**3. Probiotic microorganisms used in food products**

It is clear that the right selection and application of a probiotic strains in food materials exhibits fundamental impacts on qualitative aspects of final products, namely safety (related to the mentioned strains), health benefits (related to probiotics), sensory attributes and even, the price. Therefore, selecting the adequate probiotic strains is the first prerequisite for designing a specific probiotic food product. The incorporation of incorrectly identified probiotic bacteria in functional food products clearly has public health implications, by undermining the efficiency of probiotics and by affecting public confidence in functional

matrices. In this chapter, the concept of ingestion and delivery of probiotic microorganisms

Probiotic microorganisms are available in three different types for direct or indirect human consumption: 1) culture concentrate to be added to a food (dried or deep-freeze form) for industrial or home uses, 2) food products (fermented or non-fermented), and 3) dietary supplements (drug products in powder, capsule or tablet forms) (Tannis, 2008). Consumption

Worldwide, the demand for consumption of functional foods is growing rapidly due to the increased awareness of the consumers from the impact of food on health. For example, in the year 2000, the world-wide market of functional foods generated US\$ 33 billion, in 2005, this total was US\$ 73.5 billion, and was US\$ 167 billion in 2010 (Granato et al., 2010). Functional foods are those that contain chemical/microbial components that may affect beneficially one or more target functions in the body, beyond adequate nutritional effects, in a way that is relevant to either the state of well-being and health or the reduction of the risk of a disease (Diplock et al., 1999). Probiotic food products are classified in the category of functional foods and represent a significant part of this market that probiotic foods comprise

During the past three decades, significant attention has been paid to dairy products containing probiotic bacteria such as fermented milks, ice cream, various types of cheese, baby-food, milk powder, frozen dairy desserts, whey-based beverages, sour cream, butter milk, normal and flavored liquid milk, and concentrated milk. Also, recently, many nondairy products such as vegetarian-based products, cereal-based products, fruit juice, soyabased products, oat-based desserts, confectionary products, breakfast cereals and baby foods) and baby foods have been developed. Causes for this ongoing trend are demands provide by vegetarianism, high prevalence of lactose intolerance in many populations around the world, and providing variety and development in probiotic food products (Granato et al., 2010; Mortazavian et al., 2011). Dairy products have the largest probiotic food market share. Today, a total of 78% of current probiotic sales in the world are delivered through yogurt (Cargill, 2009). Therefore, still, the manufacture of dairy products containing probiotic bacteria is an important issue with industrial and commercial consequences. Table 1 represents some types of probiotic products available in the world market (dairy and nondairy products). Figure 1 indicates qualitative aspects

It is clear that the right selection and application of a probiotic strains in food materials exhibits fundamental impacts on qualitative aspects of final products, namely safety (related to the mentioned strains), health benefits (related to probiotics), sensory attributes and even, the price. Therefore, selecting the adequate probiotic strains is the first prerequisite for designing a specific probiotic food product. The incorporation of incorrectly identified probiotic bacteria in functional food products clearly has public health implications, by undermining the efficiency of probiotics and by affecting public confidence in functional

of probiotic cells via food products are the most popular and widespread way.

between 60 and 70% of the total functional food market (Holzapfel, 2006).

**3. Probiotic microorganisms used in food products** 

via food products are discussed.

**2. Probiotic food products** 

of probiotic food products.

foods (Huys et al., 2006). Thus, the use of adequate tools to provide proper strain identification for legal and good manufacturing practices and to track probiotics during food production as well as during their intestinal transit are strictly necessary (Lee and Salminen, 2009).


Delivery of Probiotic Microorganisms into Gastrointestinal Tract by Food Products 125

Many of the bacteria used in probiotic preparations (bifidobacteria and lactic acid bacteria) have been isolated from human fecal samples to maximize the likelihood of compatibility with the human gut microflora and improve their chances of survival (Andersson et al., 2001). Microorganisms isolated from fermented nondairy foods have shown these abilities in *in vitro* studies (Rivera-Espinoza and Gallardo-Navarro, 2010). Probiotic organisms are predominantly bacteria selected from the genera *Lactobacillus* and *Bifidobacterium*, which are normal constituents of the human intestinal microbiota. However, species belonging to the genera *Lactococcus*, *Enterococcus*, *Saccharomyces* and *Propionibacterium* are also considered as probiotic due to their health-promoting effects (Blandino et al., 2003; Rivera-Espinoza and Gallardo-Navarro, 2010; Sanders and Huis Veld, 1999; Vinderola and Reinheimer, 2003). A primary reason for this is that both these genera are dominant inhabitants of their respective niches in the intestine (*Lactobacillus* in the small intestine and *Bifidobacterium* in the large intestine) and both have a long history of safe use and are considered as GRAS (generally regarded as safe). Of the lactobacilli, *L. acidophilus* is by far the most widely used probiotic as it has a long history of research and use. As *L. acidophilus* is one of the predominant organisms in the intestinal tract of breastfed babies, it quickly took the place of *L. bulgaricus* as the probiotic of choice in the U.S. (O'Sullivan 2006). It, therefore, has almost 100 years of use in human diets. Of the bifidobacteria, *B. longum* is particularly dominant in human intestines (Perdigon et al., 2003), It is a highly recommend *Bifidobacterium* species in commercial human probiotics (Sanders, 2006). *Bifidobacterium lactis* (*Bifidobacterium animalis* ssp. *lactis*) is a very commonly used probiotic, although it is not a normal human inhabitant. It was first isolated in 1997 from fermented milk by Meile et al. (1997) and was noted to have a higher tolerance to oxygen and other detrimental environmental conditions (generally, higher adaptation to food conditions) than other bifidobacteria (Cai et al., 2000; Ventura and Zink, 2002). The changes that occurred in *B. lactis* during its adaptation to fermentation conditions make it a very resilient strain that can remain viable during processing and storage longer than other bifidobacteria. Mentioned practical reasons contribute to its popularity. These adaptations, however, would not give it a competitive edge in the intestine as the most competitive strains lose unwanted traits in a natural environment. Although this would limit the full potential of *B. lactis*, it still has the potential for many

