Edible films and coatings from calcium caseinate and their applications
Creators: name: Akkurt, Serife
Publisher: name: No Publisher Supplied
Year: 2015

description: Calcium caseinate (CaCas), isolated from nonfat dry milk (NFDM), is a milk ingredient for the production of protein-based edible films and coatings. When the supply of NFDM exceeds the demand, the conversion of CaCas to alternative value-added products through processes such as coating may help utilize and prevent future surpluses of NFDM. This project involves two studies: the first is to produce edible CaCas films by incorporating high methoxyl pectin to improve their mechanical strength, and the second is to apply edible CaCas coating on ready-to-eat (RTE) breakfast cereals to enhance their textural and nutritional properties.   The motivation of the first study is to improve the mechanical properties of calcium caseinate-based films. Glycerol (Gly), a plasticizer, is currently used in film solutions to overcome the brittleness of CaCas films. However, Gly reduces the mechanical strength of the films (Tomasula et al. 1998). The addition of hydrophobic compounds or modifications of polymer network is a common approach to improve the mechanical properties of CaCas/Gly films through crosslinks. Pectin can be an additive to provide the crosslinks in the film molecular structure (Rees et al., 1975; Morris et al., 1982; Flutti, 2003) because pectin molecules have both carboxyl and methoxyl functional groups which crosslink with amino acids of CaCas (Chambi and Grosso 2006). In this study, high methoxyl pectin (CP) was used in CaCas/Gly film solutions to make the edible films, and its effect on elastic modulus (E), elongation at break (EAB), and tensile strength (TS) of the films were evaluated. CaCas/Gly without (Control A and F films) and with CP (A, B, E, F, G, H, and K films) film solutions were prepared based on formulations which were produced by changing the mixing sequences of compounds at the constant 15% total solid concentration. The E, EAB, and TS values of these nine different films were tested as a function of film thickness, humidity, and CP content. The magnitude of the tensile properties showed that edible CaCas/Gly films was affected by film thickness, relative humidity (RH), and CP content (Bonnaillie et al. 2014).   The motivation of the second study is to improve the nutrient profiles, extend the bowl-life, and enhance the textures of RTE breakfast cereals by using CaCas-based coating materials. RTE breakfast cereals are produced based on several steps including preprocessing, formulation, cooking, and lump breaking, coating, drying, cooling, and flaking. In the coating process, high sugar concentrates or slurries such as syrup are used to provide moisture barrier properties, preserve texture, and extend bowl-life of the cereals. Therefore, most RTE breakfast cereals contain high sugar with a range of 1-56% concentration (Albertson et al. 2013).  However, this leads to health concerns such as childhood obesity and dental problems. Current research and some companies focus on the reduction of sugar coating and the enhancement of nutrient quality of RTE flakes by investigating alternative coating materials. In this study, glucose, NFDM, CaCas, and CaCas in blends with Gly, CP, and NFDM at constant 15% total protein concentration in coating solutions were applied on Wheaties® breakfast cereals by spraying the solutions on the surface of flakes with a drying process. The coatings provided an increased protein source, longer bowl life in milk, and crunchier and crispier texture by forming a uniform, sheen, and protective coating layer on the surface of the flakes.