In recent years, scientific investigators have moved from primary role of food as the source of energy and nutrients to action of biologically active food components on human health. On the other hand, consumer interest about the active role of food in well-being and life prolongation has been increased. In this way, a novel term -functional food- was introduced which refers to preventional and/or curing effects of food beyond its nutritional value. There is a wide rage of functional foods that were developed recently and many of them are being produced in all over the world including probiotic, prebiotic and symbiotic foods as well as foods enriched with antioxidants, isoflavones, phytosterols, anthocyanins and fat-reduced, sugar-reduced or salt-reduced foods. Among these foods, probiotic functional food has exerted positive effects on the overall health. We can divide it in both probiotic dairy foods and probiotic non-dairy foods. The market of probiotic dairy foods is increasing annually. An increased demand for dairy probiotic products comes from health promotion effects of probiotic bacteria which are originally initiated from milk products, bioactive compounds of fermented dairy products and prevention of lactose intolerance. Therefore, development of these products is a key research priority for food design and a challenge for both industry and science sectors.
Literatures about probiotic application in pediatrics have some characteristics including numerous, randomized, controlled clinical trials or meta-analyses but the substantial heterogeneity of these works greatly complicates the interpretation of the results and thus makes it difficult to draw univocal and general conclusions. Despite these complications, it is possible to draw some conclusions about the clinical effectiveness of probiotics by examining the most significant literature on each pathology. In particular, there is strong evidence indicating that probiotics have preventive and therapeutic effect on pathologies such as acute diarrhea, antibiotic-associated diarrhea, NEC, and allergic pathology. It was reported that administration of L.GG to 50 infants, for a period of 6 weeks, did not improve abdominal pain but did reduce the incidence of abdominal tension compared to the placebo (Bausserman and Michail, 2005) But in other works it was clearly demonstrated that L. acidophilus did improve the symptoms in about half of the patients with IBS, that the blend of VLS#3 probiotics decreased abdominal swelling, while the combined use of L. plantarum and B. breve reduced pain intensity (Halpern, et al., 1996; Kim, et al., 2003; Saggioro, 2004). L. acidophilus and B. infantis for 4 weeks were administered alone or in combination with antibiotics ciprofloxacin for the first week to three different groups with IBS: diarrhea, constipation, and alternating diarrhea and constipation. Both therapeutic approaches have improved the quality of life and reduced symptoms in all three groups (Faber, 2000). In conclusion, although the use of some types of probiotics on IBS appears promising, additional studies are needed. Food supplementation with pre- and probiotics may reduce the prevalence for the infant in high-risk families developing an atopic eczema during the first 2 years of life. Those pregnant women should be advised to take probiotics (L. GG) in late pregnancy and the first 6 months postnatally during nursing. If breast-feeding is not possible, pro- or prebiotics can be supplemented to the infant. There are no known adverse reactions and it might prevent atopic eczema, especially in neonates after cesarean delivery. Therapeutic use of probiotics to improve atopic eczema is only supportive in infants 18 months and with IgE sensitization.
Recent experimental studies have shown that certain gut bacteria, in particular species of Lactobacillus and Bifidobacterium, may exert beneficial effects in the oral cavity by inhibiting Streptococci and Candida sp. Probiotic lactic acid bacteria can produce different antimicrobial components such as organic acids, hydrogen peroxide, carbon peroxide, diacetyl, low molecular weight antimicrobial substances, bacteriocins, and adhesion inhibitors, which also affect oral microflora. However, data is still sparse on the probiotic action in the oral cavity. More information is needed on the colonization of probiotics in the mouth and their possible effect on and within oral biofilms. There is every reason to believe that the putative probiotic mechanisms of action are the same in the mouth as they are in other parts of the gastrointestinal tract. Because of the increasing global problem with antimicrobial drug resistance, the concept of probiotic therapy is interesting and pertinent, and merits further research in the fields of oral medicine and dentistry (Meurman, 2005).
