M.J. Villanueva

High-performance liquid chromatographic determination of dietary fibre in raw and processed carrots

An HPLC method was developed to determine dietary fibre in carrots (Daucus carota L.). Primary hydrolysis of dietary fibre residue was performed with 12 M H2SO4 for 2 h at 40 degrees C and secondary hydrolysis with 0.414 M H2SO4 for 3 h at 100 degrees C. For the neutralization step prior to injection, AG4-X4 resin (Bio-Rad) was used. Neutral monosaccharides were separated using an HPX-87P column (Bio-Rad). This method was applied for evaluation of the quantitative variation of dietary fibre content in carrots during autoclaving.

Determination of dietary fibre by the AOAC method in raw and processed vegetables: peas samples

SummaryTotal dietary fibre was determinated by the enzymatic gravimetric method of the AOAC in raw and processed (autoclaved and microwave heated) peas. Pods were also analyzed. The importance of the corrections for protein and ash proposed by the AOAC method were confirmed. Starch content in the TDF residues is also reported.

Effect of autoclaving on dietary fibre content of beetroot (Beta vulgaris). Evaluation by different methods

Modifications of dietary fibre in beetroot during autoclaving have been evaluated by different methods: acid detergent (raw=1.45%; processed=1.17%) and neutral detergent (raw=2.30%; processed=2.00%), the enzymatic-gravimetric method of Asp (raw=3.35%; processed=3.34%), HPLC (raw=1.42%; processed=1.60%) and 3,5-dimethylphenol (raw=0.36; processed=0.28%). The correlation between different methodologies was studied. Autoclaving was carried out at 121°C under pressure for 15 min. Variance analysis indicated that quantitative variations originating in the thermic treatment were not statistically significant (P>0.05).