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Title: COMPOSITION FACTORS AFFECTING THE WATER VAPOR PERMEABILITY AND TENSILE PROPERTIES OF HYDROPHILIC FILMS

Author
item PARRIS NICHOLAS
item Coffin, David
item JOUBRAN REMON F
item PESSEN HELMUT

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/25/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: Films prepared from polysaccharides (starch and cellulose) and hydrocolloids (pectin, alginate, carrageenan) are strong but exhibit poor water retention properties. Most films are used to protect foods and materials from losing moisture content and hence, it is important for them to be effective barriers towards water vapor loss. The objective of this research was to improve the water retention properties of hydrocolloid films through the incorporation of proteins from inexpensive sources such as milk and the proper choice of plasticizer without significantly compromising strength. Addition of 30 wt% whole milk to the film blends effectively increased water retention ability by up to 35% with no significant loss in strength. Films prepared with sorbitol as the plasticizer exhibited the best water retention properties but tended to be stiff and in some cases too brittle for testing. The information is useful for the preparation of biopolymer films and coatings with desired strength and water retention properties to extend the shelf life of foods.

Technical Abstract: The water vapor permeability of hydrocolloid films was decreased without significantly compromising the film's tensile properties through the incorporation of casein and/or whey protein into the film and the proper choice of plasticizer. Sodium alginate film exhibited lower water vapor permeability values than films prepared using either low or high methoxylated pectin. Sodium lactate was found to be an effective plasticizer and alginate films containing 50 wt% or more sodium lactate had elongations in excess of 13%. Films prepared with sorbitol as the plasticizer had the best water vapor permeability values but tended to be stiff and in some cases too brittle for tensile measurements. Addition of whole milk to film blends effectively reduced water vapor permeability values by up to 35%.