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The potential for using extracts of press residues from black, green, red, and white currants and from sea buckthorn berries as sources of antioxidants for foods use was investigated. Press residues were extracted with ethanol in four consecutive extractions, and total Folin-Ciocalteu (F-C) reactive material and authentic phenolic compounds were determined. Radical quenching capability and mechanisms were determined from total peroxyl radical-trapping antioxidant capacity (TRAP) and oxygen radical absorbance capacity (ORAC) assays and from diphenylpicrylhydrazyl (DPPH) kinetics, respectively; specific activities were normalized to F-C reactive concentrations. Levels of total F-C reactive materials in press residue extracts were higher than in many fruits and showed significant radical quenching activity. Black currant had the highest authentic phenol content and ORAC, TRAP, and DPPH reactivity. Sea buckthorn grown in northern Finland showed extremely high total specific DPPH reactivity. These results suggest that berry press residues offer attractive value-added products that can provide antioxidants for use in stabilizing and fortifying foods.

In order to assist developing a natural, safe food-preservative, aqueous ethanolic extracts of leaves and berries of eight Finnish berry plants were fractionated with Sephadex LH-20 column chromatography. For each fraction, phenolic compounds were analyzed with NMR, UPLC-DAD-ESI-MS and HPLC-DAD. The antioxidant activities of the fractions were investigated using oxygen radical absorbance capacity (ORAC) assay, and the antibacterial activities were evaluated against foodborne pathogens Staphylococcus aureus and Escherichia coli. Antioxidant activities of the fractions correlated highly with both the total concentration and structural feature of phenolic compounds, including both flavonoids and non-flavonoid phenolics. ORAC value correlated strongly with the concentration of (+)-catechin, (−)-epicatecin, quercetin glycosides, and anthocyanins. Increase in size and number of sugar moieties may reduce the antioxidative activities of quercetin glycosides. Type of sugar moieties may have a significant role in influencing peroxyl-radicals scavenging ability of quercetin glycosides with monosaccharides as a single sugar moieties. Most of the fractions inhibited the target microbes. S. aureus strains expressed a higher sensitivity to phenolic compounds than E. coli strains.

Phenolic compounds were extracted with food grade solvent of acidified aqueous ethanol from leaves, berries, berry press cakes, and branches of Finnish berry plants and analyzed with HPLC-DAD, UPLC-DAD-ESI-MS and NMR. In addition, press cakes from two berry species and branches from one species were also extracted and analyzed with the same methods. The antioxidant activities of the extracts were evaluated using Folin-Ciocalteau, oxygen radical absorbance capacity (ORAC), DPPH free radical scavenging, and total radical trapping antioxidant parameter (TRAP) assays. The antibacterial activities were investigated against various Gram-negative and Gram-positive foodborne pathogens. The leaf extracts showed higher antioxidative activities (3–20 fold in ORAC assay, 10–20 fold in TRAP) than the berry extracts, in association with the higher contents of phenolic compounds in the leaf extracts; Strongest anti-bacterial effects was observed in the leaf extracts of lingonberry (Vaccinium vitis-idaea), sea buckthorn (Hippophaë rhamnoides ssp. rhamnoides) and saskatoon (Amelanchier alnifolia) on Staphylococcus aureus, Listeria monocytogenes, and Bacillus cereus. However, the antibacterial efficacy varied with bacterial species and strains. The Folin-Ciocalteu, ORAC, and TRAP values was strongly correlated with the total content of flavonoids with less association shown with the content of total phenolics and flavonol glycosides. The results suggest a major contribution of pranthocyanidins and flavan‐3-ols to the antioxidative activities of the extracts. The growth inhibition on Staphylococcus aureus and Bacillus cereus was clearly associated with the content of total phenolics and ellagitannins.