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Traditional fermented milk products have been prepared since ancient time by various civilizations. Despite their long history, popularity, and nutritive and healthy value, the acceleration and industrialization of food production leads to increase of the diversity of fermented milk products in the Balkan Peninsula. As a result of the multitude of food‐microbe combinations, there are thousands of different types of fermented milk products — yoghurts, yogurt‐like products, and various types of cheeses with proven health benefits. Among those products is the domestic Bulgarian yoghurt “kiselo mlyako”, whose anti‐aging effect has been scientifically studied yet at the beginning of 20th century. The current review summerizes the wide range of traditional fermented milk products at the Balkan countries, which are the primary source for their production.

In this paper, yoghurts from ultrafiltered concentrated whole milk with a volume reduction ratio 0, 2 and 3 with three different probiotic yoghurt starters were obtained. Their physiological, microbiological and rheological properties were examined. The concentrated probiotic yoghurts had high concentration of viable cells of the probiotic strain Lactobacillus delbrueckii ssp. bulgaricus (over 1010cfu/cm3). For the preparation of concentrated probiotic yoghurts the most appropriate volume reduction ratio was 2. The probiotic yoghurts with starters MZ2 and 1CM had the best structure. The concentrated probiotic yoghurts with all starters are functional foods.

This paper presents a research over possibilities to evaluate a cut surface of white brined cheese by images analysis. Samples from seven trademarks of Bulgarian white cheese in brine are evaluated by experts and their cut surfaces are captured with digital camera. A Java application for color images processing in HSI color space is developed. The application executes multilevel thresholding and produces grayscale images with four colors – white, black, light gray and dark gray. The images of all tested cheese samples are processed with this application and there are calculated ratios of pixels with the same color to all pixels in the processed images (Kdiv for white, black, light gray and dark gray colors). The cut surfaces of cheese samples are evaluated by experts and it is performed a correlation analysis between experts’ estimation and the coefficients Kdiv. The results show that there are a significant correlation between experts’ estimation and the pixels with dark gray color (their coefficient Kdiv) in the processed images.

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In the present work, ice cream mixtures with 5%, 10% and 15% lingonberry extract were studied. The lingonberry (Vaccinium vitis-idaea L.) is a source of anthocyanins and flavonoids, which are the bioactive components with good antioxidant properties. There was a significant increase in antioxidant activity (p<0.05) from 133.3 ± 5.6 mM TE/100 g to 249.8 ± 8.3 mM TE/100 g (ABTS method) with increasing the concentration of the extract from 5% to 15%, respectively. Significant changes (p<0.05) in the acidity and dry matter of the samples with lingonberry extract were recorded. After 30 days of storage, a decrease in the antioxidant properties (p<0.05) of the ice cream samples was observed but higher values (mM TE/100 g) were maintained compared to the sample without extract. The color characteristics of the samples were also influenced by the concentration of the extract used. During storage, the highest stability of the colorimetric index a* (red component) was established, which indicates relative color stability during storage.

Spirulina platensis is a cyanobacterium (blue-green algae) that grows in alkaline waters. In food industry, Spirulina’s phycocyanin is used as a natural colorant and stabilizer. The influence of three different concentrations of Spirulina platensis (0.5%, 1% and 1.5%) on physicochemical, textural, antioxidant and sensory parameters of ice cream was studied. It was found that with increasing spirulina concentration, the overrun increases from 30.6% (IC–0) to 48.3% (IC–3). The analysis of texture profile (hardness, adhesiveness, cohesiveness, gumminess) of samples showed a statistically significant difference (p<0.05) between reported values for control sample (IC–0) and the samples with spirulina. Ice cream samples supplemented with spirulina differed with significant increase (p<0.05) in antioxidant activity from 2.8±2.2 mM TE/100 g DW (control sample) to 112.9±4.1 mM TE/100 g DW (IC–3). The addition of Spirulina platensis in ice cream mixture improves its quality and antioxidant properties.

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