Search

Linoleic and linolenic acids are health-promoting compounds having a number of biological properties. In the present study, oxidative degradation of these fatty acids into off-flavor compounds in boiled potato was intended to be reduced. To that end, raw potatoes were treated by applying: (i) the commercial mixture (±)-methyl jasmonate, (ii) pure (+)-methyl jasmonate, and (iii) pure (−)-methyl jasmonate, respectively. Four cultivars (i.e., Cara, Inca Sun, Mayan Gold, and Maris Piper) were included in the study. As a result, the post-harvest application of (±)-methyl jasmonate and (+)-methyl jasmonate to raw potatoes during storage resulted in a significant decrease of lipid-derived volatile compounds in boiled potato. This suggests an inhibitory effect of both the commercial enantiomeric mixture and the pure (+)-methyl jasmonate on the lipoxygenase pathway. Stabilization of linoleic and linolenic acids against autoxidation is achieved by treatment with the enantiomeric mixture and pure (+)-methyl jasmonate. (−)-Methyl jasmonate however exhibited the opposite effect since it did not reduce lipid oxidation in boiled potato. The results found in the present work support earlier evidence on different effects of methyl jasmonate enantiomers on plant food composition. From a practical point of view, post-harvest treatments with (+)-methyl jasmonate can be used by the potato industry to obtain healthier and more pleasant products. Practical application The results found in the present study demonstrate that the practical applications of methyl jasmonate treatments minimize lipid oxidation in boiled potato. That allows us to obtain, on the one hand, tubers containing higher contents of linolenic and linoleic acids and, on the other, more pleasant flavor after boiling. The exogenous application of (+)-MJ to raw potato during storage enabled lipid oxidation in boiled potato to be reduced. Therefore, (+)-MJ treatment might be used by the potato industry to obtain a healthier and more pleasant product. [ABSTRACT FROM AUTHOR]

The effect of the postharvest application of (−) and (+)-methyl jasmonate (MJ) enantiomers on grapes antioxidant capacity, total phenolic compounds and anthocyanin concentration was examined on days 5 and 7 after treatment. The study also includes grapes treated with MJ racemic mixture and grapes without treatment (control) for comparison. Exogenous application of MJ induced an enhancement in the antioxidant activity and total phenolic compounds when compared to control grapes; this increase was higher when the enantiomers, rather than the mixture, were used (up to 42% for the antioxidant activity and for total phenolic compounds). Similarly, a significant increase was also registered in the total anthocyanin concentration when the enantiomers were applied. This increase ranged from 14 % to 42 % after 5 days of storage and from 22 % to 64 % when grapes were stored for 7 days. It was also observed an enhancement on individual anthocyanin concentration when the enantiomers were used. Nevertheless, no effects were observed on the anthocyanin relative distribution as a consequence of (−/+)-MJ, (−)-MJ and (+)-MJ treatment. Postharvest treatment of grapes with MJ enantiomers is proposed as means to increase antioxidant activity and anthocyanin concentration in grapes. [ABSTRACT FROM AUTHOR]

Abstract: The stereodifferentiation of some chiral components of importance for the character or intensity of wine aroma was achieved with headspace solid phase microextraction and multidimensional gas chromatography coupled to mass spectrometry. Chiral evaluation of linalool and 2,3-butanediol is performed in less than 75min (overall analysis time) using a polydimethylsiloxane/divinylbenzene fibre during the sample concentration step and permethylated β-cyclodextrin as the chiral stationary phase in the main column of the multidimensional system. Enantiomeric excesses of linalool and percentage values of 2,3-butanediol stereoisomers were determined in three different white wines. [Copyright &y& Elsevier]

Abstract: The optimisation of the interface performance in the on-line coupling of reversed phase liquid chromatography and gas chromatography was intended to improve the sensitivity achievable in the direct analysis of olive oils adulterated with virgin and refined hazelnut oils. The efficient elimination of the eluent coming from the pre-separation was achieved by considering some experimental variables (i.e., transfer volume, interface temperature during transfer, helium flow during both transfer and purge, and purge time) affecting the operation of a vertically positioned programmed temperature vaporizer which acted as the interface of the system. The obtained results demonstrated the possibility of evaluating the genuineness of olive and hazelnut oils as well as of detecting adulterations of olive oil with percentages of around 5% and 10% of virgin and refined hazelnut oils, respectively, in less than 30min by the method proposed. [Copyright &y& Elsevier]

Abstract: The presence or absence of filbertone in 21 admixtures of olive oil with virgin and refined hazelnut oils obtained using various processing techniques from different varieties and geographical origins was evaluated by solid phase microextraction and multidimensional gas chromatography (SPME–MDGC). The obtained results showed that the sensitivity achievable with the proposed procedure was enough to detect filbertone and, hence, to establish the adulteration of olive oil of different varieties with virgin hazelnut oils in percentages of up to 7%. The very low concentrations in which filbertone occurs in some refined hazelnut oils made difficult its detection in specific admixtures. In any case, the minimum adulteration level to be detected depends on the oil varieties present in the adulterated samples. In the present study, the presence of R- and S-enantiomers of filbertone could be occasionally detected in olive oils adulterated with 10–20% of refined hazelnut oil. [Copyright &y& Elsevier]

Abstract: A method based on the use of the through oven transfer adsorption–desorption (TOTAD) interface in on-line coupling between reversed phase liquid chromatography and gas chromatography (RPLC–GC) for the determination of chiral volatile compounds was developed. In particular, the method was applied to the study of the influence of methyl jasmonate (MJ) treatment on the production and enantiomeric composition of selected aroma compounds in strawberry. The compounds studied were ethyl 2-methylbutanoate, linalool and 4-hydroxy-2,5-dimethyl-3(2H)-furanone (i.e. furaneol), which were examined on days 3, 6 and 9 after treatment. The method developed resulted in relative standard deviations (RSDs) of 21.6%, 8.1% and 9.8% and limits of detection (LD) of 0.04, 0.07 and 0.02mg/l for ethyl 2-methylbutanoate, linalool and furaneol, respectively. The application of the RPLC–TOTAD–GC method allowed higher levels of ethyl 2-methylbutanoate, linalool and furaneol to be detected, particularly after 9 days of treatment. Besides, MJ demonstrated to affect the enantiomeric distribution of ethyl 2-methylbutanoate. On the contrary, the enantiomeric composition of linalool and furaneol kept constant in both control and MJ-treated strawberries throughout the study. These results are discussed. [Copyright &y& Elsevier]