PRELIMINARY TECHNOLOGICAL PROPERTIES ASSESSMENT OF BACILLUS SPP. ISOLATED FROM TRADITIONAL CASSAVA STARTERS USED FOR ATTIEKE PRODUCTION

This study was carried out to select Bacillus strains as potential microbial starters for cassava dough fermentation into attiéké (a fermented and steamed granular cassava, couscous-like product) regarding their enzymes (amylase, pectinase, cellulase, phytase, tannase and betaglucosidase) production. For this purpose, 42 presumptive Bacillus spp were isolated from traditional cassava starters and screened in vitro. All the selected strains produced amylase, pectinase, cellulase while 37 (88.09%) produced phytase and 27 (64.28%) were able to produce beta-glucosidase. Regarding these technological properties mainly production of all these enzymes, only 13 Bacillus strains (30.95%) could be used as potential microbial starters in association with lactic acid bacteria for the controlled fermentation of cassava dough in order to improve and standardize the organoleptic quality of attiéké by softening and detoxification actions

PRELIMINARY TECHNOLOGICAL PROPERTIES ASSESSMENT OF BACILLUS SPP. ISOLATED FROM TRADITIONAL CASSAVA STARTERS USED FOR ATTIEKE PRODUCTION

This study was carried out to select Bacillus strains as potential microbial starters for cassava dough fermentation into attiéké (a fermented and steamed granular cassava, couscous-like product) regarding their enzymes (amylase, pectinase, cellulase, phytase, tannase and betaglucosidase) production. For this purpose, 42 presumptive Bacillus spp were isolated from traditional cassava starters and screened in vitro. All the selected strains produced amylase, pectinase, cellulase while 37 (88.09%) produced phytase and 27 (64.28%) were able to produce beta-glucosidase. Regarding these technological properties mainly production of all these enzymes, only 13 Bacillus strains (30.95%) could be used as potential microbial starters in association with lactic acid bacteria for the controlled fermentation of cassava dough in order to improve and standardize the organoleptic quality of attiéké by softening and detoxification actions

Sequential adsorption of polymers: displacement or trapping?'

Sequential adsorption of carboxylated pullulan and pullulan on polystyrene-coated wafers was studied by reflectometry. The incoming pullulan partially displaced the preadsorbed carboxylated pullulan from the surface. Mixed adsorption layers were formed. By increasing the pH of the solution the carboxylated pullulan dissociated and desorbed, whereas the neutral pullulan was not influenced and remained adsorbed. A positively charged polyelectrolyte (quaternized poly(vinylpyridine)) was used as a probe for detecting the amount of trapped, negatively charged carboxylated pullulan remaining on the surface after the desorption step. This trapped carboxylated pullulan is retained by pure entanglement effects. By a mass balance calculation, the fractions of displaced, desorbed, and trapped carboxylated pullulan could be found for pullulans with different molecular weights. The shorter pullulans did not displace any carboxylated pullulan but trapped about half of the layer; the other half could desorb rapidly upon pH increase. Longer pullulan molecules could displace up to 70% of the carboxylated pullulan layer, so that smaller quantities remained to be trapped. Upon pH increase, another 10-15% desorbed, about as much as the amount trapped. Hence, during sequential adsorption both rapid displacement and trapping occur but to different extents depending on the molar mass of the polymer supplied last