Poly(vinyl alcohol)-pectin cryogels containing dyes as tracers of food spoilage.

PIÑUEL L,; MARTINEZ Y,; BRECCIA JD; CASTRO GR,

Curitiba

Congreso; 4th International Congress on Bioprocesses in Food Industries; 2010

Universidad de Curitiba

Poly(vinyl alcohol)-pectin cryogels containing dyes as tracers of food spoilage Piñuel L; Martinez Y; Breccia JD; Casto GR. Food safety is a challenge for increasing food trading in our globalized world. Successful application of international rules requires trustworthy indicators of food spoilage which must be easy to handle and cheap. Since spoilage of foods usually causes a change in the pH value, the use of labels consisting on pH indicator dyes adsorbed in organic polymers is a promising alternative to monitor the food quality during distribution and storage. In the present work, poly(vinyl alcohol) and pectin were used to synthesize a cryogel matrix by freeze-thawing cycles, for immobilization of acid-base indicators. One cationic dye (neutral red) and three anionic dyes (phenol red, bromothymol blue and indigo carmine) were chosen on the basis of their different molecular structure and physico-chemical features. When the gel discs (50 mm diameter x 2 mm width, ~17 mg) were incubated with a solution containing 0.015%w/v of the dyes, neutral red was shown to be bound to the matrix  at a reason of 85 mg dye per g of matrix, while the other ones were lower than or in the range. Binding of neutral red was studied by adding increasing dye concentration and non-linear fitted to Langmuir equation PARAMETROS.  Liberation of neutral red from the matrix after 3 washing steps was only 0.11% (vs. 10 and 20% for BB and FR, respectively). Increasing ionic strength as well as increasing temperatures were shown to higher liberation of the dye from the matrix. These data suggest electrostatic interactions between cationic dye neutral red and negatively charged patches of pectin-PVA matrix, might be the forces driving the binding of the dye.