, B, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, S, Sb, Se, Sr, Ti, Tl, V, and Zn were quantified in vine-shoot waste aqueous extracts by inductively coupled plasma−optical emission spectrometry (ICP-OES) using an ICP spectrometer (Thermo Scientific ICAP 6500 Duo, Madrid, Spain). Anion quantifications such as P, S, Cl, F, N (as NO3− and NO2−) were determined by ion chromatography (850 Professional IC Anion, Suppressor Module MSM, Metrohm, Herisau, Switzerland) coupled with a conductivity detector (model 819, Metrohm). Aliquots of 20 μL were injected after filtering through a 0.45 μm PTFE filter in a Metrosep A Supp 7 analytical column (4.0 mm i.d. × 250 mm, 5 μm particle size, Metrohm) at 50 °C. An isocratic elution was performed with 3.6 mM Na2CO3 at a flow of 0.8 mL/min. Quantification was based on calibration curves of the respective standards (Sigma-Aldrich, Steinheim, Germany) at five different concentrations (0.01−25.00 mg/L) (R2 > 0.99). All analyses were made in duplicate. Statistical Analysis. The statistical elaboration of the data was performed using SPSS version 19.0 statistical package for Windows (SPSS, Chicago, IL, USA). Phenolic, volatile, and mineral compound data were processed using the variance analysis (ANOVA). Differences

between means were compared using the least significant difference (LSD) test at a 99.95% probability level.

■

RESULTS AND DISCUSSION The first approach of this paper was to produce aqueous extracts from vine-shoot wastes of Airén white V. vinifera. Four extraction systems (CSLE, SLDE-Naviglio, ME, and PSE) were assayed with the same vine-shoot sample/water ratio, combining, according to the system selected, parameters such as time, temperature, and pressure, resulting in 21 different aqueous vine-shoot waste extracts for their study. Different extraction yields were obtained, so all data have been homogenized and expressed as milligrams per kilogram or micrograms per kilogram of dry vine-shoot matter. Extracts were characterized in terms of phenolic, volatile, and mineral compounds. All extracts had a pH value ranging from 5.93 (ME) to 6.62 (PSE). Due to the large quantity of compositional data, some chemical associations were carried out to have a general look at each extraction system and their respective conditions (Figure 1). The most concentrated family of compounds, independent of the extraction technique used, were macronutrients (major and secondary), followed by flavanols and phenolic acids, all of D



Article

Table 1. Non-Flavonoid and Flavonoid Composition (Milligrams per Kilogram Dry Weight) of Different Vine-Shoot Waste Aqueous Extractsa CSLE compound

SLDE-Naviglio

CSLE-15

CSLE-30

CSLE-60

flavanols (+)-catechin (−)-epicatechin total

390.88 ± 5.11 c 214.46 ± 30.38 b 605.33 ± 25.27 bc

402.21 ± 8.95 c 217.79 ± 17.33 b 619.99 ± 26.28 c

353.47 ± 0.29 b 197.34 ± 3.17 b 550.81 ± 3.46 b

phenolic acids trans-caffeic acid trans-p-coumaric acid ferulic acid trans-caftaric acid trans-p-coutaric acid ellagic acid gallic acid protocatechuic acid syringic acid vanillic acid total

1.92 8.49 2.20 77.60 19.39 14.10 19.40 6.94 6.37 8.38 164.79

± 0.15 a ± 0.43 d ± 0.24 b ± 2.74 b ± 0.83c ± 2.88 c ± 0.13 b ± 0.86 b ± 0.09 b ± 1.15 c ± 2.35 c

2.17 7.31 2.05 60.59 16.58 13.38 18.53 6.67 6.50 3.45 137.22

± 029 ab ± 0.11 bcd ± 0.05 b ± 2.95 a ± 0.85 abc ± 1.40 c ± 0.75 b ± 0.12 b ± 0.41 b ± 0.14 ab ± 3.38 b

2.14 7.68 2.36 55.21 14.70 10.28 20.53 6.94 6.05 4.72 130.61

± 0.03 ab ± 0.51 cd ± 0.02 b ± 0.59 a ± 0.04 a ± 0.74 bc ± 0.36 b ± 0.23 b ± 0.25 b ± 0.04 b ± 0.34 b

SLDE-Naviglio-6.5

SLDE-Naviglio-8

SLDE-Naviglio-12

80.35 ± 1.69 a 66.30 ± 1.87 a 146.65 ± 3.55 a

83.64 ± 0.65 a 67.21 ± 0.00 a 150.84 ± 0.64 a

76.41 ± 1.67 a 62.99 ± 0.94 a 139.39 ± 2.61 a

2.83 5.63 1.12 59.83 17.85 3.89 8.37 3.62 4.59 ndb 107.74

± ± ± ± ± ± ± ± ±

0.57 0.22 0.11 5.44 0.16 0.43 2.20 0.75 0.15

abc a a a b a a a a

± 0.60 a

3.06 6.22 0.93 60.34 16.18 4.98 7.21 3.34 4.91 2.56 109.72

± 0.04 bc ± 0.34 ab ± 0.05 a ± 2.41 a ± 0.82 ab ± 0.69 ab ± 0.72 a ± 0.25 a ± 0.21 a ± 0.23 a ± 2.94 a

3.43 6.76 0.92 59.96 16.08 5.57 7.80 3.25 4.62 2.70 111.10

± 0.21 c ± 0.20 abc ± 0.02 a ± 0.14 a ± 0.20 ab ± 0.70 ab ± 0.12 a ± 0.08 a ± 0.11 a ± 0.11 a ± 1.05 a

