7min) corresponding to the chicory inulin used as a standard. A minor peak with an elution time of 7.5min was detected just before the sucrose peak which could be considered as BI 6727 a fructan of low DP or fructooligosaccharide. However, for practical considerations regarding this work, these two peaks were quantified as total fructans. It was found in this way that fructan, sucrose, glucose, and fructose constituted 85.6 �� 2.52%, 4.67 �� 0.22%, 3.99 �� 0.14%, and 6.36 �� 0.54%, (dry matter) respectively, of the total sugars present in the agave fructan powder. Foregoing, it is evident that agave fructan was partially purified and additional experiments are required using more efficient filtration and purifying process than those used in the present research for treating the Agave salmiana juice and obtaining a fructan powder with chemical composition similar to the reference inulin.

The results from the HPLC analysis of samples taken indicate that the kinetics where fructan is used as a substrate, not only are the sugar of interest (Figure 4) but also show the presence of a peak with a retention time (RT) of 17.1min, which not corresponds with the RT of sugars standards provided. The compound of RT of 17.1 is not a product of the enzymatic hydrolysis of fructan powder, since its concentration remains constant during this process, the tendency of elution in HPLC of fructan goes from fructose polymer to simple sugars (high-to-low-molecular weight, as shown in Figure 3), so we concluded that the peak of 17.1 could be a polar compound and volatile.

Figure 3Gas chromatogram of polar volatile compounds of powder fructan obtained with PEG fiber and Stabilwax capillary column.The extraction of volatile polar compounds in fructan was performed by SPME and subsequently identified by GC-MS, using both procedures polar fiber and column (Figure 3). The compounds identified by GC-MS are shown in Table 2. The compounds correspond to higher percentage of acetic acid and lactic acid, the retention times obtained by HPLC for both acids are acetic acid 13.4min and 17.1min for lactic acid. According to this result, we can say that the peak retention time 17.1min fructan powder corresponds to lactic acid, this was confirmed by powder fructan enriched with lactic acid. The lactic acid is present in samples with high sugar content as a result of fermentation processes [44, 45].

Table 2Composition of volatile compounds from solid Agave salmiana, obtained from the PEG fiber and Stabilwax column (carbowax). 3.3. HPLC Analysis of the Hydrolysis KineticsAs an example, Figures (4(a) and 4(b)) present the chromatographic evolution of substrate hydrolysis and the corresponding release of sugars for experiments 2 and 6 (Table Brefeldin_A 1) with chicory inulin and agave fructan as substrates, respectively.