# Probiotics in the Sourdough Bread Fermentation: Current Status
## 4 Probiotics and Postbiotics in Sourdough and the Impact on Human Health
This antimicrobial can be applied against harmful food pathogens and used as a food preservative (preserving foods such as dairy products, canned foods, and meats) and a natural antiseptic with bactericidal or bacteriostatic effects. _Lactococcus lactis_ is the microorganism producing nisin, the first fully identified bacteriocin [128]. Among lactic acid bacteria, one of the most versatile and adaptable is _Lactiplantobacillus plantarum_, with a long history of use in foods and claims of benefits as a probiotic. This species has shown promising results in protecting post-harvest fruits and controlling mold in foods such as beverages and bread [129]. _Lactiplantobacillus plantarum_ strain ITM21B has been used to prolong bread shelf-life due to the production of antimicrobial substances, such as lactic, acetic, phenyl lactic (PLA), and hydroxy-phenyl lactic (OH-PLA) acids [130]. [PERSON] et al. 2014 [131] demonstrated that the antifungal compounds produced during fermentation resist sterilization temperatures and remain active adding value for the baking industry. The antimicrobial effect reduces the salt content in bread. Helping reduce sodium consumption to the recommended level of 5-6 g/day will benefit health, particularly regarding blood pressure and cardiovascular disease. Taking into consideration that bread and cereals represent the major sources of salt in the human diet, microbial bioprocessing has been proposed to reduce salt content while keeping the flavor [132]. In addition, the hydrolysis of flour proteins leads to the production of amino acids, organic acids, and other metabolites, improving the nutritional and functional values of sourdough bread [133]. Dietary sourdough bread increases short-chain fatty acid, isovaleric and 2-methyl butyric acids, and \(\gamma\)-aminobutyric acid (GABA) content, among other bioactive molecules [134]. The \(\gamma\)-aminobutyric acid GABA is a non-protein amino acid synthesized from L-glutamate by the glutamate decarboxylase [135]. It is a mammalian neurotransmitter involved in critical regulatory functions, hypotensive properties, anti-depressive effects, diuretic, and antioxidant effects [136]. It is present in many medicines and supplements [137]. Several strains of LAB can carry out activities that promote human health, such as modulating the immune response, preventing cancer, reducing chronic intestinal inflammation, and cholesterol levels. Other functions include improving the intestinal barrier, inhibiting pathogenic organisms, and beneficial interactions with the endogenous intestinal microbiota [138]. These bacteria are present in sourdough and liberate bioproducts in bread dough, such as vitamin B12, folate, and riboflavin [112]. Although probiotics from sourdough are not present in the intestine environment, they provide gastrointestinal benefits, including the pre-digestion of non-nutritional molecules. Sourdough bacteria and yeast decrease the phytic acid present in wheat. The phytate (myo-inositol hexaphosphate) content of whole wheat products is a concern because it inhibits the absorption of minerals, has a negative effect on the nutritional properties, and causes gastrointestinal disorders, digestive discomfort, and flatulence. On the other hand, removing wheat bran and germ reduces the nutritional value of bread. The acidification during sourdough fermentation stimulates endogenous grain phytase, but LAB and yeast phytase activity significantly reduces the phytate content of the bread [124]. Another advantage is the reduction of fermentable oligo-, di-, and monosaccharides and polyols such as sorbitol and mannitol (FODMAPS) and amylase-trypsin inhibitors (ATIs) from wheat. Both are related to trigger intestinal symptoms in irritable bowel syndrome and non-eceliac wheat sensitivity. A study by [PERSON] et al. 2022 [139], described that the longer sourdough fermentation time (12 h) caused up to 69%, 69%, and 41% reductions in fructans, raffinose, and ATIs, respectively. Low FODMAPs may be valuable for people with gastrointestinal disorders.