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BACKGROUND The nutritional effects of both table olives and olive oil are attributed not only to their fatty acids but also to antioxidant phenolics such as phenolic acids. Delays in oil processing usually result in undesirable oxidation and hydrolysis processes leading to formation of free fatty acids. These alterations create the need to process oil immediately after olive harvest. However, phenolic content decreases drastically during olive storage resulting in lower quality oil. In the present study we propose postharvest methyl jasmonate treatment as a mean to avoid changes in fatty acid composition and losses of phenolic acids during olive storage. RESULTS Contents of fatty acids and phenolic acids were estimated in methyl jasmonate treated olives throughout 30-day storage, as compared with those of untreated olives. Significant decreases of saturated fatty acids were observed in treated samples whereas increases of oleic, linoleic and linolenic acids were respectively measured (i.e. from 50.8% to 64.5%, from 7.2% to 9.1% and from 1.5% to 9.3%). Also, phenolic acid contents increased significantly in treated olives. Particularly, increases of gallic acid from 1.35 to 6.29 mg kg−1, chlorogenic acid from 9.18 to 16.21 mg kg−1, vanillic acid from 9.61 to 16.99 mg kg−1, caffeic acid from 5.12 to 12.55 mg kg−1, p-coumaric acid from 0.96 to 5.31 mg kg−1 and ferulic acid from 4.05 to 10.43 mg kg−1 were obtained. CONCLUSION Methyl jasmonate treatment is proposed as an alternative postharvest technique to traditional methods to guarantee olive oil quality when oil processing is delayed and olive fruits have to necessarily to be stored. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND Chemical elicitation is one of the most effective methods currently used to enrich plant foods in bioactive compounds. Methyl jasmonate ( MJ) has been described as a very useful elicitor of some plant compounds, polyphenols among them. The objective of this study was to determine the effects of pre-harvest MJ application on the increase in the main flavonoids and the antioxidant properties of black currant ( Ribes nigrum) cultivars. RESULTS Significant enhancement of individual and total anthocyanins was measured after elicitation with MJ, particularly when a concentration of 0.2 mmol L−1 was used. Total anthocyanins increased from 28288.74 ± 253.65 to 43561.08 ± 145.87 mg kg−1 in Ben Hope black currants after elicitation with 0.2 mmol L−1 MJ. Similarly, an increase from 35986.04 ± 287.98 to 41320.22 ± 109.38 mg kg−1 was estimated in Ben Alder cultivar. Black currant flavonols were not individually affected by the treatment; however, total flavonols increased from 3115.21 ± 12.11 to 3268.41 ± 8.91 mg kg−1 in Ben Hope and from 3016.38 ± 10.07 to 3110.95 ± 8.57 mg kg−1 in Ben Alder. Antioxidant properties of black currants as measured by DPPH and ABTS assays improved proportionally to the increase in flavonoid content after MJ elicitation. CONCLUSION Pre-harvest elicitation with MJ is proposed as a useful tool to enhance contents of anthocyanins and flavonols as well as free radical-scavenging activity of black currants. The functional black currants obtained here can be interesting for industry, for consumption as fresh fruits and for production of juice and jam. © 2015 Society of Chemical Industry [ABSTRACT FROM AUTHOR]