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.

Ethanol and water extracts were prepared from defatted cranberry pomace by pressurized liquid extraction and tested in bacterial cultures of L. monocytogenes, B. thermospacta, P. putida, lactic acid bacteria (LAB), aerobic mesophilic bacteria (AMB), and pork meat products. Anthocynanins (glucosides, galactosides and arabinosides of cyanidin and peonidins), phenolic compounds and organic acids (quinic, chlorogenic, malic and citric acids; procyanidin B3, myricetin and quercetin derivatives) were determined in the extracts. The extracts effectively inhibited the growth of tested bacteria at higher than 3.3% concentration. The effect of 2% ethanol extract additive on the inhibition of the same bacteria was also determined in non-inoculated and inoculated with bacteria pork slurry, pork burgers, and cooked ham. The results showed a significant growth inhibition of pathogenic L. monocytogenes and some other species in pork slurry, burgers and cooked ham with cranberry pomace ethanol extract as compared with the control samples. The extract also effectively inhibited the formation of oxidation indicator malondialdehyde in meat products. Slight impact of extract on some physico-chemical properties of meat products such as pH, metmyoglobin content was also observed, while it did not have significant influence on water activity. Extract addition imparted some color changes; however, it did not have negative effect on the overall sensory quality of burgers and cooked ham. High effectiveness of extract additive against pathogenic L. monocytogenes and some other tested bacteria in pork slurry, burgers and cooked ham during refrigerated storage for 16, 16 and 40 days, respectively, suggest that ethanol extract of defatted cranberry pomace may be a promising natural ingredient of meat products for increasing their microbiological safety and improving oxidative stability.