Production of volatile aroma compounds in papaya fruit(Carica papaya cv. Gold) treated with methyl jasmonate and stored at low temperature.

Abstract

Brazil stands out as the world's largest producer of papaya that is appreciated worldwide for its taste and delicate flesh. The volatile compounds contribute to the formation of aroma and flavor of the fruit, which makes them key to the development of the sensory characteristics that define its assessment by consumers. The main aroma compounds in papaya include benzyl isothiocyanate, terpenes, esters, aldehydes, alcohols, organic acids and ketones; especially the monoterpene linalool is the most abundant compound. The cold chain is essential for extending the shelf life of the fruit, even though it harms the quality by reducing the emission of volatile aroma components. Literature indicates that the postharvest treatment with methyl jasmonate (MJ) is able to reduce possible damaging effect of low temperature storage. Furthermore, the application of methyl jasmonate on fruit is able to stimulate the activity of the enzymes involved in the production of volatile compounds. Thus, this study aims to evaluate the effects of postharvest application of MJ in fruits of papaya (Carica papaya cv Golden), focusing on the compounds of the biosynthetic pathways of aroma volatiles in fruit ripened at a temperature of 22°C, as well as other stored at low temperature followed by transfer to 22°C for ripening. In addition to the profiles of volatile compounds, it will be evaluated the profiles of respiration, ethylene production, synthesis of soluble sugars and changes in skin color in order to characterize the ripening. Given the importance of linalool to the characteristic aroma of papaya, changes in the transcription of a linalool synthase gene will be also evaluated, looking for correlating it to the treatment effects in the production of volatile compounds. The data will allow inferences regarding the dependency of this gene as well their signaling by MJ and ethylene. Another result expected, based on results found in the literature, is that treatment with MJ will affect the production of volatiles and they will be preserved even after storage at low temperature. From the standpoint of postharvest biochemical research, this project also has the potential to provide background data for understanding the regulatory mechanisms of flavor biosynthesis in fruits.