Production of tartaric acid from pomace of some Anatolian grape cultivars

Production of tartaric acid from pomace of some Anatolian grape cultivators was investigated. Two different extraction methods based on either hot water or dilute acid were used. Based on the chemical analysis the amounts of CaCO3 and GaCl2 to be added into the extract were calculated and, the tartaric acid salts were precipitated as calcium tartrate. Calcium tartrate was first converted into tartaric acid by sulfuric acid treatment then, the tartaric acid was decolorized by means of active carbon and finally, crystallized under vacuum at 70 degrees C. It was found that the calcium tartrate contents using dilute acid extraction were 1.3%, 1.7%, and 2.0% whereas in hot water extraction they were 2.1%, 2.5%, and 3.1% from Emir, Okuzgozu, and Bogazkere pomaces respectively. Tartaric acid contents corresponding to these calcium tartrates were 43.9%, 43.8%, and 44.1% from Emir, Okuzgozu, and Bogazkere grape pomaces, respectively. Tartaric acid amounts recovered from Emir, Okuzgozu, and Bogazkere grape pomaces processed with dilute acid extraction were 0.4%, 0.5%, and 0.6% and from hot water extraction were 0.6%, 0.8%, and 1.1%, respectively. Of two extraction methods hot water extraction was more efficient.