Preparation of water‐based flexography printing ink by KMnO4 modified activated carbon for fruit ripening control application

Ethylene is a type of gas that fruits and vegetables can produce naturally. The release of ethylene gas from fruits and vegetables causes them to ripen and undergo physical, chemical and biological changes, such as changes in the appearance in terms of shape and colour, changes in firmness and texture, changes in taste and changes in nutritional value. Furthermore, it also facilitates the growth of microorganisms. These changes lead to spoilage if the fruit or vegetables are left to over ripen. Therefore, the prevention and reduction of damage caused by the ripening of fruits and vegetables entail reducing or slowing down the release of ethylene gas produced by them. This research project aimed to study the properties of activated carbon and potassium permanganate (KMnO4) modified activated carbon, applied as a printing layer on plastic materials for bananas, in terms of their adsorption and decomposition of ethylene. Active and water‐based flexography printing inks were prepared from water‐based binder and ethylene adsorbing and scavenging agents (activated carbon and KMnO4 modified activated carbon) at various concentrations of active agents, that is, 0.0, 5.0, 7.5 and 10.0%w/v. Then, those inks were printed on polypropylene plastic substrate. The delayed ripening of fruits results showed that the plastic materials coated with modified activated carbon inks delayed the physiology disorder (colour and firmness changing about 250% and 226%) and prolonged the storage time up to 14 days when compared with control. In addition, the functional ink layer also presented a high efficiency of abrasion resistance of about 75 cycles of rubbing at 1.8 kg. The products that stem from this research can be applied as packaging for fruits and vegetables in the form of bags, stickers and product pads that can help extend the life and slow the ripening of fruits and vegetables.