Antioxidant Rich Extracts of Terminalia ferdinandiana Inhibit the Growth of Foodborne Bacteria
1
Queensland Alliance for Agriculture and Food Innovation (QAAFI), The University of Queensland, Health and Food Sciences Precinct, 39 Kessels Rd, Coopers Plains, QLD 4108, Australia
2
Queensland Health Forensic and Scientific Services, 39 Kessels Rd, Coopers Plains, QLD 4108, Australia
3
CSIRO Agriculture and Food, 306 Carmody Road, St Lucia, QLD 4067, Australia
*
Author to whom correspondence should be addressed.
Foods 2019, 8(8), 281; https://doi.org/10.3390/foods8080281
Received: 26 June 2019
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Revised: 18 July 2019
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Accepted: 20 July 2019
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Published: 24 July 2019
(This article belongs to the Special Issue Foods of Plant Origin)
Terminalia ferdinandiana (Kakadu plum) is a native Australian plant containing phytochemicals with antioxidant capacity. In the search for alternatives to synthetic preservatives, antioxidants from plants and herbs are increasingly being investigated for the preservation of food. In this study, extracts were prepared from Terminalia ferdinandiana fruit, leaves, seedcoats, and bark using different solvents. Hydrolysable and condensed tannin contents in the extracts were determined, as well as antioxidant capacity, by measuring the total phenolic content (TPC) and free radical scavenging activity using the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay. Total phenolic content was higher in the fruits and barks with methanol extracts, containing the highest TPC, hydrolysable tannins, and DPPH-free radical scavenging capacity (12.2 ± 2.8 g/100 g dry weight (DW), 55 ± 2 mg/100 g DW, and 93% respectively). Saponins and condensed tannins were highest in bark extracts (7.0 ± 0.2 and 6.5 ± 0.7 g/100 g DW). The antimicrobial activity of extracts from fruit and leaves showed larger zones of inhibition, compared to seedcoats and barks, against the foodborne bacteria Listeria monocytogenes, Bacillus cereus, Methicillin resistant Staphylococcus aureus, and clinical isolates of Pseudomonas aeruginosa. The minimum inhibitory concentration and minimum bactericidal concentration in response to the different extracts ranged from 1.0 to 3.0 mg/mL. Scanning electron microscopy images of the treated bacteria showed morphological changes, leading to cell death. These results suggest that antioxidant rich extracts of Terminalia ferdinandiana fruits and leaves have potential applications as natural antimicrobials in food preservation.
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Keywords:
Kakadu plum; Terminalia ferdinandiana; antioxidants; antimicrobial activity; food preservation; phytochemicals; polyphenols
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MDPI and ACS Style
Akter, S.; Netzel, M.E.; Tinggi, U.; Osborne, S.A.; Fletcher, M.T.; Sultanbawa, Y. Antioxidant Rich Extracts of Terminalia ferdinandiana Inhibit the Growth of Foodborne Bacteria. Foods 2019, 8, 281. https://doi.org/10.3390/foods8080281
AMA Style
Akter S, Netzel ME, Tinggi U, Osborne SA, Fletcher MT, Sultanbawa Y. Antioxidant Rich Extracts of Terminalia ferdinandiana Inhibit the Growth of Foodborne Bacteria. Foods. 2019; 8(8):281. https://doi.org/10.3390/foods8080281
Chicago/Turabian StyleAkter, Saleha, Michael E. Netzel, Ujang Tinggi, Simone A. Osborne, Mary T. Fletcher, and Yasmina Sultanbawa. 2019. "Antioxidant Rich Extracts of Terminalia ferdinandiana Inhibit the Growth of Foodborne Bacteria" Foods 8, no. 8: 281. https://doi.org/10.3390/foods8080281
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