This investigation reports the effect of microencapsulation using different concentration of sodium alginate (1, 1,5, 2%) on the tolerance of probiotic Lactobacillus acidophilus under simulated gastrointestinal environments. Microencapsulation provided better protection at simulated conditions of gastric and bile salt. Higher surviving numbers of cells in AG 2% after incubation in gastric juice stimulated more cells to survive the sequential incubation into simulated intestinal juice and showed that the microencapsulation matrix was effective in protecting the entrapped cells with levels of survivors of 6.3 log cfu mL-1 compared to levels of 3.1 log cfu mL-1 for free cells, after 2 h in simulated intestinal juice. These studies demonstrated that microencapsulation of probiotic L. acidophilus in sodium alginate is an effective technique of protection under simulated gastrointestinal environment.
Lactic acid bacteria (LAB) are the organisms most commonly used as probiotics. Probiotic bacteria, lactic acid bacteria (LAB), which are typically associated with the human gastrointestinal tract, have been reported to suppress the growth of pathogens (Coconnier et al., 1993; Kaur, Chopra, & Saini, 2002; Lehto & Salminen, 1997; Lim, Huh, & Baek, 1993; Reid & Burton, 2002) and stabilize the digestive system by increasing intestinal barrier functions (Simon & Gorbach, 1984). Normally the stomach contains few bacteria (103 colony forming units per ml of gastric juice) whereas the bacterial concentration increases throughout the gut resulting in a final concentration in the colon of 1012 bacteria/g. Bacteria, forming the so-called resident intestinal microflora, do not normally have any acute adverse effects and some of them have been shown to be necessary for maintaining the well-being of their host. Probiotics are considered beneficial and are sometimes referred to as "friendly" bacteria. Probiotics can be found in capsule, liquid, powder, or tablet form. Once ingested, probiotics colonize the intestines and other parts of the body and can sustain themselves unless they are destroyed by antibiotics or other factors. There is some preliminary evidence that probiotic microorganisms can prevent or delay the onset of certain cancers (McIntosh et.al.,1999). This stems from the knowledge that members of the gut microflora can produce carcinogens such as nitrosamines. Therefore, administration of lactobacilli and bifidobacteria could theoretically modify the flora leading to decreased β-glucuronidase and carcinogen levels. Lactobacillus acidophilus (LAB) has excellent acid resistance and also exerts a cholesterol-lowering effect in the host (Anderson et.al.,1999). The survival of L. acidophilus in the gastrointestinal tract is essential for exertion of its potential health benefits, such as antimicrobial activity and decrease of cholesterol level. In order to exert positive health effects, LAB have to resist gastric juice and bile salts. After the LAB pass through the stomach and upper intestinal tract, it should attach to the epithelium of the intestinal tract and grow. As a guide for positive health effect, the International Dairy Federation has recommended that the bacteria be active and be present in the product at least till the level of 107 cfu/g until the product’s expiration date (Ouwehand & Salminen, 1998). If probiotic bacteria have to survive and be active in the digestive tract, they should be resistant to the defense mechanisms of the host (Jonson et.al.,1992) . The gastrointestinal transit begins by exposing L. acidophilus to low pH and pepsin in stomach. When gastric juice is secreted, it has a pH of approximately 2.0 and a...