Caseinate-based films

Among the films invesfigafed, edible films based on proteins showed the best mechanical properties. However, their barrier properties are variable (Kester and Fennema, 1986). The increase of cohesion between protein pol) eptide chains was thought to be effective toward the improvement of the barrier properties of fhe films. For insfance, fhe presence of calcium was reported to decrease the water permeability of caseinate-based film (Avena-Bustillos and Krochta, 1993). 

Avena-Bustillos, R.J. and Rrochta, J.M. Water vapor permeability of caseinate-based films as affected by pH, calcium cross-linking and lipid contents, /. Food Sci., 58, 904,1993. 

The objective in this work, was to achieve caseinate-based films with improved properties as close as possible to available packaging films based on synthetic polymers hke polyethylene [6] or plasticiz PVC [9], Such films have good elongation at break point (from 150 to 400%) and a rather low tensile strength ranging from 20 to 30 MPa. However, compared with synthetic films, casein-based films (hke most protein films) have two major drawbacks [10-12] ... 

The aim of the present work was focused on the improvement of the mechanical properties as well as the water resistance of caseinate-based films. The first part of this study deals with the control of the mechanical properties through addition of a plasticizer. A plasticizer is defined as a low volatile organic compound which causes a decrease in polymer glass transition temperature (Tg) and an increase in flexibihty and extensibility. By decreasing intermolecular forces between polymer coils, plasticizers cause an increase in material flexibility and conversely a decrease in the barrier properties due to the augmentation of the free volume [13,14]. To summarize, an initially hard and brittle material becomes soft and flexible when sufficiently... 

In addition, caseinate-based films were crosslinked with formaldehyde (HCHO). The occurrence of covalent bridges between protein chains allows water-insoluble three-dimensional network to be achieved. The crossHnking was combined with plasticizing to produce caseinate films with improved mechanical properties and water resistance which are able to replace synthetic films and to overcome protein film deficiencies. Nevertheless, in spite of crosslinked protein material being water insoluble, it was also shown that during water immersion, plasticizer exuded out of the film, even for highly crosslinked samples. 

Fabra, M.J., Hambleton, A., Talens, R, Debeaufort, R, Chiralt, A., Voilley, A. 2008. Aroma barrier properties of sodium caseinate-based edible films. Biomacromolecules, 9(5) 9, 1406-1410. 

Jagannath, J.H., Radhika, M., Nanjappa, C., Mtirali, H.S., Bawa, A.S. Antimicrobial, mechanical, barrier, and thermal properties of starch-casein based, Neem (Melia azardirachta) extract containing film. J. Appl. Polym. Sci. 101, 3948-3954 (2006)... 

Ciesla, K., Salmieri, S., Lacroix, M. y-Irradiation influence on the structure and properties of calcium caseinate-whey protein isolate based films. Part 2. Influence of polysaccharide... 

Up until the 1960s, milk protein-based materials were used for making glossy record album covers, buttons and decorative items. Labels for some cheeses are still made with crosslinked casein. The film-forming properties of casein and whey proteins were investigated with the aim of developing edible films and coatings [91, 92]. Caseins... 

Cao, Q., Zhao, H., Yang, Y. et al. (2011) Electrochemical immunosensor for casein based on gold nanoparticles and poly(L-Arginine)/multi-walled carbon nanotubes composite film functionalized interface. Biosens. Bioelectron., 26, 3469-3474. 

Few studies have focused on the biodegradability and environment-friendly aspects of protein-based products that degrade naturally or in compost. The construction of protein networks can induce marked changes in the conformation and resistance to enzymic hydrolysis and chemical attacks of proteins [194]. However, Garcia-Rodenas and coworkers [195] showed that the susceptibility of casein and wheat gluten-based films to in vitro proteolysis did not significantly differ from that noted for native proteins. 

Fabra, M. J., Talens, P. Chiralt, A. (2008). Effect of alginate and. -carrageenan on tensile properties and water vapour permeability of sodium caseinate-lipid based films. Carbohydrates Polymers, 74,419-426. 

U.S. 4,368,146 (1983) Aronson et al. (Lever Brothers) Anionic/nonionic based plus polymers and alkali metal salt of casein Rapid and uniform draining with no spotting or filming... 

According to the Fick and Henry s laws the water vapor permeability (WVP) should not be function of thickness.18,22 However, WVP of hydrophilic films can be function of the thickness.19 Tomasula et al.23 studied films made from C02-precipitated casein (C02-casein), with thickness varying from 0.110 to 0.150mm, and observed that the WVP increased significantly from 2.22 to 3.80g mm/kPa h m2. The influence of the thickness on the WVP was also observed by Cuq et al.19 and Sobral24,25 that worked with films based on myofibrillar proteins from Atlantic sardines and gelatin and myofibrillar proteins from Tilapia, respectively. 

Cellulose-based plastics, particularly cellulose nitrate and acetates, were the most commercially important semi-synthetics up to the 1940s and were used as the base for photographic film, textile fibres, moulded goods and in lacquers. Naturally occurring polymer cellulose in the form of cotton linters or wood pulp is chemically treated to increase its solubility. Cellulose has a high molecular weight of between 100000 and 500000 and an empirical formula C0H1OO5. Casein-formaldehyde is the only protein-based moulded plastic that achieved commercial success. It is based on cow s milk and is still produced in very small quantities for specialist items such as hand-coloured buttons. 

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