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.