The aim of the study was to investigate the antioxidant properties of sage oil macerates (M) in cod liver oil (CLO) during process oxidation catalyzed by UV radiation. CLO was not only subject to oxidative stabilization but also used as a solvent for active ingredients of sage. Macerates were obtained by combining the sage with CLO, homogenization, maceration, and filtration. The effect of different maceration times (0, 3, 6, 8, 10, 13, and 15 days) and different concentrations of macerate addition (5%, 10%, 25%, and 50%) on the CLO oxidation degree, which was determined by peroxide value (PV), anisidine value (AV), and Totox index, was evaluated. Additionally, the total content of polyphenols in macerates by the Folin-Ciocalteu method, antioxidant activity DPPH, and color was determined. The macerates showed antioxidant properties in CLO. The best effect was shown by the initial macerate (maceration time 0, M0), which in 25% concentration significantly inhibited oxidative processes in CLO. It was also characterized by high content of polyphenols and antioxidant activity of DPPH. Sage macerates can effectively inhibit oxidation of fish oils and prolong their durability.

Fish oils are a source of omega‐3 unsaturated fatty acids which are known for their beneficial effects on human health. These acids are highly unstable and are easily oxidized on storage, whereby their nutrition value deteriorate, undesirable flavor develops, and toxic compounds are generated. Antioxidants extend the fish oil shelf‐life. However, synthetic antioxidants may annihilate the health‐promoting properties of omega‐3 fatty acids, which is not the case when natural antioxidants are used. Application of the latter may bring about many benefits. However, the number of approved natural antioxidants is still very low. Therefore, new sources of natural antioxidants are explored among polyphenol compounds in plants, for example, in herbs, spices, or by‐products of fruit and vegetable processing. A review of studies addressing the application of natural antioxidants in the extension of fish oil shelf‐life is presented and the effectiveness of natural antioxidants in protecting long‐chain omega‐3 fatty acids is discussed. Practical applications The use of natural antioxidants in foods and food supplements raises no reservations as to the toxicological safety and is accepted by consumers. Many natural antioxidants are highly effective in inhibiting oxidation and may be successfully used to extend the shelf‐life of health‐promoting omega‐3 polyunsaturated fatty acids.

Cannabis sativa (hemp) is a plant considered to be abundant in bioactive compounds. The increasing production of hemp oil is leaving considerable amounts of hemp press cakes (HPC), which have not been sufficiently managed so far. One of the directions of development of plant-based food is the use of by-products of the agri-food industry in accordance with the idea of zero waste and the circular economy, so the purpose of this study was to determine the possibility of HPC fermentation using yogurt and kefir cultures and to determine the effect of the type of starter on the properties of the products. In the present study, starter cultures of yogurt (YO 122) and kefir (commercial grains) were used for HPC fermentation. Changes in lactic acid bacteria (LAB) and yeast population, pH, acidity, the content of bioactive compounds by spectrophotometric methods (proteins, amino acids, polyphenols, flavonoids, reducing sugars) and antioxidant activity (DDPH, ABTS, FRAP and reducing power) were determined. The results showed that it was possible to develop high-value beverages based on HPC with high fermentation efficiency: survivability of LAB and yeast (>106 CFU/g) and acidification (pH in a range of 4.82–6.36 and 5.34–6.49 for yogurt and kefir culture, respectively). Moreover, the stability of hemp protein, with its variable free amino acid composition, antioxidant potential and presented changes in polyphenolic content, was observed during storage. The presented results show a new way to manage HPC as an oil industry residue by using it as a raw material for the development of a bioactive food product and illustrate the relationship between applied starter culture, the direction of fermentation and changes in the content of bioactive compounds.

The aim of the study was to assess the antioxidant effect of concentrated oil macerate of sage (M) as a “green extract” in inhibiting the oxidation of Fish Oil (FO). In the homogenization-assisted maceration process, FO was used as a solvent for the sage active substances to produce M, which was then added to FO (25% w/w) and evaluated for its effect by monitoring the level of oxidation during refrigerated and room temperature storage. The macerate also examined polyphenols, plant pigments, DPPH antioxidant potential, oxidation level and sensory quality. It was shown that the maceration process made it possible to obtain aromatized M, containing polyphenols (carnosic acid, carnosol) and pigments, but with an increased level of peroxides, free fatty acids, compared to the control oil. M showed antioxidant properties and inhibited FO oxidation. It showed the best efficiency in FO during refrigerated storage, in the third month it reduced the level of peroxides by about 9 times, compared to the control. M retains unchanged quality at refrigerated temperature for up to 3 months. Sage macerates are „green extracts” that can be used as effective natural antioxidant additives, following preparation improvements to reduce the amount of peroxide formed.

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