Methyl jasmonate treatment of strawberry fruits enhances antioxidant activity and the inhibition of nitrite production in LPS-stimulated Raw 264.7 cells

Near-harvest application of methyl jasmonate affected phenolic content and antioxidant properties in "Thompson Seedless" grape

The influence of methyl jasmonate (MJ) preharvest treatment was investigated on some polyphenols and antioxidant systems in the "Thompson Seedless" table grape. The clusters were sprayed in the vineyard 2 days before harvest with 0, 1, 5, and 10 mM MJ. After picking, berries were stored for 6 days at 15°C, simulating marketing conditions. Total phenols and flavonoids were affected by MJ treatment, especially at 10 mM concentration, whereas total tannins were found to be unchanged. Antioxidant activity of the treated skin was noticeably higher compared with the control, together with PAL and POD activity. Although MJ had little effect on catechin and epicatechin, the levels of quercetin and rutin were noticeable. In addition, 5 and 10 mM MJ exerted a pronounced effect on transresveratrol content. These data showed that a single preharvest application close to the harvest time could be an effective treatment to promote the antioxidant properties of the grape.

Phenolic profiles and their responses to pre- and post-harvest factors in small fruits: a review

The consumption of small fruits has increased in recent years. Besides their appealing flavor, the commercial success of small fruits has been partially attributed to their high contents of phenolic compounds with multiple health benefits. The phenolic profiles and contents in small fruits vary based on the genetic background, climate, growing conditions, and post-harvest handling techniques. In this review, we critically compare the profiles and contents of phenolics such as anthocyanins, flavonols, flavan-3-ols, and phenolic acids that have been reported in bilberries, blackberries, blueberries, cranberries, black and red currants, raspberries, and strawberries during fruit development and post-harvest storage. This review offers researchers and breeders a general guideline for the improvement of phenolic composition in small fruits while considering the critical factors that affect berry phenolics from cultivation to harvest and to final consumption.

Effects of exogenous methyl jasmonate on quality and preservation of postharvest fruits: A review

Methyl jasmonate (MeJA) is a volatile hormone involved in a number of plant processes, acting as a signal in response to external stresses and modulating the biosynthesis of other phytohormones. Here, we are reviewing for the first time all reports related to the effects of exogenous MeJA on postharvest fruits. Application of MeJA during preharvest and postharvest stages has been demonstrated to enhance fruit antioxidant capacity and phenolics content, which in turn extended fruit shelf-life, enhanced fruit quality and reduced chilling injury. The postharvest application of MeJA has been reported to alter volatiles pattern and to enhance the innate disease resistance of postharvest fruits against pathogenic fungi. The results obtained using different treatment conditions, such as temperature, storage time and concentration, have been highlighted and compared along the manuscript in order to provide new insights on the applicability of MeJA for enhancing postharvest fruit quality and preservation.

Effect of postharvest methyl jasmonate treatment on fatty acid composition and phenolic acid content in olive fruits during storage

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.

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.