HIGH INTENSITY ULTRASOUND PROCESSING EFFECTS ON WHEY PROTEINS/HIDROXYPROPYLMETHYLCELLULOSE MIXTURES

ZEMA, PAULA D.; ARZENI, CAROLINA; PILOSOF, ANA MR; PÉREZ, OSCAR E

Buenos Aires

Congreso; VI Jornadas Internacionales de Coloides y Proteínas Alimentarias (JIPCA VI); 2011

Laboratorio de Nanopartículas, biopolímeros y Coloides Alimentarios, Departamento de Industrias, FCEyN, UBA. CONICET.

Proteins and polysaccharides are of ubiquitous importance in food systems since they play an essential role in their  structure, texture and stability. The main proteins present in whey are beta-lactoglobulin, alpha-lactalbumin and bovine sero-albumin and are responsible for the functional properties of whey protein concentrates (WPC). Hidroxypropylmethylcellulose (HPMC), which has methyl and hydroxypropyl groups added at the anhydroglucose backbone, is used in the food industry, printing technology, and has pharmaceutical applications, in particular for controlled drug-release. The objective of this contribution was to explore the effects of high intensity ultrasound (HIUS) application to WPC/HPMC located into the limited compatibility zone (Pérez et al, 2006).HPMC, E4M, was from The Dow Chemical Company and WPC powder, kindly given by Milka Frank, Santa Fe, Argentina, contained 78.9% of proteins. Solutions of pure components were mixed to obtain systems with WPC in the range 4-6% wt and HPMC 1% wt at pH 7. Solutions were sonicated for 20 min using an ultrasonic processor Vibra Cell Sonics, model VCX 750 (frequency: 20 kHz; amplitude: 20%). Glass tube reactor was glycerine-jacketed at 0ºC with a circulating constant temperature cooling bath. A set of HIUS-treated samples were then heated at 90ºC. Viscosity (Brookfield DV-II viscometer), dynamic rheometry (Paar-Physica rheometer), particle size (SLS, Malvern Instrument) and texture attributes (TA-TXT2, Back Extrusion Cell) were determined on samples: HIUS-treated, HIUS-treated+Heat, and control solution (with no treatment). HIUS-treated samples showed a strong decrease in the consistency index before heating. This effect was provoked mainly by the decrease of E4M viscosity in the mixed bulk solution. The dynamic rheology showed a cross-over between G´ and G” upon heating which, in turn, occurred at lower temperatures for HIUS-treated samples. Besides, the G´ values for HIUS-mixtures resulted higher, i.e. 23.7 and 9.9 Pa, treated and non-treated respectively. Protein particles of different sizes were promoted by HIUS application in mixed systems. The significant differences concerning to textural parameters (mainly adhesiveness) increased with the total biopolymer concentration into the bosom solution.This study showed that the WPC/HPMC mixtures in the limited compatible zone were remarkably influenced by HIUS application. This methodology could constitute the base for the design of fat mimetic and spreadable food materials.