Introduction

Probiotics are considered as being ‘live microorganism which administered in adequate amounts, can confer a beneficial physiological effect on the host’ (Rokka & Rantamaki, 2010). The potential health benefits of probiotics (most popular Lactobacillus acidophilus and Bifidobacteria) are such as antimutagenic and anticarcinogenic properties, anti-infection properties, immune system stimulation, serum cholesterol reduction, alleviation of lactose intolerance and nutritional enhancement (Macfarlane & Cummings, 1999; Mombelli & Gismondo, 2000). To satisfy health requirement of human, probiotics industry has developed a variety of new products. Most probiotics relevant products in food industry are dairy products, with yogurts, kefir and cultured drinks representing the major categories. The global market for probiotic ingredients, supplements and foods was worth $14.9 billion in 2007 and US$16 billion in 2008 respectively. Estimated sales target in 2013 will reach to US$19.6 billion. Presently, two largest probiotics markets are North America and Europe. Analysis of the North American Probiotics markets found that the probiotics sector earned revenues of US$ 698 million in 2006. It is expected to reach US$ 1.70 billion in 2013, with compound annual growth rate (CAGR) of 13.7% (Granato et al., 2010a). European food and beverage probiotics market is expected to rise from US$ 61.7 million in 2006 to US$ 163.5 million by 2013 (Granato et al., 2010b).

To exert their biological effects on the host, one of most important consideration is viability and activity of probiotic bacteria, even though non-viable probiotics can still have biological activity. Another concern for consumer and food producer is minimum beneficial dose per day or per gram of product. The International Dairy Federation has recommended a minimum number of 107 CFU g
۱ of the product consumed. However, most probiotics are very sensitive to environmental conditions, such as processing including oxygen stress, freezing, temperature and drying, harsh action of gastrointestinal tract such as low pH and bile salt. Therefore, development of enhancing probiotic viability techniques is highly necessary (Siuta-Cruce & Goulet, 2001; Mattila-Sandholm et al., 2002).