Maria Soral-Śmietana

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.

Buckwheat starch: structure, functionality and enzyme in vitro susceptibility upon the roasting process

Starch of dehulled buckwheat grains with a moisture content of 14.5% before and after thermal treatment (160°C/30 min) was used in this study. The crystal structure of buckwheat starch was of the A-type. The thermal process applied elicited slight changes both in infrared spectra and relative crystallinity on X-ray diffraction patterns. The scanning electron microscopy studies demonstrated polygonal and irregular shape of starch granules. After the thermal treatment, some breakings or conglomerates were noticed on the granules. The roasting process also affected a decrease in the swelling power and solubility. The release of glucose and changes in resistant starch after partial hydrolysis by pancreatic α-amylase and other intestinal enzymes were analysed as well. The scanning electron microscopy visualization indicated significant susceptibility of buckwheat starch at the beginning (0.5 h) and during 6 h in vitro amylolysis.

Native and microwaved bean and pea starch preparations: physiological effects on the intestinal ecosystem, caecal tissue and serum lipids in rats

Dietary beans and peas provide fibre, resistant starch and other nutrients that are often lacking in the human diet. The influence of native starches of beans and peas (and microwaved preparations) on N utilisation, biochemical indices in blood serum and caecal ecosystem state (SCFA, bacterial enzymes, micro-organisms) was studied in vivo. The native pea starch contained more resistant starch compared with its bean counterpart (31 v. 17 %); however, processing decreased these amounts to 25 v. 10 %. N digestibility was found to decrease considerably in all experimental groups. A considerable reduction was observed in glucose and total cholesterol concentration in rat blood serum as a result of feeding both dietary legume starch preparations under microwave treatment. This indicates that starch of bean origin activated glycolytic bacterial enzymes; however, all the analysed starches were found to reduce the activity of beta-glucuronidase. In addition, both dietary bean starches significantly induced the formation of SCFA in the caecal digesta. As compared with the control group, a significant decrease in the pH of caecal and colonic digesta was demonstrated for both bean starch preparations. In comparison with the diet with native pea starch, its microwaved preparation reduced the concentrations of acetic, butyric and propionic acids among caecal SCFA and increased the pH of caecal and colonic digesta. The atherogenic index was significantly lower in rats fed microwaved pea starch. All investigated starch preparations increased the population of Bifidobacterium spp. in caecal digesta, but were also good substrates for opportunistic Enterococcus or Escherichia coli.

Influence of Chemically-Modified Potato Starch (RS Type 4) on the Nutritional and Physiological Indices of Rats

Influence of Chemically-Modified Potato Starch (RS Type 4) on the Nutritional and Physiological Indices of Rats A biological study was undertaken to analyse the metabolic effect of feeding rats with an experimental diet in which cellulose was substituted with 20% contribution of chemically-modified potato starches (subjected to oxidation, esterification, cross-linking and dual modification). Caecum digesta mass was significantly higher in rats fed the experimental potato starch preparations compared to control group. Luminal ammonia concentration and pH of caecal or colonic content were lower as an effect of diets with all the investigated preparations. Compared to the cellulose-containing diet (control), all modified potato starch preparations raised the content of SCFA in caecum digesta when fed to rats. Significant lowering of the levels of triacylglycerols and total cholesterol was noticed for all chemically-modified starch preparations. The activity of β-glucuronidase determined upon the administration of potato starch preparations into rat diets was significantly lower as compared to the control diet. The results indicate that the chemically-modified potato starch preparations are a good substrate for the intestinal microecosystem and may promote the beneficial status of the gastrointestinal tract of rats.

Native wheat, potato and pea starches and their physically modified preparations tested in vitro as the substrates for selected Bifidobacterium strains

The wheat, potato and pea starches subjected to physical modification were studied in vitro as a substrate for selected Bifidobacterium strains (Bifidobacterium breve KN14, Bifidobacterium animalis KS20a1). The effects of these substrates on bifidobacterial growth, acidifying activity, metabolic end-products and changes in starch microstructure were assayed after 24-h fermentation. Physically modified starch preparations were better utilized substrates for growth of Bifidobacterium monocultures, in comparison with native starches. Lactic acid occurred in the highest concentration in the culture of B. breve KN14 (55–104 µmol/100 ml), whereas acetic acid was highest in the culture of B. animalis KS20a1 (329–378 µmol/100 ml). The microstructure pictures showed meaningful differences between native and modified starches stemmed from the enzymatic action of examined Bifidobacterium strains during fermentation. Obtained results confirmed the stimulation of growth and acidifying activity of selected Bifidobacterium strains by investigated physically modified starches in comparison with native starch.