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

The effect of methyl jasmonate postharvest application on the antioxidant and anti-inflammatory activity of strawberry fruits was evaluated. Results showed that the methyl jasmonate treated strawberry extract had higher antioxidant activity and suppresses the nitrite production in LPS-stimulated RAW 264.7 murine macrophages. The HPLC profiles of both treated and untreated strawberry extracts were compared. To evaluate which compounds are responsible of these higher activities it was also investigated the antioxidant and anti-inflammatory capacities of the hexane, chloroform, EtOAc, and n-butanol fractions obtained from the methyl jasmonate treated strawberry. The EtOAc and n-butanol fractions exhibited the most potent antioxidant activity compared to the hexane and chloroform fractions. In addition the n-butanol fraction was able to decrease nitrite production. The EtOAc and n-butanol fractions were analyzed by LC–MS. These results showed that methyl jasmonate promotes antioxidant and anti-inflammatory capacity of strawberry fruits by the stimulation of phenolic compounds and anthocyanins production.     

茉莉酸甲酯对草莓果实采后腐烂、苯丙烷类代谢及抗氧化活性的影响

为研究茉莉酸甲酯处理(Methyl jasmonate,MeJA)对草莓果实采后腐烂、苯丙烷类代谢及抗氧化活性的影响,将果实先于20℃下以10μmol/L MeJA熏蒸处理6h,然后转入(1±1)℃下贮藏12d,每隔3d测定果实腐烂率、苯丙烷类代谢相关酶苯丙氨酸解氨酶(PAL)、对香豆酰-CoA连接酶(4-CL)、肉桂酸羟化酶(C4H)和二氢黄酮醇还原酶(DFR)活性以及总酚、总花色苷和酚类和花色苷类单体物质含量,并且同时测定果实DPPH(1,1-diphenyl-2-picrylhydrazyl)自由基清除率和总还原力。结果显示,MeJA处理可显著抑制草莓果实贮藏期间腐烂率的上升;同时MeJA可诱导PAL、4-CL、C4H和DFR活性的上升,从而有效延缓了酚类和花色苷类物质含量的下降,提高了果实DPPH自由基清除率和总还原力,维持了果实的抗氧化活性。这些结果表明,MeJA处理在草莓果实保鲜中具有较好的应用前景。     

Effect of storage temperatures on antioxidant capacity and aroma compounds in strawberry fruit

The antioxidant capacity (measured as oxygen radical absorbance capacity, ORAC), total anthocyanins, total phenolics, aroma compounds, and postharvest quality of strawberry fruit (Fragaria x ananassa cv. Chandler) kept at 0°C, 5°C, and 10°C were investigated. Strawberry fruit stored at 10°C or 5°C showed higher antioxidant capacity, total phenolics, and anthocyanins than those stored at 0°C. However, the postharvest life based on overall quality was longer at 0°C than at 5°C or 10°C. The production of aroma compounds was markedly influenced by storage time and temperature. Individual aroma compounds were affected differently. For example, ethyl hexanoate, hexyl acetate, methyl acetate, and butyl acetate increased, while 3-hexenyl acetate and methyl hexanoate decreased during storage. In general, strawberries stored at 10°C or 5°C produced higher levels of these volatiles than those stored at 0°C. In conclusion, strawberries stored at 0°C retained an acceptable overall quality for the longest storage duration; however, berries stored at temperatures higher than 0°C showed higher content of aroma compounds and antioxidant capacity during the postharvest period.     

