One of the most promising areas of development in the human nutritional field over the last two decades has been the use of probiotics and recognition of their role in human health and disease. Lactic acid-producing bacteria are the most commonly used probiotics in foods. It is well known that probiotics have a number of beneficial health effects in humans and animals. They play an important role in the protection of the host against harmful microorganisms and also strengthen the immune system. Some probiotics have also been found to improve feed digestibility and reduce metabolic disorders. They must be safe, acid and bile tolerant, and able to adhere and colonize the intestinal tract. The means by which probiotic bacteria elicit their health effects are not understood fully, but may include competitive exclusion of enteric pathogens, neutralization of dietary carcinogens, production of antimicrobial metabolites, and modulation of mucosal and systemic immune function. So far, lactic acid bacteria isolated only from the human gastrointestinal tract are recommended by the Food and Agriculture Organization (FAO) and World Health Organization (WHO) for use as probiotics by humans. However, more and more studies suggest that strains considered to be probiotics could be isolated from fermented products of animal origin, as well as from non-dairy fermented products. Traditional fermented products are a rich source of microorganisms, some of which may exhibit probiotic properties. They conform to the FAO/WHO recommendation, with one exception; they have not been isolated from human gastrointestinal tract. In light of extensive new scientific evidence, should the possibility of changing the current FAO/WHO requirements for the definition of probiotic bacteria be considered?

The positive impact of probiotic strains on human health has become more evident than ever before. Often delivered through food, dietary products, supplements, and drugs, different legislations for safety and efficacy issues have been prepared. Furthermore, regulatory agencies have addressed various approaches toward these products, whether they authorize claims mentioning a disease’s diagnosis, prevention, or treatment. Due to the diversity of bacteria and yeast strains, strict approaches have been designed to assess for side effects and post-market surveillance. One of the most essential delivery systems of probiotics is within food, due to the great beneficial health effects of this system compared to pharmaceutical products and also due to the increasing importance of food and nutrition. Modern lifestyle or various diseases lead to an imbalance of the intestinal flora. Nonetheless, as the amount of probiotic use needs accurate calculations, different factors should also be taken into consideration. One of the novelties of this review is the presentation of the beneficial effects of the administration of probiotics as a potential adjuvant therapy in COVID-19. Thus, this paper provides an integrative overview of different aspects of probiotics, from human health care applications to safety, quality, and control.

Lactic acid bacteria (LAB), due to their many advantageous features, have been utilized in food manufacturing for centuries. Spontaneous fermentation, in which LAB play a fundamental role, is one of the oldest methods of food preservation. LAB survival and viability in various food products are of great importance. During technological processes, external physicochemical stressors appear often in combinations. To ensure the survival of LAB, adjustment of optimal physicochemical conditions should be considered. LAB strains should be carefully selected for particular food matrices and the technological processes involved. The LAB’s robustness to different environmental stressors includes different defense mechanisms against stress, including the phenomenon of adaptation, and cross-protection. Recently established positive health effects and influence on human wellbeing have caused LAB to be some of the most desirable microorganisms in the food industry. A good understanding of LAB defense and adaptation mechanisms can lead to both optimization of food production and storage conditions, as well as to obtaining LAB strains with increased tolerance to stressors. Hopefully, as a result, the final food product with naturally present or added LAB can achieve outstanding quality and safety with health benefits that meet consumer expectations.

Lactic acid fermentation is one of the oldest and most commonly used methods of bioconservation. This process is widely used for food preservation and also for a production technique that relies on the metabolism of lactic acid bacteria (LAB) to convert carbohydrates into lactic acid. This fermentation imparts unique flavors and texture of foods, extends their shelf life, and can offer health benefits. There are both traditional and new microorganisms involved in the lactic acid fermentation of food. The current review outlines the issues of fermented foods. Based on traditional fermentation methods, a broad panorama of various food products is presented, with the microorganisms involved. The methods of both traditional fermentation (spontaneous and back-slopping) as well as the importance and application of starter cultures in mass food production are presented. Currently, based on the results of scientific research, the health-promoting effect of fermented foods is becoming more and more important. This is due to the presence of probiotic microorganisms that are naturally presented or may be added to them, as starter cultures or additives, and from the presence of prebiotics and postbiotics. New innovative methods of using probiotic microorganisms open up new and broad perspectives for fermented functional foods.

Oscypek and korycinski are traditional Polish cheeses, exclusively produced in Tatra and in Podlasie region, respectively, produced from raw, unpasteurized milk. The 29Lactobacillus plantarumstrains were isolated on MRS agar from 12 cheese samples and used as a material for study. The main purpose of the work was to assess the antimicrobial properties and recognition of selected strains for the unique antagonistic activity and preservation role in food. It has been found that the highest antimicrobial activity was observed in the case ofL. monocytogenesstrains; however, the level of that activity was different depending on theLb. plantarumstrain. Strains from oscypek produced broad spectrum, and a few strains isolated from korycinski cheese produced a narrow spectrum of antimicrobial compounds, other than organic acids and hydrogen peroxide. Moreover, the antagonistic activity shown byLb. plantarumstrains is connected with the source from which a given strain was isolated. Strains isolated from oscypek cheese represented stronger activity againstL. monocytogenes, whereas strains isolated from korycinski cheese were more active againstE. coli. StrainsLb. plantarumOs13 and Kor14 could be considered as good candidates for protective cultures to extend durability of food products.