Dorina R Chambre1, Mihaela Tociu2, Michaela D Stanescu2, Crisan Popescu3. 1. Faculty of Food Engineering, Tourism and Environmental Protection, Institute for Research, Development and Innovation in Technical and Natural Sciences, Aurel Vlaicu University, Arad, Romania. 2. Faculty of Applied Chemistry and Material Sciences, Politehnica University, Bucharest, Romania. 3. KAO European Research Laboratories, KAO Germany GmbH, Darmstadt, Germany.
Abstract
BACKGROUND: The oils obtained from grape seeds are becoming a valuable way of exploiting winery waste and their properties are scrutinized for evaluating the potential usages. We examined the oils extracted with petroleum ether from grape seeds of four varieties of grapes (Cabernet Sauvignon, Feteasca Neagra, Merlot and Pinot Noir) from Romania looking at the influence of the fatty acid profile and of the antioxidants on their thermal behavior. RESULTS: The fatty acid profiles of the oils were evaluated by 1 H-NMR spectroscopy, and the oil antioxidant capacity was determined by cupric ion reducing antioxidant capacity (CUPRAC) method. The main fatty acid component in all the oils is linoleic acid (over 70%), which, due to its known health benefits, make the oils of commercial interest. The thermal stability of grape seed oils appears to be mainly influenced by the percentage of polyunsaturated fatty acids in their composition, less polyunsaturated fatty acids making the oils more stable. The antioxidant compounds affect only the initial stage of the decomposition by limiting the formation of hydroperoxides in the allylic positions of the fatty acid chain. CONCLUSION: Compared to pure samples of glyceryl-unsaturated fatty acids (glyceryl-trioleate, glyceryl-trilinoleate), the grape seed oils exhibit higher thermal stability, due to the presence of antioxidant compounds and to a synergistic action of unsaturated and saturated fatty acids, smaller percentage of the polyunsaturated and higher percentage of the saturated fatty acids enhancing the stability.
BACKGROUND: The oils obtained from grape seeds are becoming a valuable way of exploiting winery waste and their properties are scrutinized for evaluating the potential usages. We examined the oils extracted with petroleum ether from grape seeds of four varieties of grapes (Cabernet Sauvignon, Feteasca Neagra, Merlot and Pinot Noir) from Romania looking at the influence of the fatty acid profile and of the antioxidants on their thermal behavior. RESULTS: The fatty acid profiles of the oils were evaluated by 1 H-NMR spectroscopy, and the oil antioxidant capacity was determined by cupric ion reducing antioxidant capacity (CUPRAC) method. The main fatty acid component in all the oils is linoleic acid (over 70%), which, due to its known health benefits, make the oils of commercial interest. The thermal stability of grape seed oils appears to be mainly influenced by the percentage of polyunsaturated fatty acids in their composition, less polyunsaturated fatty acids making the oils more stable. The antioxidant compounds affect only the initial stage of the decomposition by limiting the formation of hydroperoxides in the allylic positions of the fatty acid chain. CONCLUSION: Compared to pure samples of glyceryl-unsaturated fatty acids (glyceryl-trioleate, glyceryl-trilinoleate), the grape seed oils exhibit higher thermal stability, due to the presence of antioxidant compounds and to a synergistic action of unsaturated and saturated fatty acids, smaller percentage of the polyunsaturated and higher percentage of the saturated fatty acids enhancing the stability.