Modification of hydroxypropylmethylcellulose by high-intensity ultrasound

CAMINO, NERINA; PÉREZ, OSCAR E; PILOSOF, ANA MR.

Le Mans, Francia

Congreso; Food Colloids 2008. Polymeres, Colloids and Interfaces; 2008

Universite du Maine

 High intensity ultrasound (HIUS) is one of the few methods that allows the preparation of submicron or nano emulsions. Nevertheless it has been reported that because of cavitation, HIUS can modify the structure of some proteins and polysaccharides. Therefore, the objective of this study was to evaluate the effect of application of high-intensity ultrasounds on HPMC solutions of different concentration and the impact on their emulsifying performance. Solutions of different commercial HPMC of the same type and degree of substitution, but differing in molecular weight were prepared at 0.2 – 3 % wt concentration and submitted to HIUS (Vibra Cell  Sonics, model VCX 750 at a frecuency of 20kHz and an  amplitude of 20%) during 20 minutes at controlled temperature (35- 40 ºC). The size distributions and Zaverage (Zav) of particles, before the treatment, immediately after and 3 days after treatment, were measured by dynamic laser light scattering (Zetasizer Nano-Zs, Malvern Instruments). Depending on the HPMC type and concentration, the application of HIUS resulted in an increase of Zav or did not modify it as compared to the untreated samples. When the Zav increased it was observed that with time the size became smaller and similar to the untreated samples. In spite of the observed changes, the performance of all the HPMC samples on 10:90 oil-in-water emulsions formed by HIUS was similar. The observed HPMC association under HIUS treatment could be ascribed to transient cluster formation by enhancement of hydrophobic associations involving methyl substituents.