Pineapple juice of low acid content was prepared by removal of acids by using weakly basic anion exchange resin, IRA-93. The changes in the contents of titratable acid, pH and total soluble solids of model solutions that contained the principal constituents of pineapple juice (citric acid, citrate salt and sucrose) were investigated. The adsorption of individual acids and changes in composition of juice after a de-acidification process were explored. The adsorbed acids were recovered as solutions by some eluants, and studies on colour development in the recovered solutions carried out. The solutions of adsorbed acids recovered by NaOH from the resin, which had been treated by model solutions, were brown in colour. The brown colour was also found immediately when NaOH was added to the resin treated with pineapple juice but it was not found in the treated juice during acid removal treatment when its pH rose to 10. A greater amount of the dark colour was observed in the desorbed solution from the resin that had been treated with pineapple juice. The use of sulphuric acid, sodium chloride, sodium sulphate, sodium bicarbonate and phosphate buffer solution to desorb the acids from pineapple juice-treated resins reduced the intensity of the colour, measured at pH 3.5, of desorbed acid solutions. The colours of the desorbed solutions were pH dependent. Either solution of sulphuric acid or sodium chloride has a comparable desorbing power to a solution of sodium hydroxide whereas the rest has a lower desorbing power / Master of Science (Hons) (Food Science)
| Identifer | oai:union.ndltd.org:ADTP/235686 |
| Date | January 1994 |
| Creators | Paotrakool, Jiraporn, University of Western Sydney, Hawkesbury, Faculty of Science and Technology, School of Food Science |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Source | THESIS_FIST_XXX_Paotrakool_J.xml |
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