# Effect of Sea Buckthorn (_Hippocampae rhamnes_ L.) Mousse on Properties of Probiotic Yoghurt
## 4 Discussion
### Yoghurts
#### 4.2.4 Microbiological Evaluation  
The activity of the appropriate groups of microorganisms is the basic indicator of the microbiological quality of yoghurt. Apart from the presence of typical flora, its survival is important during the entire shelf-life of the product [70]. The conducted microbiological analysis showed that the dominant species of the characteristic microflora of the tested yoghurts were lactic acid bacteria and bacteria of the genus _Lactobacillus_ and _Bifidobacterium_ derived from the starter culture. An appropriately high concentration of these microorganisms allows to obtain a product with the expected flavour and aroma. According to the guidelines of the _Codex Alimentarius_[71], the number in one gram of product should be at least \(10^{7}\) cfu [72]. In the current study, this value was obtained and maintained throughout the storage period of material batches. Maintaining high concentrations of yoghurt bacteria in refrigerated storage is difficult. Many studies have shown that the number of yoghurt bacteria is then reduced to a level lower than \(10^{7}\) cfu/g [73]. According to [PERSON]'s research [74], only a few percent of yoghurts had the desired number of live lactobacilli during the final storage period. The addition of fruit filling, as research showed, could reduce the number of yoghurt bacteria [75]. In the present study, such an effect of sea buckthorn mouse on lactic acid bacteria, _Lactobacillus_, was not observed, and a temporary decrease in the concentration of _Bifidobacterium_ was recorded only in the first week of storage. A high concentration of yoghurt bacteria determines their functional and probiotic features. Research has shown that the application of lactic acid microorganisms in the diet has a positive effect on the stimulation of the body's immune processes by increasing lymphocyte activity, stabilizing intestinal microbiota, and improving nutrient digestibility and assimilation [76]. Hygienic quality is an important aspect of the shelf life and quality of yoghurt during storage. No growth of saprophytic and pathogenic flora of fecal origin, anaerobic microorganisms, or pathogenic Salmonella and Campylobacter bacilli was observed in the conducted experiments. This confirms the effectiveness of the pasteurization process and good quality of the raw material. These results were consistent with those obtained by other authors, who indicated a small percentage of the tested batches of marketed yoghurts [75; 77]. The presence of yeast-like fungi at the level of \(10^{2}\), noted in yoghurt enriched with sea buckthorn mouse, and their persistence throughout the storage period, should be attributed to the contamination of the additive. Their presence could indicate that the yoghurt batch was deteriorating quickly [78]. The lack of fungal flora development in the tested yoghurt batch was the result of the antagonistic effect of lactic acid against yeast cells. At the same time, an increase in the number of yeasts could stimulate the development of lactic acid bacteria and lower pH of the product, while protecting it against the development of unfavourable flora. This synergism has not been fully elucidated and requires further research on the flora of fermented milk products [79]. This is a result indicating that, despite the high quality of the raw material and the application of thermal disinfection treatments of milk batches, additives of natural origin can be a source of contamination of the final product. Simultaneously, the presence of yeast does not always have to be a negative phenomenon, and with appropriate cooling conditions, preventing their uncontrolled growth, it can stimulate a favourable yoghurt flora.