## 4 Discussion  
There is a worldwide increase in consumer interest in organic foods and those with health-promoting properties. Awareness is growing regarding the composition and quality of food products offered on the market. Fermented dairy products, including yoghurt, are a valuable source of nutrients, as well as live LAB strains, which are characterized by antimicrobial activity, among other things, allowing for the maintenance a healthy intestinal microbiota [2]. The use of the manufacturer's declared bacterial species and the maintenance of their counts at a level of not less than \(10^{8}\) CFU/g until the last day of the expiration date for consumption is a key condition from the consumer's point of view [3]. In our study, we quantified the number of LAB in different types of yoghurts available in Poland. This study showed a decrease in LAB with shorter shelf lives in the following yoghurts: bio natural (\(-0.29\) log CFU/g) and probiotic (\(-0.18\) log CFU/g). The LAB count levels did not fall below the recommended value. Similar results are presented by [PERSON] et al. [24], [PERSON] et al. [25] and [PERSON] et al. [26]. [PERSON] et al. [24] showed a statistically significant decrease in the levels of _Bifidobacterium_ spp., _L acidophilus_ and _S. thermophilus_ in yoghurts between the 7 th and 14 th days of storage. [PERSON] et al. [27] showed that the longer the storage time was, the more _L. casei_ abundance decreased, although it did not fall below the WHO recommended values in any sample. In contrast, [PERSON] et al. [28] showed that the total number of viable bacteria in soy yoghurt first increased and then decreased, but all of them met the standard for the number of viable bacteria in probiotic foods. In this study, the highest decrease in LAB was shown for probiotic yoghurt, which is consistent with the results obtained by [PERSON] et al. [29]. According to [PERSON] et al. [30], the decrease in the number of live bacteria during yoghurt storage is mainly related to the phenomenon of acidification during refrigerated storage. Different results regarding the change in bacterial counts during product storage time were obtained by [PERSON] et al. [31] and [PERSON] et al. [32]. In both studies, there were no major fluctuations in bacterial counts during storage [31,32]. In the study by [PERSON] et al. [31], throughout the storage period, the number of bacteria was higher than the dose (\(10^{7}\) CFU/g) recommended by the WHO. In the present study,  
Figure 7: Changes in the number of tested foodborne bacteria in the presence of individual _Lactobacillus_ species (LRA—_Lactobacillus rhamnus_; LPA—_Lactobacillus paracase_; LAC MIX—_L. rhamnus_ and _L. paracasei_). a–c—values marked with different letters differ in a statistically significant way (\(p\leq 0.05\)). there was an increase in bacterial counts in Greek-type yoghurt (0.17 log CFU/g), bio drinkable with strawberries (0.45 log CFU/g) and in bio yoghurt with forest fruits (0.45 log CFU/g) during product storage. [PERSON] and [PERSON] [33] showed that the addition of forest fruit puree to probiotic yoghurt effectively promoted the growth of probiotic bacteria. [PERSON] et al. [16] took into account the addition of blackberry juice to yoghurt and showed its positive effect on the growth of _Lactobacillus_ spp. Different results regarding bacterial counts during the storage of fruit yoghurts were obtained by [PERSON] et al. [34]. During 14 days of product storage, there was a decrease in the viability of _L. acidophilus_, while the number of _Bifidobacterium bifidum_ remained constant. _L. rhamnus_ and _L. paracasei_ were isolated from the yoghurts tested. The obtained results differed from the composition on the packaging of the tested yoghurts. On the other hand, [PERSON] [35] showed the presence of _L. rhamnus_ (DNA-DNA hybridization) in the tested yoghurts, despite the manufacturer's declaration of the presence of Biogarde or Bioghurt culture (which includes _L. acidophilus_ and/or _B. bifidum_ in addition to _S. thermophilus_).