Ewa Czerniawska-Piątkowska

The change of fatty acids composition of Polish biscuits during storage.

Commercially available Polish biscuits were stored for 10months under different storage conditions i.e. in temperatures of 5°C and 20°C. The chemical quality alteration caused by chemical reactions occurring within biscuits were studied in terms of change of composition of fat extracted from studied samples in one-month intervals. Correlation of data from standard methods e.g. gas chromatography or classic titration with FT-IR spectroscopy, was followed by calculation of four statistical models that accurately predicted peroxide value, oxidative stability, polar fraction content and unsaturated trans fatty acid content in any samples. On the basis of data obtained, scheme of chemical reactions involved in oxidation process was suggested. A critical time of storage was proposed as an indicator of the period of the highest rate of chemical changes. Among factors considered to influence oxidative stability, the following had the greatest impact: initial water content, initial fat content, and time of storage.

Influence of milk, milk fractions and milk proteins on the growth and viability of mastitis-causing Staphylococcus aureus strain

Abstract The aim of this study was to investigate the impact of milk and milk fractions (cell-reduced, skim and whey) obtained from different cows on the growth rate of mastitis-causing Staphylococcus aureus strain at low inoculum density, simulating the early phase of intramammary infection. The association of the selected milk proteins, including α-lactalbumin, β-lactalbumin, lactoferrin, bovine serum albumin, γ-globulin and casein with the bacterial growth was also analysed. Twelve Polish Holstein-Friesian cows having no history of mastitis during the previous and current lactation were selected for this study. The S. aureus strain used in this study was isolated from a cow with clinical mastitis and was characterised by confirmed ability to spread among cows within a herd. Linear regression coefficients were calculated for associations between milk constituents and bacterial counts in whole milk as dependent variables. The comparison of bacterial growth between whole milk, cell reduced, skim and whey fractions was determined by a one-way analysis of variance (ANOVA). The results of the present study showed that the growth of mastitis-causing S. aureus was less stimulated by whole milk samples and their individual fractions in comparison to the nutrient microbiological medium. The strongest inhibition of bacterial growth was observed for whey fraction. Lactoferrin was the only protein causing a slight decrease in the growth of S. aureus. It was concluded that, depending on its growth medium and antimicrobial properties, milk may be among the factors of key importance for the incidence of this disease among individual cows.

Morphometry of the alimentary system of the long-tailed chinchilla (Chinchilla lanigera)

Streszczenie. Badania wykonano na 40 szynszylach długoogoniastych (Chinchilla lanigera) (20 samic i 20 samców). Zmierzono długość narządów wewnętrznych układu trawiennego oraz ich masę. W celu porównania badanych cech metrycznych samca i samicy dane liczbowe poddano analizie statystycznej. Na podstawie uzyskanych wyników stwierdzono, że średnia długość przełyku, krzywizny większej żołądka i jelita ślepego była większa u samców. Po oszacowaniu masy narządów wewnętrznych ustalono, iż u samca większą wartość niż u samic osiągała masa żołądka i dwunastnicy wraz z zawartym w tych organach pokarmem oraz masa dwunastnicy oczyszczona z resztek treści pokarmowej. Badania pozwoliły wykazać też, że samice charakteryzowały się dłuższymi jelitami niż samce. Stosunek jelita cienkiego do jelita grubego wynosił u samic 1 : 1,52, a u samców 1 : 1,58.