Nowadays, the development of functional food products including probiotics, prebiotics, and synbiotics, which have an important role in the diet in terms of protecting and/or improving human health, come into prominence. Among those, synbiotics as a combination of probiotics and prebiotics have a synergetic health-promoting influence. In this regard, synbiotic foods mainly include dairy and non-dairy food products, such as confectioneries or unfermented beverages. However, there are limited studies in the literature regarding the potential synbiotic combinations in baked goods particularly bread as a staple food.
Up to now, the most commonly used probiotic bacteria in potential synbiotic combinations in bread are Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus plantarum, and Lactobacillus rhamnosus, which belong to Lactobacillaceae family and also Bifidobacterium animalis, Bifidobacterium adolescentis and Bifidobacterium longum which are species of Bifidobacteriaceae family. However, one of the main challenges in the production of synbiotic bread is generally related to the heat sensitivity of probiotic bacteria during the baking process. To protect the probiotic bacteria regarding their viability and stability during the heating process, they should be encapsulated and then added to the food structure, or should be covered with an edible film/coating on the bread crust structure. In addition, PRO-PRE co-encapsulation, in other terms co-delivery or co-entrapment, of probiotics with prebiotics is a promising application regarding both stability and viability of living probiotics. In this regard, the mostly utilized wall materials which have prebiotic potential are high-amylose maize starch (Hi-maize), chitosan, and some hydrocolloids such as pectin, xanthan gum, gum arabic, gellan gum, tragacanth gum, carboxymethyl cellulose, hydroxypropyl methylcellulose for preparing co-encapsulated probiotic bacterial strains. Similarly, probiotic incorporation was also conducted by prebiotic edible films/coating using some hydrocolloids such as gellan gum and konjac glucomannan. Moreover, recently it is revealed that some probiotic microorganisms particularly Bacillus coagulans, could be also a promising solution in accordance with this purpose. Similarly, although Saccharomyces cerevisiae var. boulardii is the only probiotic yeast and is used in several different food products, there is no study in the literature based on it as a probiotic source of synbiotic combinations in bread, as far as we know. On the other hand, inulin is the major directly-utilized prebiotic source in potential synbiotic combinations in bread.
To sum up, the following studies should focus on the survival of more probiotic microorganisms, especially Bacillus coagulans and Saccharomyces boulardii, optimization of different encapsulation techniques, wall materials, film/coatings together with different types and concentrations of prebiotic sources used in other cereal-based food products, and also in gluten-free bread. Moreover, the viability of probiotics with prebiotics which are used directly, or as a wall material for encapsulation or edible film/coating should be assessed from a holistic perspective regarding the nutritional, technological, and sensorial properties of bread.
