Adsorptive recovery of health-beneficial compounds from apple juice.

Background -- Numerous epidemiological studies have revealed a positive correlation between a diet rich in fruits and vegetables and a decreased incidence of certain degenerative diseases. Therefore, research interest has been focused on plant secondary metabolites, such as polyphenolics and carotenoids, which have been shown to exert certain health-beneficial effects. There is a need to find commercially appropriate means to isolate and concentrate these compounds as ingredients for functional or enriched foods. Objective -- The objective of this study was to systematically investigate the effect of various parameters on the adsorption and desorption behaviour of monomeric and polymeric phenolic compounds using a food grade polymeric adsorption resin. Design -- Batch adsorption experiments on a laboratory scale were conducted with fixed amounts of a diluted apple juice concentrate and weighed portions of a methacrylic resin under continuous stirring in a nitrogen atmosphere. The juice was allowed to be in contact with the resin until saturation conditions were achieved. Accelerated Solvent Extraction (ASE) technology was applied to study the elution efficiency of different solvents using resin which had been saturated with apple polyphenolics. Outcomes -- Although commonly applied in industrial processes there is still a lack of experimental data to predict performance thus making these processes empirical in nature. In contrast to previous findings on the adsorption behaviour of isolated flavonoids a lower pH value improved the adsorption efficiency. Moreover, a decrease in temperature and a higher feed concentration and juice : resin ratio increased the amount of phenolics bound to the resin. For the recovery of the compounds, the temperature during the elution step was the most important parameter besides the solvent composition. Conclusions -- The present study allows the development of efficient and cost-effective industrial processes that can also be applied to other matrices in order to fractionate and concentrate phenolic compounds for the production of tailor-made plant extract ingredients. [ABSTRACT FROM AUTHOR]