Effect of methyl jasmonate on quality and antioxidant activity of postharvest loquat fruit

BACKGOUND: Loquat fruit is rich in natural antioxidants and has shown a remarkably high antioxidant activity. To search for an effective method for maintaining or even improving antioxidant activity during postharvest storage, we investigated the effect of 10 µmol L^?1 methyl jasmonate (MeJA) treatment on levels of major individual sugars and organic acids, total phenolics, total carotenoids, total flavonoids and antioxidant activity in loquat fruit during storage at 1 °C for 35 days. RESULTS: The MeJA‐treated fruit exhibited significantly lower levels of respiration rate, ethylene production, phenylalanine ammonia‐lyase and polyphenol oxidase activities, and higher levels of sugars, organic acids, total phenolics and total flavonoids than control fruit. Meanwhile, the treatment also maintained significantly higher antioxidant activity as measured by the scavenging capacity against 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH), superoxide and hydroxyl radicals, and by the reducing power test compared to the control. There was a significant positive linear relationship between total phenolic content and DPPH radical scavenging activity. CONCLUSION: MeJA treatment can improve the quality and functional properties of harvested loquat fruit by maintaining a higher level of antioxidants and enhancing antioxidant activity. Copyright © 2009 Society of Chemical Industry     

Determination of major volatile compounds during the production of fruit vinegars by static headspace gas chromatography-mass spectrometry method

A static headspace gas chromatography coupled to mass spectrometry (SHS-GC-MS) method was validated to determine several major volatile components during the production process of fruit vinegars. The method is simple, fast, linear in the working range, suitably sensitive, repeatable and reproducible, and has a good degree of accuracy for most of the compounds studied. Different conditions were tested in the production process of vinegars by means of double fermentation. The addition of SO₂ and pectolytic enzymes produced a considerable increase in methanol and acetaldehyde, especially in strawberry purees, whereas pressing led to a loss of these volatile compounds. In the alcoholic fermentation of persimmon and strawberry purees, the Saccharomyces cerevisiae strain used had a great influence on the production of acetaldehyde and higher alcohols in wines. Considering the influence of these studied compounds in the final profile of the vinegars, our results showed that the S. cerevisiae strain isolated in this study produced the most suitable wine substrates for the production of vinegars. Moreover, semisolid fruit substrate provides better results than liquid substrate. Inoculated acetification in wood recipients yielded vinegars with a better volatile profile, as these contained higher levels of most compounds except acetaldehyde.     

Methyl jasmonate enhances antioxidant activity and flavonoid content in blackberries (Rubus sp.) and promotes antiproliferation of human cancer cells

The effects of preharvest methyl jasmonate (MJ) application on fruit quality, antioxidant activity and flavonoid content in blackberries (Rubus sp.) were determined. Anticancer activity against human lung A549 cells and HL-60 leukemia cells was also evaluated. Three blackberry cultivars (Chester Thornless, Hull Thornless and Triple Crown) were used in these experiments. Blackberries treated with MJ (0.01 and 0.1 mM) had higher soluble solids content, and lower titratable acids than untreated fruit as well as enhanced content of flavonoids and increased antioxidant capacity. Extracts of treated fruit showed enhanced inhibition of A549 cell and HL-60 cell proliferation and induced the apoptosis of HL-60 cells. Cultivar Hull Thornless had higher soluble solids and lower titratable acids compared to cv. Chester Thornless and Triple Crown. On the basis of fresh weight of fruit, Hull Thornless also had significantly higher anthocyanin, total phenolic content, antioxidant and antiproliferation activity than other two cultivars.     

Impact of postharvest methyl jasmonate treatment on the volatile composition and flavonol content of strawberries

