Treatment of fresh water hyacinth with essential oil emulsion and subsequent use of the plant material for control of Aspergillus flavus on rice dessert products

Essential oil emulsion, which is generally functionalized to have increased antifungal activity, has high solubility in water. The objective of this research was to develop an essential oil emulsion for absorption by water hyacinth plants in order to produce an essential oil absorbent material as a carrier of essential oil vapor that can be released to control mold in an enclosed packaging system. The fresh water hyacinth adsorbed the Michelia alba oil emulsion (100 µL/mL to 500 µL/mL) through its root system, transporting it to the stems and leaves after submerging the plant into the M. alba oil emulsion for 48 h. Dried sections (root, stem, and leaf) of the water hyacinth plant with absorbed M. alba essential oil emulsion released the M. alba vapor, inhibited Aspergillus flavus growth on malt extract agar (MEA), and also Thai dessert (Ja Mongkut) with the highest antifungal activity achieved with the concentration 500 µL/mL. The maximum essential oil absorption (345 µL/g) in the fresh plant was achieved after 48 h. The dried water hyacinth (≥ 0.4 g/L air) completely inhibited the growth of A. flavus for at least 7 days. In addition, the absorbent material prevented the growth of A. flavus on the Thai dessert (Ja Mongkut) with approximately 100% effectiveness (versus the control) for 10 days, thereby extending the shelf-life 2.5-fold in when compared with the control without essential oil.