According to results published in the Journal of Food Science, bread baked with the salt-stressed yeast (Saccharomyces cerevisiae) reduced the time for fermentation by about 25 per cent, as well as improving the overall sensory properties.
The results indicate that all the major parameters of the finished bread were improved in the salt-stressed bread, offering opportunities for bread makers.
“Not only shorter fermentation time but also softer bread, and significant sensory properties for aroma, taste, and overall acceptability were obtained,” wrote the researchers from the National Pingtung University of Science and Technology in Taiwan and Rutgers University in the US.
“It was concluded that salt-stressed Baker’s yeast had significantly improved bread quality.”
Rising to the challenge
According to the Federation of Bakers, which represents the interests of the UK's largest baking companies, 25 million tonnes of bread are produced every year by the western European bread industry. Industrial bakers dominate some markets like Britain and Ireland, where they represent over 80 per cent of the market.
The new research reports an “innovative bread making process” whereby Baker’s yeast was stressed in 7 per cent salt solution. Bread was then baked with the salt-stressed yeast using a traditional straight dough process. Six different breads were formulated with different sugar levels, including 8, 16, and 24 per cent sugar, with traditional or salt-stressed yeast.
The results showed that the bread produced with the salt-stressed yeast and a sugar level of 16 or 24 per cent had significantly reduced fermentation times of 23 and 28 per cent, compared to the controlled bread when the yeast was salt-stressed for 40 minutes.
Furthermore, 40 minutes of salt stress resulted in a significant increase in gas and bread volumes, compared to the control bread. Bread produced with the salt-stressed yeast was also reported to be “softer and significantly improved sensory properties for aroma, taste, and overall acceptability were obtained”.
Glycerol content is key
Commenting on the mechanism, the researchers report that exposure of the yeast to salt solutions leads to an accumulation of glycerol in the cell membranes. Increases in volume may be due to “glycerol acting as a lubricant for the gas bubbles, allowing greater expansion”, suggested the Taiwanese and Rutger researchers.
“Specific volume increased with increasing levels of glycerol. Therefore, the larger loaf would have a less dense gluten network giving less resistance to compression,” they said.
“Overall, better sensory properties for aroma, taste, and overall acceptability were obtained for samples made with salt-stressed Baker’s yeast for 40 min compared to control samples.”
Source: Journal of Food Science
Published online ahead of print, doi: 10.1111/j.1750-3841.2009.01337.x
“A Novel Bread Making Process Using Salt-Stressed Baker's Yeast”
Authors: Lien-Te Yeh, Albert Linton Charles, Chi-Tang Ho, Tzou-Chi Huang