# Probiotics in the Sourdough Bread Fermentation: Current Status
## 4 Probiotics and Postbiotics in Sourdough and the Impact on Human Health
Relative to fermentative processes, many bioproducts are present in sourdough fermentation. [PERSON] et al. [100] demonstrated 118 bioactive compounds in sourdough fermentation. Some of these health benefits and others are summarized in Table 3.  
\begin{table}
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**Inoculum** & **Compound** & **Property** & **Reference** \\ \hline _Wickerhamomyces anemallus_ P4 & \multirow{2}{*}{Phytase} & Decrease phytate and increase & \multirow{2}{*}{[95]} \\ _Levilacobacillus brevis_ TMW 1.211, & & & \\ _Pediococcus clauseseiii_ TMW 2.340 & O2-substituted & & \\ from breweries & (1,3)-\(\beta\)-D-glucan & Improving water binding capacity & [96] \\ \multirow{6}{*}{_Weissella confusa_/cibaria 3 MI3} & \multirow{6}{*}{Dextran} & Technological properties of dough & \multirow{6}{*}{[97]} \\  & & and bread, such as water absorption, & \\ \cline{1-1} \  
One important point is that most probiotics die when the bread is baked at high temperatures. However, most health benefits continue, mostly, not with probiotics at intestinal epithelial cell colonization but in sourdough dough. It is essential to note that active biomolecules could be present in the baked bread. Different conditions, varying temperatures, baking time, and fermentation parameters could influence the heat resistance of some bioproducts, and they could be present as nutrients and fibers such as \(\beta\)-glucan and resistant starch [120]. Increasingly, the literature discusses this important point. If the baking time is shortened by increasing the baking temperature or reducing the bread size, higher residual viability of LAB species may be obtained after baking [121]. Studies with \(L\). _plantarum_ at three different baking temperatures showed a reduction from 8.8 log CFU/g to 4-5 log CFU/G [122]. Concerning yeast, the count decreased from an initial value of 9 log CFU/g to 4 log CFU/g with baking at 200 \({}^{\circ}\)C for 13 min [121]. During the baking process, cell lysis of microorganisms delivers cellular debris that may also have beneficial properties functioning as postbiotics. Examples of postbiotic compounds that are present in sourdough are short-chain fatty acids (SCFAs), secreted proteins/peptides, bacterios, secreted biosurfactants, amino acids, flavonoids, EPS, vitamins, organic acids, and other molecules discussed in this review. Remains of microbial cell structures such as peptidoglycan from bacterial cell walls, pili, fimbrie, flagella, cell-surface-associated proteins, cell-wall-bound biosurfactants, and cell supernatants are also postbiotic components that have potential health benefits in the host [47; 123]. There is both a growing demand from consumers for additive-free, safe, and nutritious foods and for bread with a longer shelf-life and less staling due to microbial spoilage, and sourdough offers some advantages [124]. Several microorganisms, mainly LAB, have antimicrobial properties, which favors their use as probiotics and as a bioprotective culture in fermented products. [PERSON] et al. [125] suggest that metabolites with this effect produced by LAB may synergistically modulate the local microbial ecology, such as in the gut. Some strains of LAB can produce a variety of other antimicrobial compounds, such as organic acids (lactic, acetic, formic, propionic, and butyric acids). Organic acids have been described with antifungal actions against _Aspergillus_, _Fusarium_, _Monilia_, and _Penicillium_[126]. Ethanol, fatty acids, enzymes, acetoin, hydrogen peroxide, diacetyl, antifungal compounds (propionate, phenyl-lactate, hydroxyphenyl-lactate, cyclic dipeptides, and 3-hydroxy fatty acids), bacteriocins (nisin,  
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reuterin, reutericyclin, pediocin, lacticin, enterocin, and others), and bacteriocin-like inhibitory substances (BLIS) are also described in the literature [127]. Bacteriocins are a class of antimicrobial proteins or peptides considered safe for the body and do not induce resistance.