Antioxidant Japanese plum (Prunus salicina) microparticles with potential for food preservation

• Plum skin and flesh fibre microparticles (MPCs) retained polyphenols after extraction.
• Proanthocyanidin pentamers (200–170 mg/100g) were the main phenolics in MPCs.
• Anthocyanins (3-galacto and rutinoside) and quercetins were significant in skin MPCs.
• Antioxidant MPCs gave radical scavenging, reducing activity and cellular protection.
• Pectins in pulp and lignin in skin MPCs can provide functionality as food additives.

Fibre microparticles (MPCs) obtained from Japanese plum (Prunus salicina) skin and flesh through ethanolic extraction retained polyphenolic compounds, mainly proanthocyanidins, in 170–200 mg/100 g MPCs levels. Also, phenolics such as anthocyanins (cyanidin 3-galactoside and 3-rutinoside), responsible for red-purple colour, and flavonoids (quercetin derivatives), were found in significant proportions only in the skin MPCs. The MPCs-polyphenolic extract showed antioxidant capability (DPPH and FRAP assays) as well as protective effect against the oxidative stress induced by tert-butylhydroperoxide (t-BOOH) when biologically evaluated on kidney cells, joined to a low cytotoxicity (50%-cytotoxic concentration >100 µg/mL). This is important since health benefits of barely absorbed proanthocyanidins rest on their permanence into the intestine, interfering with oxidative stress implicated in inflammatory disorders. Higher proportions of pectins found in flesh MPCs and of lignin in skin MPCs can provide different fibre functionality. Plum MPCs obtained can be useful as antioxidant natural additives and ingredients for functional food preservation.