a ISSN 0101-2061 (Print) ISSN 1678-457X (Online) Food Science and Technology DDOI http://dx.doi.org/10.1590/1678-457X.08317 Chemical composition of cold pressed Brazilian grape seed oil Fernanda Branco SHINAGAWA1, Fernanda Carvalho de SANTANA1, Elias ARAUJO1, Eduardo PURGATTO1, Jorge MANCINI-FILHO1* Abstract Grape seed oil (GSO) is an important by-product of the wine-making industry which has received attention as an alternative source of vegetable oils; its chemical compounds can be influenced by agricultural practices and industrial processing. Knowledge of the composition of Brazilian GSO is scarce; thus, this study aimed to analyze the chemical characteristics, as well as the antioxidant activity of these oils. GSO samples were obtained from Brazilian markets and showed significantly high amounts of phenolic, γ-tocotrienol and phytosterols as well as, the presence of several volatile compounds. Based on these results, is possible to show that oils exhibited good antioxidant activity. Therefore, it can be inferred that Brazilian GSO had a considerable content of phytochemical compounds with biological activity, which allows its association with other vegetable oils. Keywords: seed oils; micronutrients; antioxidant activity. Practical Application: In this study Brazilian grape seed oils were found to have potential to be used for some industrial sectors, such as food ingredients and cosmetics industry. They showed high amount of polyunsaturated fatty acid and significant amount of vitamin E, phenolics, phytosterols and volatile compounds. The knowledge regarding the composition of the products is important once they are made from a sustainable way. 1 Introduction Recent data from the Food and Agriculture Organization order to expand the knowledge of its characteristics and infer of the United Nations (2014) shows that Brazil is the eleventh its potential for human health. highest grape producer in the world and its harvest corresponds to approximately 1.5 million tons of grapes (Instituto Brasileiro 2 Material and methods de Geografia e Estatística, 2012). The Rio Grande do Sul 2.1 Reagents and standards state remains notable as the largest national producer, with 829.589 tons of production per year, representing approximately All solvents were analytical grade, used within their expiration 55% of Brazil’s total cultivation within an increase of the wine dates and purchased from Merck (Darmstadt, Germany). sector nationwide. The hexane and isopropanol used in this study were high performance liquid chromatography (HPLC) grade. Furthermore, There is a worldwide trend to seek new sources of vegetable oil, the boron trifluoride-methanol solution 14% (BF 14%), fatty and a wide range of research has been conducted to identify new 3 acid methyl ester (FAME) mix (C4:0-C24:0), methyl tridecanoate oils from fruit, and especially fruit seeds (Madawala et al., 2012). (C13:0), tocopherols (α-tocopherol, β-tocopherol, γ-tocopherol, In this context, cold pressed grape seed oil is an environmentally δ-tocopherol), δ-tocotrienol, campesterol, stigmasterol, sitosterol, suitable vegetable oil as it is a value added by-product of wine 5-α-cholestane and β-carotene (type II, synthetic) were obtained and grape juice-making process. from Sigma-Aldrich (St. Louis, MO, USA). Lipid content in grape seed is around 7-20%. The importance of grape seed use is mainly due to the fact that it is rich in lipids 2.2 Oil samples and bioactive compounds, such as vitamin E, phytosterol and phenolic compounds, among other components with biological GSO was obtained from Brazilian markets between July 2012 and August 2013. The cold pressed samples were identified activity, which are important for food, pharmaceutical and as follows: UVB (Antônio Prado, RS, Brazil), URS (Bento cosmetic industries (Kim et al., 2013; Rockenbach et al., 2010; Gonçalves, RS, Brazil), OOV (Guaribalde, RS, Brazil) and CAC Nakamura et al., 2003). (Estância Velha, RS, Brazil). After receiving the samples at the Motivated by the lack of information on the chemical data Lipids Laboratory (Faculty of Pharmaceutical Science, University of grape seed oil (GSO) produced in the world and mainly by the of São Paulo, São Paulo, Brazil), they were fractionated into absence of information for Brazilian oils, the aim of this study amber glass bottles, nitrogen gas was added in the headspace was to analyze the chemical composition of Brazilian GSO in and the samples were maintained at –20 °C until further analysis. Received 07 Mar., 2017 Accepted 25 July, 2017 1 Department of Food Science and Experimental Nutrition, Faculty of Pharmaceutical Science, Universidade de São Paulo – USP, São Paulo, SP, Brazil *Corresponding author: [email protected] 164 164/171 Food Sci. Technol, Campinas, 38(1): 164-171, Jan.