Tartar Stabilization of Concord Grape Juice by Means of Ion Exchange Resins

Studies on Quality of Grape Juice Part XII

Abstract

Prevention of tartar or argol precipitation in single strength juice of Concord grape (Vitis labrusca L.), that is tartar stabilization, was investigated by means of ion-exchange resins in batch system. Addition of weak basic anion resins, either Diaion WA 10 or Diaion WA 30 resulted in lowering of the titratable acidity. The decrease of acidity was nearly reached to a steady state for 30min after addition of resins. The acidity and tartaric acid in the grape juice treated by 3% (w/v) of weak basic anion resins decreased to 63% and 70%, respectively. On the other hand, potassium content dropped using strong acidic cation resins, either Diaion SK 1 B or Diaion SK 116. The potassium of the grape juice treated by SK 116 decreased to 30% or below, compared with initial potassium content. The tartar precipitation was not observed in the Concord grape juice treated by the weak basic anion resin followed by the strong acidic cation resin. However, the ratio of decrease of soluble solids and amino-form nitrogen was 10 and 30%, respectively. Anthocyanin content in the grape juice treated by both the weak basic and the strong acidic resins was only half of initial content due to adsorption by the resins. From these results, advantage of ion exchange resins was discussed to save labor power and shorten consuming-time in the tartar removal process during the manufacture of grape juice.