positives during its transient passage through the intestine (O'Sullivan, 2006).

have adaptation to milk and other food substrates.

clinical trials (Lee and Salminen, 2009; Ventura and Perozzi, 2011).

While emphasizing the importance of strain-specificity of technological attributes of probiotics, some generalizations can still be made on the robustness of probiotic organisms. Generally, lactobacilli are more robust than bifidobacteria (Erkkilä et al., 2001; Mättö et al., 2006; Ross et al., 2005). There is a wider range of probiotic *Lactobacillus* species that are technologically suitable for food applications than bifidobacteria (Lee and Salminen, 2009). They are resistant to low pH, have native association with traditional fermented foods, and

A significant proportion of the commercialized probiotic bacterial species was originally selected on the basis of their technological stability (e.g., viability during food processing and storage), survival during intestinal transit, and health benefits on consumers. Good probiotic strains have demonstrated health and safety data from randomized, controlled


Table 1. Some types of probiotic products available in the world market (dairy and non dairy products)

Fig. 1. Qualitative aspects of probiotic food products.

**Dairy products Reference Non dairy products Reference** 

**Acidophilus butter** Gomes and Malcata (1999) Chocolate Possemiers et al. (2010)

probiotic drink

soybean)

Oi and KIitabatake

Feng et al. (2005)

(2003)

Kaur et al (2009) Starch-saccharified

**Frozen yogurt** Davidson et al. (2000) Meat products Rouhi et al. (2010)

Table 1. Some types of probiotic products available in the world market (dairy and non

**Qualitative aspects probioticfood products**

Convenience

Health benefits

Safety

Environmental aspects

**Frozen synbiotic dessert** Tempeh (base on

Maragkoudakisa et al.

Patrignani et al. (2009)

Kaur et al. (2009)

(2006)

(2008)

Fig. 1. Qualitative aspects of probiotic food products.

Economical aspects

Sensory characteristics

**Frozen dairy dessert** Shah and Ravula (2000) **Corn milk yogurt** Supavititpatana et al.

**Banana-based yogurt** Sousa et al. (2007)

**Yog-ice cream** El-Nagar et al. (2002)

**Mango soy fortified probiotic yogurt** 

**Traditional Greek** 

**High pressurehomogenized probiotic fermented** 

**Mango soy fortified probiotic yogurt** 

dairy products)

**yogurt** 

**milk** 

Many of the bacteria used in probiotic preparations (bifidobacteria and lactic acid bacteria) have been isolated from human fecal samples to maximize the likelihood of compatibility with the human gut microflora and improve their chances of survival (Andersson et al., 2001). Microorganisms isolated from fermented nondairy foods have shown these abilities in *in vitro* studies (Rivera-Espinoza and Gallardo-Navarro, 2010). Probiotic organisms are predominantly bacteria selected from the genera *Lactobacillus* and *Bifidobacterium*, which are normal constituents of the human intestinal microbiota. However, species belonging to the genera *Lactococcus*, *Enterococcus*, *Saccharomyces* and *Propionibacterium* are also considered as probiotic due to their health-promoting effects (Blandino et al., 2003; Rivera-Espinoza and Gallardo-Navarro, 2010; Sanders and Huis Veld, 1999; Vinderola and Reinheimer, 2003). A primary reason for this is that both these genera are dominant inhabitants of their respective niches in the intestine (*Lactobacillus* in the small intestine and *Bifidobacterium* in the large intestine) and both have a long history of safe use and are considered as GRAS (generally regarded as safe). Of the lactobacilli, *L. acidophilus* is by far the most widely used probiotic as it has a long history of research and use. As *L. acidophilus* is one of the predominant organisms in the intestinal tract of breastfed babies, it quickly took the place of *L. bulgaricus* as the probiotic of choice in the U.S. (O'Sullivan 2006). It, therefore, has almost 100 years of use in human diets. Of the bifidobacteria, *B. longum* is particularly dominant in human intestines (Perdigon et al., 2003), It is a highly recommend *Bifidobacterium* species in commercial human probiotics (Sanders, 2006). *Bifidobacterium lactis* (*Bifidobacterium animalis* ssp. *lactis*) is a very commonly used probiotic, although it is not a normal human inhabitant. It was first isolated in 1997 from fermented milk by Meile et al. (1997) and was noted to have a higher tolerance to oxygen and other detrimental environmental conditions (generally, higher adaptation to food conditions) than other bifidobacteria (Cai et al., 2000; Ventura and Zink, 2002). The changes that occurred in *B. lactis* during its adaptation to fermentation conditions make it a very resilient strain that can remain viable during processing and storage longer than other bifidobacteria. Mentioned practical reasons contribute to its popularity. These adaptations, however, would not give it a competitive edge in the intestine as the most competitive strains lose unwanted traits in a natural environment. Although this would limit the full potential of *B. lactis*, it still has the potential for many positives during its transient passage through the intestine (O'Sullivan, 2006).