-Mar. 2018 Shinagawa et al. 2.3 Color parameters the HPLC retention time with those of standard compounds under the same operating conditions, and the quantification Color parameters were evaluated by colorimeter (ColorQuest was based on an external standard method. The results were XE, Hunter Assoc. Laboratory, Reston, USA), with a field of expressed in mg 100 g-1 of oil. view of 10°, D65 type illuminant and slit diameter of 1 mm. The following color coordinates were determined in the Cielab system: lightness (L*), redness (a*, red to green axis) and 2.7 Total phenolics yellowness (b*, yellow to blue axis). The phenol extraction was carried out with a methanolic extract obtained according to Bail et al. (2008) and quantification 2.4 Fatty acid composition was based on the colorimetric method by Hills & Swain (1959) using Folin-Ciocalteau adapted to a microplate reader Fatty acid methyl esters (FAME) were obtained using BF3 ® 14% according to the Ce 2-66 method (American Oil Chemists’ (Biotek , Synergy HT model, Winooski, VT, USA). Absorption was measured at 720 nm. A standard curve was used, with gallic Society, 2009). Separation of FAME was performed using a gas -1 chromatograph (Shimadzu Plus 2010, Kyoto, Japan), equipped with acid (0.50 to 5.00 mg mL ), obtaining a correlation coefficient a split injector system, an auto-sampler and fused silica capillary of 0.9987. The content of phenolic compounds in the oils was column (SP-2560, 100 m × 0.25 mm × 0.2 µm). The column expressed as mg of gallic acid equivalents per 100 grams of -1 temperature gradient was programmed between 140 and 220 °C sample (mg GAE 100 g ). and detection was performed with a flame ionization detector (FID) at 260 °C. Helium was used as a carrier gas (1 mL min-1). 2.8 Total carotenoids FAME were identified by comparing the retention time of the Total amounts of carotenoids were determined using sample peaks with a standard mixture of 37 fatty acid methyl Ranjith et al. (2006) following some modifications. GSO were esters, C4:0-C24:0 (Sigma Chemical Co St. Luis, MO, USA). dissolved in hexane (0.1 g mL-1), vortexed for 30 s with NaCl The results were expressed as direct area % for each peak identified. 0.5%, and centrifuged for 10 min at 1500 g. Aliquots of 250 µL of the upper phase were collected and measured at 460 nm with 2.5 Phytosterol composition a microplate reader. Carotenoid quantification was based on a Phytosterol determination was followed by Duchateau et al. calibration curve with β-carotene standard, type II: synthetic (2002) with some modifications. Internal standard 5-α-colestane (Sigma-Aldrich Co., St. Louis, USA). The results were expressed (1.0 mg mL-1 hexane) was added to each sample before as mg of β-carotene equivalent per one hundred grams of oil saponification (methanolic KOH 3% at 50 ± 2 °C for 3 hours). (mg bCE 100 g-1 of oil). After three extractions with hexane, the organic phase was collected, evaporated and ressuspended in 150 µL of hexane 2.9 Total chlorophylls before injection into a GC system. A gas chromatograph (Shimadzu Plus GC 2010, Kyoto, Japan) equipped with a FID Total chlorophyll analysis was performed by Minguez- detector and a fused silica capillary column LM 5 (5% phenyl Mosquera et al. (1991) based on a dilution of the sample in 95% methylpolysiloxane 60 m × 0.25 mm internal diameter cyclohexane PA, then read at 670 nm using spectrophotometric with 0.25 µm particle size) was used. The GC program was as equipment. Quantification was conducted by the following equation: 6 2 follows: column temperature, 290 °C; detector temperature, Total Chlorophyll = (Absorbance × 10 ) / (613 × 10 × oil density) 300 °C; helium (1 mL min-1); and split ratio 1/50. Phytosterols and the results were expressed as milligrams per kilogram of -1 were identified and quantified by comparing the relative retention chlorophyll oil (mg kg ). time of standard campesterol (C5157), stigmasterol (S 6126) and β-sitosterol (S 9889) (Sigma-Aldrich Co., St. Louis, USA). 2.10 Volatile compounds The results were expressed in mg 100 g-1 of oil. Volatile compounds were extracted by headspace solid-phase microextraction and analyzed by gas chromatographic mass- 2.6 Tocopherol/Tocotrienol profile spectrometric method (HS-SPME-CG/MS). SPME compatible α-, β- and γ-tocopherol and γ-tocotrienol levels were vials containing 1 g of the each oil were extracted isothermally determined according to the Ce 8-89 method (American Oil for 24 h to produce sufficient amounts of analytes at room Chemists’ Society, 2009). The oil samples were diluted with hexane temperature (25 °C) and then the headspace was absorbed using a (0.1 g mL-1) and filtered through a 0.22 µm PTFE membrane filter. pre-conditioned column (Supelco 57330-U, Melbourne, Australia) Then, samples were analyzed by an HPLC (Shimadzu CBM-20A, for 30 minutes. After sampling had been carried out, the SPME Kyoto, Japan) consisting of an RF-10AXL fluorescence detector fiber was immediately exposed to the inlet temperature of the (excitation = 295 nm and emission = 330 nm).