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The main aim of this study was to search the influence of exogenous addition of rosavin precursor: cinnamyl alcohol on the enhancing of rosavins content in callus culture of R. rosea, cultured on solid and liquid media (CCA). This is the first report – according to available literature – which concerns its biotransformation on solid medium conditions. The two strains of R. rosea tissue cultures showed different ability of cinnamyl alcohol glycosides production: both of them produced rosin (with or without supplementation), but the obtained level of rosavin production was notable higher in case of supplementation of the strain induced from axially buds of R. rosea. The exogenous cinnamyl alcohol was added into medium at concentration of 2.5 mM/L or 5 mM/L in the day of the inoculation. The application of 2.5 mM cinnamyl alcohol resulted in the increase of rosin content in the callus started from hypocotyle to very high levels: 1056.183 mg/100 g on solid medium and 776.330 mg/100 g in liquid medium. The content of rosavin showed the same growing tendency, but the final concentration of this phenylopropanoid in the supplemented callus tissue was about 7 times lower as compared to the roots of intact plant (63.603 mg/100 g). Addition of cinnamyl alcohol also enhanced rosarin biosynthesis but only in small amount: to 4.896 mg/100 g on solid medium. Callus tissue obtained from axially buds and treated by cinnamyl alcohol (2.5 mM) produced rosavin in a higher concentration: 92.801 mg/100 g and reached one fifth part of the amount produced by roots. The process of supplementation with cinnamyl alcohol influenced the enhanced biosynthesis of another bioactive substances as well (salidroside, tyrosol, chlorogenic acid). The obtained results confirmed that even on a solid medium the callus tissue can produce the characteristic active substances and the concentration of some of them, mainly rosin and rosavin, can be significantly improved by addition of the precursors to the medium.
The aim of the present study was to test the possibility of enhancing the synthesis of flavor compounds with a traditional yogurt culture and a culture containing microflora composed of: S. thermophilus : L. delbrueckii ssp. bulgaricus : Bifidobacterium (TBB yogurt) and Str. thermophilus : L. acidophilus : Bifidobacterium (TAB yogurt). Milk was enriched with lactose (10 g/L), glucose (0.7 g/L), sodium proteinate (25 g/L), sodium citrate (3 g/L), a mixture of citric acid (1 g/L) and sodium citrate (3 g/L), and threonine (1 and 3 g/L). The following determinations were made in fresh yogurts (ripened for 24 h) and yogurts stored for 7 and 14 days: active acidity, lactic acid – according to Lunder, acetaldehyde, diacetyl, acetoin, ethanol, and volatile free fatty acids by gas chromatography. All products were evaluated organoleptically. It was found that from among the substances whose effects on the synthesis of flavor compounds were studied in this experiment particular attention should be paid to threonine. The addition of this amino acid significantly affected the rate of acetaldehyde formation (an increase by 10.24-22.56 mg/L) in all kinds of yogurt. The modification of milk composition had a profound influence on the levels (increase or decrease) of all flavor compounds in yogurt samples, as well as on their sensoric attractiveness.
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