A combination of direct analysis in real time (DART) ionization coupled to time-of-flight mass spectrometry (TOFMS) and chemometrics was used for animal fat (lard and beef tallow) authentication. This novel instrumentation was employed for rapid profiling of triacylglycerols (TAGs) and polar compounds present in fat samples and their mixtures. Additionally, fat isolated from pork, beef, and pork/beef admixtures was analyzed. Mass spectral records were processed by principal component analysis (PCA) and stepwise linear discriminant analysis (LDA). DART-TOFMS profiles of TAGs were found to be more suitable for the purpose of discrimination among the examined fat types as compared to profiles of polar compounds. The LDA model developed using TAG data enabled not only reliable classification of samples representing neat fats but also detection of admixed lard and tallow at adulteration levels of 5 and 10% (w/w), respectively. The presented approach was also successfully applied to minced meat prepared from pork and beef with comparable fat content. Using the DART-TOFMS TAG profiles of fat isolated from meat mixtures, detection of 10% pork added to beef and vice versa was possible.

Rohlík B-A., Pipek P., Pánek J. (2013): The effect of natural antioxidants on the colour and lipid stability of paprika salami. Czech J. Food Sci., 31: 307-312.The typical red colour of paprika salamis is a very important quality attribute but it is also very susceptible to oxidation. Rosemary extracts and lycopene appear to be efficient antioxidants for dry fermented sausages. The complicated structure of dried sausages with different kinetics of colour changes was evaluated using VIA software NIS-Elements 2.20 and lightness L*, redness a*, yellowness b*, mean red (R), mean green (G), and mean blue (B) were measured; the ratio of red r = R/(R + G + B) and hue h = arctg (a*/b*) were calculated. The addition of rosemary extract has positively affected the colour and suppressed lipid oxidation in both meat and lard particles in the paprika salami. Even more satisfactory results were obtained by adding both the rosemary extract and lycopene. Video image analysis enabled to perform colour measurements of meat and lard particles separately, which could not be done by any available method (reflective spectrophotometry).

Rohlík B.-A., Pipek P., Pánek J. (2010): The effect of natural antioxidants on the colour of dried/cooked sausages. Czech J. Food Sci., 28: 249-257.The colour changes caused by haem pigment oxidation were evaluated in the slices of dried sausages. To slow down these unwanted changes, several colourants and extracts from spices (rosemary, allspice, nutmeg, black pepper, clove, sandal wood, cochineal) were added to the meat product. The colour was evaluated using video image analysis (NIS Elements 2.0 software). The addition of antioxidants showed a positive effect on the colour stability and elimination of colour varieties in different parts of the dried sausage. These colour changes (decrease of redness a*) in cuts of dry sausages exposed to air and the light are influenced by the concentration of rosemary oleoresin, mostly by its light fraction. Video image analysis proved to be a suitable and simple method to monitor these colour changes of dried sausages.

Mathematical modeling of thin-layer solar drying of eland jerky was investigated in this study. Eland jerky was compared to traditional beef jerky, inasmuch as both were treated with traditional jerky marinade (TM), traditional marinade with honey (TMH) and compared to an untreated control (C). The influence of the marinades on the drying process was statistically significant. Based on the coefficients of determination, the root mean square errors and the chi-squares, the two-term model was found to be the most suitable model for describing the solar drying kinetics of eland jerky. The mean effective moisture diffusivities of solar dried eland meat for the C, TM and TMH samples were 2.07 Â 10 −10 , 1.45 Â 10 −10 and 1.43 Â 10 −10 m 2 .s −1 , respectively. The activation energy values for solar dried eland jerky were 23.75, 26.22 and 26.97 kJ mol −1 for C, TM and TMH, respectively.

ABSTRACTŠimoniová A., Rohlík B.-A., Škorpilová T., Petrová M., Pipek P. (2013): Differentiation between fresh and thawed chicken meats. Czech J. Food Sci., 31: 108-115.Adulteration of fresh meat and its possible substitution with frozen and thawed meat represents a problem, since thawed meat has not only lower sensory qualities than fresh meat but also a lower price. Commercial enzymatic kits seem to be a solution to reveal such unfair practises and were applied to detect the activity of specific enzymes, citrate synthase, mitochondrial enzymes that are released from the organelles destroyed by frost. We determined, whether the meat of slaughtered chicken was fresh or frozen/thawed, and to provide convincing results. The absolute results vary with the type of meat and depend on the enzyme used. However, the enzyme activity in the exudates of frozen/ thawed meat is always higher than in fresh meat. This value further increases with each subsequent freezing cycle. The determination of citrate synthase activity was done only in the exudate released from the examined meat samples. However, to determine the enzymes activity directly in unpacked meat, which have not released any exudate, is the subject of further research.