OPTIMIZATION OF THE EXTRACTION OF POLYPHENOLS FROM GRAPE SEEDS

Abstract

In the present work the extractability of polyphenols from grape seed has been studied. In winemaking, the degree of use of grapes as a material for the production of wine or juice reaches the maximum value of 80%, leading to the formation of considerable amounts of secondary products (marc, stalks, yeast, tartaric acid salts). Regarding the chemical composition, secondary winemaking products represent a valuable bonus material for the manufacture of a wide variety of products with an important role in the national economy. The determination of the quantity of the total amount of polyphenols with the help of Folin-Ciocalteu method in a stirred reactor at laboratory scale was made. Different values of temperature, time and concentration of the reagent were applied during the extractions to search for the optimal parameters where the extractability will be the most efficient in quantity and quality. A pulsed electric field was applied on the raw material to study its effect and check its fiability. The effect of the extractability was influenced by the parameters of the applied electric field, due to different values of intensity of the electric field, the number and the duration of impulse. The greater amount of extracted polyphenols was obtained at high temperatures, 30 minutes of extraction, with a concentration of ethanol of 40 %. The grape seed represents a valuable material which contains precious components and therefore the study of extractability is interesting from both scientific and economic point of view.