Effect of Concentration by Boiling at Atmospheric Pressure on Mineral Content of White and Red Grape Juices

Pekmez (molasses), concentrated by boiling in open vessel at atmospheric pressure from sugar-rich fruit and vegetable juices, is a traditional product consumed widely in Turkey. In this works, heat treatment during the concentration by boiling in open vessel at atmospheric pressure was examined the effect on major and minor elements of grape juices. After the white and red grape juice were concentrated in open vessel at atmospheric pressure up to 50, 60 and 70 o Bx, minerals in samples were determined by ICP-AES. The content of Ca, B, Fe, K, Mn, and P increased in both grape juices concentrated up to 50 and 60 o Bx, and decreased in 70 o Bx. The highest decrease was occurred to be 96.83% in Pb of red grape juice during the concentration process. While, similar to the red grape juice, the most reduction was seen to be 79.23% in Pb of white grape juice concentrated up to 70 o Bx, decrease in the content of Ni, Zn, Fe, Cu and S was determined to be 74.37, 45.30, 34.88, 31.15 and 26.16%, respectively.