The effect of heating at various temperatures (30, 40, 50, 60, 70 and 80 °C) on dynamic viscosity, colour, 5-hydroxymethylfurfural (5-HMF) concentration and diastase activity of raw rape honey were assessed. In fresh honey, moisture, ash, free acidity, pH and electrical conductivity averaged 185.3 g kg(-1), 1.2 g kg(-1), 18.71 mEq kg(-1), 4.2 and 0.25 mS cm(-1), respectively. Heating significantly (p ≤ 0.05) increased lightness (L*), yellowness (b*), chroma (C*), hue (h°) values, but decreased redness (a*). The viscosity at 20 °C (33.6 Pa s) differed significantly (p ≤ 0.01) with those at 30, 40 and 50 °C (8.2, 2.5, and 1.6 Pa s, respectively). Diastase activity decreased concomitant with heating at higher temperatures. Honey heated at 80 °C for 15 min showed the maximum increase of 5-HMF content, with an average of 1.9 mg kg(-1) (62 %), compared to unheated samples. Heating for 15 min between 50 °C and 80 °C did not significantly degrade the quality of the honey, but, slightly enhanced formation of 5-HMF and reduced the diastase activity.

No abstract

The stability of the physico-chemical and sensory characteristics of yoghurts during refrigerated storage is important for industry and the consumer. The aim of the study was to evaluate the nutritional value, microbiological quality, sensory properties, and structure of natural probiotic yoghurts made with the addition of sea buckthorn fruit mousse during refrigerated storage. In this study, we produced natural, probiotic organic yoghurts with the addition of superfoods, i.e., sea buckthorn (Hippophae rhamnoides L.) fruit mousse, using ABT-1 probiotic yoghurt starter culture based on Lactobacillus acidophilus LA-5, Bifidobacterium lactis BB-12, and Streptococcus thermophilus. Physico-chemical (acidity, nutritional value, and structure) as well as microbiological and sensory changes occurring during 21-day refrigerated storage were determined. The yoghurts were characterized by high sanitary and hygienic quality during the whole refrigerated storage. Fourier-Transform Infrared (FTIR) spectra were also used in the analyses of the obtained yoghurt samples. The applied yoghurt additive was visible at the spectral level as an increase in the intensity of the characteristic bands for vibrations related to protein, fat, and polysaccharide structures. Sea buckthorn can be used as a modern and unconventional addition to yoghurts with health-promoting properties. Micrographic studies have shown that the addition of sea buckthorn mousse significantly changes the microstructure of the yoghurt. The structure of sea buckthorn to yoghurt seems to be more susceptible to the influence of damaging factors, which is also confirmed by the FTIR test conducted during the storage.

No abstract

The aim of the study was to determine the effect of age of cows, i.e. subsequent lactation and stage of lactation, on bioactive whey protein content in milk of dairy cows of six primary breeds kept in Poland. In all cases the significant correlations between lactoferrin concentration in milk and stage of lactation was stated. Its content gradually increased with the course of lactation but the changes in the content of this protein were highly dependent on breed of cows, what was indicated also by high interactions between breed and stage of lactation.