The antioxidative activity of a total of 92 phenolic extracts from edible and nonedible plant materials (berries, fruits, vegetables, herbs, cereals, tree materials, plant sprouts, and seeds) was examined by autoxidation of methyl linoleate. The content of total phenolics in the extracts was determined spectrometrically according to the Folin-Ciocalteu procedure and calculated as gallic acid equivalents (GAE). Among edible plant materials, remarkable high antioxidant activity and high total phenolic content (GAE > 20 mg/g) were found in berries, especially aronia and crowberry. Apple extracts (two varieties) showed also strong antioxidant activity even though the total phenolic contents were low (GAE < 12.1 mg/g). Among nonedible plant materials, high activities were found in tree materials, especially in willow bark, spruce needles, pine bark and cork, and birch phloem, and in some medicinal plants including heather, bog-rosemary, willow herb, and meadowsweet. In addition, potato peel and beetroot peel extracts showed strong antioxidant effects. To utilize these significant sources of natural antioxidants, further characterization of the phenolic composition is needed.

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Aims: To investigate the antimicrobial properties of phenolic compounds present in Finnish berries against probiotic bacteria and other intestinal bacteria, including pathogenic species. Methods and Results: Antimicrobial activity of pure phenolic compounds representing flavonoids and phenolic acids, and eight extracts from common Finnish berries, was measured against selected Gram‐positive and Gram‐negative bacterial species, including probiotic bacteria and the intestinal pathogen Salmonella. Antimicrobial activity was screened by an agar diffusion method and bacterial growth was measured in liquid culture as a more accurate assay. Myricetin inhibited the growth of all lactic acid bacteria derived from the human gastrointestinal tract flora but it did not affect the Salmonella strain. In general, berry extracts inhibited the growth of Gram‐negative but not Gram‐positive bacteria. These variations may reflect differences in cell surface structures between Gram‐negative and Gram‐positive bacteria. Cloudberry, raspberry and strawberry extracts were strong inhibitors of Salmonella. Sea buckthorn berry and blackcurrant showed the least activity against Gram‐negative bacteria. Conclusions: Different bacterial species exhibit different sensitivities towards phenolics. Significance and Impact of the Study: These properties can be utilized in functional food development and in food preservative purposes.

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This study was aimed at evaluating the antioxidant effectiveness of R-tocopherol and its watersoluble analogue, Trolox, in different lipid systems. The oxidative stability of lipids in bulk and emulsion systems at 37 °C decreased in the order corn oil triglycerides > methyl linoleate > linoleic acid. In both bulk and emulsified linoleic acid, Trolox was a better inhibitor of hydroperoxide formation and decomposition than R-tocopherol. However, in bulk methyl linoleate and corn oil triglycerides, although Trolox was a better inhibitor of hydroperoxide formation, in emulsions, R-tocopherol was a better inhibitor of both the formation and decomposition of hydroperoxides. In emulsified methyl linoleate and corn oil, the partition coefficients of Trolox between lipids and water at high concentrations were not affected by Tween 20, and the antioxidant activity of Trolox decreased because it partitioned into the water phase and Tween 20 micelles. In contrast, in linoleic acid emulsified with Tween 20, the formation of mixed micelles of linoleic acid and Tween 20 increased the percentage of Trolox in the water phase and Trolox was more effective as an antioxidant than R-tocopherol because it diffused in the water phase and into mixed micelles. The physical states of lipid systems affect the distribution of antioxidants and thus significantly influence their antioxidant behavior. Because linoleic acid has unique physical properties in aqueous micelles, it may not be a valid substrate for evaluating food antioxidants.