Degradation of β-carotene in amorphous polymer matrices. Effect of water sorption properties and physical state.

Background: The use of encapsulation in amorphous matrices of carbohydrate and/or polymer formed during dehydration processes to enhance the stability and retention of labile compounds is increasing in the food and pharmaceutical industries. Efforts to improve encapsulating properties have been made using mixtures of carbohydrates with proteins or gums in different proportions. The objective of the present work was to study the stability of encapsulated β-carotene and its degradation kinetics in maltodextrin/gum arabic and maltodextrin/gelatin matrices in relation to the physical properties and state of the dehydrated matrix.

beta-carotene encapsulation in a mannitol matrix as affected by divalent cations and phosphate anion.

The effects of addition of divalent cations and phosphate buffer on the degree of beta-carotene encapsulation in a mannitol matrix during freeze-drying were analyzed. The degradation rate of encapsulated beta-carotene as a function of % RH and its relationship with the physical state of the matrix during storage at 25 degrees C was also studied. The presence of phosphate salts significantly delayed mannitol crystallization at a highly satisfactory degree during freeze-drying and, consequently, the degree of beta-carotene encapsulation increased.

Structural collapse prevents beta-carotene loss in a supercooled polymeric matrix.

The kinetics of degradation and surface color changes of beta-carotene encapsulated in a polymeric matrix (PVP-40) and its relationship with physical changes (manifested as structural collapse) of the matrix were studied during storage of samples at several water activities at constant temperature. The degradation rate constants obtained decreased with an increase in the relative humidity (RH) of the storage atmosphere. Beta-carotene losses were observed mainly at RHs below the glass transition temperature (Tg) of the corresponding systems, and the lower degradation constant rates were observed under conditions where the matrices were fully plasticized (i.