František Kreps

Valorisation of softwood bark through extraction of utilizable chemicals. A review

Softwood bark is an important source for producing chemicals and materials as well as bioenergy. Extraction is regarded as a key technology for obtaining chemicals in general, and valorizing bark as a source of such chemicals in particular. In this paper, properties of 237 compounds identified in various studies dealing with extraction of softwood bark were described. Finally, some challenges and perspectives on the production of chemicals from bark are discussed.

Composition of fatty acids and tocopherols in peels, seeds and leaves of Sea buckthorn

Abstract Peels, seeds and leaves of the Sea buckthorn were extracted by methanol and chloroform and characterized in terms of the fatty acids (FA) and tocopherol composition. All morphological parts of Sea buckthorn contained these biologically active compounds useful in medicine, pharmacology, human nutrition and cosmetics. The highest amount of α-tocopherol was found in peels (1103 mg kg-1). The lowest content of α-tocopherol was found in leaves (659 mg kg-1). Delta-tocopherol was found in higher amount in peels 1757 mg kg-1. Seeds contained 95 mg kg-1 of delta-tocopherols. Gamma-tocopherol was found in seeds (459 mg kg-1), peels (188 mg kg-1) and in leaves (587 mg kg-1). β-tocopherol was present only in seeds (171 mg kg-1). Unsaturated fatty acids were dominant in all morphological parts of Sea buckthorn. The highest amounts of unsaturated fatty acids (92 rel. %) were determined in seeds. Dominant fatty acids of seeds were linoleic acid (37 %), α-linolenic acid (30 %) and vaccenic acid (20 %). Leaves were rich in α-linolenic acid (51 %). Dominant fatty acids of peels were oleic acid (16 %), palmitic acid (33 %) and palmitoleic acid (29 %).

Antibacterial and antifungal activity of phytosterols and methyl dehydroabietate of Norway spruce bark extracts

The current study focuses on the analysis of in vitro biological activity of extract from bark of Norway spruce (Picea Abies), which can find potential application in food and cosmetic industry and pharmacology. Milled bark was subjected to Soxhlet extraction and supercritical fluid extraction to obtain two ethanol extracts. These extracts were further used to obtain their pre-extracts to n-hexane. It was investigated whether beta-sitosterol exhibits bacteriostatic activity necessary to observe antimicrobial and antifungal activity of methyl dehydroabiatate. This synergic effect and bacteriostatic activity of beta-sitosterol have not been previously reported. The greatest inhibition zone of n-hexane pre-extracts was confirmed in bacterium Pseudomonas aeruginosa (0,9 - 1,5 cm) and yeast Alternaria alternata (0,7 - 1,6 cm). It is novel, the antioxidant, antimicrobial and antifungal activity of spruce bark extracts assessed in terms of food and cosmetic fortification.

Influence of storage and microwave heating on stability of soya spread lipids with linseed content

Influence of storage and microwave heating on stability of soya spread lipids with linseed content We have chosen to experiment with soya spreads containing linseeds, which enrich the spreads with essential fatty acids and valuable related substances. The soya spreads with linseeds represent an ideal combination for nutritionally valuable foods with health benefits. In this work we examined the influence of microwave heating and storage on stability of linseed oil and soya spread lipids. Industrially produced soya spreads (S1) with addition of 5, 7 and 10 % linseeds and linseed oil were stored without a protective atmosphere in refrigerator at 5 °C. The lipids of commercial soya spreads (S2) enriched with 2, 5 and 10 % ground linseeds and soya spread lipids (S2) without linseeds were microwave-heated. The data obtained from experiments have shown that the storing of linseed oil for 30 days in refrigerator has caused excess of the maximum acceptable peroxide value (Food Codex of SR). Microwave-heated lipids from commercial soya spreads (S2) enriched with 2 % ground linseeds have the best result of stability and protective factor, compared with lipids from 5 and 10 % linseeds enriching soya spreads (S2). After the 5, 10 and 20 min of microwave heating, the lipids of soya spread (S2) enriched with 2 % ground linseeds have the protective factor 1.02, 1.15 and 1.43 respectively, compared with lipids from soya spread (S2) without linseeds. The microwave heating for 5 min has been accompanied by a decreasing of hydroperoxides and by formation of secondary oxidation products.

Influence of rapeseed meal on lard stability

Abstract The experiment focused on the possibility to utilise the antioxidant potential of rapeseed meal to stabilize fats. The lard, which was used for this purpose, was characterized by gas chromatography. At first the non-sieved meal was added in lard. It is the least technologically difficult method of utilizing meal. Then, the meal was sieved to obtain five fractions, which were added to lard. The aim was to find a fraction of meal that would best stabilize the lard. The results of lard stability with added fractions were compared with the stability of lard enriched with non-sieved meal. Finally, we obtained ethanol and ethyl acetate extracts from non-sieved meal and from the fraction which was the best stabiliser of lard. The aim was to study the effect of these extracts on the stability of lard. Rapeseed meal has stabilized the lard already at 0.5 wt. % content. The non-sieved meal addition of 1, 2 or 4 wt. % has improved the stability of lard by 1.2-2 times. Adding 8-15 wt. % of meal into lard has increased its stability by 3-8 times. The best lard stability has been determined in the fraction retained on the sieve with mesh size 0.15 mm. The lard with added sieved meal has gained a comparable stability the same as after addition of non-sieved meal. The lard with the same additions of extracts (ethanol and ethyl acetate) from non-sieved meal and from meal with sizes 0.15-0.315 mm was more stable than the lard with addition of meal alone. The lard containing ethanol extracts (0.5 wt. %) has a better stability than the lard containing butylated hydroxytoluene (0.02 wt. %).