COMPARATIVE STUDY ON USING ETHANOL AND METHANOL FOR BLACK GRAPES POLYPHENOLS EXTRACTION

Nadia Paun, Violeta Niculescu*, Marius Miricioiu

National Research and Development Institute for Cryogenics and Isotopic Technologies – ICSI Rm. Valcea, 240050, Rm. Valcea, Uzinei Street no. 4, P.O. Box Râureni 7, Valcea, Romania

ABSTRACT

Grape skins are sources for phenolic compounds that contribute to the sensory characteristics and beneficial bioactive properties of many processed foods. Phenolics are widespread constituents of plant foods (fruits, vegetables, cereals, olives, legumes, chocolate) and beverages (tea, coffee, beer, wine), and partially responsible for the overall organoleptic properties of plant foods. Anthocyanins, one of the six subgroups of a large group of plant polyphenol constituents known as flavonoids, are responsible for the orange, red, blue and purple colours of many fruits and vegetables (apples, berries, beets, and onions). It is known that phenolics are the most important compounds affecting flavour and colour difference among wines; they react with oxygen and are critical to the preservation, maturation and aging of the wine. The purpose of this study was to determine and evaluate total phenolic and anthocyanin contents in the ethanol and methanol extracts of the black grapes skins.

Keywords: anthocyanins; extraction; grapes; polyphenols.