Propriedades de equilibrio de sistemas aquosos com acidos policarboxilicos, açucares e sucos de frutas. / Properties of balance of watery systems with acid policarboxilicos, you sweeten and fruit juices.
AUTOR(ES)
Maria Cristina Bevitori Maffia de Oliveira
DATA DE PUBLICAÇÃO
2005
RESUMO
Polycarboxylic acids are important constituents of coffee extract, fermented milk, fruit juice and tomato paste. Sugars occur extensively in food systems like fruit, honey, milk and vegetable. Polycarboxylic acids and sugars are the main soluble solids in fruit juice. Experimental measurement and estimation of equilibrium properties are of great value in research and industrial field. The aim of the present work was to correlate and predict equilibrium properties in aqueous polycarboxylic acid and sugar systems, by using the UNIFAC (UNIversal Functional -group Activity Coefficient) model, which was extended to take into account the partial dissociation of the polycarboxylic acid. The developed model did accurately correlate and predict water activity, pH, solubility, freezing point and boiling temperature in binary, ternary and complex aqueous systems with polycarboxylic acids and sugars. Water activity, freezing point and boiling temperature of fruit juices (grapefruit, lemon, orange, pineapple and tangerine) were accurately predicted, by using their polycarboxylic acid and sugar composition, with deviation of 0.46 %, 0.47 % and 0.04 %, respectively. The pH deviation (6.60 %) could be improved by considering the fruit juice exact composition, despite its variability with fruit cultivation, geography, maturity, season and variety.
ASSUNTO(S)
suco de frutas sugar acids equilibrio acidos fruit juice equilibrium açucar
