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The objective of this study was to establish the effects of chestnut tannin extract or vitamin E added to linseed oil-enriched diets on growth performance, meat quality, and intestinal morphology of broiler chickens. A total of 240 day-old Ross 308 male broiler chicks were included in trial. 5% of cold-pressed linseed oil was included in finisher diets (21–40 days), and three feeding treatments with four replicates were formed: finisher without additives finisher + 200 IU vitamin E/kg finisher + 500 mg/kg of chestnut wood tannin extract. No significant influence of treatments was established on body weight or feed conversion ratio. A negative effect on feed intake (p < 0.05) was found in the vitamin E group. The addition of vitamin E increased the dressing percentage (p < 0.05) and increased the breast meat yield (p < 0.01) compared to the control group. No significant effects were found on the water holding capacity or pH of breast meat. The highest level of AST (p < 0.01) and ALT (p < 0.05) was recorded in vitamin E group. The addition of chestnut tannin extract in feed increased villus height, villus height: crypt depth ratio, and villus area compared to the other two groups (p < 0.05). It can be concluded that vitamin E supplementation improves carcass percentage and breast meat yield, while chestnut tannins improve the intestinal morphology of broiler chickens when added to oil-enriched diets.The objective of this study was to establish the effects of chestnut tannin extract or vitamin E added to linseed oil-enriched diets on growth performance, meat quality, and intestinal morphology of broiler chickens. A total of 240 day-old Ross 308 male broiler chicks were included in trial. 5% of cold-pressed linseed oil was included in finisher diets (21–40 days), and three feeding treatments with four replicates were formed: finisher without additives finisher + 200 IU vitamin E/kg finisher + 500 mg/kg of chestnut wood tannin extract. No significant influence of treatments was established on body weight or feed conversion ratio. A negative effect on feed intake (p < 0.05) was found in the vitamin E group. The addition of vitamin E increased the dressing percentage (p < 0.05) and increased the breast meat yield (p < 0.01) compared to the control group. No significant effects were found on the water holding capacity or pH of breast meat. The highest level of AST (p < 0.01) and ALT (p < 0.05) was recorded in vitamin E group. The addition of chestnut tannin extract in feed increased villus height, villus height: crypt depth ratio, and villus area compared to the other two groups (p < 0.05). It can be concluded that vitamin E supplementation improves carcass percentage and breast meat yield, while chestnut tannins improve the intestinal morphology of broiler chickens when added to oil-enriched diets.

In a previous study, we examined the synergistic effects of the dietary supranutritional supplementation with vitamin E, vitamin C, and Se on the in vivo antioxidative status of broilers under conditions of dietary oxidative stress induced by feeding a diet high in n-3 PUFA. In this study, we examined the effect of their inclusion on the quality characteristics and oxidative stability of raw or cooked meat, both fresh or after a long-term frozen storage. Four hundred 21-day-old Ross 308 male broilers were allocated to 5 experimental groups fed 5% linseed oil-enriched finisher diets (days 21 to 40): Cont (recommended levels of vitamin E, C, and selenium), +E (200 IU vitamin E/kg feed), +C (250 mg vitamin C/kg feed), +Se (0.2 mg selenium/kg feed), or +ECSe (concentrations as in the sole supplementation, combined). Animal performance and carcass characteristics were monitored at the age of 40 D. Breast meat samples of 12 chickens per group were analysed fresh, fresh after frozen storage, cooked fresh, and cooked after frozen storage (2 × 2 factorial design) for parameters of meat quality (water-holding capacity—WHC, pH, and color) and oxidative stability (concentrations of vitamin E, malondialdehyde—MDA, antioxidant capacity of the water-soluble compounds—ACW, and fatty acid composition). Vitamin E alone (+E) and combined with Se and vitamin C (+ECSe) increased the α-tocopherol concentration in breast muscle, and showed similar protective effects against lipid peroxidation measured as MDA regardless of the frozen storage or cooking. The sole supplementation of vitamin C or selenium showed no effects on the meat quality parameters. In conclusion, the dietary supranutritional inclusion of vitamin E inhibited the lipid peroxidation in fresh, frozen stored, cooked fresh, and frozen stored meat in broilers fed with diets rich in n-3 PUFAs. Even though no clear synergistic effects of the supranutritional supplementation of vitamin C and Se with vitamin E were detected, their dietary inclusion did not negatively affect broilers carcass and meat quality parameters.

