Anthocyanin composition of the red wine Babić affected by maceration treatment

Identification of anthocyanins in the wine made of the Croatian autochthonous grape variety of Babić (Vitis vinifera L.) was carried out and their profile was determined by means of high-performance liquid chromatography with diode array and mass spectrometric detection. Dependence of anthocyanins content and profile on maceration treatment conditions was investigated. Statistically significant differences of anthocyanins concentration in wines Babić produced by various maceration treatments were confirmed by the use of multivariate analysis of variances. The investigation results indicated that the maceration temperature exerts higher influence on anthocyanins concentration than the duration of maceration. In addition, on the basis of anthocyanin composition and using different multivariate statistical analyses, differentiation of wines Babić according to maceration treatments was procured.     

Hydrogen gas sensing properties of WO3 sputter-deposited thin films enhanced by on-top deposited CuO nanoclusters

Magnetron-based gas aggregation cluster source (GAS) was used to prepare high-purity CuO (cupric oxide) nanoclusters on top of sputter-deposited thin film of tungsten trioxide (WO₃). The material was assembled as a conductometric hydrogen gas sensor and its response was tested and evaluated. It is demonstrated that addition of CuO clusters noticeably enhances the sensitivity of the pure WO₃ thin film. With an increasing amount of CuO clusters the sensitivity of CuO/WO₃ system rises further. When CuO clusters form a sufficiently thick and compact layer, the resistance response is reversed. Based on the sensorial behavior, conventional and near-ambient pressure X-Ray photoemission spectroscopies, and resistivity measurements, we propose that the sensing mechanism is based on the formation of nano-sized p-n junctions in between p-type CuO and n-type WO₃. The advantages of the GAS technique for preparing sensorial and/or catalytically active materials are emphasized.     

Intracellular disintegration by shockwave pretreatment accelerates “dry fermentation”

Dry fermentation refers to the process of anaerobic digestion that does not take place in a mixable liquid environment but in stacks loaded into airtight chambers. Since it is difficult for anaerobic consortia to decompose biomass without operating fluid, the process of dry fermentation is time consuming and considered technically inefficient. However, the construction costs of such biogas plants are significantly lower in comparison to conventional continuous technologies. Shockwave pretreatment is a modern method of intracellular disintegration that occurs purely on the basis of physical forces. It was confirmed for the first time that shockwaves are capable of accelerating methanogenesis, even in technologies that do not utilise a process liquid. This finding opens up new opportunities with regards to the processing of feedstock such as solid biowaste.     

Rapid and Sensitive Detection of Staphylococcus aureus in Food Using Selective Enrichment and Real-Time PCR Targeting a New Gene Marker

Staphylococcus aureus is a bacterial pathogen considered a principal etiological agent of food poisoning. The aim of this study was to develop and evaluate a rapid and sensitive method for the detection of S. aureus in food by using selective enrichment and a new species-specific real-time polymerase chain reaction (PCR). Specific primers and a TaqMan probe targeted to specific S. aureus gene encoding for acriflavine resistance protein were designed. The real-time PCR was highly specific for S. aureus with 100% inclusivity and 100% exclusivity determined using 83 S. aureus strains and 64 non-S.-aureus strains. PCR detection limit of 6.8 × 10¹ and 3.4 × 10¹ CFU ml⁻¹ were obtained with 100% and 70% detection probability, respectively. The single selective enrichment based on the study of different enrichment conditions was selected and a lysis by boiling was used to obtain bacterial DNA. Out of 112 food samples analyzed, 61 were positive by the PCR-based method and 53 by the standard method. Out of ten food matrices artificially contaminated at a level of 10° CFU g⁻¹, ten and six were positive by the respective methods. Moreover, 10° CFU 10 g⁻¹ was detected in all ten artificially contaminated samples after a large-scale enrichment using PCR-based detection, in contrast to seven false negative by standard detection. The developed method facilitated the detection of S. aureus on the next day after the sample reception. This method can be used for S. aureus detection as a faster, highly specific, and more sensitive alternative to microbiological method with the potential for providing of improved food-processing hygiene control.