In Vitro Activity of Water Extracts of Olive Oil against Planktonic Cells and Biofilm Formation of Arcobacter-like Species.

Extra-virgin olive oils contain many bioactive substances that are phenolic compounds. The survival of Arcobacter-like strains in non-buffered (WEOO) and buffered (BEOO) extracts of olive oils were studied. Time kill curves of different strains were measured in the environment of olive oil extracts of different grades. The activity of the extracts was also monitored for biofilm formation using the Christensen method. In vitro results revealed that extra-virgin olive oil extracts exhibited the strongest antimicrobial effects, especially non-buffered extracts, which exhibited strain inhibition after only 5 min of exposure. The weakest inhibitory effects were observed for olive oil extracts. A decrease in biofilm formation was observed in the environment of higher WEOO concentrations, although at lower concentrations of extracts, increased biofilm formation occurred due to stress conditions. The dialdehydic forms of oleuropein derivatives, hydroxytyrosol, and tyrosol were the main compounds detected by HPLC-CoulArray. The results indicate that not all olive oils had a similar bactericidal effect, and that bioactivity primarily depended on the content of certain phenolic compounds.

Determination of vitamin E in margarines and edible oils using square wave anodic stripping voltammetry with a glassy carbon paste electrode.

A new electroanalytical method for determination of vitamin E in the form of the total content of tocopherols present in margarines and edible oils has been developed. The method is based on extraction of these biologically active compounds into silicone oil, acting as lipophilic binder of glassy carbon paste electrode, with subsequent electrochemical detection by square wave anodic stripping voltammetry (SWASV) in 0.1M HNO3. The values of vitamin E contents were expressed as mass equivalent of α-tocopherol known as the most active form of this lipophilic vitamin. The linear ranges for α-tocopherol determination were 5×10-7-4×10-5 and 5×10-8-1×10-5molL-1 with the detection limits of 1×10-7 and 3.3×10-9molL-1 for 5 and 15min accumulation, respectively. The results have shown that SWASV with extraction step is very sensitive method for the determination of vitamin E, being comparable to reversed-phase high performance liquid chromatography chosen as reference method.

Content of 5-hydroxymethyl-2-furfural in biscuits for kids.

5-hydroxymethyl-2-furfural (5-HMF) is a thermal decomposition product of saccharides. There are two main ways for the formation of 5-HMF. First, 5-HMF is forming during Maillard reaction and second, during thermic dehydration of saccharides under acid conditions. Significant parameters of 5-HMF formation are temperature, time, pH, water activity, type of saccharide and amino acids. It is suspected that 5-HMF has genotoxic, mutagenic and carcinogenic potential. This chemical can be found in many food sources, e.g. honey, dried fruits, fruit juice and concentrates, alcoholic beverages, bakery products, roasted nuts and seeds, brown sugar, and milk. The present study aimed to determine the amount of 5-HMF in children´s biscuits. The examined samples were divided into three groups. The first group of biscuits claimed availability for children older than six months, the second for children older than one year. The third group did not give a determined age range. For the assessment of 5-HMF, a HPLC method with UV/VIS detection was used. In the first group of samples, the amount of 5-HMF ranged from 0.34±0.04 to 1.73±0.03 mg/kg, in the second group from 0.57±0.09 to 1.78±0.07 mg/kg, and in the third group the amounts of 5-HMF were from 1.80±0.05 to 34.99±0.22 mg/kg. In conclusion, the results showed that the content of 5-HMF in biscuits without age group determination was significantly higher than in biscuits with declared availability for children older than six months or one year. Since the acceptable daily intake is 2 mg/kg bw, the established amount of 5-HMF in all samples cannot be regarded as dangerous in a normal dose of biscuits.