BACKGROUND: Although strawberry aroma is very complex, certain compounds have been described as main contributors, i.e. furanones, aldehydes, alcohols, sulfur compounds and particularly methyl and ethyl esters. In addition, strawberries possess potent antioxidant activity because of their high content of phenolic compounds. Among them, flavonols are highlighted as important antioxidant compounds in strawberry. The objective of this study was to assess the effect of methyl jasmonate (MJ) on the composition of the major contributors to aroma and on the content of certain flavonols in strawberry fruits. RESULTS: The levels of all studied volatile compounds were significantly affected by MJ treatment, though the individual effect differed according to the specific compound considered. Most of them increased significantly (P < 0.05), except methyl butanoate, which always showed higher levels in untreated strawberries. In contrast to aroma compounds, the change in the concentration of flavonols (i.e. myricetin, quercetin and kaempferol) was not significant in MJ‐treated strawberries. Considering the health‐promoting activity of these compounds, further investigations on the experimental conditions related to the treatment are required to control flavonol bioformation by means of MJ. CONCLUSION: The exogenous application of MJ vapour to strawberry enhances, in general, the production of the most relevant aroma‐active compounds. On the contrary, MJ treatment does not appear to influence the levels of myricetin, quercetin and kaempferol. Thus postharvest MJ treatment is proposed as an approach to obtain improved strawberry fruits in terms of sensory quality and health‐promoting properties. Copyright © 2010 Society of Chemical Industry     

Headspace volatile compounds during osmotic dehydration of strawberries (cv Camarosa): Influence of osmotic solution composition and processing time

The influence of the type of sugar in the osmotic solution and of the time of processing on the volatile compounds of strawberries was studied, in order to optimize the technique as a pre-treatment to further processing. Strawberries of cultivar ‘Camarosa’, cut into 1 cm thick slices, were subjected to osmotic dehydration at 30 °C for 1, 2, 4 and 6 h using either 60% (w/w) sucrose or 60% (w/w) sorbitol solutions. Volatile compounds of fresh and processed strawberry slices were analyzed by static headspace—gas chromatography. Osmotic treatments provoked a loss in volatile compounds due to the migration, mainly of esters, into the osmotic media. The variations in the volatile pattern depended on both time of treatment and type of osmotic solution. The greater changes occurred after 2 h in sucrose; with a promotion of fermentative volatiles (acetaldehyde, ethyl acetate), and a decrease in the other volatiles. Using sorbitol as osmotic agent, the major variations in the volatile pattern occurred after 4 h of osmosis, and the fermentative process was less important than in sucrose, as sorbitol could be less effective in forming a peripheral layer at the fruit surface and/in reducing tissue porosity.     

Isolation,identification, and antioxidant activity of anthocyanin compounds in Camarosa strawberry

This paper explores the bioactive composition of strawberry (Camarosa variety) [Fragaria × ananassa (Rosaceae Family)] describing its anthocyanin composition and measuring the antioxidant activity (AA) of isolated pigments.     

Phenolic acids, flavonoids, vitamin C and antioxidant capacity of strawberry juices processed by high-intensity pulsed electric fields or heat treatments

The effect of high-intensity pulsed electric fields (HIPEF) processing (35 kV/cm for 1,700 μs in bipolar 4-μs pulses at 100 Hz) on individual phenolic compounds (phenolic acids and flavonoids), vitamin C and antioxidant capacity of strawberry juice was evaluated and compared to heat (90 °C for 60 or 30 s) and fresh juice as a reference. Although strawberry juice underwent a substantial depletion of health-related compounds with storage time irrespective of the treatment conducted, ellagic acid was enhanced. HIPEF-treated strawberry juice maintained higher amounts of phenolic acids (ellagic and p-coumaric acid) and total anthocyanins than the thermally treated juices during the storage period. Regarding the antioxidant capacity, similar DPPH and ABTS values were obtained so that differences among pasteurized juices were non significant. HIPEF processing may be a technology as effective as thermal treatments not only to achieve safe and stable juices, but also to obtain juices with a high content of antioxidant compounds.     

Evaluation of volatile compounds and antioxidant capacity of some commercial rums from Dominican republic

Some Dominican ‘heavy’ rums, of a single brand, available commercially and labelled as 8, 15, 18, 21 and 25 year‐old have been evaluated and compared. Headspace solid‐phase microextraction (HS‐SPME) coupled to gas chromatography–mass spectrometry (GC–MS) was used to analyse volatile compounds and crocin kinetic competition test to evaluate their antioxidant capacity. The alcohols and esters profiles of rums labelled as 21‐ and 25 year‐old were similar. The alcohols and fatty acids profiles of rums labelled as 15 and 18 year‐old were similar. The esters profile of rums labelled as 8 and 15 year‐old was similar. Significant differences were found for aldehydes and volatile phenols between all the rum samples. The antioxidant capacity resulted significantly higher in the older rums (21 and 25 year‐old) than in the younger ones (8, 15 and 18 year‐old).     

