Mechanical properties starch-based edible films

An edible film should have good water vapor barrier properties (low or no water permeation and diffusion through film), which should not increase or increase very little with increasing relative vapor pressure (Lawton, 1996). Films should withstand mechanical stress and strain to such an extent that they do not break easily under a decent mechanical force (Talja et al, 2008). Thus, composition of starch-based films is an important factor influencing its barrier and mechanical properties. Also, starch-based edible films may have an impact on the sensory and textural characteristics of the food. 

Talja, R. A., Heleln, H., Roos, Y. H., Jouppila, K. (2008). Effect of type and content of binary polyol mixtures on physical and mechanical properties of starch-based edible films. Carbohydrate Polymers, 71, 269-276. 

Effects of Content and Type of Binary Polyol Mixtures on Physical and Mechanical Properties of Starch-Based Edible Films... 

In this study, we investigated effects of binary mixtures (1 1) of glycerol, xylitol, and sorbitol on physical and mechanical properties of potato starch-based edible films stored at various relative humidities. 

Mechanical properties for starch-based edible films plasticized with different contents (a) and types (b) of binary polyol mixtures and stored at various relative humidities. 

Maran, J. R, Sivakumar, V., Sridhar, R., Immanuel, V. P. (2013). Development of model for mechanical properties of tapioca starch-based edible films., (Complete), 159 168. 

Previous studies have shown that films cast from high-amylose starch have better film-forming and mechanical properties [80, 108, 109]. Furthermore, both amylose and amylopectin have shown excellent oxygen-barrier characteristics, which is one of the advantages of using edible hydrophilic starch-based films for food protection [110]. 

Jimenez A, Fabra MJ, Talens P, Chiralt A (2010) Effect of lipid self-association on the microstructure and physical properties of hydroxypropyl-methylcellulose edible films containing fatty acids. Carbohydr Polym 82 585-593 Jimenez A, Fabra MJ, Talens P, Chiralt A (2013) Phase transitions in starch based films containing fatty acids. Effect on water sorption and mechanical behavior. Food Hydrocolloid 30 408-418 Jin Z, Hsieh F, Huff HE (1994) Extmsion of com meal with soy fiber, salt, and sugar. Cereal Chem 7 227-234... 

Modified or unmodified starch is one of the most used biopolymer for making biodegradable or edible packaging film because of its low cost, availability, and film-forming ability. Starch-based films are transparent, flavorless, tasteless, and colorless. Due to their hydrophilic nature, the films produced firom starch possess poor gas and water vapor barrier properties These films also have poor mechanical strength and hence several modifications and additives are required to improve the barrier and mechanical properties. This limits their potential to be used as a raw material for the development of food packaging materials to a large extent. 

Wang Z, Zhou J, Wang X, Zhang N, Sun X, Ma Z (2014) The effects of ultrasonic/microwave assisted treatment on the water vapor barrier properties of soybean protein isolate-based oleic acid/stearic acid blend edible films. Food Hydrocolloids 35 51-58 Wihodo M, Moraru Cl (2013) Physical and chemical methods used to enhance the structure and mechanical properties of protein films a review. J Food Eng 114(3) 292-302 Woehl MA, Canestraro CD, Mikowski A, Sierakowski MR (2010) Bionanocomposites of thermoplastic starch reinforced with bacterial cellulose nanofibers effect of enzymatic treatment on mechanical properties. Carbohydr Polym 80 866-873 Xu YX, Kim KM, Hanna MA, Nag D (2005) Chitosan-starch composite film preparation and characterization. Ind Crops Prod 21 185-192... 

Extrusion is a cost effective manufacturing process. Extrusion is popularly used in large scale production of food, plastics and composite materials. Most widely used thermoplastics are processed by extrusion method. Many biopolymers and their composite materials with petroleum-based polymers can also be extruded. These include pectin/starch/poly(vinyl alcohol) (Fishman et al. 2004), poly(lactic acid)/sugar beet pulp (Liu et al. 2005c), and starch/poly(hydroxyl ester ether) (Otey et al. 1980), etc. In this study, composite films of pectin, soybean flour protein and an edible synthetic hydrocolloid, poly(ethylene oxide), were extruded using a twin-screw extruder, palletized and then processed into films by compression molding process or blown film extrusion. The films were analyzed for mechanical and structural properties, as well as antimicrobial activity. 

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