Polyphenols from waste streams of food industry: valorisation of blanch water from marzipan production

Waste fractions of food processing are promising sources of polyphenols, which are of high demand because of their favourable bioactivities. More recently, also wastewater and process water fractions are in focus of research and technologies for downstream processing, which is reviewed here. Adsorption as well as membrane technologies are widely used to achieve selective recovery of polyphenols from waste water. For technical implementation the processing of waste fractions must be separated from the primary food production process. Therefore, the key step is the efficient transfer of the waste fractions into a storable and transportable form of polyphenol-enriched fractions. This strategy is shown exemplarily for the marzipan production. Almond skin and blanch water are waste fractions containing catechin and procyanidins, for which a recycling concept has been developed. The polyphenolic ingredients of the blanch water can be specifically adsorbed by means of Amberlite resins or zeolites with high yield followed by ultrafiltration.

Selective sorption of palladium by thiocarbamoyl-substituted thiacalix[n]arene derivatives immobilized on amberlite resin: application to leach liquors of automotive catalysts

Thiocarbamoyl-substituted thiacalix[n]arene derivatives immobilized on amberlite resins have the potential for application as new adsorbents for selective separation of Pd(ii) ions from leach liquors of automotive catalysts.

Further studies on the adsorption of plant phenols by synthetic polymers

Pyrocatechol, catechol, caffeic acid, chlorogenic acid, safflor yellow A, safflor yellow B, precarthamin and carthamin were effectively adsorbed by insoluble polyvinyl-N-pyr­rolidone (PVP) in a neutral buffer solution. These eight phenols also bound with Amberlite XAD resins, however, the rate was found to be far less efficient than that of PVP. The average rate of the phenol binding was calculated as following order (%): PVP (42.7), Amberlite XAD-2 (16.6), Amberlite XAD-4 (10.1), Amberlite XAD-7 (13.0), Amberlite XAD-8 (17.7). No 3,4-dihydroxyphenylalanine was adsorbed by PVP, while the O-dihydroxylic acid could be removed by Amberlite XAD-4, XAD-7 and XAD-8. Data from using different weights of the test polymers showed that the rate of the phenol adsorption rose in proportion to each increasing amount of the adsorbents. PVP also admittedly maintained its predominent capacity for phenol binding over that of each member of the Amberlite resins.