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High-efficiency removal of phytic acid in soy meal using two-stage temperature-induced Aspergillus oryzae solid-state fermentation

Authors

  • Liyan Chen,

    Corresponding author
    1. Bioprocessing and Renewable Energy Laboratory, Department of Grain Science and Industry, Kansas State University, Manhattan, KS, USA
    • Correspondence to: Liyan Chen, Bioprocessing and Renewable Energy Laboratory, Department of Grain Science and Industry, Kansas State University, 1980 Kimball Avenue, Manhattan, KS 66502, USA. Email: liyan@ksu.edu

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  • Praveen V Vadlani,

    1. Bioprocessing and Renewable Energy Laboratory, Department of Grain Science and Industry, Kansas State University, Manhattan, KS, USA
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  • Ronald L Madl

    1. Bioprocessing and Renewable Energy Laboratory, Department of Grain Science and Industry, Kansas State University, Manhattan, KS, USA
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Abstract

BACKGROUND

Phytic acid of soy meal (SM) could influence protein and important mineral digestion of monogastric animals. Aspergillus oryzae (ATCC 9362) solid-state fermentation was applied to degrade phytic acid in SM. Two-stage temperature fermentation protocol was investigated to increase the degradation rate. The first stage was to maximize phytase production and the second stage was to realize the maximum enzymatic degradation.

RESULTS

In the first stage, a combination of 41% moisture, a temperature of 37 °C and inoculum size of 1.7 mL in 5 g substrate (dry matter basis) favored maximum phytase production, yielding phytase activity of 58.7 U, optimized via central composite design. By the end of second-stage fermentation, 57% phytic acid was degraded from SM fermented at 50 °C, compared with 39% of that fermented at 37 °C. The nutritional profile of fermented SM was also studied. Oligosaccharides were totally removed after fermentation and 67% of total non-reducing polysaccharides were decreased. Protein content increased by 9.5%.

CONCLUSION

Two-stage temperature protocol achieved better phytic acid degradation during A. oryzae solid state fermentation. The fermented SM has lower antinutritional factors (phytic acid, oligosaccharides and non-reducing polysaccharides) and higher nutritional value for animal feed. © 2013 Society of Chemical Industry

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