While emphasizing the importance of strain-specificity of technological attributes of probiotics, some generalizations can still be made on the robustness of probiotic organisms. Generally, lactobacilli are more robust than bifidobacteria (Erkkilä et al., 2001; Mättö et al., 2006; Ross et al., 2005). There is a wider range of probiotic *Lactobacillus* species that are technologically suitable for food applications than bifidobacteria (Lee and Salminen, 2009). They are resistant to low pH, have native association with traditional fermented foods, and have adaptation to milk and other food substrates.

A significant proportion of the commercialized probiotic bacterial species was originally selected on the basis of their technological stability (e.g., viability during food processing and storage), survival during intestinal transit, and health benefits on consumers. Good probiotic strains have demonstrated health and safety data from randomized, controlled clinical trials (Lee and Salminen, 2009; Ventura and Perozzi, 2011).

Delivery of Probiotic Microorganisms into Gastrointestinal Tract by Food Products 127

Care must be taken in selecting the most appropriate strain for a particular food application. Indeed, the first step in incorporating a probiotic into a food is identifying compatibilities between the attributes of the selected strains and the food production steps, food matrix and storage conditions. Selection of probiotic strains used in food products should be according to both the criteria of compatibility with and resistance to the product and *in vivo* conditions in order to increase the viability of the probiotic bacterial strains (Korbekandi et al., 2011). The tolerance of probiotics both to the product and to the internal conditions of the living consumer is strain-dependent (strain-specific). Suitable probiotic strains are those enable to maintain their survival and stability during commercial production of products as well as during the storage period (Godward et al., 2000; Talwalker and Kailasapathy, 2004). Furthermore, high viable survival rate during delivery through the gastrointestinal tract is necessary to allow enough live cell arrival to the human intestine. Therefore, selection of resistant probiotic strains against production, storage and gastrointestinal tract condition is of prime importance. Researchers have indicated that the survival of bacteria against harsh conditions in food products such as pH, titrable acidity, oxygen toxicity, freezing and low temperatures and storage temperatures are species- and strain-specific (Godward et al., 2000; Kailasapathy and Sultana, 2003; Ravula and Shah, 1998; Takahashi et al., 2007; Tamim

Selected probiotic strains should also results in adequate sensory characteristics of final product. Some studies have shown that flavor is the first indicator with respect to the choice of a food, followed by considerations with respect to health (Mohammadi and mortazavian, 2011; Tuorila and Cardello, 2002). Consumers are not interested in consuming a functional food if the added ingredients confer disagreeable flavors on the product, even if this results in advantages with respect to their health. Therefore, a pleasant aroma and taste profiles are of importance in the formulation of probiotic functional foods and is strain-dependent. The metabolism of the probiotic cultures can result in the production of components that may contribute negatively to the taste and aroma of the product, such as acetic acid produced by *Bifidobacterium* spp. during fermentation and over storage period. Figure 3 shows main

pH and titrable acidity of probiotic products considerably affect cell survival of probiotic microorganisms (Mortazavian et al., 2010). Low pH is of the most important factor that restricts the growth and stability of probiotic bacteria in fermented products. Hydrogen ions damage probiotic cells via disrupting mass transfer through the cell membranes and acidic starvation of the cells (Mortazavianand and Sohrabvandi, 2006). Very low pH ranges in fermented milks might cause an increase in the concentration of undissociated organic acids in them and, as a result, enhances the bacteriocidal effect of these acids. The aforementioned effect of organic acids arises from their lipophilic nature. They can be transferred through the microbial cells and dissociate within them, changing the intracellular pH. Also, organic acids might bind to various intracellular compounds. Both of these phenomena disturb cell

The optimum pH for growth of *Lactobacillus acidophilus* is 5.5-6.0, but for bifidobacteria this range is 6.0 –7.0 (De Vuyst, 2000). In food products, lactobacilli are able to grow and survive

criteria for selection of probiotic strains in food products.

**4.1 Strains of probiotic bacteria** 

et al., 2005).

**4.2 pH and titrable acidity** 

metabolism (Korbekandi et al., 2011).