stilbenes piceid trans-resveratrol total

3.73 ± 0.48 b 21.03 ± 4.96 b 24.76 ± 5.44 b

3.80 ± 0.19 b 21.22 ± 5.30 b 25.02 ± 5.49 b

3.50 ± 0.03 b 28.56 ± 3.90 b 32.06 ± 3.93 b

0.50 ± 0.04 a 0.66 ± 0.05 a 1.16 ± 0.09 a

0.50 ± 0.12 a 0.79 ± 0.20 a 1.29 ± 0.32 a

0.58 ± 0.01 a 1.32 ± 0.09 a 1.90 ± 0.10 a

others pyrogallol sinapaldehyde total

21.46 ± 0.19 a 2.32 ± 0.26 a 23.78 ± 0.45 a

20.49 ± 0.64 a 2.32 ± 0.11 a 22.81 ± 0.74 a

19.91 ± 0.32 a 2.19 ± 0.00 a 22.11 ± 0.32 a

36.43 ± 0.38 b nd 34.43 ± 0.38 b

34.09 ± 2.44 b nd 34.09 ± 2.44 b

33.57 ± 0.09 b nd 33.57 ± 0.09 b

a

CSLE, conventional solid−liquid extraction (CSLE-15, 15 min; CSLE-30, 30 min; CSLE-60, 60 min); SLDE-Naviglio, solid−liquid dynamic extraction (SLDE-Naviglio-6.5, 5 min in the static phase and 1.5 min in the dynamic phase; SLDE-Naviglio-8, 5 min in the static phase and 3 min in the dynamic phase; SLDE-Naviglio-12, 9 min in the static phase and 3 min in the dynamic phase). Different letters in the same row indicate significant differences among extraction conditions according to the LSD test (α < 0.05). The mean values (n = 4) are shown with their standard deviation. bnd, not detected.

them expressed in milligrams per kilogram. The volatile content was the lowest, expressed in micrograms per kilogram, the most abundant being furanic compounds. CSLE and SLDE-Naviglio techniques produced the most concentrated extracts in relation to the groups of compounds previously discussed. Both extraction techniques are very different from one another, equating a conventional solid−liquid extraction technique with a novel technique based on a suction effect generated by a compression/decompression cycle (SLDE-Naviglio). The other two innovative extraction systems tested, ME and PSE, showed lower compositional data in comparison with CSLE and SLDENaviglio, and, more importantly, they did not show significant differences between any of the conditions test. It has to be pointed out that all SLE systems extracted the same number of compounds, except for vanillic acid and ferulic acid (not found in PSE system) and sinapaldehyde, D-limonene, and linalyl acetate (not found in SLDE-Naviglio). To differentiate extracts according to the different extraction conditions, a discriminant analysis was performed (Figure 2a). Three main groups can be distinguished, which were clearly separated by two canonic discriminating functions, explaining 47.7% of the total variance with the first function and 87.3% together with the second function. One of the groups encompasses the ME and PSE systems, whereas the other two groups account for CSLE and SLDE-Naviglio systems. The

compounds that contributed most to the differentiation (Figure 2b) are phenolic compounds, especially gallic acid, ellagic acid, (−)-epicatechin, and trans-caftaric acid. In terms of minerals, calcium, iron, and boron showed the highest weight on the canonic coefficients. However, no volatile compound contributed to this differentiation. It is surprising that general parameters such as total phenolic index (TPI) or °Brix values were not selected for these differentiations. TPI and °Brix higher values were found in ME (61.60 and 3.55, respectively) and CSLE (45.8 and 2.88, respectively) techniques, followed by SLDE-Naviglio (13.90 and 2.0, respectively) and PSE (11.13 and 0.9, respectively). The objective of the present research is to get aqueous extracts for agricultural purposes to be applied as a mix. For this reason, the composition discussion will focus on the CSLE and SLDE-Naviglio extraction systems as they are the ones with the highest concentration of valuable compounds (phenolic and volatile compounds, minerals), although they may be in detriment of a specific compound extracted by the other tested techniques. Furthermore, it is interesting to point out that both systems are not of remarkable energy requirements with respect to other extractive processes. For example, CSLE is the process traditionally more used in industries. E



Article

Phenolic Composition by HPLC-DAD-MS. Table 1 lists the concentration of the phenolic compounds identified within the Airén vine-shoot waste aqueous extracts obtained by CSLE and SLDE-Naviglio. Significant differences were found among both extraction systems, as CSLE extracts were more concentrated that SLDE-Naviglio ones, independent of the extraction conditions tested, except for the group named “others”. (+)-Catechin and (−)-epicatechin were the only flavanol compounds detected in all extracts. By CSLE it was possible to extract 4 times more flavanols than with SLDE-Naviglio (Table 1), suggesting that higher temperature (100 °C) favored their release in comparison with room temperature conditions (25− 27 °C). (+)-Catechin represented 60% of the CSLE total flavanol fraction, whereas in SLDE-Naviglio it was approximately 80% of the total content. When Airén vine-shoots were extracted by ethanol superheated liquid extraction (SHLE), (+)-catechin, pyrogallol, and syringic acid were the most abundant compounds.13 Among phenolic acids, trans-caffeic acid was the only compound for which the concentration was higher when the SLDE-Naviglio extraction system was used. trans-Caffeic acid concentration (Table 1) was higher in the present extracts than the one found (19 μg/kg) in other vine canes of which extracts were obtained by CSLE with an ethanol aqueous solution.14 This compound was not detected when SHLE was used as extraction system.13 trans-p-Coumaric and ferulic acids were highly extracted in terms of temperature, due to the high concentrations found in CSLE extracts. The presence of the hydroxycinnamoyltartaric acids (trans-p-coutaric and transcaftaric) has not been previously reported in the literature in any type of wood. Such compounds are identified as oxidation substrates and browning precursors in white wines.33 transCaftaric acid was the third compound in abundance within the phenolic pool (Table 1), especially when CSLE-15 was used. The content of trans-p-coutaric acid was significantly higher for CSLE-15 and CSLE-30 than for the other conditions tested. The presence of low molecular weight compounds such as gallic and ellagic acids indicated that vine-shoots contain as well hydrolyzable tannins, although other authors13 did not found ellagic acid in Airén vine-shoots. The concentration of gallic acid was higher than that of ellagic acid, favored by the CSLE system that produced a 50% more concentrated extract than SLDE-Naviglio, independent of the conditions tested on each system (Table 1). Protocatechuic acid, related to gallic acid by dealcoholization, was extracted by CSLE rather than by SLDENaviglio. An opposite behavior was found by pyrogallol, included in the “others” chemical group (Table 1) and which is related to gallic acid by decarboxylation. This latest compound, together with trans-caffeic acid, was highly extracted at room temperature (25−27 °C) (SLDE-Naviglio) rather than at 100 °C (CSLE), but no significant differences were observed when the different compression/decompression times were tested (Table 1). Syringic acid was highly extracted by the CSLE system, showing the same behavior as most phenolic compounds. Vanillic acid behavior was different between the assayed extracts, as the higher concentration was quantified in CSLE15, which indicated that higher extraction temperature but shorter times favored its extraction. This observation may be also justified by the fact that 3 mg/kg of this compound was quantified when SHLE was used.13

