Dubravka Vitali

Bioaccessibility of Ca, Mg, Mn and Cu from whole grain tea-biscuits: Impact of proteins, phytic acid and polyphenols

Levels of some essential minerals (Ca, Mg, Cu and Mn) were determined in ten different types of experimentally prepared hard biscuits. In relation to the wheat flour-based reference sample, other investigated samples were enriched with different ratios of integral raw materials of different origin or various dietary fibers in view of improving their functionality and nutritive quality. The goal of the research was to evaluate enriched biscuits as additional sources of calcium, magnesium, copper and manganese in nutrition and to investigate if the modifications of wheat flour based biscuit composition significantly change the amounts of total and bioaccessible minerals in the final product. Since our results indicated significant changes of mineral bioaccessibility among the samples, obtained results were correlated to the content of proteins, phytic acid and polyphenols for the sake of assessing their impact as limiting factors of mineral bioaccessibility in these types of foods.

The content of essential and toxic elements in Croatian propolis samples and their tinctures

Summary There is a general lack of scientific literature dealing with the mineral composition of propolis, despite the fact that the presence of minerals in plant tissues can significantly affect the pharmacotherapeutic properties of derived products. Raw propolis samples collected from different Croatian regions and their respective tinctures were therefore analysed for mineral composition by atomic emission/absorption spectrometry. Contents of macro- and trace elements (Ca, K, Mg, Na, Al, B, Ba, Cr, Cu, Fe, Mn, Ni, Sr and Zn) were determined. Levels of toxic elements (As, Cd, Hg, and Pb) were also analysed, since they are possible environmental contaminants that could be transferred into propolis products for human consumption. Following the European Pharmacopoeia requirements for quality control of herbal drugs, crude propolis samples were also analysed for total ash content. Significant correlation between the total mineral content and total ash of raw propolis (r = 0.9273) showed that total ash might serve as the first information that justifies the need for detailed mineral analysis of tested samples. Among analysed minerals, Ca, Mg, K, Al, Fe and Zn were found to be the most abundant in raw propolis, ranging from 12.06 (Mg) to 932.6 mg/100g (Zn). Mineral contents of all investigated tinctures were significantly lower compared to the respective raw propolis samples. Extractability was variable due to influence of the sample matrix and correlated with the mineral content of raw propolis only in the case of Fe, Mg, Sr and Zn. All samples met the World Health Organization (WHO) standards regarding the maximum permitted amounts of Hg, Pb, As and Cd except for two raw propolis samples with increased lead content indicating pollution of the collection areas.

Chemical traits and antimicrobial activity of endemic Teucrium arduini L. from Mt Biokovo (Croatia)

Chemical composition of the essential oil (analysed by GC-FID and GC-MS), the content of macroelements and trace elements (analysed by ICP-AES), and antimicrobial activities were investigated in Teucrium arduini L. from Mt Biokovo (Croatia). Additionally, a study on the types and distribution of glandular trichomes which produce essential oils was investigated. The oil was characterized by a high concentration of sesquiterpene hydrocarbons (68.5%) of which β-caryophyllene (32.9%) and germacrene D (16.4%) being the major compounds. Among the macroelements, the content of calcium was the highest (9772 mg/kg), while the content of sodium was the smallest (117.74 mg/kg). Among the micronutrients, the most represented element was iron (72.07 mg/kg). The content of each investigated toxic metal (As, Hg, Pb, Cd and Cr) was below permissible levels. The essential oils showed antimicrobial activity against bacterial species tested, with MIC values ranging from 6.25 mg/mL to 37.50 mg/mL. Fungal species were susceptible with MIC values from 7.81 mg/mL and 25.00 mg/mL.