Kernel brown centres in macadamia: a review
M. D. Le LagadecQueensland Primary Industries and Fisheries, Bundaberg Research Station, 49 Ashfield Road, Bundaberg, Qld 4670, Australia. Email: danielle.lelagadec@dpi.qld.gov.au
Crop and Pasture Science 60(12) 1117-1123 https://doi.org/10.1071/CP08403
Submitted: 11 November 2008 Accepted: 3 August 2009 Published: 23 November 2009
Abstract
The incidence of kernel brown centres in macadamia (Macadamia integrifolia and M. tetraphylla and hybrids) has increased substantially in Australia. Although the defect amounts to only ~1% of all kernels processed in Australia, it costs the macadamia industry over AU$2 million per annum. Little formal research has been conducted, although the defect is mentioned widely in informal grower journals. Possible causal factors are reviewed in this article. Evidence suggests that kernel brown centres may be associated with exposure of enzymes in cell membranes and are also associated with incorrect nut-in-shell drying regimes. There appears to be an interaction among nut-in-shell moisture content, nut drying regime, and the incidence of brown centres. There is some indication that storage of wet nuts in poorly ventilated silos increases the potential for developing kernel brown centres. It is recommended that future research focusses on these issues.
Additional keywords: internal discoloration, kernel quality, kernel browning.
Acknowledgments
Sincere thanks are due to Dr Chris Menzel, Dr David Walton, Mr Paul O’Hare, and Mr Shane Dullahide for their constructive criticism of the manuscript. Dr Cameron McConchie is thanked for his help with the biochemical aspects of this manuscript. This study was financially supported by the Queensland Primary Industries and Fisheries, the Australian Macadamia Society, and Horticulture Australia Ltd.
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