Survival Of Free And Encapsulated Bifidobacterium Bifidum F-35and Their Effects On The Phvsicochemical. Microbiological, Rheological And Sensory Characteristics Of Set-yogurt

Microencapsulation was implemented through the emulsification technique to producemultiphase microcapsules consisted of whey protein isolate and sodium alginate to confer thesufficient protection for Bifidobacterium bifidum F-35against the adverse conditions of yogurtenvironment. The B. bifidum F-35was incorporated into yogurt and divided to four types of set-yogurts involved free cells, encapsulated cells with whey protein (MCWP), double-coated cells bywhey protein then sodium alginate (MCWP-AL) and sample without B. bifidum F-35was designedas control treatment. The microcapsules characteristics and the effects at yogurt properties wereanalyzed. The shapes of microcapsules were detected by scanning electron microscopy (SEM) toshow the spherical shapes for both types with different sizes of10μm for MCWPand280μm forMCWP-AL.The encapsulation influenced the physiochemical, microbiological, rheological andsensory evaluations of set-yogurt. The treatment of MCWP-ALexhibited a higher microbial load ofLAB and B. bifidum F-35than treatments of MCWPand free cell with positive results aroundcoliform bacteria, moulds&yeast at all treatments.Encapsulation led to significant lower (P<0.05) at titrable acidity, moisture andsyneresis values, and a higher pH, total solid and lactose values than treatment of free cells aswell as proximity of encapsulated treatments characteristics MCWPand MCWP-ALtoward thecontrol treatment. Diacetyl were higher at treatment of free cells than control or encapsulatedtreatments prior to storage and after7day, but it soon disintegrated. In contrast, the acetoin waslower at free cells treatment than other treatments prior to storage and after7day.TPA values of chewiness, adhesiveness, gumminess and hardness at the encapsulatedtreatment MCWPdiffered significantly (P<0.05) prior to storage and after14day in comparison tothe control treatment. The encapsulated treatment MCWP-ALdiffered (P0.05) non-significantlycompared with the control treatment at parameters of chewiness, gumminess and hardness priorto storage.Behavior of B. bifidum F-35toward overall acceptability affected by the materials ofencapsulation as was expected, which gave a creamy texture for treatment of MCWP-ALwasfavored by the panelists. But it was flawed the slightly of bitterness taste. The encapsulatedtreatment MCWPremained mild fairly up to the end of storage. Whereas, the treatment of freecells was described by the panelists as sour taste and bad texture.