First Steps in the Development of a Wheat Flour Based Lactic Acid Fermentation Technology. Culture Medium Optimization

K. Hetényi, Á. Németh and B. Sevella

Abstract
Batch fermentation experiments were performed to evaluate the potentials of different fractions of wheat as alternative carbon and nitrogen source for an economical production of lactic acid by a homofermentative mesophilic bacterium (Lactobacillus sp. MKT-878 NCAIM B02375). Hydrolysing the starch content of wheat results in well consumable glucose solution, and simultaneously by hydrolysing the insoluble protein content (gluten) of wheat the nitrogen source can be assured as well. The necessary yeast extract concentration was 30 g L–1 on hydrolysed wheat starch solution without gluten fraction. By means of an optimization process we found that the gluten fraction can substitute the major part of the added yeast extract as nitrogen source, and on the basis of a statistical experimental design we created an optimized medium with 8 g L–1 yeast extract and 16 g L–1 gluten supplementation, resulting in 3.54 g L–1h–1 productivity which can be considered as an industrially acceptable process output.

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Keywords
Gluten, hydrolysis, lactic acid, wheat, yeast extract