Optimization of milk-based medium for efficient cultivation of Bifidobacterium pseudocatenulatum G4 using face-centered central composite-response surface methodology.

This study was undertaken to optimize skim milk and yeast extract concentration as a cultivation medium for optimal Bifidobacteria pseudocatenulatum G4 (G4) biomass and ß -galactosidase production as well as lactose and free amino nitrogen (FAN) balance after cultivation period. Optimization process in this study involved four steps: screening for significant factors using 2(3) full factorial design, steepest ascent, optimization using FCCD-RSM, and verification. From screening steps, skim milk and yeast extract showed significant influence on the biomass production and, based on the steepest ascent step, middle points of skim milk (6% wt/vol) and yeast extract (1.89% wt/vol) were obtained. A polynomial regression model in FCCD-RSM revealed that both factors were found significant and the strongest influence was given by skim milk concentration. Optimum concentrations of skim milk and yeast extract for maximum biomass G4 and ß -galactosidase production meanwhile low in lactose and FAN balance after cultivation period were 5.89% (wt/vol) and 2.31% (wt/vol), respectively. The validation experiments showed that the predicted and experimental values are not significantly different, indicating that the FCCD-RSM model developed is sufficient to describe the cultivation process of G4 using skim-milk-based medium with the addition of yeast extract.

A nutritious medida (Sudanese cereal thin porridge) prepared by fermenting malted brown rice flour with Bifidobacterium longum BB 536.

The nutritive value of spontaneously fermented brown rice flour medida, a Sudanese cereal thin porridge, is low. This study was carried out to improve the nutritional quality of medida. The flour was soaked and malted at 30◦C to optimise the protein content. Flour malted for two days had the highest protein content. Skim milk was added to the malted brown rice flour medida and fermented using Bifidobacterium longum BB 536. Maximum count of B. longum BB 536 up to 9 log CFU/ ml was attained at 4.6 final fermentation pH. The resultant viscosity was similar to that of the spontaneously fermented brown rice flour medida. There was significant (P< 0.01) increase in both the energy density and the protein content, having increased 12 folds and 24 folds, respectively. The essential amino acids including lysine and methionine were highly augmented. The resultant medida have stable flowing characteristics and meet the whole protein and energy requirements for infants and children aged 1 - 10 years old.