| dc.description.abstract | Numerous studies have shown that lactic acid bacteria (LAB) may provide health benefits if they live in human gastrointestinal track at a sufficient amount. This fact encourages the development of the use of LAB as probiotic in food products, for example in powdered infant formula. The aim of the present study was to evaluate the ability of L. rhamnosus R21 to compete with one of pathogenic bacteria that commonly contaminate powdered infant formula, namely Salmonella Typhimurium. Lactic acid bacteria used in this study was isolated from breast milk, namely Lactobacillus rhamnosus R21. In addition, this study may indicate the effect of reconstitution temperature towards bacterial competition. Competition between L. rhamnosus R21 and S. Typhimurium was tested by measuring viability after reconstitution at 27, 60, and 70 oC and the growth of both bacteria during hang time of 0, 2, 4, 6, and 8 hours. The doses of L. rhamnosus R21 used in this study were 109, 108, and 106 CFU/mL. These bacteria competed with 104 CFU/mL of S.Typhimurium at three different reconstitution temperatures: 27, 60, and 70 °C. The results showed that L. rhamnosus R21 was more resistant to reconstitution temperature of 60 and 70 oC than S. Typhimurium.Competition between both bacteria showed that an amount of 109 CFU/mL L. rhamnosus R21 was able to inhibit the growth of S. Typhimurium in reconstituted infant formula for 8 hours of hang time. The inhibition values are 3.84 log CFU/mL (27°C), 3.96 log CFU/mL (60 °C), and 3.16 log CFU/mL (70 °C). While, an amount of 108 and 106 CFU/mL L. rhamnosus R21 performed less inhibition to S. Typhimurium. The ability of L. rhamnosus R21 to lower the pH value by producing lactic acid has important role in competition with S. Typhimurium. While the reconstitution temperature did not significantly affect the competition between both bacteria. | en |