An important group of phenolic compounds is the stilbenes, which are best represented by trans-resveratrol, and it is identified in a wide variety of plant spices, especially in grapevines.34−36 trans-Resveratrol has attracted research interest because of its demonstrated therapeutic effects, antiinflammatory or even anticancer ones.34 The glycosylated form of resveratrol, piceid, may also be found in the same or lower proportion depending on grape variety. The higher concentration of trans-resveratrol has been reported by some authors, between 1100 and 5000 mg/kg, in different vine-shoot cultivars, especially high in Pinot noir,12 whereas in Turkish cultivars the concentration was around 2.5 μg/kg.14 Although Delgado de la Torre et al.13 did not find trans-resveratrol in Airén vine-shoots, it was found in the present aqueous extracts. Especially interesting is the CSLE concentration, which was approximately 20 times more concentrated than by SLDENaviglio (Table 1). The differences found between both systems indicate that the extraction temperature is an important parameter to enhance the extraction of this compound, but no significant differences were found in terms of time when the CSLE conditions were tested. Several factors could produce the differences found with other authors’ references, not only by the grape variety, but the health of the grape vine and grape canes, together with the differences on the extraction system used.11,35 The other identified stilbene, piceid, was not detected by any other authors, and it had the same behavior as its nonglycosylated derivate when CSLE was compared with the SLDE-Naviglio. The concentration of the piceid was 7 times lower than that of trans-resveratrol. Other stilbenes (transpiceatannol, trans-ε-viniferin, or vitisinol among others) have been also characterized in other vine-shoot cultivars,11,12 but those compounds could not be detected in the present aqueous extracts. It is surprising that sinapaldehyde was not found in SLDENaviglio extracts in comparison with CSLE extracts, but it was quantified in those extracts previously reported.13 Compounds such as acetovanillone, pyrocatechol, 4-hydroxybenzoic acid, and coniferaldehyde referred to in the Delgado de la Torre et al.13 study were looked for but not found in our extracts. Volatile Composition by HS-SBSE-GC-MS. Table 2 summarizes the results of volatile compounds identified, classified into different families according to their chemical structure, within the Airén vine-shoot waste aqueous extracts obtained by CSLE and SLDE-Naviglio. It is the first time that vine-shoot waste aqueous extract volatile composition is quantified, as only a qualitative profile was carried out by Delgado de la Torre et al.15 Because the vine-shoots are subjected to a degradation process while extracting, cellulose and lignin may release such important aroma compounds. In all extracts, the furanic compounds were the most abundant followed by alcohols and acids. For both extraction systems, furanics showed around 48% of the total content; however, alcohols and acids presented some differences. If in SLDENaviglio alcohols reached around 30% of the total content, in the CSLE extraction system they were about 20%. With regard to acids, the higher proportion within the total content was observed by CSLE, 24 versus the 16% reached by the SLDENaviglio system. Significant differences were found among the extraction systems used, depending on the extraction conditions tested; both extraction systems did not extract the same number of compounds. For example, D-limonene and linalyl acetate were not found in SLDE-Naviglio extraction system. F


G

12.16 3.90 322.72 338.78

1460.00 1192.04 54.27 54.38 40.05 2800.74

aldehydes benzaldehyde nonanal vanillin total

furanic compounds furfural 5-hydroxymethylfurfuralc 5-methylfurfural 2-furanmethanolc methyl furoatec total

others D-limonene geranyl acetone linalyl acetate β-ionone

± 84.85 a ± 43.42 a ± 5.02 a ± 1.70 a ± 1.15 a ± 136.14 a

± 0.68 a ± 0.93 ab ± 21.44 b ± 19.83 a

± 56.94 c ± 7.03 ab ± 2.42 bc ± 0.06 ab ± 0.00 ab ± 2.25 ab ± 8.71 a ± 15.84 c ± 2.46 a ± 78.16 a

± 133.19 a ± 41.05 bc ± 0.21 c ± 174.46 ab

0.08 4.20 0.17 2.65

± ± ± ± 0.03 0.49 0.01 0.81

bc ab b a

44.65 ± 5.47 a 27.59 ± 1.09 a 72.24 ± 4.38 ab

1135.84 76.45 14.87 7.58 0.94 26.83 53.98 269.60 29.58 1615.67

alcohols 1-hexanol 3-hexen-1-ol, (Z) 1-octen-3-ol 1-nonanol linalool α-terpineol guaiacol benzyl alcohol 2-phenylethanol total

lactones trans-whiskey lactone cis-whiskey lactone total

1126.93 252.67 78.49 1458.09

CSLE-15

acids hexanoic acid octanoic acid decanoic acid total

compound

± 169.71 ab ± 78.49 a ± 8.27 a ± 6.11 c ± 9.66 a ± 86.49 a

± 2.89 c ± 0.08 a ± 30.62 c ± 33.59 b

± 43.66 b ± 9.31 a ± 1.70 ab ± 1.48 a ± 0.01 ab ± 2.08 a ± 8.23 a ± 16.57 d ± 2.87 a ± 82.92 a

± 100.04 b ± 1.47 ab ± 5.65 ab ± 104.21 b

0.09 5.84 0.13 3.13

± ± ± ±

0.01 0.44 0.04 0.33

c bc ab a

34.96 ± 3.31 a 26.40 ± 8.12 a 61.36 ± 11.42 a

1920.00 1630.10 85.41 82.27 62.54 3680.32

90.16 2.96 523.49 616.61

889.09 69.38 10.92 7.03 0.93 15.51 49.54 428.92 32.91 1504.23

1671.27 138.84 49.45 1859.56

CSLE-30

CSLE

± 141.42 b ± 128.93 a ± 10.63 a ± 4.11 bc ± 8.23 a ± 272.05 a

± 1.73 c ± 0.95 a ± 37.82 c ± 37.04 b

± 38.03 a ± 3.41 a ± 1.50 a ± 0.82 a ± 0.01 b ± 8.22 b ± 1.82 b ± 19.33 e ± 0.21 a ± 73.33 a

± 36.37 b ± 2.70 a ± 6.92 a ± 26.75 b

0.03 3.35 0.08 2.64

± ± ± ±

0.01 0.56 0.02 0.45

ab a a a

42.88 ± 5.63 a 49.58 ± 5.66 bc 92.46 ± 11.29 ab

2200.00 1560.07 88.28 67.83 55.58 3971.05

93.84 2.93 528.12 624.89

554.49 66.03 8.94 5.44 0.99 40.19 92.07 582.43 20.85 1371.43

1760.76 110.27 41.95 1912.98

CSLE-60

4.84 1.08 0.51 0.71

e ab abc c

± 159.10 ab ± 209.61 a ± 27.26 a ± 6.56 a ± 21.34 a ± 423.87 a

± 0.88 a ± 1.26 b ± 26.46 ab ± 28.60 a

± 1.26 a ± 7.30 b ± 0.88 a ± 4.81 b ± 6.36 b

± ± ± ±

± 92.32 a ± 11.14 abc ± 2.65 c ± 83.83 a

nd 4.55 ± 0.50 ab nd 2.34 ± 0.02 a

69.54 ± 6.35 b 89.49 ± 5.04 d 159.03 ± 11.38 c

1762.50 1523.27 96.63 51.94 61.28 3495.61

12.10 6.46 233.94 252.50

1476.35 84.11 13.84 12.05 ndb 14.14 82.51 177.45 221.93 2082.38

743.18 175.30 68.53 987.00

SLDE-Naviglio-6.5

Table 2. Volatile Composition (Micrograms per Kilogram Dry Weight) of Different Vine-Shoot Waste Aqueous Extractsa SLDE-Naviglio

64.54 de 1.57 ab 0.09 c 0.92 c

± 17.68 ab ± 172.36 a ± 23.97 a ± 11.56 c ± 27.97 a ± 149.65 a

± 0.83 a ± 0.57 ab ± 27.56 ab ± 28.96 a

± 2.70 b ± 4.08 a ± 4.08 bc ± 6.42 c ± 76.24 b

± ± ± ±

± 158.87 a ± 36.73 c ± 4.22 bc ± 199.83 a

nd 6.38 ± 0.02 c nd 1.64 ± 0.58 a

31.54 ± 4.58 a 43.94 ± 2.10 ab 75.48 ± 2.47 ab

1812.50 1522.83 113.88 87.72 73.52 3610.45

11.86 5.28 268.81 285.95

1350.74 85.59 17.19 14.18 nd 42.31 46.71 264.21 289.39 2110.31

893.62 267.35 62.81 1223.78

SLDE-Naviglio-8

± 212.13 a ± 249.10 a ± 6.99 a ± 1.92 bc ± 6.06 a ± 476.21 a

± 6.40 b ± 0.80 b ± 12.39 a ± 5.20 a

± 22.57 cd ± 4.14 c ± 1.22 abc ± 0.37 bc ± 0.60 b ± 3.54 b ± 3.48 a ± 9.53 ab ± 5.71 d ± 51.16 b

± 71.32 a ± 45.64 bc ± 0.90 c ± 24.77 a

nd 2.94 ± 0.34 a nd 2.28 ± 0.07 a

34.06 ± 3.77 a 64.00 ± 3.85 c 98.06 ± 0.09 b

1475.00 1286.38 61.65 70.77 47.48 2923.29

60.73 6.69 208.71 276.13

1242.91 94.65 12.09 10.94 1.83 32.95 45.94 216.34 354.09 2011.73

875.45 244.53 66.54 1186.51

SLDE-Naviglio-12

Journal of Agricultural and Food Chemistry Article


Article

SLE, conventional solid−liquid extraction (CSLE-15, 15 min; CSLE-30, 30 min; CSLE-60, 60 min); SLDE-Naviglio, solid−liquid dynamic extraction (SLDE-Naviglio-6.5, 5 min in the static phase and 1.5 min in the dynamic phase; SLDE-Naviglio-8, 5 min in the static phase and 3 min in the dynamic phase; SLDE-Naviglio-12, 9 min in the static phase and 3 min in the dynamic phase). Different letters in the same row indicate significant differences among extraction conditions according to the LSD test (α < 0.05). The mean values (n = 6) are shown with their standard deviation. bnd, not detected. c Identification only tentative and expresed as μg/kg of furfural. dExpresed as μg/kg of 3-methyl-1-pentanol.

The obtained extracts were rich in acids, especially in hexanoic. No significant differences in total acids were observed among the extraction systems used, except for CSLE-30 and CSLE-60, with the highest concentrations due to the hexanoic acid; thus, longer times favor its extraction. In other woods, such as seasoned oak wood chips of American origin, these acid compounds were also found.37,38 Total alcohols showed significant differences regarding the extraction system, as SLDE-Naviglio produced the highest content, independent of the extraction conditions tested. A clear behavior for each compound was not observed under SLDE-Naviglio conditions, such as the case of the 1-hexanol, the most abundant alcohol. The presence of 1-hexanol was expected, because it is derived from the unsaturated fatty acids, which are present in all plants.39 On the other hand, 3-hexen-1ol (Z) content was affected significantly by SLDE-Naviglio-12 conditions; guaiacol content was significantly higher in SLDENaviglio-6.5, being quantified as 4% of the total alcohols fraction, whereas in SLDE-Naviglio-8 and SLDE-Naviglio-12 conditions it was only about 2%. α-Terpineol concentration was significantly lower under SLDE-Naviglio-6.5 conditions. The compounds more influenced by SLDE-Naviglio were linalool and 2-phenylethyl alcohol, the first quantified only in SLDE-Naviglio-12 and the second increasing when the compression/decompression times were longer. About the influence of CSLE conditions, 1-hexanol content decreased significantly with extraction time, going from 71% of the total alcohols fraction by CSLE-15 to 40% with CSLE-60. With regard to linalool, although no statistical differences were observed, it is worth mentioning that it is an important odorant terpene present in grapes, especially in Muscat varieties, which gives them their characteristic aroma.40 Benzyl alcohol and guaiacol contents were highest in CSLE-60 conditions, reaching 42.5 and 6.7%, respectively, of the total alcohols. Guaiacol is a volatile phenol common in other types of woods, such as oak, chestnut, ash, acacia, or cherry, because their source is lignin,41,42 and it is one of the most abundant compounds in commercial aqueous oak extracts (0.21 mg/L).19 These oak extracts, when applied to vineyard by a foliar treatment, increased the concentration of glycosidically bound aroma precursors of guaiacol in grapes and the concentration of this compound in their respective wines.18 In the same way, recent works have also shown that the application of an aqueous solution of guaiacol stimulated the varietal aroma composition of grapes, showing an important influence in the aroma of wines.19 Total aldehydes showed significant differences with regard to the extraction system, as CSLE-30 and CSLE-60 had the highest content with around twice those of the CSLE-15 and SLDE-Naviglio systems. Vanillin was the major aldehyde, having a big influence in the total aldehydes content, its concentration ranging from 76% for SLDE-Naviglio-12 to 95% for CSLE-15. Vanillin is one of the most important odorant compounds present in commercial aqueous oak extracts used within grapevines,19 providing them a vanilla aroma. In wines from such grapevines, a significant increase in vanillin content and woody aroma was observed.18 The reported levels of these compounds were similar to those found in some varieties of oak chips.41,42 Besides, Delgado de la Torre et al.15 suggested the possibility of using vine-shoots in wines as flavoring agents, after observing similar chromatographic peak areas of a comparative study with oak chips. As vanillin, the highest benzaldehyde content was at CSLE-30 and CSLE-60, around