The number of microbial cells in the human gut is 10 times more than the number of cells in the adult body (Mountzouris and Gibson, 2003). So, the change of microbial balance in human intestine can impress the host health. The ratio between the beneficial microbes (probiotics) and harmful microbes would have an important effect on host health. One way to keeping up the probiotic cells in the gut, is to entering probiotics into the intestine through the regular consumption of food containing these bacteria. Among the functional foods, the dairy probiotic products, especially ice cream and cheese are good vehicle to transfer probiotics to the human intestinal tract (Homayouni, 2008a; Homayouni et al., 2012). Dairy products have an important role in human health and form the main part of the food pyramid. The therapeutical and health care characteristic of fermented dairy products has been used over long years. Another way to keeping up the probiotic cells in the gut is to entering prebiotics into the intestine through the regular consumption of foods containing these components. It is clear that versus probiotics the amounts of prebiotics do not changes during the passage from upper intestinal tract (Homayouni, 2008a).
The main role of food is providing enough nutrients to meet metabolic requirements in human body, while giving the consumer a satisfaction feeling and well-being (Homayouni, 2008a). Beyond meeting nutrition needs, food may have different physiological functions and may play detrimental or beneficial roles in some diseases (Koletzko et al., 1998). Functional foods were developed in order to promote a well-being state, improving health, and reducing the diseases risk. "Functional food" means; special foods which have preventional and/or curing effects beyond its nutritional (Homayouni, 2008a). There is a wide rage of functional foods that were developed recently and many of them are being produced in all over the world including probiotic, prebiotic and symbiotic foods as well as foods enriched with antioxidants, isoflavons, phytosterols, anthosyanins and fat-reduced, sugar-reduced or salt-reduced foods. Among these foods, probiotic functional foods are the first choice to exert positive effects on the human health. Probiotic functional foods were divided into dairy probiotic foods and non-dairy probiotic foods. Some of dairy probiotic foods including probiotic ice cream, frozen fermented dairy deserts, probiotic cheese, bio-yoghurt, drinking yoghurt, kefir, Freeze-dried yoghurt and spray dried milk powder have been employed as possible delivery vehicles for probiotic bacteria (Haynes and Playne, 2002; Homayouni et al., 2008b; Homayouni et al., 2012; Ejtahed et al., 2011; Ejtahed et al., 2012; Mirzaei et al., 2012 Kailasapathy and Rybka, 1997; Ravula and Shah, 1998; Stanton et al., 2001). Probiotics are distinct as live micro-organisms which, when administered in sufficient amounts present a health benefit on the host (Food and Agriculture Organization of United Nations; World Health Organization - FAO/WHO, 2002; Homayouni, 2009). In recent years probiotic bacteria have increasingly been incorporated into dairy foods as dietary adjuncts.
Consumption of probiotic bacteria via dairy food products is an ideal way to re-establish the intestinal micro-floral balance. It must conform to certain requirements for a dairy food product to be considered as a valuable alternative for delivery of probiotic bacteria in one hand and for variety of probiotic cultures to use as a dietary adjunct and to exert a positive influence in the other hand. The culture must be native of the human gastrointestinal tract, having the ability to ferment prebiotics, survives passage through the stomach and small bowel in adequate numbers, be capable of colonizing in site of action, and have beneficial effects on human health. In order to survive, the strain must be resistant to acidic conditions (gastric pH 1-4), alkaline conditions (bile salts present in the small bowel), enzymes present in the intestine (lysozyme) and toxic metabolites produced during digestion (Homayouni et al., 2008d). For example in traditional yoghurt production,
2. Dairy probiotic foods
As mentioned before, dairy functional foods beyond its basic nutritional value has physiological benefits. Milk has an outstanding position in the development of functional foods because it has Omega-3, phytosterols, isoflavins, conjugated linoleic acid, minerals, and vitamins. Dairy products such as ice cream, cheese, yogurt, Acidophilus-Bifidus-milk, Ayran, Kefir, Kumis, Doogh containing probiotics and dairy beverages (both fermented and non-fermented) have long been considered as important vehicles for the delivery of probiotics. In fermentation process, acids such as lactic acid, acetic acid and citric acid are naturally produced. These acids are commonly used as organic acids to enhance organoleptic qualities as well as safety of food products. Lactic acid bacteria are found to be more tolerant to acidity and organic acids than most of the pathogens and spoilage micro-organisms.
