Enrichment of Flavonoids and Removal of Organic Acid by Treatment of Weak-Base Anion Resins

In the manufacture of flavonoids-enriched hawthorn juice, a high concentration of organic acids is the main problem. In order to produce high quality juice and facilitate its use in many food products, an investigation on the deacidification of Chinese hawthorn juice using an ion exchange process was initiated. Among the tested five resins, D301G was found to perform the best, allowing the production of hawthorn juice with the lowest acidity and highest content of flavonoids. After optimization, a temperature of 30 °C and a flow rate of 10 BV/h were selected, respectively. When one cycle of processing (23 BV) was finished, the physiochemical characteristics of combined juices were analyzed. It was found that over 55 % of initial acid was removed; the concentrated flavonoids reached 3.8 g/kg; and the sugars and minerals contained in the juice underwent negligible changes. Additionally, after regeneration of D301G with 20 cycles, the resin still possessed strong capacity to reduce organic acids and retain flavonoids. Therefore, the current investigation proved that an adsorption processing of hawthorn juice with weakly basic anion exchange resins enabled production of flavonoids-enriched juices with low amount of titratable acidity and without affecting sugars and minerals.