a

2.80 ± 0.14 a 7.75 ± 1.06 a 15.76 ± 0.50 a 2.61 ± 0.55 a 8.52 ± 0.43 a 19.15 ± 1.58 a 3.49 ± 1.08 a 8.28 ± 3.01 a 18.65 ± 4.57 a 3.70 ± 4.02 a 8.04 ± 1.24 a 17.84 ± 2.84 a 2.60 ± 0.14 a 6.59 ± 0.44 a 18.38 ± 0.39 a 2.24 ± 0.37 a 4.47 ± 0.27 a 13.81 ± 1.94 a stilbene 1d stilbene 2d total

SLDE-Naviglio CSLE

CSLE-30 compound

Table 2. continued

CSLE-15

CSLE-60

SLDE-Naviglio-6.5

SLDE-Naviglio-8

SLDE-Naviglio-12


H



Article

Figure 3. Chromatographic peaks corresponding to volatile cis- and trans-stilbenes at SIM mode, with characteristic m/z at 179 and 180, respectively, identified for the first time in vine-shoots.

Table 3. Mineral Composition (Milligrams per Kilogram Dry Weight) of Different Vine-Shoot Waste Aqueous Extractsa CSLE CSLE-15

CSLE-30

SLDE-Naviglio CSLE-60

SLDE-Naviglio-6.5

SLDE-Naviglio-8

SLDE-Naviglio-12

major macronutrients nitrogen (as nitrate) 6.36 ± 0.22 d nitrogen (as nitrite) 1.23 ± 0.04 a phosphorus 249.90 ± 8.62 a potassium 1534.63 ± 52.93 a total 1792.11 ± 61.82 a

3.49 1.44 229.19 1467.80 1701.91

± 0.12 b ± 0.05 a ± 7.91 a ± 50.63 a ± 58.70 a

6.15 1.44 258.30 1413.07 1678.65

± 0.21 d ± 0.05 a ± 8.91 a ± 48.74 a ± 57.91 a

2.05 6.50 301.61 1435.00 1745.15

± 0.07 a ± 0.22 b ± 10.40 b ± 49.50 a ± 60.20 a

4.36 7.37 306.99 1421.42 1740.13

± 0.15 c ± 0.25 c ± 10.59 b ± 49.03 a ± 60.02 a

4.36 7.79 323.90 1541.34 1877.39

± 0.15 c ± 0.27 c ± 11.17 b ± 53.17 a ± 64.76 a

secondary macronutrients calcium 236.16 magnesium 254.61 sulfur 1278.38 total 1769.15

± 8.15 a ± 8.78 a ± 44.10 ab ± 61.02 ab

266.91 267.94 1197.41 1732.25

± 9.21 a ± 9.24 ab ± 41.30 a ± 59.75 a

260.56 261.58 1374.32 1896.46

± 8.99 a ± 9.02 ab ± 47.40 abc ± 65.41 abc

388.73 316.73 1546.98 2252.44

± 13.41 b ± 10.92 c ± 53.36 c ± 77.69 d

367.21 297.76 1357.61 2022.58

± 12.67 b ± 10.27 bc ± 46.83 ab ± 69.76 bcd

394.11 275.73 1425.78 2095.61

± 13.59 b ± 9.51 ab ± 49.18 bc ± 72.28 cd

micronutrients boron iron copper zinc manganese chlorine total

± 0.02 b ± 0.03 b ± 0.01 a ± 0.05 a ± 0.07 a ± 5.41 ab ± 5.59 ab

0.80 1.36 0.24 1.56 2.38 151.29 157.61

± 0.03 c ± 0.05 d ± 0.01 a ± 0.05 a ± 0.08 ab ± 5.22 a ± 5.44 a

0.92 1.13 0.20 1.59 2.34 159.08 165.25

0.40 0.35 0.97 1.63 2.42 187.83 193.60

± 0.01 a ± 0.01 a ± 0.03 bc ± 0.06 a ± 0.08 b ± 6.48 c ± 6.68 c

0.39 0.30 0.96 1.61 2.34 178.35 183.95

0.66 0.83 0.17 1.49 2.05 156.83 162.04

± 0.03 d ± 0.04 c ± 0.01 a ± 0.05 a ± 0.08 ab ± 5.49 ab ± 5.70 ab

± 0.01 a ± 0.01 a ± 0.03 b ± 0.06 a ± 0.08 ab ± 6.15 bc ± 6.35 bc

0.42 0.30 1.06 2.20 2.58 184.76 191.32

± 0.01 a ± 0.01 a ± 0.04 c ± 0.08 b ± 0.09 b ± 6.37 c ± 6.60 c

a

CSLE, conventional solid−liquid extraction (CSLE-15, 15 min; CSLE-30, 30 min; CSLE-60, 60 min); SLDE-Naviglio, solid−liquid dynamic extraction (SLDE-Naviglio-6.5, 5 min in the static phase and 1.5 min in the dynamic phase; SLDE-Naviglio-8, 5 min in the static phase and 3 min in the dynamic phase; SLDE-Naviglio-12, 9 min in the static phase and 3 min in the dynamic phase). Different letters in the same row indicate significant differences among extraction conditions according to the LSD test (α < 0.05). The mean values (n = 4) are shown with their standard deviation. I



