A new procedure to prepare transparent, colourless and low-water-soluble edible films using blood plasma from slaughterhouses

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.

Automated summary

This study successfully described a new method to prepare water-insoluble edible films from bovine and porcine blood plasma, without the use of crosslinkers, for the production of sustainable packaging materials. The new films showed superior visual appearance, microstructure, and mechanical properties compared to the control film.