Chemical composition of seeds of four Bulgarian grape varieties

Composição química das grainhas de quatro castas búlgaras

¹ Department of Chemical Technology, University of Plovdiv “Paisii Hilendarski”, 24 Tzar Assen Str., 4000 Plovdiv, Bulgaria
² Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Science, 1113 Sofia, Bulgaria

^* corresponding author: Tel: +359 32 261269; +359 32 261 277; e-mail: magzlat@uni-plovdiv.bg

Received: 21 January 2016
Accepted: 2 June 2016

Abstract

The composition of grape seeds from two white dessert (‘Bolgar’ and ‘Super ran Bolgar’) and two red wine Bulgarian varieties (‘Mavroud’ and ‘Shiroka melnishka loza’) was investigated. The content of proteins was established by Kjeldhal method and was found to be 6.3 – 8.9%. The content of carbohydrates - calculated as the difference of mean values: 100 - (amount in percentage of oil, moisture, protein and ash) - was 65.5 – 70.9%. The content of oil – by extraction with n-hexane - was 11.6 - 16.5%. The content of phospholipids was determined spectrophotometrically after isolation by chromatographic methods and was found to be 0.6 - 0.9%, including phosphatidylcholine, phosphatidylinositol and phosphatidic acids. The sterol content determined by gas chromatography was 0.3 – 0.4% while β-sitosterol (70.0 – 72.1%) and campesterol (18.5 – 19.9%) were the major components. In the phospholipids and sterol esters, saturated and monounsaturated fatty acids presented higher amount than the triacylglycerols. Fatty acids of sterol esters and phospholipids were determined by gas chromatography after isolation. The quantity of palmitic acid in the phospholipid fraction was 43.4 – 59.4%, the content of oleic acid was 9.0 – 14.0% and the content of linoleic acid was 10.0 – 24.5% while in the sterol esters, the predominant ones were mainly linoleic (40.7 – 53.8%), oleic (24.9 – 35.5%) and palmitic acids (13.0 – 16.7%). Linoleic (68.5 – 72.3%) and oleic acids (16.3 – 18.7%) were found to be the main components of the triacylglycerols. The tocopherol content varied from 67.7 mg kg-1 to 290.5 mg kg-1 where α-tocopherol (74.8 – 84.4%) was the predominant component.

Resumo

Foi estudada a composição das grainhas de duas castas brancas (‘Bolgar’ e ‘Super ran Bolgar’) e de duas castas tintas búlgaras (‘Mavroud’ e ‘Shiroka melnishka loza’). O teor de proteínas foi determinado pelo método de Kjeldhal, estando compreendido entre 6.3 e 8.9%. O teor de glúcidos – calculado como a diferença de valores médios: 100 - (teor em percentagem do óleo, humidade, proteína e cinzas) – foi de 65.5 – 70.9%. O teor de óleo – extraído com n-hexano – foi de 11.6 - 16.5%. A concentração de fosfolípidos foi determinada espectrofotometricamente após isolamento por métodos cromatográficos, sendo de 0.6 - 0.9%, incluindo fosfatidilcolina, fosfatidilinositol e ácidos fosfatídicos. A fração dos esteróis, determinada por cromatografia gasosa, representou 0.3 - 0.4%, sendo maioritariamente constituída por β-sitosterol (70.0 – 72.1%) e por campesterol (18.5 – 19.9%). Nos fosfolípidos e ésteres de esteróis, os ácidos gordos saturados e monoinsaturados apresentaram preponderância relativamente aos triacilgliceróis. A análise dos ácidos gordos foi efetuada, após isolamento, por cromatografia gasosa. Na fração fosfolipídica, a quantidade de ácido palmítico variou entre 43.4 e 59.4%, a de ácido oleico foi de 9.0 – 14.0% e a de ácido linoleico foi de 10.0 – 24.5%. Já nos ésteres de esteróis, observou-se predominância do ácido linoleico (40.7 – 53.8%), do ácido oleico (24.9 – 35.5%) e do ácido palmítico (13.0 – 16.7%). Verificou-se ainda que os ácidos linoleico (68.5 – 72.3%) e oleico (16.3 – 18.7%) constituíam os principais componentes dos triacilgliceróis. O teor de tocoferol variou entre 67.7 mg kg-1 e 290.5 mg kg-1, sendo preponderante o α-tocoferol (74.8 – 84.4%).