Development and characterization of a novel edible extruded sheet based on different casein sources and influence of the glycerol concentration

Different source of casein depending on their extraction method from milk are available on the market. Sheets from 3 different types of casein (rennet casein, acid casein and sodium caseinate) were developed using a dry process: extrusion. Casein sourcing, plasticizer concentration (13.2% w/w or 24.2% w/w) and relative humidity environment were studied for each sheet through color, density and porosity, water sensitivity and mechanical properties evaluation. A wide range of properties seems to be available through casein based sheets depending on casein source, which affected greatly water solubility (caseinates are 100% water soluble compare to acid and rennet casein). Besides, acid and rennet casein have different behaviour with water and even more with higher glycerol amounts. Indeed, rennet casein sheet is less sensitive to water than acid casein sheet at low glycerol concentration (13.2% w/w) but at the opposite, at high glycerol amount in sheets, rennet casein sheet is more hydrophilic than acid casein sheets. Extrusion is an easy scale up process and it was used to produce casein based sheets with improved water vapor permeability (WVP). These findings can be used to find the suitable food packaging application for each casein based sheet with a low cost and efficient process.