1. Materials and methods:
Quantitative profile of LAB and yeasts in home-made sauerkrauts of different cultivars
Strnad Szymon, Satora Paweł, Makarewicz Małgorzata, Drożdż Iwona, Błaszczyk Urszula
Wydział Technologii Żywności
Katedra Technologii Fermentacji i Mikrobiologii Technicznej
Uniwersytet Rolniczy w Krakowie
introduction:
Sauerkraut is obtained traditionally by spontaneous fermentation of cabbage with autochthonous microbiota inhabiting the leaves surface. During the process microbiota produces from the carbohydrates crucial lactic acid, which sustains the pH value low. Growth of the pH value may cause the appearance of putrefactive bacteria, spoiling the silages [Pundir and Jain, 2010].
The aim of the conducted research was to assess the quantitative composition of yeasts and bacterial microbiota typical for the fermentation process of cabbages belonging to three various cultivars. Chosen cultivars are popular among the producers of sauerkraut in Poland. Mentioned microorganisms are mainly bacteria belonging to the group of lactic acid bacteria (LAB) [Beganović et al., 2014].
Results:
Figure 1 Microbial growth during cabbage cv. Ambrosia fermentation
Materials and methods:
Sauerkraut was prepared in a laboratory scale by the means of traditional cabbage fermentation in stoneware vessels. Vegetables were deprived of outer leaves and hearts and then shredded with a slicer. Processed material was weighed and mixed with 2.5% NaCl, placed in stoneware vessels and fermented for 16 days in 20°C.
During the first phase of fermentation 1 mL of brine sampled from each variety after dilution was spread onto WL Nutrient Agar with chloramphenicol (Merck) and MRS Agar (Biocorp) supplemented with 2.5% NaCl for the quantitative determination of microorganisms. After incubating at 20ºC for 48h (LAB) or 72h (yeasts) colonies were enumerated. The examined brine was sampled every day during the first phase of fermentation (days 1st to 4th) and five times up till the end of the investigated process (days 8th, 10th, 11th, 14th and 16th).
Figure 2 Microbial growth during cabbage cv. Avak fermentation
Conclusion:
Anaerobic microbiota was isolated from the brine during the tests;
All the tested cultivars varied in the numbers of yeast and LAB cells present throughout the process;
Repeteable tendencies in the occurring microbiota were noticed;
LAB appeared most abundantly during the 4th day of the fermentation.
Figure 3 Microbial growth during cabbage cv. Vestri fermentation
Literature:
Beganović J., Kos B., Pavunc A.L., Uroić K., Jokić M., Šušković J Traditionally produced sauerkraut as source of autochthonous functional starter cultures. Microbiological Research. 169, 7-8:
Pundir R.K., Jain P Change in Microflora of Sauerkraut During Fermentation and Storage. World Journal of Dairy & Food Sciences 5 (2),