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M. T. Liong and N. P. SHAH. School of Molecular Sciences, Victoria Univ., Werribee Campus, PO Box 14428, Melbourne City Mail Centre, Melbourne, Victoria, 8001, Australia Elevated serum cholesterol level has been associated with increased risk of coronary heart disease. Consumption of food products containing probiotics have been proposed to reduce serum cholesterol level. Prebiotics have synergistic effects in selectively stimulating growth of probiotics, improving their survivability and bioactivity. However, the mechanisms for cholesterol removal and the interactions between probiotic and prebiotics to remove cholesterol are poorly understood. Our objectives were to study the i) mechanism of cholesterol removal by L. casei ASCC 292 and ii) examine the interaction with FOS and maltodextrin in removal of cholesterol. Cholesterol assimilation was determined by the difference in cholesterol content in the medium before and after incubation period. Binding of cholesterol to cells was determined using growing, heat-killed and resting cells. Incorporation of cholesterol into cellular membrane was evaluated through changes in cellular lipid profiles using gas chromatography. Interaction between L. casei ASCC 292 with FOS and maltodextrin for cholesterol removal, growth, substrate utilization, yield and production of short-chain-fatty acids (SCFA) were evaluated statistically using response surface methodology. There was a good correlation between cholesterol assimilation and cell growth. The capability of L. casei 292 to remove cholesterol in dead and resting stage signified that cholesterol might be removed via binding to cells. The alteration in hexadecanoic, octadecanoic, total saturated and unsaturated fatty acids indicated that cholesterol might be incorporated into the cellular membrane. The second-order polynomial regression models showed that FOS and maltodextrin exhibited synergistic effects with L. casei 292 for removing cholesterol, enhancing growth and the production of SCFA. Response surface produced showed that cholesterol removal was growth associated and substrate dependent. These findings suggest that L. casei ASCC 292 could remove cholesterol via various mechanisms. FOS and maltodextrin exhibited synergistic properties with L. casei ASCC 292 for removal of cholesterol in a growth- and substrate-reliant manner.
Session 33, Food Microbiology: General
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |