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.

One of the most common materials used for packaging is low density polyethylene film. To improve the water vapour transfer of the film, zeolite¡polymer composite films and perforated films are produced. The solid-low density polyethylene composite films were prepared by extrusion of polyethylene beads coated with hot zeolite particles of a definite size range in an industrial extruder (-420/+212, -212/+106, -106/+53 microparticles/g of polyethylene beads). A needle (0.2, 0.5 and 1.75 mm in diameter) attached to the tip of a soldering gun was used for the production of the perforated polyethylene films (1, 3, 6, 12, 18 and 24 holes per 38.5 cm2). The overall evaluation indicates that the water vapour transfer rates can be modified by the composite and the perforated films, which provides packaging material variety for foods of different moisture content. The solid- polyethylene composite films showed less permeability to water vapour than the polyethylene film. This may be attributed to two reasons: the available polyethylene area is reduced by the presence of solid particles and these solid particles have an important sorption property. The water vapour transfer rates increased by the perforated films.