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Synthesis of aroma volatile compounds in raspberries (Rubus idaeus cv. autumn Bliss) after postharvest treatment with the phythormone methyl-jasmonate

Grant number: 13/07519-1
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): June 01, 2013
Effective date (End): May 31, 2014
Field of knowledge:Agronomical Sciences - Food Science and Technology
Principal Investigator:Eduardo Purgatto
Grantee:Caroline de Aquino Guerreiro
Home Institution: Faculdade de Ciências Farmacêuticas (FCF). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The changes in the biosynthesis of volatile compounds during ripening of raspberries (Rubus idaeus) contribute to the development of two sensory attributes essential for its acceptance by consumers: the aroma and taste. The biochemical pathways involved in the formation of volatile compounds commonly found in raspberries has been described in other fruits, which is consistent with the hypothesis of these metabolic pathways being conserved in many species. However, the regulatory mechanisms behind the changes on gene expression and enzyme activities that take place in the formation of aroma in raspberries, and fruits in general, remain unclear. In climacteric fruits, there is little doubt about the role of ethylene in the induction of enzymes related to biosynthetic pathways of esters, aldehydes, alcohols and other compounds with aromatic notes. However, recent evidences have pointed out to the involvement of other hormonal classes. In non-climacteric fruits such as raspberries, the role of ethylene seems to be marginal and the involvement of other hormones is more evident. Studies have found that the jasmonates - in particular methyl jasmonate (MJ) - are capable to increase the production of several classes of volatiles by inducing the gene expression of enzymes related to their respective biosynthetic pathways. Taking these previous observations as a basis, the aim of this study is to evaluate the postharvest effects of methyl jasmonate treatment on the synthesis of aroma volatile compounds of raspberries. To this end, fruits harvested at the white stage will be treated with MJ and ripening parameters as ethylene production, respiration, color, levels of soluble sugars and organic acids will be monitored and compared to untreated control fruits. The volatile compounds will be analyzed by gas chromatography coupled to mass spectrometry (GC-MS) and the levels of key compounds will be compared with those found in the control group. All analyzes will be performed on samples stored at 5oC and collected in a daily basis. This study aimed to evidence the effects of MJ on the production of raspberry aroma compounds and identify the classes affected by the treatment, thus providing a scientific basis for a better understanding of hormonal regulation of the volatile compounds synthesis in this fruit, and compare to results obtained in other fruits, climacteric and non-climacteric. Once evidenced changes that can positively impact the aroma, the project would provide support to the proposition of jasmonates as an alternative for the treatment of fruits in order to maintain the sensory characteristics along the postharvest life. (AU)