Mogućnost primjene bakterije Lactobacillus reuteri, izolirane iz kiselog tijesta, kao dodatka starter-kulturi, radi poboljšanja kakvoće kruha

Retardation of microbial spoilage of bread can be achieved by the use of spontaneous sourdough with an antimicrobial activity. This study was undertaken to identify lactic acid bacteria naturally occurring in spontaneous sourdough and use them for quality improvement and prolonging shelf life of rye, wheat and rye with wheat bread. Identification of isolates from spontaneous sourdough by pyrosequencing assay showed that Lactobacillus reuteri were dominant lactic acid bacteria. The isolates showed a wide range of antimicrobial activity and displayed a synergistic activity against other lactobacilli, some lactococci and foodborne yeasts. The best application of spontaneous sourdough was noticed in the rye bread with the lowest crumb fi rmness of the fi nal product, although the sensory results of wheat and rye with wheat bread did not statistically diff er from control bread. L. reuteri showed a high preserving capacity against fungi during storage. This may be due to bacteriocins and various fatty acids secreted into the growth medium that were identified by agar well diffusion assay and gas chromatography. L. reuteri showing high antimicrobial activity have the potential to be used as a starter additive that could improve safety and/or shelf life of bread.Usporavanje mikrobnog kvarenja kruha može se postići uporabom kiselog tijesta koje ima antimikrobni učinak. U ovom su radu identificirane bakterije mliječno-kiselog vrenja prirodno prisutne u kiselom tijestu, te su upotrijebljene za poboljšanje kakvoće i produljenje trajnosti raženog, bijelog i miješanog raženog kruha. Pirosekvenciranjem su identificirani izolati iz kiselog tijesta, te je utvrđeno da među mliječno-kiselim bakterijama prevladava bakterija Lactobacillus reuteri. Izolati su imali antimikrobni učinak na razne uzročnike kvarenja i sinergistički učinak na druge vrste bakterija Lactobacillus i Lactococcus, te na kvasce. Najbolji je učinak dodatka izolata iz kiselog tijesta postignut u raženom kruhu, koji je imao najmanju tvrdoću mrvica, no senzorska se svojstva bijelog i miješanog raženog kruha, u usporedbi s kontrolnim uzorkom, nisu bitno promijenila. Bakterija L. reuteri učinkovito je spriječila pojavu plijesni na kruhu tijekom skladištenja, vjerojatno zato što je u podlogu za rast lučila bakteriocine, koji su identificirani pomoću metode difuzije u jažicama agara, te razne masne kiseline, određene plinskom kromatografijom. Zaključeno je da L. reuteri ima izražen antimikrobni učinak, pa se može upotrijebiti kao dodatak starter-kulturi radi sprečavanja kvarenja i/ili produljenja trajnosti kruha

Changes in antagonistic activity of lactic acid bacteria induced by their response to technological factors

This study examined the changes in antagonistic activity of selected lactic acid bacteria (LAB) in response to technological factors used in food production. The antimicrobial activity of 12 selected LAB strains was assessed against the bacterial and fungal strains using the agar well diffusion method. Sodium chloride (NaCl) 6.5–8.0%, glucose 20-30% and pH 4.0, pH 8.0 and higher were the most crucial factors in reducing the spectra of the microorganisms antagonized. Heating at 80 °C or 100 °C had a greater negative impact than 63 °C on the antifungal activity of LAB. Freezing at –72 °C eliminated the antifungal activity, or it changed from fungicidal to fungistatic. Although each LAB demonstrated the ability to retain antimicrobial activity induced by various technological factors, Lactococcus lactis 768/5 was superior in retaining high antimicrobial activity against tested indicator strains

Potential of Lactobacillus reuteri from Spontaneous Sourdough as a Starter Additive for Improving Quality Parameters of Bread

Retardation of microbial spoilage of bread can be achieved by the use of spontaneous sourdough with an antimicrobial activity. This study was undertaken to identify lactic acid bacteria naturally occurring in spontaneous sourdough and use them for quality improvement and prolonging shelf life of rye, wheat and rye with wheat bread. Identification of isolates from spontaneous sourdough by pyrosequencing assay showed that Lactobacillus reuteri were dominant lactic acid bacteria. The isolates showed a wide range of antimicrobial activity and displayed a synergistic activity against other lactobacilli, some lactococci and foodborne yeasts. The best application of spontaneous sourdough was noticed in the rye bread with the lowest crumb fi rmness of the fi nal product, although the sensory results of wheat and rye with wheat bread did not statistically diff er from control bread. L. reuteri showed a high preserving capacity against fungi during storage. This may be due to bacteriocins and various fatty acids secreted into the growth medium that were identified by agar well diffusion assay and gas chromatography. L. reuteri showing high antimicrobial activity have the potential to be used as a starter additive that could improve safety and/or shelf life of bread

An Inulin-Enriched Soy Drink and Its Lowering Effect on Oxidized Low Density Lipoproteins in Healthy Volunteers

Due to selection of appropriate ingredients and parameters, a microbiologically-safe drink enriched with soy protein isolate (SPI) and prebiotic dietary fiber inulin with high scores of acceptability was produced. The results of medical nutrition survey showed that on the 21 day of using drink the level of oxidized low density lipoproteins (LDL) significantly decreased while the other biochemical parameters of blood of healthy patients as compared to the control tests remained unchanged. As well there was no apparent impact on the intestinal microflora balance of recipients established

An inulin-enriched soy drink and its lowering effect on oxidized low density lipoproteins in healthy volunteers

Due to selection of appropriate ingredients and parameters, a microbiologically-safe drink enriched with soy protein isolate (SPI) and prebiotic dietary fiber inulin with high scores of acceptability was produced. The results of medical nutrition survey showed that on the 21 day of using drink the level of oxidized low density lipoproteins (LDL) significantly decreased while the other biochemical parameters of blood of healthy patients as compared to the control tests remained unchanged. As well there was no apparent impact on the intestinal microflora balance of recipients established