A new procedure to prepare transparent, colourless and low-water-soluble edible films using blood plasma from slaughterhouses. (June 2021) - Álvarez, Sara
Highlights: New transparent and insoluble films were prepared using blood from slaughterhouses. The pigments of the previously acidified plasma remain in the ethanol solution. The precipitated proteins form a homogeneous and compact film matrix. The new films showed better mechanical properties than the control films. Abstract: Some attempts to produce films using blood plasma proteins can be found in the literature; however, due to their high solubility in water, it is usually necessary to use crosslinkers, which may entail some disadvantages. In this work, a procedure to prepare water-insoluble edible films from bovine and porcine blood plasma without using crosslinkers is described for the first time, with the objective of producing sustainable packaging materials from livestock blood. For this purpose, the blood plasma fraction was acidified and treated with ethanol to precipitate the proteins, which were solubilised in water and mixed with glycerol in order to produce a film-forming solution. The generated films were investigated to determine light absorbance, transparency, microstructure, mechanical properties and solubility at several pHs and compared with a control film prepared with untreated plasma. The new films presented in this work were completely transparent and colourless on visual inspection, in contrast to the yellowish-orange colour of the control films. Furthermore, the microstructure of these new films was more homogeneous, and therefore they showed better mechanical properties than the control film. Finally, these films were found to be highly insoluble in buffer solutions of close to neutral pH, whereas the control film was almost completely solubilised in the same buffers.