to room temperature and filtered. pH of supernatant was adjusted to 6.5 with Ca(OH),, centrifuged and dried by lyophilization.
Papain h ~d r o / ~x i . ~: 500 g of casein were suspended in 5 1 of water and pH was adjusted to 6.5. A suspension of casein was heated to 37 'C and 2 g of papain were added. Hydrolysis was conducted for 16 h and after that time the way of treating was the same as during pepsin hydrolysis.
The following analyses were made: growth-promoting activity of Bifidohacfrriurn bifidztm according to MIKOLAJCIK et ill. [-I]. total non-protein according to BUDSLAWSKI [I] and free amino acids nitrogen by the method of O R l m S ~. Z 151. aminowgars by the method of KUMAR et al. [3].
The replts from Fig. I show that all casein bifidus factor samples stimulate the growth of Bifidobactrrium bifidurn. Among the examined samples the best results were obtained with acid CBF, whichcontains the highest quantity of aminowgars (Table I).
The growth requirements of B!fidobacreriuni bifidrrni are complex (61. These bacteria require for their growth not only peptide fraction but also carbohydrate ingredients. Casein bifidus factor supplies both these components.
According to likrature information a casein bifidus factor stimulates growth of Bi/?dobarterium bifdum not only under in \itro condition but it can also promote a rich growth of these bacteria in an intestinal tract [6]. Due to this fact the chemical properties are very important. From the data presented in Table 1 it results that papain CBF contains the highest quantity of nitrogen and the lowest quantity ofash. Completely opposite quantities of these two ingredients appear in acid CBF.
Although acid CBF stimulates the growth of Bifidobacferium hifidurn in the best way, the high ash content may be the main di4advantage for the application of this factor in infant milk formula production.