Egyptian people are cheese consumer more than market milk consumer. White pickled cheese is the main soft cheese highly accepted by most citizens. The unique manufacture step of pickled cheese (Domiati cheese) is the addition of 10-12% salt directly to cheese milk before renneting. The use of raw milk, and the high salt concentration did not give the opportunity for starter culture application. The Egyptian standardization No. 1008/2005 demanded the necessity of cheese milk heat treatment for various cheese types. It is well known that cheese from row milk is not safe, but it has high organoleptic evaluation. It is very important to find suitable starter for our salty cheese, to have better taste and flavor for having healthy cheese (Healthy is better than tasty).
Probiotic bacteria defined as "live microorganisms which, when administered in adequate amounts, confer a health benefit on the host". (WHO, 2001)
There is a growing agreement on the beneficial effects of bifidobacteria in human health. It is now clear that bifidobacteria that exist in the large intestine are helpful for maintenance of human health. The production of cheeses containing probiotic is an effort to expand the range of probiotic dairy products. The incorporation of such health enhancing cultures would only result in a functional product if the cultures were to maintain viability during cheese ripening and if it do not adversely affect the quality of the product (Khalifa, 2005).
The global probiotics market totaled 31.8 billion and 34.0 billion in 2014 and 2015 respectively. The market should total 50.0 billion by 2020, growing at a compound annual growth rate of 8.0% from 2015 to 2020. The global probiotics market for the food and beverage industry totaled 23.2 billion and 24.8 billion in 2014 and 2015 respectively. (Agheyisi, 2016).
Although Bifidobacteria have been considered to be the most important organisms in infants, and lactobacilli and Escherichia coli are more numerous bacteria for children and adults than Bifidobacteria, it has now become clear that Bifidobacteria also constitute one of the major bacteria in the colonic flora of healthy children and adults. In the feces of children and adults, the numbers of Eubacteria, and Peptococcaceae outnumber Bifidobacteria, which constitute 5 - 10% of the total flora. The number of Enterobacteriaceae and Streptococci decreases to less than 108 cfu gram-1 of feces. Lactobacilli, and Veillonellae are often found, but the numbers are usually less than 108 cfu gram-1 of feces. In elderly persons Bifidobacteria decrease or disappear, Clostridia including C. perfringens significantly increase, and lactobacilli, Streptococci, and Enterobacteriaceae also increase as shown in (Fig. 1) (Mitsuoka, 1990). .
Fig. 1. Changes in the fecal flora with increased age (Mitsuoka, 1990).
For dietary organisms to be beneficial in food systems, they should maintain viability in the food until the time of consumption and be present in significant numbers, at levels of at least 107 viable cells per gram or milliliter of product (Ishibashi and Shimamura, 1993). For this reason, changes in the numbers of bacteria during ripening period must be known. Cheeses have a number of advantages over fresh fermented products such as yoghurt as a delivery system for viable probiotic to gastrointestinal tract as they tend to have higher pH, relatively higher fat content and more solid consistency. These offer protection to probiotic bacteria during storage and passage through the gastrointestinal tract (Ong, 2007).
A number of studies have addressed development of probiotic cheeses using Karish cheese (Osman, 2000), Cheddar cheese (Brearty et al., 2001), Tallage cheese (El-Zayat and Osman, 2001) and white soft cheese (Yilmaztekin et al., 2004 ; El-Fak et al., 2005; Yerlikaya, & Ozer, 2014; and Haddad et al., 2015).
Traditionally, starters are not used in the manufacture of Egyptian cheeses. Several attempts have been made to isolate salt tolerant organisms from ripened Domiati Cheese for use as starters. These include Enterococcus faecalis, Pedicoccus spp., Lb. mesenteroides and Lb. casei (El- Gendy et al., 1983). They are considered to be suitable starters for Domiati cheese made from pasteurized milk (Abd El-Salam and Alichanidis, 2004). Several starters have been evaluated for the manufacture of White brined cheeses and it has been suggested that lactococci and Lactobacillus delbrueckii subsp. bulgaricus, or even a yoghurt culture can give satisfactory results with respect to acidification of the milk (Bintsis and Papademas, 2002).
In this study, four probiotic strains including Bifidobacterium bifidum, Bifidobacteria longum, Lactobacillus delbrueckii ssp. bulgaricus, and Streptococcus thermophilus were examined as a potential candidate for incorporation in soft cheeses.
These strains have been selected based on their acid and bile tolerance, adhesion to intestinal cell line, oxygen sensitivity, anticarcinogenic properties and ability to modify gut microflora of human subjects (Lankaputhra & Shah, 1998; McIntosh et al., 1999; Crittenden et al., 2001; Ong 2007).
The objective of this study is to:
1- To find out a suitable starter for Egyptian soft white cheese made from heat treated milk (pasteurized).
2- The possibility of introducing Probiotic bacteria as a portion of the starter with keeping the quality and characteristic of our distinguished Egyptian soft cheese.
3- To run a comparative study about the proper percentage of the different strains under the study.
4- Evaluation of different combination of starter on the character of resultant soft white cheese.
5- Evaluate the benefit of probiotic soft cheese as a source of anti-hypercholesterolemia using the in vivo studies.