Elżbieta Biedrzycka

Effect of non-digestible oligosaccharides on gut microecosystem in rats

Abstract Effect of commercial or new-developed preparations of non-digestible oligosaccharides: fructo-oligosaccharides, lactulose, corn dextrins and corn resistant starch, on microecology of Wistar rats was investigated. A control group was fed a casein diet with 10% cellulose. The experimental groups were administered diets in which cellulose was replaced by the examined preparations. After 4-week feeding experiments, a high increase in live bifidobacteria number by 1.2 and 1.4 log cfu/g of faeces was found in groups fed resistant starch and lactulose. An increase in coliform number by 0.6–0.8 log cfu/g was found in all the groups. No or only negligible changes in numbers of the total mesophilic aerobic and facultatively anaerobic bacteria count, and the spores of anaerobic and aerobic bacteria, were observed. Fructo-oligosaccharides and lactulose lowered pH and gave the best trophic effect in caecum (significantly increased weights of: caecum with contents, cecal walls and cecal contents as well as dry weight of contents), whereas resistant starch increased markers of unhealthy cecal changes (N-NH3 content and β-glucuronidase activity). The activity of bacterial saccharolytic enzymes changed in a substrate-specific manner in relation to the examined non-digestible oligosaccharide preparations.

Diet and Health: Apple Polyphenols as Antioxidants

The traditional American rhyme says, “an apple a day keeps the doctor away.” What has made apples exceptional and appreciated for a million years? Besides their content of pectin, vitamins and minerals, they are considered to be a good source of antioxidants that scavenge and neutralize free radicals, which in turn play a role in the onset of cardiovascular diseases and cancers. Polyphenols are major antioxidants in apples, however, the antioxidants vary with the apple variety, and the post-harvest storage conditions. Further, the polyphenols are distributed differently throughout the fruit (skin or flesh). The paper reviews the present knowledge on apple polyphenols, their bioavailability and pro-health functionality.

Interaction of Bifidobacterium and Salmonella during associated growth

Interaction of 15 Bifidobacterium (belonging to species B. animalis, B. globosum and B. breve) and six Salmonella (belonging to species S. enteritidis and S. typhimurium) strains was examined during associated growth at optimum conditions for the two genera. All strains of Bifidobacterium investigated were antagonistic to Salmonella. Three strains of Bifidobacterium bactericidal to Salmonella were identified. The kinetics of Salmonella inhibition was as follows: growth of Salmonella was inhibited before the end of the exponential phase, then succeeded by a rapid decrease of live-cell numbers at the beginning of the stationary phase, after which the cell death rate was lower. Growth of Bifidobacterium in the associated cultures was similar to that in monocultures.

Utilization of resistant starch of native tapioca, corn and waxy corn starches and their retrograded preparations by Bifidobacterium

Anaerobic fermentation of native starches from tapioca, normal and waxy corn, and their laboratory modified preparations, by selected Bifidobacterium strains (Bifidobacterium pseudolongum KSI9, Bifidobacterium breve KN14, and Bifidobacterium animalis KS20a1) was carried out under in vitro conditions. The growth and acidifying properties of bifidobacteria and utilization of resistant starches were determined in relation to glucose in the control sample. The preparations obtained from normal and waxy corn starches were the best substrates for growth of B. breve KN14, even compared with glucose. The growth of B. animalis KS20a1 was comparable, both on native and modified starches, whereas the starch preparations better stimulated the growth and acidifying activity of B. pseudolongum KSI9, as compared with native starches. The resistant starch fractions of all preparations were generally utilized to a higher degree (64–85%) compared with native starches (56–79%). The results of the study indicate that tapioca and corn starches, both native and modified, could be substrates beneficial for the enhancement of Bifidobacterium intestinal populations.