The reactivity of tocopherols with 2,2-diphenyl-1-picrylhydrazyl (DPPH) was studied in model systems in order to establish a method for quantifying vitamin E in plant oils. The method was optimized with respect to solvent composition of the assay medium, which has a large influence on the course of reaction of tocopherols with DPPH. The rate of reaction of α-tocopherol with DPPH is higher than that of γ-tocopherol in both protic and aprotic solvents. In ethyl acetate, routinely applied for the analysis of antioxidant potential (AOP) of plant oils, reactions of tocopherols with DPPH are slower and concentration of tocopherols in the assay has a large influence on their molar reactivity. In 2-propanol, however, two electrons are exchanged for both α- and γ-tocopherols, independent of their concentration. 2-propanol is not toxic and is fully compatible with polypropylene labware. The chromatographically determined content of tocopherols and their molar reactivity in the DPPH assay reveal that only tocopherols contribute to the AOP of sunflower oil, whereas the contribution of tocopherols to the AOP of linseed oil is 75%. The DPPH assay in 2-propanol can be applied for rapid and cheap estimation of vitamin E content in plant oils where tocopherols are major antioxidants.

Antioksidanti so snovi, ki preprečujejo oksidacijo drugih molekul. Najpogosteje jih najdemo v različnih živilih, predvsem v sadju in zelenjavi. Velikokrat jih dodamo živilom kot prehranska dopolnila. Najpomembnejši antioksidanti v rastlinskih oljih so predvsem različni analogi vitamina E, tokoferoli in tokotrienoli. Nekatera nerafinirana rastlinska olja pa vsebujejo tudi druge, bolj polarne antioksidante, kot so sezamol, pinoresinol, tirozol in hidroksitirozol ter njihove derivate, kjer se olja ekstrahirajo skupaj z vitaminom E. Namen magistrske naloge je bil določitev antioksidativnega potenciala različnih rastlinskih olj v polarni in nepolarni frakciji z DPPH v različnih topilih. DPPH metoda je ena najpogostejših metod za določanje antioksidativnega potenciala (AOP) olj. AOP smo analizirali v etilacetatu in mešanici alkoholov, ki je vsebovala kislinsko bazni par. Pri svojem delu smo uporabljali oljčno, sezamovo, laneno in sončnično olje. Ugotovili smo, da je bil prispevek polarne frakcije k AOP večji v oljčnem in sezamovem olju kot v lanenem in sončničnem olju. Prav tako je iz naših rezultatov razvidno, da je AOP polarne in nepolarne frakcije olj aditiven s skupnim AOP olj. DPHH metodo v mešanici alkoholov in kislinsko baznega para lahko uporabimo za hitro oceno vsebnosti tokoferolov v sončničnem in lanenem olju. Antioxidants are substances, that prevent oxidization of other molecules. They can be found in various foods most commonly in vegetables and fruits. They are often added to food as food additives. The most important antioxidants in plant oils are various analogs of vitamin E, tocopherols and tocotrienols. Some unrefined plant oils also contain some other, more polar antioxidants, such as sesamol, pinoresinol, tyrosol and hydroxytyrosol and their derivates, that are extracted along with vitamin E into the oils. The aim of this master thesis was to determine the antioxidative potencial of different plant oils in polar and non-polar fraction with DPPH in various solvents. DPPH method is one of the most frequent methods for evaluation of antioxidant potential (AOP) of oils. AOP was analyzed in ethylacetate and in the mixture of alcohols containing acid base pair. We found out, that the contribution of polar fraction to the AOP was greater in olive and sesame oil than in linseed and sunflower oil. Our data also show, that the sum of AOP for polar and non-polar fraction is the same as the AOP of unfractionated oil. DPPH assay performed in the mixture of alcohols containing acid base pair can be applied for rapid estimation of tocopherol content in sunflower and linseed oils.