2.1. Probiotic ice cream
Probiotic ice cream can be produced by incorporation of probiotic bacteria in both of fermented and unfermented mix (Homayouni et al., 2008b; Homayouni et al., 2012). Ice cream is ideal vehicle for delivery of these micro-organisms in the human diet (Akin et al., 2007; Kailasapathy and Sultana, 2003; Ravula and Shah, 1998; Homayouni et al., 2008d; Homayouni et al., 2012).
Homayouni et al. (2008d) studied the survival of probiotics in simulated ice cream and gastrointestinal conditions in order to select appropriate probiotic strains for use in probiotic ice cream. The growth and survival rate of
2.2. Probiotic cheese
Survival in processing conditions, presence of oxygen, degree of acidity, ability to grow well in milk-based products and to rapidly acidify milk, thus reducing the fermentation time and, consequently, contamination risk during preparation of inoculums are important factors for probiotic bacteria such as
Antagonism between bacteria is often based on the production of metabolites that inhibit or inactivate more or less specifically other related starter organisms or even unrelated bacteria. While antagonism caused by bacteriocins, peptides, or proteins exhibiting antibiotic properties has been described as a limiting factor for combinations of starters and probiotics (Joseph et al., 1998), antagonism caused by hydrogen peroxide, benzoic acid, biogenic amines, and lactic acid may have considerable effects on probiotics in probiotic cheese. The physiological state of the probiotics may be of considerable importance for survival during ripening and/or storage if probiotics are added to the probiotic cheese after fermentation (Desmazeaud, 1996; Lankaputhra et al., 1996; Leuschner et al., 1998; Weber, 1996).
In probiotic cheese, probiotic cells must be able to grow and/or multiply in the human intestine and therefore should be able to survive during the passage through the gastrointestinal tract (GIT), which involves exposure to hydrochloric acid in stomach and bile in small intestine (Stanton et al., 2003). In fact, cheese provides a valuable vehicle for probiotic delivery, due to creation of a buffer against the high acidic environment in the gastrointestinal tract, and thus creates a more favorable environment for probiotic survival throughout the gastric transit, ought to higher pH. Moreover, the dense matrix and relatively high total solids as well as fat content of cheese may offer additional protection to probiotic bacteria in stomach (Bergamini et al., 2005; Ross et al., 2002). The presence of the prebiotics inulin and oligofructose can promote growth rates of
2.3. Probiotic yoghurt
Yoghurt has been historically recognized to be ‘a healthy food’ with therapeutically effects. There has been a considerable increase in the popularity of yoghurt especially probiotic yoghurt in recent years. The conventional yoghurt starter bacteria,
Similar processing to traditional yoghurt is applied for production of bio-yoghurt with incorporation of live probiotic starter cultures. Heat treated homogenized milk with an increased protein content (3.6–3.8%) is inoculated with the conventional starter culture at 45°C or 37°C and incubated for 3.5 and 9 h, respectively. The probiotic culture can be added prior to fermentation simultaneously with the conventional yoghurt cultures or after fermentation to cooled (4°C) product before packaging. Bio-yoghurt, containing
Viability of both
2.4. Probiotic milk
Technology of bifidus milk and acidophilus-bifidus milk manufacturing is similar to acidophilus milk. Milk is standardized to desire protein and fat levels in both products. Then, for manufacture of bifidus milk, milk is heat-treated at 80-120°C for 5-30 min and rapidly cooled to 37°C. Heat-treated milk is inoculated with frozen culture of
3. Development of functional dairy foods
Innovation is today’s business demand and development of a new functional food is an expensive process and is very important for both food companies and consumers. Regulations should encourage food companies to follow functional food development. Development of dairy probiotic products requires detailed knowledge of both products and customers. It needs to manage customer knowledge effectively (Walzem, 2004; Jousse, 2008). Fundamental risks can affect the development of new functional food products and may leads to fail the development process. Development of new functional food products is very challenging and it has to complete the consumer’s expectations for palatable and healthy products (Fogliano and Vitaglione, 2005; Granato et al., 2010; Shah, 2007). So, the development and commerce of functional food products is rather complex, expensive, and uncertain. Key points regarding for a successful functional food product development are consumer demands, technological conditions, and legislative regulatory background. However, consumer’s knowledge of the health effects of specific ingredients can affect the acceptance