Delayed harvest reduces quality of raw and roasted macadamia kernels

BACKGROUND: Macadamia integrifolia, M. tetraphylla and their hybrids are cultivated for their edible kernels. Abscised macadamia fruit is gathered from the ground, and harvest intervals vary due to management decisions or unavoidable delays. In this study, macadamia fruit from cultivar HAES 344 was harvested between May and August in three experiments in south‐east Queensland, Australia. Control fruit was dehusked, dried and evaluated immediately, while delayed harvest fruit remained on the ground under trees for periods of 3 and 5 weeks before processing. Whole kernel weight, shoulder damage and weight of pieces were assessed for raw kernels, and kernel colour mottled colour and surface damage were assessed after roasting. RESULTS: Delaying harvest for 3 weeks in experiment 1, and 3 or 5 weeks in experiment 2 reduced whole kernel and increased shoulder damage and weight of pieces. Experiment 3 raw kernel was not affected. After‐roast darkening increased in all experiments, and roasting produced severe mottled colour in one experiment, and severe surface damage in two of three experiments. CONCLUSION: Macadamia kernels may deteriorate rapidly when harvest is delayed, and both raw and roasted kernel quality may be affected. Shorter harvest intervals, preferably less than 3 weeks, will help maintain optimum kernel quality. Copyright © 2008 Society of Chemical Industry