Abstract
Papaya fruit is of economic importance to Brazil (second highest global producer), however, this fruit is very perishable with high weight loss, rapid ripening and accelerated senescence. It is a climacteric fruit, with ethylene and respiratory climacteric peaks, and is highly susceptible to post-harvest phytopathogens. Edible coatings are considered attractive alternatives for fruit preservation, as they can provide an efficient gas barrier, reduce moisture loss, and in some cases, act as an antimicrobial agent. Carnauba wax is most commonly used for fruit coatings, as it is an effective barrier to water loss. Some recent studies have reported carnauba coatings, normally applied as microemulsions, formulated in a nanostructured format. Development, characterization and application of carnauba wax nanoemulsion-coatings was the subject of a previous investigation (MScwork of the candidate), and these coatings are more amenable to essential oil incorporation due to smaller sized lipid micelles in the coating structure. Additionally, hydroxypropyl methylcellulose (HPMC) is a polysaccharide with good film forming ability, and coatings made from this material have significant gas exchange properties. The combination of lipids and polysaccharides can result in improved properties reflecting the advantages of both types of materials, namely water and gas barrier functions. Furthermore, the addition of anti-microbial ginger extracts into carnauba wax nanoemulsion/HPMC matrix, have the potential to reduce product decay. Several essential oils have been tested against post-harvest pathogens of papaya fruit, though more studies are needed concerning their application in coatings. Edible coatings may affect flavor, the aroma profile and creation of off-flavor compounds in fruits. The understanding of how coatings affect the production and retention of fresh flavor in intact papaya is important for the design of appropriate coating formulations. Therefore, the main aim is to prepare anti-microbial edible coatings that can maintain papaya quality, reduce decay and extend papaya shelf-life. Coating effects on aroma volatile profile, fruit pathogens and post-harvest fruit decay will be evaluated. (AU)
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