of specific functional food. Therefore, functional ingredients that are in consumers mind for a long period of time, such as minerals, fiber, and vitamins, achieve considerably higher rates of consumer acceptance than new products, such as foods enriched with probiotics, prebiotics, flavonoids, carotenoids, and conjugated linilenic acid (CLA). Several ways to make a functional food product is to eliminating an allergenic protein, lactose, phenylanine and etc from the natural food product; by fortification with a micronutrient; by adding antioxidants, probiotics or prebiotics); by replacing a component, or by increasing bioavailability or stability of a component known to produce a functional effect or to reduce the disease-risk potential of the food (Roberfroid, 2000; Siro, et al., 2008; Granato, et al., 2010). Field of functional probiotic foods requires the cooperation of food technologists, nutritionists, medical doctors, and food chemists in order to obtain innovative products. In this way, these foods may be able to adjust physiological parameters related to health status or disease prevention in human. So, the design and development of functional probiotic foods is a scientific work (Hasler, 1998; Walzem, 2004; Fogliano and Vitaglione, 2005) which is an expensive and multistage process that takes into account many factors, such as sensory acceptance, physical and microbial stability, price, and chemical and other intrinsic functional properties to be successful in the marketplace. Moreover, consumer attitude toward the functional probiotic product also needs to be understood and taken into consideration.
4. Consumer attitude toward functional dairy foods
The development of functional probiotic foods is increasing, as their market increases day by day, although the consumer's information about these foods is increasing without relation to gender, age, and educational or economic levels of the consumers. The therapeutical effect of a functional probiotic food may depend on the consumer’s characteristics and the type of carrier and enrichment considered. For instance, yoghurt is most preferred by its enrichment with calcium and fiber. Ingredients such as vitamins and minerals applied in fortification of functional foods are widely recognized and accepted by consumers, but new functional ingredients such as probiotics and prebiotics are not common to them. So, there is a need for increasing the consumer knowledge with respect to these new special ingredients (Hillian, 2000; Luckow and Delahunty, 2004; Ares and Gambaro, 2007; Vianna et al., 2008).
The sensory properties of prebiotic functional foods in comparison with conventional products can lead to different acceptance level. Oligofructose provides some suitable sensory properties such as rounder mouth feel, reduced aftertaste, and slight sweetness to the products. These properties are responsible for high score values for taste, creaminess, and overall acceptability of functional food products. The first important marker in choosing a functional food is flavor, and health consideration is in the second order. If the ingredients added give unpleasant flavors to the product, consumers are not interested in consume such functional probiotic food even if this results in health advantages. This means that flavor is correlated to intrinsic sensory properties of the product such as overall acceptability. In general, as functional products consumption increases, the acceptance of such products may increase, even if the sensory profiles are different from conventional products. When functional ingredients such as probiotics are added to dairy foods, consumers must be aware of probiotics health benefits in order to recognize the functional probiotic foods as being more beneficial than the conventional ones. Functional probiotic food industry should communicate with consumer in a clear way and this is one of the most important aspects for success (Tepper and Trail, 1998; Matilla-Sandholm et al., 1999; Roberfroid, 2000; Tuorila and Cardello, 2002; Nicolay, 2003; Vieira, 2003; Homayouni, 2008a).
The future success of functional probiotic dairy foods in marketplace depends on consumer acceptance of such products. The consumers must be convinced by its health claims through clear, honest, and definite messages to agree to pay the cost associated with functional probiotic dairy foods. Development of probiotic dairy products is a key research priority for food design and a challenge for both industry and science sectors. Among the functional foods, the dairy probiotic products, especially ice cream and cheese are good vehicle to transfer probiotics to the human intestinal tract. Additional way to keeping up the probiotic cells in the gut is to entering prebiotics into the intestine through the regular consumption of food containing these components. It is clear that versus probiotics the amounts of prebiotics do not changes during the passage from upper intestinal tract.