Controlled ethylene-releasing from V-type starch coated with sodium alginate for banana ripening via changing the humidity of environment

A carrier of storing and releasing ethylene was prepared using V-type starch (VS) or cross-linked VS as core and sodium alginate (SA) as shell. Fourier Transform InfraRed spectra revealed that the VS was successfully cross-linked and its stability in water was enhanced. Scanning electron microscopy (SEM) images confirmed that ethylene was encapsulated into VS or cross-linked VS and then coated with SA-Ca2+ matrix to form close-knit beads. The SA beads contained 0.48–0.67 mol ethylene per Kg starch and maintained a very slow ethylene-releasing rate at 4 °C for 7 d in a dry storage condition. SA shell absorbed the water from the air and swelled after being exposed to an environment with certain humidity, triggering a stable release of ethylene within 7 h. In the ripening process, banana treated with 30 mg ethylene carriers in a 2.5 L container had a delayed maturation compared to the pure ethylene treatment along, and finally, ripening effect of carriers was equal to 10 nmol L−1 ethylene gas. This carrier can accomplish stability gas storage in dry condition, precisely controlled and targeted applications of ethylene under humidity ambience for agricultural applications.