Researchers say they have figured out why kefir grains extend the shelf life of sourdough bread.
A study published in the journal Food Chemistry say that kefir grains contain organic acids that can double the shelf life of sourdough bread.
“The results obtained in this study showed that sourdough bread made with kefir grains contains respectable amounts of organic acids that seem to play a major role against Bacillus spp., which are responsible for rope spoilage, as proved by DGGE analysis and sensorial tests,” said the study authors.
Member of the Bacillus genus are the main strains involved in rope spoilage, which after staling is the biggest cause of bread deterioration. When rope spoilage occurs bread becomes discoloured and sticky.
In 2010, the same researchers involved in the present study talked up the shelf-life extending potential of sourdough bread made with Kefir grains, which are produced from cheese whey, a major liquid waste from the dairy industry.
The explained that the grains contain organic acids that can double the shelf life of sourdough bread
Eight day shelf life boost
In the current study, the team explained that organic acids and conducted tests that showed how kefir grains could delay rope spoilage.
To reach these conclusions, they analyzed four sourdough breads through sensorial tests and denaturing gradient gel electrophoresis (DGGE), a technique that separates DNA fragments.
They found that breads prepared with kefir grains started to show rope spoilage after 15 days of storage, compared to seven days for control samples prepared with wild microflora.
Food Chemistry, Volume 143, 15 January 2014, Pages 139–146
‘Effect of a Thermoascus aurantiacus thermostable enzyme cocktail on wheat bread quality’
Authors: D.S. Oliveira, J. Telis-Romero, R. Da-Silva, C.M.L. Franco