Postbiotics: Science, Technology and Applications

The digestive system has an explicit role in decomposing nutrients into energy and other necessary substances required by the body. The gastrointestinal tract contains a complex set of different microorganisms. It is considered the most dynamic and active organ in the body from a biological perspective. The environmental condition and daily diet are principal parameters that significantly influence the composition of gut microbiota. From birth to middle age, it undergoes significant changes. Several factors, such as maternal microbiota, birth status (natural, cesarean section), postpartum nutrition practices, microbial infections, overuse of antibiotics, diet (highly processed, low fiber), chronic diarrhea, and stress in life, have a significant effect on the gut microbiome. All of these factors lead to impaired bowel function and health. One of the most important strategies for overcoming dysbiosis conditions and establishing eubiosis conditions is the employment of foods containing probiotic, prebiotic, and postbiotic ingredients. Hence, this chapter provides a review of the concept and health-promoting issues regarding probiotics and prebiotics, with a focus on their biological role in the establishment of health.

Probiotics are helpful microorganisms that are resistant to biliary, gastric, and pancreatic secretions and can attach to the epithelial cells and colonize the surface of the intestinal cells. These capabilities are the main mechanisms of probiotics that allow them the adaptation to gut conditions. Probiotic cells attach to the intestinal cells and inhibit the attachment of enteric pathogenic germs to the intestinal mucosa by producing growth-inhibitory elements such as short-chain fatty acids, bacteriocin, and toxic oxygen metabolites. Attaching to the mucosal layer is essential for their functions, but it can increase the possibility of translocation and pathogenicity. On the other hand, there are also concerns about the possible transmission of antimicrobial resistance properties from probiotic strains to pathogenic bacteria in the gut environment. Consequently, the use of probiotics is entirely safe only in healthy people, and also it should be used with caution in children, the elderly, pregnant women, and immunocompromised patients. In recent years, scientists take a new approach to using probiotics in a non-viable form (currently known as postbiotics) to overcome the technological, economic, and clinical problems regarding the application of live probiotics. Hence, this chapter provides an overview of the nutritional and clinical concerns caused by probiotic intake in vulnerable patients, with emphasis on the application of a non-viable form of probiotics as a promising alternative.

The process of producing and distributing probiotics in the matrices of a wide variety of foods in the form of living cells has often been associate with difficulties. Several investigations have been doing to develop or optimize various approaches to maintain the viability of probiotic microbes. On the other hand, in recent years (mainly since 2010), a great deal of attention has been paid to using non-viable forms (postbiotics) bacteria as substitutes for probiotics. The term “postbiotic” refers to modified inactivated microbial cells, cell fractions, or cell metabolites that are naturally or synthetically generated by live probiotic cells and exert biological health-promoting effects to the host when administered in sufficient amounts. This chapter provides an overview of key concepts and main constituents of postbiotics, with emphasis on their biological activities.

Fermentation process is the fundamental and natural way to produce postbiotics. In this process, different microbial strains exploit prebiotics to generate a wide variety of postbiotics with several health-promoting effects (e.g., antimicrobial, antioxidant, anticancer, etc .), by natural methods or in response to environmental conditions. Further, postbiotics play a substantial role in the enrichment of the food matrix. In addition to the natural methods in postbiotics production, different laboratory methods can be used to produce a purer form and with high functionality in fermented and non-fermented food, which in turn improves their nutritional values, shelf-life, and health-beneficial effects in consumers. This chapter will discuss the main laboratory postbiotic production process, with emphasis on their quality controls.

Recent investigations have reported that the intestinal microbiome community possesses a significant health-promoting effect on the host physiology by the secretion of small biomolecules that exerts a unique ability to modulate the host cellular pathways. These small molecules act as a beneficial tool for host-microbial interactions and communication. Based on current evidence, postbiotics have the potency to be a safe and appropriate alternative to prevent side effects pertinent to probiotics besides the enforceable benefits such as treatments of some human complications. These beneficial effects are feasible through various mechanisms that are explained in related chapters. Some of the clinical advantages associated with postbiotics can refer to modulating the immune system, anti-diarrhea, anti-blood pressure activity, reducing blood cholesterol, anti-oxidant and anticancer activity, as well as suppressing cell proliferation. These properties indicate that postbiotics can improve the host’s health circumstances, albeit with unknown mechanisms. Another substantial advantage of postbiotics returns to their desirable immune condition. In this case, there is no need to adsorb the trillions of live microorganisms. Besides, it is possible to impose the postbiotics in a controlled and standard way. However, the live microbes' functions depend on their interactions in the gut and their metabolical activities. Therefore, the compounds of specified bacteria may turn into a biological strategy as a complementary treatment of many important diseases. The main challenge in this respect is the scientific knowledge transformation to commercial applications, which constitute a bridge between science and industry.

Currently, bioactive compounds with health-promoting properties such as probiotics, prebiotics, and postbiotics have been gaining researchers’ consideration. Probiotics and postbiotics are frequently employed in various pharmaceutical industries and/or commercial food-based crops. These bioactive elements can be related to the host eukaryotic cells and possess a vital role in keeping and reestablishing host health. Notwithstanding the efficiency of live probiotic cells, scientists have employed the novel concept of “postbiotic” to augment their advantageous effects as well as to meet the requirements of consumers to provide a safe product. The outcomes of recent investigations suggest that postbiotics might be a suitable substitute for live probiotics and can be used in medical, veterinary, and food practice to hinder and treat some diseases, enhance animal health status and develop functional foods. Currently, scientific reports approved that postbiotics, as a potential substitute, may possess superiority regarding safety issues compared to their parent probiotic cells, and because of their exclusive features in terms of technological, clinical, and economic aspects, can be employed as hopeful approaches in the drug and food industry for developing health benefits, and therapeutic targets. The chapter describes the potential applications of postbiotics in pharmaceutical formulations and commercial food-based crops for health advancement, hindrance of disease, and utilization as complementary treatments.

The matrix of foods and beverages (fermented or/and non-fermented), especially those considered a regular part of the daily diet, are genuine options to add postbiotic ingredients for carrying them. Along with increasing consumer knowledge about the health-promoting effects of functional foods, their demands rise. Hence, in the industrial sector, its promotion is also appreciated. Over the past two decades, as researchers have focused on bioactive compounds, many of these compounds have been identified. Still, despite extensive research, a small number of these compounds have been successfully incorporated into the functional food matrix. It indicates the need for more knowledge and investigation to study the nature of the bioactive compound and high-performance biotechnology methods to using these compounds in the food industry. In this case, postbiotic compounds were also in the early stages of their entry into the food industry, and for a successful presence in this field, they face technological, legal, and commercial challenges. Consequently, understanding the characteristics of postbiotic compounds and nanostructure carriers is essential for designing the best delivery system. This chapter provides an overview of the challenges and strategies for adding postbiotic compounds into the food matrix.