Article

cation micronutrients, the most abundant was manganese and the lowest was iron. The mineral contents quantified in Airén vine-shoot aqueous extracts were lower than the ones referred for other cultivars,10,14 although it was dependent on the grape variety and the soil composition. Anyway, the mineral content found in Airén aqueous vine-shoot extracts could be sufficient to support the plant nutrition whether they are directly applied on the leaves or suitably diluted, as other byproducts.46 From a long time ago, foliar fertilization based on micronutrients has been used, because it reduces the need for soil-applied fertilizer and the leaching of nutrients, decreasing the impact on the environment of fertilizers’ salts. It does not totally replace soil-applied fertilizer, but it does increase the uptake and hence the efficiency of the nutrients applied to the soil.46 In such a way, the presence of small quantities of major nutrients such as N, P, and K, in the vine-shoot aqueous extracts, may leave the opportunity to be applied at any time depending on the needs of the crop. In the case of grapevines it is known that N is the major nutrient affecting vigor and must quality; for this reason it is used in great quantities, but it results as well in poorer wine quality.47 In the case of K, it is widely used in viticulture as it can increase grape yield, as a result of increased cluster number and weight.48 Phosphorus is also an essential nutrient for vines as it favors root development,49 although their quantity requirements are lower than those for N and K. The extraction technique used did not modify the potassium content in all extracts, but it increased significantly the content of nitrogen as nitrite and phosphorus when SLDE-Naviglio was used, whereas nitrogen, in the form of nitrate, which is the preferable form to be taken up by plants, was significantly higher when CSLE-15 or CSLE-60 was used. Such nutrients (N, P, K) are the main nutritive sources for plants, so foliar fertilization can be one of their possible uses, because they are already dissolved in water, which is the main requisite to be assimilated by the plants. In should be pointed out that when nutrients are applied to the soil in forms available to the plants, important losses are produced because they can react with soil components, giving insoluble forms. Secondary macronutrient and micronutrient contents were higher in extracts from the SLDE-Naviglio system than in the CSLE one, independent of the extraction conditions tested. It is worth mentioning that the highest boron content is by CSLE60 and that of iron by CSLE-30. The SLDE-Naviglio extraction technique did not show a clear behavior related to micronutrients. In conclusion, it has been observed that vine-shoot waste aqueous extracts from V. vinifera Airén variety obtained by CSLE and SLDE-Naviglio were the highest concentrated extracts in phenolic, volatile, and mineral valuable compounds. Such compositions suggest that these wastes may have a new potential uses as bioestimulants or foliar fertilizers in the vineyard. It could be implemented in the “Sustainable Viticulture” concept, where the cycle of the vine could be closed, as such vine-shoot extracts may modulate the grape quality, returning to the grapevines what they took from the soil, and even enhancing the terroir effect. Moreover, these extracts may be produced in the owner wineries, using the facilities available once the winemaking process ends.

15% of total aldehydes, followed by SLDE-Naviglio-12, where its percentage was the highest, 22% of total aldehydes. As expected, furanic compounds were the most abundant volatile compounds found in the vine-shoot aqueous extracts, because they are carbohydrate derivatives appearing in other woods such as oak, chestnut, cherry, or ash.42 Their total content was not dependent on the extraction system used, as no significant differences were observed between them. Furfural and 5-hydroxymethylfurfural were the most abundant furanic compounds (53 and 43%, respectively), as it was observed in the aqueous oak extracts used as plant biostimulants.19 Compounds such as 5-methylfurfural and methyl furoate were not influenced by the extraction system and conditions used. Most furanic compounds were also found in previous vine-shoot aroma research.15 It is important to emphasize the presence of whiskey lactone compounds, which are characteristic mainly in oak woods, but they were not previously detected in other vine-shoot wastes;15 however, these lactones come from the degradation of lipids, and they are abundant in oak green wood.43 They were influenced by the extraction system, especially cis-whiskey lactone, which reached the highest concentration when SLDNaviglio-6.5 was used. Both whiskey lactones are compounds present in aqueous oak extract,19 and recently it has been observed that when a solution of whiskey lactones was used in grapevines, wines from such grapes had enhanced varietal aroma after the malolactic fermentation.44 Because it has been shown that some of these compounds presented in both vineshoots and oak aqueous extracts, then the same applications carried out with the latest could be performed. With regard to the compounds grouped as “others”, no significant differences were found between the extraction systems used, except for D-limonene and linalyl acetate, which were not present in SLDE-Naviglio extracts. The latest behavior suggests that the extraction of such compounds was temperature dependent (CSLE vs SLDE-Naviglio). Geranyl acetone, which appears in all extracts, did not show a clear behavior. β-Ionone is a norisoprenoid compound known as an important varietal aroma in grapes and wines, but it was not affected by the extraction system and conditions used. Although the stilbenes fraction has been widely studied in different vine canes,11,12 until now no reference about the two volatile stilbenes found in the present extracts has been mentioned in other woods. However, such compounds were detected during the lignin pyrolysis produced in pulping of corn.45 Figure 3 illustrates the chromatographic profiles of such compounds, with m/z 179 and 180. Neither stilbene showed significant differences among SLDE-Naviglio and CSLE extraction systems and their respective conditions, but according to previous authors,45 stilbene structures are stable even at pyrolysis temperature. Mineral Composition by ICP-OES. The mineral composition of the different vine-shoot extracts is listed in Table 3, excluding the ones with a concentration 1 g/kg) corresponded to potassium and sulfur nutrients, followed by calcium, magnesium, and phosphorus with concentrations around 0.3 g/kg. Among the other nutrients, the most abundant was chlorine (approximately 0.2 g/kg), followed by nitrogen as nitrate or nitrite depending on the extraction system used. As J



