Changes in the chemical and microbiological properties of spontaneous rye sourdough during fermentation | Spontāno rudzu maizes ieraugu ķīmisko un mikrobioloģisko rādītāju izmaiņas fermentācijas laikā
2010
Kozlinskis, E., Latvia Univ. of Agriculture, Jelgava (Latvia). Faculty of Food Technology. Dept. of Food Technology | Skudra, L., Latvia Univ. of Agriculture, Jelgava (Latvia). Faculty of Food Technology. Dept. of Food Technology | Rakcejeva, T., Latvia Univ. of Agriculture, Jelgava (Latvia). Faculty of Food Technology. Dept. of Food Technology | Kunkulberga, D., Latvia Univ. of Agriculture, Jelgava (Latvia). Faculty of Food Technology. Dept. of Food Technology
In traditional rye bread baking in Latvia, a spontaneous sourdough starter is used which microflora is determined in flour and in microorganism cultures in the external environment. The aim of this research was to analyze the chemical and microbiological parameters of spontaneous sourdough starters that were prepared using two types of flour - 100% medium extraction (ash content - 1.45%) rye flour (starter U), and 80% medium extraction rye flour with addition of 20% of biological enzyme-rich rye flour (starter M). Total titratable acidity (TTA) and pH were measured in each preparation step. Organic acids and reduced sugars were determined using HPLC (Agilent 1100). Amino acids as well as vitamins E, B1, B2, and B5 were determined in all samples. DNA was extracted directly from starter samples or from washed cells plated on MRS media. Microbial diversity of lactic acid bacteria (LAB) species was investigated using amplified V3 regions of 16S rDNA gene from the sourdough DNA. Denaturing gradient gel electrophoresis (DGGE) was used for community fingerprinting. Both sourdough starters (U and M) showed acceptable final pH and TTA values after a 48-hour fermentation (pH 4.05 and 4.11, and TTA - 13 and 12.6 respectively) representing active metabolism of LAB, and contained acceptable amounts of lactic acid bacteria - 7.24 and 7.62 log10 CFU g-1 respectively. Both spontaneous starter samples contained biologically active compounds which benefit the technological process of rye bread making. This is the first study to gain insight into the microflora of a spontaneous starter made in Latvian bread industry by using genetic methods.
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