Non-protein amino acids in Australian acacia seed: Implications for food security and recommended processing methods to reduce djenkolic acid

Published Date

15 July 2015, Vol.179:109–115, doi:10.1016/j.foodchem.2015.01.072

Title 

Non-protein amino acids in Australian acacia seed: Implications for food security and recommended processing methods to reduce djenkolic acid

• Author 

• Berin A. Boughton ^a
• Priyanka Reddy ^a
• Martin P. Boland ^a,b
• Ute Roessner ^a,c
• Peter Yates ^d,e,,

• aMetabolomics Australia, School of Botany, The University of Melbourne, Parkville, VIC 3010, Australia
• bSchool of Psychological and Clinical Sciences, Charles Darwin University, Casuarina, NT 0909, Australia
• cAustralian Centre for Plant Functional Genomics, The School of Biosciences, University of Melbourne, Parkville, VIC 3010, Australia
• dWorld Vision Australia, Burwood East, VIC 3151, Australia
• eResearch Institute for Environment and Livelihoods, Charles Darwin University, Casuarina, NT 0909, Australia

Received 9 September 2014. Revised 5 December 2014. Accepted 13 January 2015. Available online 20 January 2015.

Highlights

• •
  Australian acacia has potential to contribute to the agriculture of semi-arid Africa.
• •
  Five Australian acacia varieties were screened for toxic non-protein amino acids.
• •
  Australian acacia found to contain elevated levels of nephrotoxic djenkolic acid.
• •
  The implications of acacia use as a famine food explored.
• •
  Djenkolic acid content reduced to safe levels by roasting for between 8 and 10 min.

Abstract

Seed of Australian acacia species, Acacia colei, Acacia elecantha, Acacia torulosa, Acacia turmida and Acacia saligna, were analysed for the presence of toxic non-protein amino acids and the levels of essential amino acids. Amines were derivatised with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate before analysis using liquid chromatography electrospray ionisation triple quadrupole mass spectrometry (LC-ESI-QQQ-MS). Multiple reaction monitoring (MRM) with optimised transitions and collision energies for each analyte were employed. The known nephrotoxic compound djenkolic acid was found to be present at elevated levels in all species tested. The lowest levels were in A. colei (0.49% w/w) and the highest in A. saligna(1.85% w/w). Observed levels of djenkolic acid are comparable to measured and reported levels found in the djenkol bean. Subsequent testing of seed processing methods showed djenkolic acid levels can be significantly reduced by over 90% by dry roasting at 180 °C rendering the seed safe for human consumption.

Chemical compounds studied in this article

• Djenkolic acid (PubChem CID: 68134)
• Mimosine (PubChem CID: 440473)
• Lanthionine (PubChem CID: 98504)
• (S)-carboxymethyl cysteine (PubChem CID: 193653)
• Canavanine (PubChem CID: 439202)

Keywords

• Acacia
• Acacia saligna
• Acacia colei
• Acacia torulosa
• Acacia tumida
• Acacia elacantha
• Djenkolic acid
• Food security
• Famine food
• Non-protein amino acid
• Essential amino acid
• Derivatisation
• Mass spectrometry
• Collision induced dissociation
• Multiple reaction monitor

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• DOCX (159K)

Supplementary data 1

• ⁎ 
  Corresponding author at: Research Institute for Environment and Livelihoods, Charles Darwin University, Casuarina, NT 0909, Australia. Tel.: +61 437918419.

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