■

Article

and Chardonnay grapes after an oak extract application to the grapevines. Food Chem. 2013, 138, 956−965. (17) Martínez-Gil, A. M.; Garde-Cerdán, T.; Zalacain, A.; PardoGarcía, A. I.; Salinas, M. R. Applications of an oak extract on Petit Verdot grapevines. Influence on grape and wine volatile compounds. Food Chem. 2012, 132, 1836−1845. (18) Martínez-Gil, A. M.; Garde-Cerdán, T.; Martínez, L.; Alonso, G. L.; Salinas, M. R. Effect of oak extract application to Verdejo grapevines on grape and wine aroma. J. Agric. Food Chem. 2011, 59, 3253−3263. (19) Pardo-García, A. I.; Martínez-Gil, A. M.; Cadahía, E.; Pardo, F.; Alonso, G. L.; Salinas, M. R. Oak extract application to grapevines as a plant biostimulant to increase wine polyphenols. Food Res. Int. 2014, 55, 150−160. (20) Luque-Rodríguez, J. M.; Luque de Castro, M. D.; Pérez-Juan, P. Dynamic superheated liquid extraction of anthocyanins and other phenolics from red grape skins of winemaking residues. Bioresour. Technol. 2007, 98, 2705−2713. (21) Luque-Rodríguez, J. M.; Pérez-Juan, P.; Luque De Castro, M. D. Extraction of polyphenols from vine shoots of Vitis vinifera by superheated ethanol-water mixtures. J. Agric. Food Chem. 2006, 54, 8775−8781. (22) Spigno, G.; Tramelli, L.; De Faveri, D. M. Effects of extraction time, temperature and solvent on concentration and antioxidant activity of grape marc phenolics. J. Food Eng. 2007, 81, 200−208. (23) Vilkhu, K.; Mawson, R.; Simons, L.; Bates, D. Applications and opportunities for ultrasound assisted extraction in the food industry. A review. Innovative Food Sci. Emerging Technol. 2008, 9, 161−169. (24) Mustafa, A.; Turner, C. Pressurized liquid extraction as a green approach in food and herbal plants extraction. A review. Anal. Chim. Acta 2011, 703, 8−18. (25) Pourmortazavi, S. M.; Rahimi-Nasrabadi, M.; Hajimirsadeghi, S. S. Supercritical fluid technology in analytical chemistry. A review. Curr. Anal. Chem. 2014, 10, 3−28. (26) Wissgott, U.; Bortlik, K. Prospects for new natural food colorants. Trends Food Sci. Technol. 1996, 7, 298−302. (27) Naviglio, D. Naviglio’s principle and presentation of an innovative solid-liquid extraction technology: Extractor Naviglio®. Anal. Lett. 2003, 36, 1647−1659. (28) Naviglio, D.; Pizzolongo, F.; Ferrara, L.; Aragòn, A.; Santini, A. Extraction of pure lycopene from industrial tomato by-products in water using a new high-pressure process. J. Sci. Food Agric. 2008, 88, 2414−2420. (29) Chan, C. H.; Yusoff, R.; Ngoh, G. C.; Kung, F. W. L. Microwave-assisted extractions of active ingredients from plants. J. Chromatogr., A 2011, 1218, 6213−6225. (30) Teo, C. C.; Chong, W. P. K.; Ho, Y. S. Development and application of microwave-assisted extraction technique in biological sample preparation for small molecule analysis. Metabolism 2013, 9, 1109−1128. (31) Rubiolo, P.; Sgorbini, B.; Liberto, E.; Cordero, C.; Bicchi, C. Essential oils and volatiles: Sample preparation and analysis. A review. Flavour Fragrance J. 2010, 25, 282−290. (32) Pardo-García, A. I.; Martínez-Gil, A. M.; López-Córcoles, H.; Zalacain, A.; Salinas, M. R. Effect of eugenol and guaiacol application on tomato aroma composition determined by headspace stir bar sorptive extraction. J. Sci. Food Agric. 2013, 93, 1147−1155. (33) Ferrandino, A.; Carra, A.; Rolle, L.; Schneider, A.; Schubert, A. Profiling of hydroxycinnamoyl tartrates and acylated anthocyanins in the skin of 34 Vitis vinifera genotypes. J. Agric. Food Chem. 2012, 60, 4931−4945. (34) Shakibaei, M.; Harikumar, K. B.; Aggarwal, B. B. Review: Resveratrol addiction: to die or not to die. Mol. Nutr. Food Res. 2009, 53, 115−128. (35) Karacabey, E.; Mazza, G. Optimization of solid-liquid extraction of resveratrol and other phenolic compounds from milled grape canes (Vitis vinifera). J. Agric. Food Chem. 2008, 56, 6318−6325. (36) Teissedre, P. L. Wine and health. Biochem. Grape Berry 2012, 269−285.

AUTHOR INFORMATION

Corresponding Author

*(M.R.S.) Phone: +34 967 599210. Fax: +34 967 599238. Email: [email protected]. Funding

Many thanks for the financial support given by the Ministerio de Economı ́a y Competitividad of the Spanish government to Project AGL2012-33132. Notes

The authors declare no competing financial interest.

