Enhancement of nutritionally significant constituents of black currant seeds by chemical elicitor application.

Black currant seeds are obtained as a residue during juice production. Black currant seed oil contains high amounts of nutritionally desirable constituents such as γ-linolenic acid (GLA), α-linolenic acid (ALA) and stearidonic acid (SA), as well as certain phenolic acids, which act as natural antioxidants. Fatty acids and phenolic acids of seeds from black currant cultivars after elicitation with methyl jasmonate (MJ) were examined. GLA contents around 25% with respect to total fatty acid content were measured in seeds after pre-harvest treatment of black currants with 0.02mM MJ in 0.05% Tween-20. High GLA samples also exhibited high SA content (higher than 10% with respect to total fatty acid content); however, ALA dropped (from 16% to 10%). High GLA content seeds also showed increased contents of gallic, caffeic, p-coumaric and ferulic acids. In particular, seeds from 0.02mM MJ treated Ben Hope black currants exerted contents of gallic, caffeic, p-coumaric and ferulic acids of 201.4, 125.9, 201.3 and 112.5µgg(-1)vs 124.3, 58.6, 165.4 and 95.8µgg(-1) measured in seeds from untreated Ben Hope black currants. Comparable results were obtained for Ben Alder and Ben Gairn berries. Chemical elicitation with 0.02 MJ is proposed as an industrial practice in such a way that, after consideration of quality issues, it would be obtained high added value black currant seeds.

Accumulation of anthocyanins and flavonols in black currants (Ribes nigrum L.) by pre-harvest methyl jasmonate treatments.

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.