Effect of different protein extracts from Dosidicus gigas muscle co-products on edible films development

The co-products produced in the processing industry of Dosidicus gigas muscle, is a good source of polymeric material for film developing. The objective of this work was to compare different ways of protein recovery to find the best conditions of material for edible film developing. The proteins were recovered by water, salt, alkaline and acidic solubilisation. The highest protein solubilisation was obtained at alkaline conditions (≥70%) and DSC confirmed a partial denaturalization in saline and alkaline solution and total at acidic conditions, while SDS-PAGE confirmed a hydrolysis effect at pH 3. According to FTIR, the loss of secondary structure at pH 10 led to a stronger bonding film network and the hydrolysis at pH 3 resulted in more protein-plasticizer and protein–water interactions. Both alkaline and acidic conditions led to transparent and microbiologically stable films, the alkaline-film being more water resistant and with less protein release in water contact. Both alkaline- and acidic-films resulted in the more flexible and more resistant, especially at alkaline conditions. While salt-extract did not improve any mechanical property of the corresponding film compared with water-film, both films presented the lower solubility and the more water resistance but were not microbiologically stable and had poorer mechanical properties.