Аннотация:Introduction: The influence of chitosan’s physicochemical characteristics on thefunctionality of lactic acid bacteria and the production of lactic acid remainsvery obscure and contradictory to date. While some studies have shown astimulatory e ect of oligochitosans on the growth of Lactobacillus spp, otherstudies declare a bactericidal e ect of chitosan. The lack and contradiction ofknowledge prompted us to study the e ect of chitosan on the growth andproductivity of L. bulgaricus in the presence of chitosan and its derivatives.Methods: We used high molecular weight chitosan (350 kDa) and oligochitosans(25.4 and 45.3 kDa). The experiment was carried out with commercial strainof L. bulgaricus and the low fat skim cow milk powder reconstituted withsterile distilled water. After fermentation, dynamic viscosity, titratable acidity, pH,content of lactic acid, colony forming units, chitosan and oligochitosans radiiwere measured in the samples. Fermented dairy products were also examinedusing sodium dodecyl sulfate electrophoretic analysis, gas chromatographymass spectrometry and light microscopy.Results and discussion: The results of the study showed that when L. bulgaricuswas cultured in the presence of 25.4 kDa oligochitosans at concentrations of0.0025%, 0.005%, 0.0075% and 0.01%, the average rate of LA synthesis over 24hours was 11.0 × 10−3mol/L/h, 8.7 × 10−3mol/L/h, 6.8 × 10−3mol/L/h, 5.8× 10−3mol/L/h, respectively. The 45.3 kDa oligochitosans had a similar e ect,while the average rate of lactic acid synthesis in the control sample was only3.5 × 10−3mol/L/h. Notably, 350 kDa chitosan did not a ect the rate of lacticacid synthesis compared with the control sample. Interestingly, interaction ofchitosan with L. bulgaricus led to a slowdown in the synthesis of propanol, anincrease in the content of unsaturated and saturated fatty acids, and a change inthe composition and content of other secondary metabolites. The quantity of L.bulgaricus in a sample with 0.01% chitosan exceeded their content in the controlsample by more than 1,700 times. At the same chitosan concentration, thefermentation process was slowed down, increasing the shelf life of the fermentedmilk product from 5 to 17 days while maintaining a high content of L. bulgaricus(6.34 × 106CFU/g).
