Study On The Microencapsulation Of Lactic Acid Bacteria With High Adsorption Of Lead And Its Characterization

In this study,Pediococcus pentosaceus 10-a-1 with high tolerance and adsorption capacity of lead was encapsulated with alginate by internal emulsification method.Then the processing parameters were optimized.The effects of the chitosan coating on the embedding rate,particle size and enteric solubility of microcapsules were investigated.Further,the viability and the ability of adsorbing lead of two kinds of microcapsules under continuous simulate gastric and intestinal fluids treatment were investigated,as well as the stability of the microcapsules during storage at different temperatures.The experimental results were as followed:Optimum process conditions were determined as sodium alginate concentration was 3%,water-oil ratio at 30:120,calcium acid ratio at 3:1,stirring speed was 600 rpm,calcium-gel ratio was at 1.5:9.Under the optimized conditions,the encapsulation rate of the sodium alginate microcapsules reached 86.3%and the average particle size was 139.03?m.The particle distribution was relatively concentrated and the shape of microcapsules was uniform,neat and smooth.After the encapsulation of sodium alginate microcapsules by chitosan,the embedding rate of microcapsules decreased to 65.6%and the particle size of microcapsules increased to 185.66 ?m.In simulated intestinal juice(SIJ),alginate microcapsules were released more rapidly than sodium alginate-chitosan microcapsules.Two kinds of microcapsules were completely released after 90 min.After simulated gastric juice(SIJ)treatment for 120min and simulated intestinal juice(SIJ)treatment for 240 min,the survival rate of bacteria in sodium alginate microcapsules and sodium alginate-chitosan microcapsules was 46.13%and 76.91%,respectively.Double-layer microcapsules showed better tolerance to gastric and intestinal fluids.The adsorption rate and amount of lead by Pediococcus pentosaceus 10-a-1 treated with continuous simulated gastroenteric fluid were significantly decreased.Two kinds of microcapsules could effectively reduce the weakened ability of bacteria to absorb lead after the treatment of gastroenteric liquid.The adsorption rate and capacity of lead on sodium alginate microcapsules was 74.74%and the adsorption capacity was 7.29 mg/g.Meanwhile the adsorption rate and capacity of lead on sodium alginate-chitosan microcapsules was 76.52%and the adsorption capacity was 7.46 mg/g.The adsorption capacity of lead in double layer microcapsule was better.The survival rate of sodium alginate-chitosan microcapsule was the highest when stored at 4? and 20? for 28 days.Viable count of sodium alginate-chitosan microcapsules stored at 4? was 9×107CFU/mL,while microcapsules stored at 20?reached 3.8×107 CFU/mL.Viable count of sodium alginate microcapsule stored at 4? and 20? were 6.3×107 CFU/mL and 2.45×107 CFU/mL,respectively.Viable counts of control were 1.52×106 CFU/mLand 3.4×105CFU/mL,respectively.