Viscosity Study of Mucilages Extracted from Abelmoschus esculentus, Beilschmiedia mannii, Corchorus olitorius and Irvingia gabonensis from Côte d’Ivoire

Abstract

Aims: The present work evaluates some rheological characteristics of mucilages of selected mucilaginous food plants from the Ivorian flora. Study Design: Mucilage food plants edible parts were dried, mucilage were extracted and viscosity parameters analyzed. Place and Duration of Study: The study was conducted in Laboratory of Biochemistry and Food Sciences, Biosciences Unit, at Felix Houphouet-Boigny University between January and December 2014. Methodology: The study was carried out on fruits of A. esculentus (okra), B. mannii (sran), I. gabonensis (kplé) and leaves of C. olitorius (kplala) collected. The mucilage of different plants has been extracted by optimization methods. Then, the effects of pH, temperature, NaCl, KOH and concentration on mucilages viscosity have been studied. Results: After extraction of the mucilages by appropriate methods, extraction yields and hydration capacity were determined. The mucilage contents of B. mannii, I. gabonensis, A. esculentus and C. olitorius were respectively 63.00 ± 2.69%, 56.34 ± 5.44%, 34.86 ± 5.27% and 25.81 ± 4.13%. Scanning electron microscope (SEM) observations of the mucilages have showed varying forms. Their viscosity was determined under the influence of mucilage concentration, pH and temperature, as well as NaCl and KOH concentrations. The mucilage concentration, pH and temperature, as well as NaCl and KOH concentrations significantly differentiate the viscosity of the solutions (P <0.001). The increase in mucilage concentration (0 to 1%) and pH (3 to 8) increased the viscosity (0 to 801.93 ± 15.90 cP and 10.23 ± 0.70 cP to 574.60 respectively. On the other hand the elevation of the contents in NaCl of 0 to 1% (m/v) generated a decrease of the viscosity of the mucilaginous solutions of 535.00±24.53 to 69.70±2.95 cP. With KOH, concentrations of 0 to 0.4% (m/v) increased the viscosity of the mucilages from 100.00 ± 12.23 to 673.00 ± 9.92 cP, while contents from 0.4 to 1% reduced it from 673.00 ± 9.92 to 72.60 ± 13.39 cP. The heating of the mucilages from 20 to 120°C drastically reduced their viscosity of 546.20 ± 7.37 to 44.40 ± 4.07 cP, however, retrogression produced the opposite effect. Conclusion: B. mannii mucilage exhibited a higher viscosity than other mucilage samples relative to factors Tests, with the exception of temperature.