Use of sweet sorghum juice for lactic acid fermentation: preliminary steps in a process optimization

Authors

  • Kata Hetényi,

    1. Budapest University of Technology and Economics, Department of Applied Biotechnology and Food Science, H-1111 Müegyetem rkp. 3, Hungary
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  • Kinga Gál,

    1. Budapest University of Technology and Economics, Department of Applied Biotechnology and Food Science, H-1111 Müegyetem rkp. 3, Hungary
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  • Áron Németh,

    1. Budapest University of Technology and Economics, Department of Applied Biotechnology and Food Science, H-1111 Müegyetem rkp. 3, Hungary
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  • Béla Sevella

    Corresponding author
    1. Budapest University of Technology and Economics, Department of Applied Biotechnology and Food Science, H-1111 Müegyetem rkp. 3, Hungary
    • Budapest University of Technology and Economics, Department of Applied Biotechnology and Food Science, H-1111 Müegyetem rkp. 3, Hungary.
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Abstract

BACKGROUND: Lactic acid has many applications in the chemical industries and it can be produced economically by microorganisms using biomass raw materials of different origins. Sweet sorghum juice is a high sugar content raw material with potential for lactic acid production because after hydrolysis of its sucrose content the remaining glucose and fructose can supply the carbon demand of most lactic acid bacteria. However, satisfying the nitrogen and B-vitamin needs of the bacteria by supplementation with yeast extract and/or other alternative nitrogen-containing supplements can make the process too expensive.

RESULTS: Using a statistical optimization process much of the yeast extract can be replaced by a cheaper alternative nitrogen source, namely wheat gluten. This resulted in a fermentation with 99% lactic acid yield and 3.04 g L−1 h−1 volumetric productivity.

CONCLUSION: Using response surface methodology (RSM) media optimization was performed for lactic acid fermentation with an industrially acceptable result, reducing the costs of raw materials by half, replacing yeast extract by an alternative nitrogen source and applying yeast extract only as a source of micro-elements (vitamins, salts, etc.) Copyright © 2010 Society of Chemical Industry

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