Writing in the Journal of the Science of Food and Agriculture, Munich University scientists report that amaranth-based sourdough fermented using Lactobacillus helveticus showed the best sensory scores.
Amaranth is already used in bakery products, note the researchers, but the use is limited due to unfavourable technological properties. Such products are usually formulated in combination with other gluten-free cereals such as rice, maize or millet as their main ingredient, they added.
Sourdough may provide a solution, however, and results from the new study indicate that various lactic acid bacteria strains may be suitable starter cultures for the production of amaranth-based gluten-free products.
“The results [of our study] provide relevant information on the fermentation properties required of a customised starter for amaranth flour,” wrote the researchers, led by Mario Jekle.
Great hopes for sourdough
Sourdough has already been identified as an ideal gluten-free food. A review published in the journal Food Microbiology indicated that sourdough could help solve the gluten-free issue.
Lead author of the review Prof Elke Arendt from the School of Food and Nutritional Sciences, University College Cork told FoodNavigator recently: “Sourdough has a lot of potential, particularly from a flavour and structure perspective. The strains used are also anti-fungal and that can extend the shelf-life of bread without the need of chemical preservatives.”
But employing sourdoughs requires a detailed knowledge of the strains and starter cultures for each grain. Sorghum sourdough would need a specific strain, like Lactobacillus reuteri or Lactobacillus fermentum, while buckwheat flour would require other starter cultures.
“I have great hopes for sourdough in gluten-free bread,” said Prof Arendt.
And with global market reported to be worth $2.6bn by 2012, up from $1.56bn last year, according to Packaged Facts, there is clearly the financial incentive to produce new foods for this category.
Jekle and his co-workers tested the fermentation properties of Lactobacillus plantarum, L. paralimentarius and L. helveticus in amaranth-based sourdough. The results showed only small variations between the starter cultures, but sensory analysis by 25 trained tasters indicated significant differences between the resulting sourdoughs.
The highest scores for the bread were obtained for the sourdough prepared with the L. helveticus.
The study was performed in wheat bread, but the results have implications for gluten-free products. “The results of this study will form a basis for the development of a specialised starter culture for amaranth flour,” wrote the researchers. “Consequently, it should be possible to take advantage of this raw material and increase the range of high-quality baked goods from amaranth.”
Some companies supplying ingredients for the manufacture of gluten-free foods already offer ingredients based on ancient grains – especially since they tend to have high nutrient levels and there have been concerns that products made with rice, corn and potato flour leave nutrients to be desired.
For instance ConAgra Mills in the US has a range of naturally gluten-free flours from quinoa, teff, amaranth, millet and sorghum. This year it launched a new flour blended from these that is intended to tick all the nutrition boxes for gluten-free eaters.
Source: Journal of the Science of Food and Agriculture
Published online ahead of print, doi: 10.1002/jsfa.4091
“Effects of selected lactic acid bacteria on the characteristics of amaranth sourdough”
Authors: M. Jekle, A. Houben, M. Mitzscherling, T. Becker