Dairy products enriched with minerals and probiotics play an important role in the development of functional foods. Bifidobacterium animalis ssp. lactis Bb-12 and Lactobacillus rhamnosus are probiotic cultures that have documented positive effects on human health. It also provides the right amount of calcium, which ensures the proper functioning of the human body. The aim of this study was to evaluate the applicability of various calcium salts for the production of milk fermented by two probiotic monocultures. The influence of the type of added salt on fermentation dynamics, bacterial viability, as well as physicochemical and texture properties were determined. This study was intended to develop a recipe for functional probiotic milk enriched in 80 mg Ca 100 g⁻¹ of milk. The present study clearly showed that probiotic fermented milks may be good calcium carriers. Their use led to a novel probiotic product, which requires further research in order to minimize off-taste and off-odor, e.g. by adding aromatic fruit pulp. The fortification of milk with six calcium salts affected fermentation dynamics and the viability of Bifidobacterium Bb-12 and Lb. rhamnosus. All fermented milk met the minimum therapeutic criteria for 21 days of storage (>7 log cfu g⁻¹). Along with the extension of storage time, decreased color brightness L* was observed in all fermented milk, and the range of changes depended on the type of calcium salts and the type of bacteria. Syneresis was most limited by fortification with calcium citrate. However, the addition of calcium lactate adversely affected the hardness of the acid gel. In the opinion of consumers, the use of probiotic monoculture significantly affected off-taste, fermentation odor and off-odor, and the type of calcium salts used significantly affected milky-creamy taste, sour taste, and off-odor.

The enrichment of commonly consumed foods with bioactive components might be helpful in promoting health and reducing the risk of disease, so the enrichment of probiotic fermented milk with vitamin C can be considered appropriate. The effect of vitamin C addition depends on the source of origin (rosehip, acerola and ascorbic acid in powder form) on the growth and survival of Lactobacillus rhamnosus and the quality of fermented milk on the 1st and 21st day of storage was analyzed. The pH, total acidity, vitamin C, syneresis, color, texture profile and numbers of bacterial cells in fermented milk were determined. The organoleptic evaluation was also performed. The degradation of vitamin C in milk was shown to depend on its source. The lowest reduction of vitamin C was determined in milk with rosehip. The least stable was vitamin C naturally found in control milk. The addition of rosehip and acerola decreased syneresis and lightness of milk color, increasing the yellow and red color proportion. In contrast, milk with ascorbic acid was the lightest during the whole experimental period and was characterized by a very soft gel. The growth of Lactobacillus rhamnosus during fermentation was most positively affected by the addition of rosehip. However, the best survival of Lactobacillus rhamnosus was demonstrated in milk with acerola. On the 21st day of storage, the number of L. rhamnosus cells in the control milk and the milk with vitamin C was >8 log cfu g⁻¹, so these milks met the criterion of therapeutic minimum. According to the assessors, the taste and odor contributed by the addition of rosehip was the most intense of all the vitamin C sources used in the study.

The aim of this study was to assess the possibility of using collagen protein hydrolysate in the production of milk fermented by Bifidobacterium animalis ssp. lactis Bb-12 and Lactobacillusrhamnosus. Physicochemical and organoleptic properties were studied and microbiological analysis of fermented milk was performed on days 1 and 21 of storage. Milk with the addition of 3% collagen protein hydrolysate was pasteurized (85 °C/30 min), divided into two groups, cooled to 37 °C and inoculated: the first group with Bifidobacteriumanimalis ssp. lactis Bb-12, second with Lactobacillus rhamnosus. Incubation was carried out at 37 °C/10 h. After 21 days of refrigerated storage, the pH value decreased in all analyzed milk samples. Collagen protein hydrolysate was a good milk additive to increase gel hardness and reduce syneresis. Moreover, its addition did not change the taste and odour of milk fermented with the use of Bifidobacterium Bb-12 and Lactobacillus rhamnosus. Collagen protein hydrolysate favourably stimulated the survival of Bifidobacterium Bb-12 during 21 days of storage. After 21 days of cold storage in milk with collagen, the number of Lactobacillus rhamnosus cells was reduced by 0.11 log cfu g⁻¹.

Collagen has become popular in dietary supplements, beverages and sports nutrition products. Therefore, the aim of this study was to evaluate the possibility of using various doses of collagen and collagen hydrolysate to produce probiotic sheep’s milk fermented with Lactobacillus acidophilus, Lacticaseibacillus casei, Lacticaseibacillus paracasei and Lacticaseibacillus rhamnosus. The effects of storage time, type and dose of collagen, and different probiotic bacteria on the physicochemical, organoleptic and microbiological properties of fermented sheep’s milk at 1 and 21 days of refrigerated storage were investigated. The addition of collagen to sheep’s milk increased the pH value after fermentation and reduced the lactic acid contents of fermented milk compared to control samples. After fermentation, the number of probiotic bacteria cells was higher than 8 log cfu g⁻¹. In sheep’s milk fermented by L. acidophilus and L. casei, good survival of bacteria during storage was observed, and there was no effect of collagen dose on the growth and survival of both strains. The addition of collagen, both in the form of hydrolysate and bovine collagen, resulted in darkening of the color of the milk and increased the sweet taste intensity of the fermented sheep’s milk. However, the addition of hydrolysate was effective in reducing syneresis in each milk sample compared to its control counterpart.

The global market for sheep’s milk and its products is increasing due to higher demand for cheese and traditional dairy products, and as a novelty, sheep’s milk is an ingredient in infant formulas and nutraceuticals. The aim of this study was to determine the properties of fermented sheep’s milk, which combines probiotic benefits with increased dietary fiber content. The influence of the applied dose of chokeberry fiber on the growth of living cells of Lactobacillus acidophilus and Lactobacillus rhamnosus in fermented sheep’s milk was also evaluated. Sheep milk with the addition of 0% (control sample), 1.5%, and 3.0% chokeberry fiber was fermented by two different probiotic monocultures L. acidophilus and L. rhamnosus. In the fermented milk, pH value, syneresis (%), color, and texture were determined. Furthermore, the microbiological analysis and an organoleptic evaluation were performed. With the increasing dose of chokeberry fiber, the pH value decreased already before the fermentation process. After fermentation, the milk’s pH values with fiber were still lower than those in the control sample. Presumably, more acidic metabolites were produced by L. acidophilus, causing a more intense reduction of the pH value than L. rhamnosus both in control milk and in milk with the addition of fiber. The addition of chokeberry fiber affected the stimulation of the growth of both types of bacteria. In the milk sample without fiber addition, a more significant number of viable cells were counted for L. acidophilus by 0.5 log CFU g^-1 more than the milk fermented with L. rhamnosus. Furthermore, in milk fermented by L. acidophilus with 1.5% chokeberry fiber (LA1), the number of viable bacterial cells was higher than that in milk fermented by L. rhamnosus with the same addition of fiber (LR1). However, in sample LA3, the number of viable bacterial cells was lower than that in sample LR3. Tested fermented sheep milk met the Recommendation of the International Dairy Federation’s requirements regarding the number of live bacterial cells for dairy probiotics. The addition of chokeberry fiber increased syneresis in each fermented milk group, regardless of the bacteria used for fermentation. Moreover, the use of fiber caused a significant reduction in brightness , an increase of red color, and a decrease of yellow color. Milk fermented with L. acidophilus was characterized by a harder gel, compared to their analogues fermented with L. rhamnosus. The addition of fiber intensified the sour taste and the taste of the additive in both types of fermented sheep milk.