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Rodriguez-Solana R.,University of Vigo | Rodriguez-Solana R.,Laboratory of Agro food Biotechnology | Rodriguez-Solana R.,Agricultural University of Athens | Daferera D.J.,Agricultural University of Athens | And 4 more authors.
Industrial Crops and Products | Year: 2014

Three different techniques: the classical gas chromatography-mass spectrometry (GC-MS) and two "green" alternative techniques to the classical chromatography, the spectroscopic techniques Fourier transform infrared (FT-IR), and dispersive-Raman were employed to characterize the main chemotypes of different essential oils from plants of the Lamiaceae family and to compare between techniques. Gas chromatography-flame ionization detector (GC-FID) was also employed to quantify the main compounds present in essential oils isolated by hydrodistillation (HD) and semi-quantify essential oil composition isolated by HD and simultaneous steam distillation - solvent extraction (SDE). While GC cannot differentiate between pure and mixed chemotypes of a compound, FT-IR, and Raman methods allow the creation of libraries, through which chemotype determination is feasible even for mixed chemotypes, thus combining robustness with being rapid and non-destructive techniques. © 2014 Elsevier B.V.

Salgado J.M.,IBB Institute for Biotechnology And Bioengineering | Rodriguez-Solana R.,Laboratory of Agro food Biotechnology | Rodriguez-Solana R.,University of Vigo | Curiel J.A.,Laboratorio Y Tecnologia Of Alimentos Y Nutricion | And 7 more authors.
Enzyme and Microbial Technology | Year: 2014

In situ extractive fermentation was used to produce 4-vinyl derivatives from hydroxycinnamic acids extracted from corn cobs by recombinant Escherichia coli cells expressing Lactobacillus plantarum phenolic acid descarboxylase (PAD) gene. This microorganism mainly produced 4-vinylphenol (4VP) from p-coumaric acid (p-CA). In the first study , we observed that the concentrations of 4VP are higher than 1g/L which had a negative impact on decarboxylation of p-CA to 4VP by recombinant E. coli cells. Because of this, and in order to improve the downstream process, a two-phase aqueous-organic solvent system was developed. The results of the extractive fermentation indicated that it was possible to use hydrolyzates as aqueous phase to bioproduce 4VP, and recover simultaneously the product in the organic phase containing hexane. The detoxification of pre-treated corn cob alkaline hydrolyzate improved 4VP production up to 1003.5mg/L after 24h fermentation (QP=41.813mg/Lh). Additionally, preliminary experiments using cells immobilized in calcium alginate showed to be a good system for the biotransform of p-CA to 4VP in extractive fermentation, although the process hindered partially the recovery of 4VP in the organic phase. © 2014 Elsevier Inc.

Rodriguez-Solana R.,University of Vigo | Rodriguez-Solana R.,Laboratory of Agro food Biotechnology | Salgado J.M.,IBB Institute for Biotechnology And Bioengineering | Dominguez J.M.,University of Vigo | And 3 more authors.
Industrial Crops and Products | Year: 2014

Fennel (Foeniculum vulgare Miller) is an aromatic plant used, among other applications, in the production of traditional herbal liqueurs. In this study, essential oils from fennel were extracted applying two techniques, Soxhlet and accelerated solvent extraction (ASE). The extracts obtained were characterized by GC-MS. Taking into account that estragole is the major constituent of fennel and due to recent studies pointed out its possible carcinogenic properties; this compound was also quantified by GC-FID. The quantification method showed good linearity (r2=0.998) and precision (RSD<5%) with low values of detection (LOD) and quantification (LOQ) limits. A Box-Behnken design was used to correlate three independent variables (temperature, contact time sample-solvent and number of cycles) with the amount of estragole extracted. Meanwhile, the response surface methodology was applied to optimize the extraction of estragole by ASE. The optimal conditions were 125°C, 7min and 3 cycles. On the other hand, the Soxhlet technique was studied step-by-step. Two variables were optimized: time (4 and 8h) and solvents, according to their polarity. Methanol and 4h of extraction showed the best results both qualitatively and quantitatively. The Soxhlet technique provided higher performance of extraction and greater amounts of compounds extracted compared to ASE, but similar concentration of estragole. The shorter time of extraction and the lower amount of solvent used justify the ASE technique choice to characterize fennel essential oils. © 2013 Elsevier B.V.

Rodriguez-Solana R.,University of Vigo | Rodriguez-Solana R.,Laboratory of Agro food Biotechnology | Salgado J.M.,IBB Institute for Biotechnology And Bioengineering | Dominguez J.M.,University of Vigo | And 3 more authors.
Phytochemical Analysis | Year: 2015

Introduction - Plants from the Lamiaceae family have been known traditionally for their beneficial health-promoting properties, attributed to their anti-inflammatory, anaesthetic and anti-microbial effects.Objective - The purposes of this study was to characterise the essential oils from four Lamiaceae plants by applying different extraction techniques.Methods - Accelerated solvent (ASE), Soxhlet and supercritical fluid (SFE) extraction methods were compared for their efficiency in obtaining the essential oils from plants. The volatile compounds were identified by GC-MS and the main chemotype was quantified by GC with flame ionisation detection (FID). Phenolic compounds were identified and quantified by HPLC and electrospray ionisation (ESI) with MS/MS.Results - The essential oils Mentha piperita (ct. menthol/menthone), Rosmarinus officinalis L. (ct. eucalyptol/camphor) and Origanum vulgare (ct. carvacrol/thymol), whereas Thymus vulgaris L. was found to be a pure chemotype (ct. thymol). All three extracts also contained six phenolic compounds. The highest extraction yields were achieved by the Soxhlet and ASE techniques, with M. piperita and R. officinalis L. producing the highest concentrations of rosmarinic and carnosic acids. Finally, it was observed that M. piperita and O. vulgare produced the highest total phenolic content, whereas R. officinalis L. and T. vulgaris L. produced the highest anti-oxidant activity.Conclusion - The ASE and Soxhlet extraction techniques presented the highest yields of volatile and phenolic compounds, showing their suitability to characterise the chemical profile of aromatic plants. Copyright © 2014 John Wiley & Sons, Ltd. Copyright © 2014 John Wiley & Sons, Ltd.

Salgado J.M.,Laboratory of Agro food Biotechnology | Salgado J.M.,University of Vigo | Rodriguez-Solana R.,Laboratory of Agro food Biotechnology | Rodriguez-Solana R.,University of Vigo | And 5 more authors.
Bioresource Technology | Year: 2012

The enzyme PAD from Lactobacillus plantarum CECT 748 T decarboxylates some cinnamic acids namely p-coumaric acid (p-CA), caffeic acid (CA), and ferulic acid (FA) into their corresponding 4-vinyl derivatives (4-VD): 4-vinyl phenol (4-VP), 4-vinyl catechol (4-VC), and 4-vinyl guaiacol (4-VG), respectively, which are valuable food additives mainly employed as flavouring agents. The gene encoding this enzyme was cloned and overexpressed in Escherichia coli. Recombinant E. coli cells overproducing L. plantarum PAD showed a preference to degrade mainly p-CA and CA. Sterilized liquors obtained after alkaline hydrolysis of corn cob or alkaline hydrolysis of the solid residue coming from acid hydrolysis of corn cob were employed as growth media in fermentations performed in shaker or bioreactor. The fermentative process allowed converting 2222.8mg/L p-CA into 993.9mg/L 4-VP. The process described here allowed the production with a high-yield of a valuable food additive from a by-product of the food industry. © 2012 Elsevier Ltd.

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