Articles
Changes in phenolic composition of table olives produced under regulated deficit irrigation during natural fermentation
Article number
1458_13
Pages
99 – 106
Language
English
Abstract
Regulated deficit irrigation enables a reduction in water application without significantly impacting yield and fruit quality.
The influence of two irrigation treatments was evaluated in natural debittered olives (Cobrançosa) from irrigation without water stress (FI) and regulated deficit irrigation (RDI) treatments.
At the beginning of fermentation, the concentration of hydroxytyrosol, verbascoside, and isoverbascoside was more concentrated in samples from FI. At the same time, oleuropein, the main phenolic compound responsible for bitterness, the phenolic acid chlorogenic, luteolin, luteolin-7-glucoside, and quercetin rutinoside were higher in olives from RDI treatment.
Despite these differences, they were not statistically important, as well as the sum fraction of phenolic compounds.
During fermentation, and in both irrigation treatments, the concentration of all individual phenolic compounds, namely oleuropein, decreased, while the concentration of hydroxytyrosol increased due to the hydrolysis of oleuropein.
The higher changes in oleuropein were observed in the first week after the beginning of fermentation, in which a decrease of less than one-third of the initial content in olives from FI was observed, while in RDI it was about half.
At the end of fermentation, the oleuropein content in olives from FI is close to zero, whereas in RDI, it remains at 25% of the initial content.
In contrast, an increment in the content of hydroxytyrosol of 300 to 350% was observed in olives from FI and RDI treatments, respectively.
It can be concluded, therefore, that it is possible to reduce the amount of water applied and improve the quality of table olives.
The influence of two irrigation treatments was evaluated in natural debittered olives (Cobrançosa) from irrigation without water stress (FI) and regulated deficit irrigation (RDI) treatments.
At the beginning of fermentation, the concentration of hydroxytyrosol, verbascoside, and isoverbascoside was more concentrated in samples from FI. At the same time, oleuropein, the main phenolic compound responsible for bitterness, the phenolic acid chlorogenic, luteolin, luteolin-7-glucoside, and quercetin rutinoside were higher in olives from RDI treatment.
Despite these differences, they were not statistically important, as well as the sum fraction of phenolic compounds.
During fermentation, and in both irrigation treatments, the concentration of all individual phenolic compounds, namely oleuropein, decreased, while the concentration of hydroxytyrosol increased due to the hydrolysis of oleuropein.
The higher changes in oleuropein were observed in the first week after the beginning of fermentation, in which a decrease of less than one-third of the initial content in olives from FI was observed, while in RDI it was about half.
At the end of fermentation, the oleuropein content in olives from FI is close to zero, whereas in RDI, it remains at 25% of the initial content.
In contrast, an increment in the content of hydroxytyrosol of 300 to 350% was observed in olives from FI and RDI treatments, respectively.
It can be concluded, therefore, that it is possible to reduce the amount of water applied and improve the quality of table olives.
Authors
A. Fernandes-Silva, M. Sousa, R. Carvalho, A. Inês
Keywords
Olea europaea L., Cobrançosa, texture, oleuropein, hydroxytyrosol, biophenols
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