most important stages in producing date juice is purification and decolorization because the extracted date juice is brown and unsuitable for use in food industries. Liming-phosphatation is an alkaline clarification which is based on the reaction of lime and phosphoric acid, producing calcium phosphate, such that suspended particles in extracted juice are entrapped in the coagulum and removed. Saturated lime (212g CaO/Lit) was added to date juice with a 15min holding time; then phosphoric acid was gradually added to the mixture to form calcium phosphate. Electrical conductivity and turbidity tests were used to determine the best pH for clarification. Findings indicated that the best pH for the removal of turbidity was from 4.5 to 5, whereas minimum electrical conductivity (lowest ash content of juice) was at a pH of about 6 to 6.5. Minimum of turbidity was selected to be the best point for alkaline clarification of date juice, but at this pH, some of the calcium phosphates were in soluble forms. To prevent lime precipitation, it is necessary to heat date juice after liming–phosphatation (15min, 70°C), depending on the variety of the date, turbidity removal was 93-97% and Colour removal at 420 and 560 nanometer were 6-19% and 14-19%, respectively
کلید واژگان :date juice .clarification .turbidity,. calcium phosphate . electrical conductivity, phosphatation
ارزش ریالی : 600000 ریال
با پرداخت الکترونیک