Development and validation of a HPLC-DAD method for simultaneous determination of main potential ABE fermentation inhibitors identified in agro-food waste hydrolysates

Abstract

Lignocellulosic agro-food wastes are regarded as interesting carbohydrate sources for acetone-butanol-ethanol (ABE) fermentation. However, the physicochemical and enzymatic pretreatments applied to release their sugars generate inhibitory compounds that hinder the fermentation. The release of inhibitory compounds in the hydrolysates of four agro-food industrial wastes [apple pomace (AP), potato peel (PP), brewers' spent grain (BSG) and coffee silverskin (CS)] obtained after various chemical pretreatments (acid, alkali, organic solvents and surfactant pretreatments) was analyzed. Sixty-seven potential inhibitors were identified by gas chromatographymass spectrometry (GC-MS) and were classified into non-aromatic compounds (aliphatic acids, nitrogen-containing compounds, furans and fatty acids) and aromatic compounds (phenolics and non-phenolics). Then, a high performance liquid chromatography (HPLC) method with diode array detection (DAD) was developed and validated for the quantification of the main potential inhibitors identified in the hydrolysates (i.e. gallic, 3,4-dihydroxybenzoic, 2,5-dihydroxibenzoic, 4-hydroxybenzoic, 3-hydroxybenzoic, vanillic, caffeic, syringic, p-coumaric, and ferulic acids, vanillin, syringaldehyde and caffeine). The proposed HPLC-DAD method was simple, fast and robust and allowed the direct injection of samples without previous preparation, enabling the simultaneous quantification of the abovementioned compounds for the first time. The method was successfully applied to the analysis of AP, PP, BSG and CS hydrolysates.

Revisiting the production of L( +)-lactic acid from vine shoots: bioconversion improvements by employing thermotolerant bacteria

“…When comparing both alkaline pretreatments, it can be observed that the washing step removes formic acid, acetic acid, and total phenolic compounds to a great extent. As for the acidic treatment, it produced the highest amounts of acetic acid, levulinic acid, 5-HMF, and furfural, which is in agreement with the capacity of strong acids to hydrolyse carbohydrate polymers and degrade hexoses and pentoses into inhibitory substances (Palmqvist and Hahn-Hägerdal 2000;Paniagua-García et al 2019). In any case, it was possible to minimise inhibitor generation during acidic pretreatment, thanks to the RSM performed on vine shoots, especially in terms of formic acid (section "Establishment of optimal conditions for the acidic pretreatment").…”

Voltammetric Sensor Based on the Poly(p-aminobenzoic Acid) for the Simultaneous Quantification of Aromatic Aldehydes as Markers of Cognac and Brandy Quality

“…The analytical characteristics obtained are significantly improved compared to those reported for the simultaneous determination of syringaldehyde and vanillin using voltammetry [ 26 ] and other methods [ 8 , 9 , 10 , 11 , 12 , 13 , 15 , 16 , 17 ] ( Table 5 ), as well as for the individual determination of the aldehydes [ 48 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 ] ( Table S1 ).…”

“…Simultaneous quantification of syringaldehyde and vanillin has been successfully achieved using high-performance liquid chromatography (HPLC) [ 8 , 9 , 10 , 11 ] and ultra-HPLC [ 12 , 13 , 14 , 15 ] with UV- [ 8 , 12 ], diode-array [ 9 , 10 , 11 ], and tandem mass-spectrometric [ 13 , 14 , 15 ] detection. Capillary electrophoresis with UV-detection [ 16 ] and high-performance capillary electrophoresis with diode-array detection [ 2 , 17 ] have been developed for the simultaneous determination of syringaldehyde and vanillin in cognac, brandy, and aged wine distillates.…”