Effect of cultural system and storage temperature on antioxidant capacity and phenolic compounds in strawberries

The effects of cultural systems and storage temperatures on antioxidant enzyme activities and non-enzyme antioxidant components in two cultivars (‘Earliglow’ and ‘Allstar’) of strawberries were investigated. Fruit samples were hand-harvested from organic and conventional farms in Maryland, USA, and were stored at 10, 5 and 0 °C. The results from this study showed that strawberries grown from organic culture exhibited generally higher activities in antioxidant enzymes. Moreover, the organic culture also produced fruits with higher level of antioxidant contents. Strawberries stored at higher temperature (10 °C) had higher activities of antioxidant enzymes and antioxidant capacities than those stored at lower temperatures (0 or 5 °C), in both organic and conventional cultural systems. In conclusion, strawberries produced from organic culture contained significantly higher antioxidant capacities and flavonoid contents than those produced from conventional culture, and even though low storage temperatures retarded decay, they also reduced the increase in antioxidant activities.     

Preharvest application of methyl jasmonate increases fruit quality and antioxidant capacity in raspberries

The effects of preharvest methyl jasmonate (MJ) application on fruit quality, flavonoid content and antioxidant capacity in black raspberry cv. Jewel (Rubus occidentalis L) and red raspberry cv. Autumn Bliss (Rubus idaeus subsp.) were studied under field condition. Raspberries treated with MJ had higher soluble solids content, total sugars, fructose, glucose, sucrose and lower titratable acids (TAs), malic acid and citric acid than untreated fruit. MJ also significantly enhanced the content of flavonoids and the antioxidant capacities in the fruit. The cv. Jewel had higher soluble solids and lower TAs compared with the cv. Autumn Bliss. On the basis of fresh weight of fruit, ‘Jewel’ also had significantly higher anthocyanin, total phenolic content and antioxidant activity than ‘Autumn Bliss’.     

Nitrogen addition influences formation of aroma compounds,volatile acidity and ethanol in nitrogen deficient media fermented by Saccharomyces cerevisiae wine strains

The effects of nitrogen addition into nitrogen deficient/depleted media on the release of aroma compounds post-fermentation were investigated in three commercial yeast strains of Saccharomyces cerevisiae which highlight the yeast strain effect as well as nitrogen effects. By comparing the two timings of nitrogen addition, prior to fermentation or later at stationary phase (72 h), it was shown that nitrogen addition at stationary phase significantly decreases ethanol and acetic acid formation and significantly increases the following compounds: 2-phenylethanol, ethyl isobutyrate, 2-phenylethyl acetate, ethyl 2-methylbutyrate and ethyl propionate in the three strains, and also isovaleric acid, isoamyl alcohol and ethyl isovalerate in both PYCC4072 and UCD522. The strain EC1118 produced significantly less medium chain fatty acids, hexanoic, octanoic and decanoic acids and their respective esters after nitrogen addition. Therefore, timing of nitrogen addition to a ferment media can vary the concentration of certain aroma compound and might provide a means for varying wine composition.     

