Production of volatiles in brown boronia flowers after harvest Pilot-scale research

The transfer of postharvest technology from laboratory-scale studies in regulated environments to pilot-scale, on-farm application was examined, and the effect of postharvest incubation on eight major volatiles was detailed. Brown boronia flowers (Boronia megastigma) were incubated in shade-cloth bags (18 kg per sample) for up to 33 h after harvest under ambient conditions, on-farm. The effect of manually mixing flowers to replenish oxygen and avoid accumulation of excess thermal load under these conditions was studied by comparison with not mixing. After incubation, flowers were frozen in polyethylene brigs in cardboard boxes (9 kg) and stored at -18°C until extraction. Flowers were thawed and extracted with solvent on a pilot-scale to yield the floral extract (concrete) from which absolute was prepared; all samples were analysed by GC for volatile content. There were no temperature differences related to mixing flowers throughout incubation. There was a significant increase in the concentration of floral extract after 16 h in the mixed flowers, and after 24 h in the unmixed flowers; maximum increases in mixed and unmixed flowers were 20 and 25% greater than at harvest, respectively. The concentration of total volatiles in the mixed flowers increased rapidly but not significantly within the first 8 h of incubation, subsequently declining. In flowers that were not mixed, similar trends in the first 16 h were observed, with a subsequent significant increase in the concentration of total volatiles after 24-32 h of incubation to a maximum concentration 50% greater than at harvest. The major volatile, β-ionone, followed similar trends, however with a more dramatic decline in mixed flowers after 8 h incubation, and an overall increase of about 75% relative to at-harvest concentrations in unmixed flowers.