RESUMEN

Derived compounds from lignin have been used as substrates for chemical and biological processes for obtainment bioproducts. The ferulic acid is a lignocellulosic biomass whose biotransformation in flavors compounds was described. The objective of this study was the bioconversion of ferulic acid to 4-vinylguaiacol by Klebsiella pneumoniae TD 4.7. The biotransformation of commercial ferulic acid into 4-vinylguaiacol in a semi synthetic liquid medium containing the ferulic acid at an initial concentration of 300 mg L-1 reached 32.4%. The ferulic acid obtained from alkaline hydrolysis of the sugar cane bagasse at 300 mg L-1 allowed the yield of 1.3 mmol L-1 of 4-vinylguaiacol, corresponding to 81.7% of the ferulic acid content. The data indicated that the bacterial strain decarboxylated the ferulic acid to 4-vinylguaiacol and the presence of an active cell associated ferulic acid decarboxylase. The enzyme showed maximum activity at pH 5.5 and 40 °C and was stable at pH range 4.5 to 9.0 and temperature up 20 to 45 °C. According to these biochemical properties and performance to bioconversion of ferulic acid to 4-vinylguaiacol, this enzyme could be viable for application in food industry.

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RESUMEN

Nine yeast strains isolated from Latin American biodiversity were screened for ferulic acid (FA) consumption and conversion into aroma compounds such as vanillin, vanillic acid (VA), and 4-vinylguaiacol (VG). Selected strains (Rhodotorula mucilaginosa UFMG-CM-Y3647, UFMG-CM-Y2190, UFMG-CM-Y665) were evaluated in flask experiments to investigate the influence of the pH media on bioconversion and a two-step process was conducted to maximize the metabolites production. The effect of pH was found to be significantly important for FA bioconversion, as acidic conditions (pH < 6.0) improved VA accumulation, with highest production of 1.14 ± 0.02 and 1.25 ± 0.03 g/L shown by UFMG-CM-Y3647 and UFMG-CM-Y2190, respectively. The two-step process favored 4-VG production for most strains, being UFMG-CM-Y2190 the best producer, its cultures reaching 1.63 ± 0.09 g/L after 55 hr, showing a productivity of 29.59 ± 1.55 mg/(L·hr), as glucose affected the metabolites pool and redirected yeast metabolism. R mucilaginosa UFMG-CM-Y3647 was selected for scaled-up cultivations in a 2-L bioreactor, where pH-controlled pH 5.5 and aeration of 2.5 vvm was found to be the best condition to improve VA productivity, attaining final concentrations of 1.20 ± 0.02 g/L-1 (78% molar yield) and a productivity of 40.82 ± 0.57 mg/(L·hr).

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RESUMEN

This work aimed at determining 4-vinylguaiacol and 4-vinylphenol in the top-fermented wheat beers using different wavelength and the mobile phase for HPLC. Best results for isocratic elution were obtained at 260 nm and the mobile phase comprising methanol/ultrapure water/phosphoric acid (400/590/10, V/V). Under these conditions, the retention time of 4-vinylguaiacol and 4-vinylphenol was 25 and 27min, respectively.