■

REFERENCES

(1) European Parliament. Directive 2008/98/EC of the European Parliament and of the Council on waste and repealing certain directives. Off. J. Eur. Union 2008, 3−4. (2) SEVI. Rev. Semana Vitivinicola 2014, 3421, 467−470. (3) Cheng, V. J.; Bekhit, A. E. A.; Sedcole, R.; Hamid, N. The impact of grape skin bioactive functionality information on the acceptability of tea infusions made from wine by-products. J. Food Sci. 2010, 75, 167− 172. (4) Pedroza, M. A.; Carmona, M.; Salinas, M. R.; Zalacain, A. Use of dehydrated waste grape skins as a natural additive for producing rosé wines: study of extraction conditions and evolution. J. Agric. Food Chem. 2011, 59, 10976−10986. (5) Jiménez Gómez, S.; Cartagena Causapé, M. C.; Arce Martínez, A. Distribution of nutrients in anaerobic digestion of vine shoots. Bioresour. Technol. 1993, 45, 93−97. (6) Pardo, J.; Gea, F. J.; Pardo, A.; Navarro, M. J. Characterization of some materials derived from the grapevine industry and their use in traditional composting in Castilla-La Mancha (Spain). Mushroom Sci. 1995, 14, 213−221. (7) Corcho-Corral, B.; Olivares-Marín, M.; Fernández-González, C.; Gómez-Serrano, V.; Macías-García, A. Preparation and textural characterisation of activated carbon from vine shoots (Vitis vinifera) by H3PO4-chemical activation. Appl. Surf. Sci. 2006, 252, 5961−5966. (8) Portilla, O. M.; Rivas, B.; Torrado, A.; Moldes, A. B.; Domínguez, J. M. Revalorisation of vine trimming wastes using Lactobacillus acidophilus and Debaryomyces hansenii. J. Sci. Food Agric. 2008, 88, 2298−2308. (9) Jiménez, L.; Angulo, V.; Ramos, E.; De la Torre, J. L.; Ferrer, A. Comparison of various pulping processes for producing pulp from vine shoots. Ind. Crops Prod. 2006, 23, 122−130. (10) Mendívil, M. A.; Muñoz, P.; Morales, M. P.; Juárez, M. C.; García-Escudero, E. Chemical characterization of pruned vine shoots from la Rioja (Spain) for obtaining solid bio-fuels. J. Renewable Sustainable Energy 2013, 5, No. 033113. (11) Gorena, T.; Saez, V.; Mardones, C.; Vergara, C.; Winterhalter, P.; Von Baer, D. Influence of post-pruning storage on stilbenoid levels in Vitis vinifera L. canes. Food Chem. 2014, 155, 256−263. (12) Vergara, C.; Von Baer, D.; Mardones, C.; Wilkens, A.; Wernekinck, K.; Damm, A.; Winterhalter, P. Stilbene levels in grape cane of different cultivars in southern Chile: determination by HPLCDAD-MS/MS method. J. Agric. Food Chem. 2012, 60, 929−933. (13) Delgado de la Torre, M. P.; Ferreiro-Vera, C.; Priego-Capote, F.; Pérez-Juan, P. M.; Luque De Castro, M. D. Comparison of accelerated methods for the extraction of phenolic compounds from different vine-shoot cultivars. J. Agric. Food Chem. 2012, 60, 3051− 3060. (14) Ç etin, E. S.; Altiñöz, D.; Tarçan, E.; Göktürk Baydar, N. Chemical composition of grape canes. Ind. Crops Prod. 2011, 34, 994− 998. (15) Delgado de la Torre, M. P.; Priego-Capote, F.; Luque de Castro, M. D. Comparative profiling analysis of woody flavouring from vineshoots and oak chips. J. Sci. Food Agric. 2014, 94, 504−514. (16) Martínez-Gil, A. M.; Angenieux, M.; Pardo-García, A. I.; Alonso, G. L.; Ojeda, H.; Salinas, M. R. Glycosidic aroma precursors of Syrah K



Article

(37) Alañoń , M. E.; Ramos, L.; Díaz-Maroto, M. C.; Pérez-Coello, M. S.; Sanz, J. Extraction of volatile and semi-volatile components from oak wood used for aging wine by miniaturised pressurised liquid technique. Int. J. Food Sci. Technol. 2009, 44, 1825−1835. (38) Fernández de Simón, B.; Sanz, M.; Cadahía, E.; Poveda, P.; Broto, M. Chemical characterization of oak heartwood from Spanish forests of Quercus pyrenaica (Wild.). Ellagitannins, low molecular weight phenolic, and volatile compounds. J. Agric. Food Chem. 2006, 54, 8314−8321. (39) Schwab, W.; Davidovich-Rikanati, R.; Lewinsohn, E. Biosynthesis of plant-derived flavor compounds. Plant J. 2008, 54, 712−732. (40) Agosin, E.; Belancic, A.; Ibacache, A.; Baumes, R.; Bordeu, E.; Crawford, A.; Bayonove, C. Aromatic potential of certain Muscat grape varieties important for Pisco production in Chile. Am. J. Enol. Vitic. 2000, 51, 404−408. (41) Culleré, L.; Fernández de Simón, B.; Cadahía, E.; Ferreira, V.; Hernández-Orte, P.; Cacho, J. Characterization by gas chromatography-olfactometry of the most odor-active compounds in extracts prepared from acacia, chestnut, cherry, ash and oak woods. LWT− Food Sci. Technol. 2013, 53, 240−248. (42) De Simón, B. F.; Esteruelas, E.; Muñoz, A. M.; Cadahı ́a, E.; Sanz, M. Volatile compounds in acacia, chestnut, cherry, ash, and oak woods, with a view to their use in cooperage. J. Agric. Food Chem. 2009, 57, 3217−3227. (43) Doussot, F.; De Jéso, B.; Quideau, S.; Pardon, P. Extractives content in cooperage oak wood during natural seasoning and toasting; influence of tree species, geographic location, and single-tree effects. J. Agric. Food Chem. 2002, 50, 5955−5961. (44) Pardo-García, A. I.; De La Hoz, K. S.; Zalacain, A.; Alonso, G. L.; Salinas, M. R. Effect of vine foliar treatments on the varietal aroma of Monastrell wines. Food Chem. 2014, 163, 258−266. (45) Bai, X.; Kim, K. H.; Brown, R. C.; Dalluge, E.; Hutchinson, C.; Lee, Y. J.; Dalluge, D. Formation of phenolic oligomers during fast pyrolysis of lignin. Fuel 2014, 128, 170−179. (46) Tejada, M.; Gonzalez, J. L. Effects of foliar application of a byproduct of the two-step olive oil mill process on rice yield. Eur. J. Agron. 2004, 21, 31−40. (47) Pérez-Á lvarez, E. P.; Martínez-Vidaurre, J. M.; Martín, I.; GarcíaEscudero, E.; Peregrina, F. Relationships among soil nitrate nitrogen and nitrogen nutritional dtatus, yield components, and must quality in semi-arid vineyards from Rioja AOC, Spain. Commun. Soil Sci. Plant Anal. 2013, 44, 232−242. (48) Amiri, M. E.; Fallahi, E. Influence of mineral nutrients on growth, yield, berry quality, and petiole mineral nutrient concentrations of table grape. J. Plant Nutr. 2007, 30, 463−470. (49) Mengel, K.; Kirkby, E. A. Principles of Plant Nutrition, 4th ed.; International Potash Institute: Worblaufen-Bern, Switzerland, 1987.

L


Vine-Shoot Waste Aqueous Extracts for Re-use in Agriculture

Recommend Documents