A rapid differentiation between oak honeydew honey and nectar and other honeydew honeys by NMR spectroscopy

An NMR-based approach for rapid differentiation of oak honeydew honey from all other honey types (floral and other honeydew honeys) was proposed. It is based on the identification of the signals of the protons and the carbon of the methylene group of quercitol in the ¹H and ¹³C NMR spectra of honey. The presence of quercitol was supported by TOCSY spectroscopy. Quercitol is a deoxyinositol which is regarded as a good taxonomic marker for the genus Quercus. All samples of oak honeydew honey contained quercitol, while in floral honey samples and honeydew honeys from fir and spruce it was absent. In addition, the described approach is promising with respect to quercitol quantification in honey by qNMR.     

Kinetics of lipid oxidation in the presence of cinnamic acid derivatives

The effects of seven (prenyl‐ and methoxy‐) derivatives of cinnamic acid (0.1 mM) on the kinetics of lipid (sunflower oil triacylglycerols, TGSO) bulk phase oxidation at 80 °C have been compared. Synthesis of prenyl cinnamic acid derivatives: 3‐prenyl‐4‐hydroxy‐cinnamic acid (PHC), 3,5‐diprenyl‐4‐hydroxy‐cinnamic acid (DPHC), 2,2‐di‐methyl‐6‐carboxy‐ethenyl‐2H‐benzopyran (DMCB), 2,2‐dimethyl‐6‐carboxy‐ethenyl‐8‐prenyl‐2H‐benzopyran (DCEPB) present in Brazilian propolis has been performed. The monoprenyl derivative (PHC) has been found to exert a higher antioxidant activity as compared to the diprenyl derivative (DPHC). However, cinnamic acid derivatives DMCB and DCEPB have caused no change in the kinetics of TGSO oxidation. The results obtained have been compared with those on related compounds containing a cinnamic acid moiety as a structural feature, such as 4‐hydroxy‐cinnamic (p‐coumaric), 3‐methoxy‐4‐hydroxy‐cinnamic (ferulic) and 3,5‐dimethoxy‐4‐hydroxy‐cinnamic (sinapic) acids, as well as with data on butylated hydroxytoluene (BHT) and α‐tocopherol (αToc). PHC has shown a stronger antioxidant efficiency than BHT, p‐coumaric and ferulic acid, but a weaker antioxidant efficiency than α‐Toc and sinapic acid. The observed antioxidant effect of DPHC was stronger than that of p‐coumaric and ferulic acids and weaker than that of α‐Toc, BHT and sinapic acid.     

Effect of starter species on the content of some volatile aromatic compounds of kashkaval “Balkan” and kashkaval “Vitosha”

Four kinds of starter cultures created in this country were used for production of kashkaval “Vitosha” and kashkaval “Balkan”. In the process of ripening and storage of the products the changes of some aroma compounds taking part in flavour formation were followed besides acidity, pH and percentage of sodium chloride. Two of the aroma compounds, i.e. diacetyl and ethanol, were of outstanding importance for the quality of kashkaval “Vitosha”, whereas in respect to kashkaval “Balkan” such a relationship was not established. Inference was drawn that the product's flavour was dependent on starter culture and kind of milk.     

The specific chemical profile of Mediterranean propolis from Malta

Seventeen Maltese propolis samples were studied by GC–MS after silylation. They exhibited the typical Mediterranean chemical profile, rich in diterpene compounds (18–92% of TIC, GC–MS): 32 individual diterpenes were identified; 22 of them were present in each specimen. The other abundant compound group was that of sugars and sugar derivatives. In some samples, however, another compound group was observed (0–12% of TIC, GC–MS); the corresponding mass spectra were consistent with mono- and sesquiterpenyl esters of substituted benzoic acids. Two new propolis constituents of this group, daucane diterpene esters of hydroxybenzoic acids, were isolated. Their origin is suggested to be Ferula communis, as they are taxonomic markers for this species. All propolis samples were active against Staphylococcus aureus but only those with high concentrations of terpenyl esters showed antifungal activity against Candida albicans. The present results confirm that Mediterranean propolis is a valuable natural product with potential to improve human health.     

The effect of malondialdehyde in the diet of pregnant and lactating female rats on the lipid peroxidation process and physical development of newborn rats

Intake of malonic dialdehyde (MDA) with drinking water by pregnant and lactating rats did not result in MDA accumulation in their body or in significant shifts in the system lipid peroxidation--antioxidant activity (LPO-AOA). However, two litters of progeny from rats, that ingested MDA, were found to be nonviable with drastically diminished mass of their brain and significant shifts in the system LPO-AOA. High content of MDA, sharply reduced concentration of lipid hydroperoxides, and lowered AOA were detected in the brain tissue, red blood cells and blood plasma of 15-day rats whose mothers ingested MDA during pregnancy and lactation. The lowered activity of the system LPO-AOA in the test young rats was attended by retardation of their physical development.