Production of aroma volatile compounds from peppers (Capsicum chinense and Capsicum baccatum) treated with methyl-jasmonate after harvest

Abstract

The changes in volatile compounds produced during the ripening of chili pepper fruit (Capsicum sp.) contribute to the development of two fundamental sensory attributes: the aroma and the taste. The biochemical pathways associated with the fruit aroma formation have been characterized and have been seen to be conserved along with many species. However, the regulatory mechanisms on the gene expression and enzymatic activities of these pathways remain little understood. In climacteric fruits, it is clear the ethylene involvement in the induction of the genes that encode enzymes related to the synthesis of esters, aldehydes, alcohols and terpenes, and other aroma volatile compounds. On the other hand, the role of ethylene in aroma production in non-climacteric fruit, such as chili pepper, remains unclear and other hormones seem to be more relevant. Some studies have been demonstrated to jasmonates, particularly methyl-jasmonate (MJ) is able to induce the increase in the production of volatile compounds, by the induction of aroma-related gene expression. Taking this into account, the aim of this project is to evaluate the effects of methyl-jasmonate treatment on the post-harvest biosynthesis of aroma. Taking this into account, the aim of this project is to evaluate the effects of methyl-jasmonate treatment of post-harvest biosynthesis of aroma volatile compounds of two different chili peppers: Habanero (Capsicum chinense) and dedo-de-moça (Capsicum baccatum). Fruits will be harvested at the breaker stage (yellowish or reddish, depending on the pepper fruit) and will be treated with MJ. Next, changes in the ripening parameters (ethylene production, respiration, color changes) will be determined and compared with the non-treated control group. This work aims to identify which classes of volatile organic compounds are affected by MJ treatment in chili peppers and provides outcomes for a better understanding of the hormonal regulation of aroma formation for non-climacteric fruit. The reason for the choice of two Capsicum species is to evaluate if the same biochemical pathways are affected by MJ, which would point out a conservative mechanism in the genus. Once the MJ has an impact on flavor, the project can provide basic information to drive the use of this hormone as an alternative for a postharvest treatment which objective would be the maintenance of the sensory quality of pepper fruit. This project is part of a research work that aims to characterize how some plant growth regulators act on volatile synthesis in fruits economically important. Thus, the results will be compared with that previously and currently obtained in tomato, raspberry, strawberry, papaya, and banana, covering, this way, both climacteric, and non-climacteric fruits. (AU)