Impact of high-intensity pulsed electric fields variables on vitamin C, anthocyanins and antioxidant capacity of strawberry juice

A response surface methodology was used to determine the combined effect of HIPEF critical processing conditions on vitamin C, anthocyanins and antioxidant capacity of strawberry juice. Keeping constant the electric field strength at 35 kV/cm and the treatment time at 1000 μs, the treatments were set at frequencies from 50 to 250 Hz, pulse width from 1 to 7 μs using monopolar or bipolar mode. A second order response function covering the whole range of experimental conditions was obtained for each health-related compound. Strawberry juice antioxidant potential was affected linearly by frequency, pulse width and pulse polarity. The quadratic term of frequency and the combined effect of frequency and pulse width were also significant. HIPEF treatments conducted at 232 Hz with bipolar pulses of 1 μs led to strawberry juices with the greatest presence of health-related compounds. The evaluation of the HIPEF critical parameters influence on health-related compounds can contribute to achieve optimal processing conditions to obtain strawberry juices with high antioxidant potential.     

柠檬醛对草莓贮藏期间品质和抗氧化能力的影响

目的 探讨不同植物精油对草莓贮藏期间品质和抗氧化能力的影响，为草莓保鲜提供新的方法。方法 以“红颜”草莓为试材，分别用不同质量浓度（40、80、160和320 μg/mL）的百里香精油、丁香花精油、肉桂精油、枯茗醛和柠檬醛进行处理，测定其在20℃贮藏期间的失重率、腐烂指数、理化性质、抗氧化物质含量和抗氧化酶活性等指标。结果 柠檬醛在40 μg/mL质量浓度时具有最佳保鲜效果，能够有效地降低草莓果实的失重率和腐烂指数，延缓可溶性固形物、可滴定酸和抗坏血酸含量的下降，维持较高的总酚和总黄酮含量，并提高果实对1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl, DPPH）自由基和羟基自由基的清除能力。此外，该处理还能显著提高过氧化氢酶、超氧化物歧化酶、抗坏血酸过氧化物酶等抗氧化酶的活性，且有效抑制丙二醛含量的升高。结论 柠檬醛在草莓贮藏中具有良好的保鲜效果，能够保持其品质和营养价值，这为柠檬醛在水果贮藏保鲜中的应用提供了依据。     

The effects of exogenous ethylene and methyl jasmonate on the accumulation of phenolic antioxidants in selected whole and wounded fresh produce

Selected fruits and vegetables were exposed to wounding, methyl jasmonate (MJ) or ethylene (ET) stress and effects on the phenylpropanoid metabolism were determined. Lettuce, cilantro, cabbage, green beans, apples, plums, peaches, table grapes, strawberries, bell peppers, asparagus, celery, carrots, radishes, potatoes, and jicama were evaluated for phenolic content and antioxidant capacity (AOX). The phenolic synthesis response to the stresses was tissue-dependent, including decreases, increases or no effects. The use of phytohormones enhanced the wound response on some crops, confirmed by an increase in phenylalanine ammonia lyase (PAL) activity and HPLC phenolic profiles. Several reasons could explain the phenolic accumulation, including the plant genetic machinery, the presence of a common signalling response and differences in phenolic synthesis and degradation kinetics. The synthesized phenolics increased the overall AOX (μg trolox/g FW) of the tissue. Furthermore, the specific AOX (μg trolox/mg phenolics) of the synthesized phenolic compounds was influenced by type of tissue and phytohormone used.     

Effect of BTH on antioxidant enzymes,radical-scavenging activity and decay in strawberry fruit

The effect of benzo-thiadiazole-7-carbothioic acid S-methyl ester (BTH), at 0.2 g/l, on antioxidant enzymes, radical-scavenging activity and decay development in strawberry (Fragaria × ananassa Duch.) fruit, was investigated. The results showed that BTH treatment enhanced the activities of antioxidant enzymes, including superoxide dismutase, ascorbate peroxidase, and glutathione reductase. The treatment increased the contents of phenolic and anthocyanin in strawberry fruit, as well as radical-scavenging capacity, expressed as 1,1-diphenyl-2-picrylhydrazyl and superoxide radical values and reducing power. The treatment also decreased the development of decay compared to control fruit. These results indicated that BTH might increase the disease resistance of strawberry fruits by enhancing their antioxidant systems and their free radical-scavenging capabilities.