Article

Fatty acids, phenolic compounds and antioxidant capacity of the seeds from nine grape cultivars (Vitis vinifera L.)

Ácidos gordos, compostos fenólicos e actividade antioxidante de grainhas provenientes de nove castas (Vitis vinifera L.)

¹ Viticulture Research Institute, Atatürk Strt, Horozköy Ave., 45125 Yunusemre/Manisa, Turkey
² Bati Akdeniz Agricultural Research Institute, Demircikara Strt. Paşa Kavakları Ave. No:11 Antalya, Turkey

^* Corresponding author: Tel.: +902362111071; e-mail: aligguler@gmail.com

Received: 14 June 2021
Accepted: 13 September 2021

Abstract

Seeds are one of the main parts of the grapes, and they contain important constituents such as polyphenols, lipids, proteins and carbohydrates. In this study, oil contents, fatty acid composition, total phenolic content, total flavonoid content, monomeric flavan-3-ols and antioxidant capacities of nine grape seeds from nine cultivars were investigated. The correlations between the analyzed parameters were also examined. The oil contents of seeds ranged from 4.96 to 13.35%. Linoleic acid was the predominant fatty acid in the seeds, and it was followed by oleic acid, palmitic acid, stearic acid, linolenic acid, 11-eicosenoic acid and arachidic acid. Total phenolic and total flavonoid contents were 646.50-1120.78 mg GAE/g and 336.69-589.85 mg CE/g, respectively. ‘Italia’ seeds had the highest antioxidant capacity for DPPH and CUPRAC assays while ‘Cabernet Sauvignon’ seeds had the lowest one. The (-)-epigallocatechin, (+)-catechin, (-)-epigallocatechin gallate, (-)-epicatechin and (-)-epicatechin gallate contents in the seeds varied from 1.23 to 6.53 mg/g, 11.61 to 80.20 mg/g, 0.21 to 0.51 mg/g, 2.78 to 48.26 mg/g and 0.08 to 1.50 mg/g, respectively. The (+)-catechin and (-)-epicatechin were the major flavan-3-ol compounds in the grape seeds. Significant correlations were found between total phenolic content, total flavonoid, RSA (DPPH Radical scavenging activity), CUPRAC (Cupric reducing antioxidant capacity) and flavan-3-ols. Consequently, the current study findings support previous information that grape seeds are an important source of antioxidants as well as unsaturated fatty acids, which have positive effects on human health.

Resumo

As grainhas são uma das principais partes da uva e contêm polifenóis, lípidos, proteínas e hidratos de carbono. Neste estudo, foram avaliados o teor de óleo, a composição em ácidos gordos, os teores de fenólicos totais, teores de flavonóides totais, de 3-flavanóis monoméricos e a atividade antioxidante em grainhas de nove castas. As correlações entre os parâmetros analisados foram também examinadas. O teor de lípidos das grainhas variou de 4,96 a 13,35%. O ácido linoléico foi o ácido gordo predominante nas grainhas, seguido pelo ácido oleico, ácido palmítico, ácido esteárico, ácido linolénico, ácido 11-eicosenoico e ácido eicosanoico. Os teores de compostos fenólicos e flavonóides totais foram de 646,50-1120,78 mg GAE/ge e de 336,69-589,85 mg EC/g, respetivamente. As grainhas da casta ‘Itália’ apresentaram a maior capacidade antioxidante para os ensaios DPPH e CUPRAC, enquanto as grainhas de ‘Cabernet Sauvignon’ apresentaram os valores mais baixos. Os teores de (-)-epigalhocatequina, (+)-catequina, (-)-epigalhocatequina galhato, (-)-epicatequina e (-)-epicatequina galhato nas grainhas variaram de 1,23 a 6,53 mg /g, 11,61 a 80,20 mg/g, 0,21 a 0,51mg/g, 2,78 a 48,26 mg/ge 0,08 a 1,50 mg /g, respetivamente. A (+)-catequina e (-)-epicatequina foram os principais 3-flavanóis nas grainhas. Foram encontradas correlações significativas entre o teor de polifenóis totais totais, flavonóides, RSA, CUPRAC e 3-flavanóis. Consequentemente, os resultados deste estudo corroboram resultados anteriores, evidenciando que as grainhas são uma fonte importante de antioxidantes, bem como de ácidos gordos insaturados, que têm efeitos positivos na saúde humana.