Grapes are widely studied worldwide due to their bioactive properties1. The EMBRAPA and the IAC (Instituto Agronômico de Campinas), from the genetic improvement, produced the Maximum hybrid grapes (IAC 138-22), which are the result of the cross between the grapes Syrah (Vitis vinifera) and Seibel 11342 (hybrid). The aim of the present study was to evaluate the total of phenolic, antioxidant activity of IAC 138-22 grape and analyze the amount of fatty and methyl esters of fatty acids in seeds of this fruit. The grapes were collected at 5 different stages during the grape maturation in a vineyard at Santa Teresa - ES. Afterwards, they were separated into skin, pulp and seed, frozen, freeze-dryed and crushed for the preparation of ethanolic extracts by ultrasonic assisted maceration. The skins (C1 to C5), pulps (P1 to P5) and seeds (S1 to S5), with 1 being the greenest stage, 2, 3 and 4 the intermediate stages and 5 the more mature stage. The content of total phenolic substances was determined by the Folin-Ciocalteu2 method. The antioxidant activity of the extracts was evaluated by the DPPH method3, sequestration of superoxide radicals4 and hydrogen peroxide5. The fat extraction of the grape seeds was carried out according to the method described by Bligh and Dyer6 and this fat was submitted to derivatization process. The total phenolics were higher in (S1 and C1) with averages of 204.5 and 50.6 mg of gallic acid/g of extract and lower in (S5 and C3) with 134.4 and 15.3 mg of gallic acid/g of extract, respectively. Only in P3 were found 3 mg of gallic acid/g of extract. The results for antioxidant activity by DPPH was very weak for all the pulps tested; weak for C2, C3, C4 and C5; moderate for C1 and very strong for all seeds. No pulp extract presented antioxidant activity by the superoxide radical method (O2.-). Seeds were able to react with (O2.-), presenting I% between 65 (S3) and 80% (S2) in the concentration of 154 μg/mL and 52.7 (S1) and 61.2% (S2) in concentration of 77 μg/mL. Only C2 presented values of I% above 50% in the concentrations of 256 and 128 μg/mL. The skins and pulps were not able to neutralize the hydrogen peroxide (H2O2) at the concentrations used (500 to 30 μg/mL). Seed 1 showed I% ranging from 61 (37 μg/mL) to 53 (100 μg/mL). Seeds 2, 3 and 4 showed an average of 53% of H2O2 neutralization at concentrations of 75, 100 and 100 μg/mL, respectively. Seed 5 showed 59% (100 μg/mL), 56% (150 μg/mL) and 51% (200 μg/mL) of antioxidant activity. The fatty contents were highest in S2 (18%), equals in S1 and S4 (17%), 16% in S3 and minors in S5 (12%). The major fatty acids found in grape seeds were: linoleic acid (ɷ6), oleic acid (ɷ9) and palmitic acid, with a mean of 70%, 17% and 8%, respectively. The highest values of ɷ6 were found in S1 (71.14%) and the lowest in S5 (64.91%). When considering ɷ9, we observed the inverse, with 15.54% in S1 and 18.74% in S5. The highest percentage of palmitic acid was found in S5 (9.50%) and the lowest in S3 (6.18%).
References.
1. Avila PEA, Murrieta MSV, Hernández MOF, Cortéz MSL. 2016. Relationship between elemental composition of grapeyards and bioactive compounds in the Cabernet Sauvignon grapes Vitis vinifera harvested in México. Food. Chem., 23(1), 79-85.
2. Singleton VL, Orthofer R, Lamuela-Raventos R.M. 1999. Analysis of total phenols and others
oxidation substrates and antioxidants by means of Folin-Ciocaulteau reagent. Method. Enzymol. 299(1), 152-178.
3. Scherer R, Godoy H. 2009. Antioxidant activity index (AAI) by the 2,2-diphenyl-1-picrylhydrazyl method. Food. Chem., 112(1), 654-658.
4. Suzumura K, Yasuhara M, Narita H. 1999. Superoxide anion scavenging properties of fluvastatin and its metabolites. Chem. Pharm. Bull., 47, 1477-1480.
5. Pick, E; Keisari, Y. 1980. A simple colorimetric method for the measurement of hydrogen peroxide produced by cells in culture. J. immunol. Methods., 38(1505), 161-170.
6. Bligh EG, Dyer WJ. A rapid method of total lipid extraction and purification. Can. J. Biochem. Physiol., 37(8), 911-917.