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Physical, Chemical and Biochemical Modifications of Protein-Based Films and Coatings: An Extensive Review

View Article: PubMed Central - PubMed

ABSTRACT

Protein-based films and coatings are an interesting alternative to traditional petroleum-based materials. However, their mechanical and barrier properties need to be enhanced in order to match those of the latter. Physical, chemical, and biochemical methods can be used for this purpose. The aim of this article is to provide an overview of the effects of various treatments on whey, soy, and wheat gluten protein-based films and coatings. These three protein sources have been chosen since they are among the most abundantly used and are well described in the literature. Similar behavior might be expected for other protein sources. Most of the modifications are still not fully understood at a fundamental level, but all the methods discussed change the properties of the proteins and resulting products. Mastering these modifications is an important step towards the industrial implementation of protein-based films.

No MeSH data available.


Effect of plasticizer content on thermoplastic processing, adapted from [4].
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ijms-17-01376-f001: Effect of plasticizer content on thermoplastic processing, adapted from [4].

Mentions: Increasing the chain mobility by denaturation of the film forming proteins is essential for thermoplastic processing. Changes in chain mobility are related to thermal transitions such as the glass transition temperature (Tg) and flow temperature (Tf), also referred to as the softening temperature, which occurs at higher temperature. Above the Tf the protein-based mixture exhibits the low viscosity necessary to process the material. Unfortunately, proteins with less than 5% water have a Tg above or equal to their decomposition temperature [180]. The temperature difference between the Tg and Tf of soy and gluten based films is about 40 °C [181]. Moreover, films based solely on proteins are fragile and brittle because of the bonds and interactions between the protein chains [182]. As shown in Figure 1, the addition of plasticizers resolves this issue by impairing macromolecular associations and therefore reducing the Tg and Tf. The chain mobility increases on addition of plasticizers, due to replacement of protein interactions with protein-plasticizer interactions [183].


Physical, Chemical and Biochemical Modifications of Protein-Based Films and Coatings: An Extensive Review
Effect of plasticizer content on thermoplastic processing, adapted from [4].
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037656&req=5

ijms-17-01376-f001: Effect of plasticizer content on thermoplastic processing, adapted from [4].
Mentions: Increasing the chain mobility by denaturation of the film forming proteins is essential for thermoplastic processing. Changes in chain mobility are related to thermal transitions such as the glass transition temperature (Tg) and flow temperature (Tf), also referred to as the softening temperature, which occurs at higher temperature. Above the Tf the protein-based mixture exhibits the low viscosity necessary to process the material. Unfortunately, proteins with less than 5% water have a Tg above or equal to their decomposition temperature [180]. The temperature difference between the Tg and Tf of soy and gluten based films is about 40 °C [181]. Moreover, films based solely on proteins are fragile and brittle because of the bonds and interactions between the protein chains [182]. As shown in Figure 1, the addition of plasticizers resolves this issue by impairing macromolecular associations and therefore reducing the Tg and Tf. The chain mobility increases on addition of plasticizers, due to replacement of protein interactions with protein-plasticizer interactions [183].

View Article: PubMed Central - PubMed

ABSTRACT

Protein-based films and coatings are an interesting alternative to traditional petroleum-based materials. However, their mechanical and barrier properties need to be enhanced in order to match those of the latter. Physical, chemical, and biochemical methods can be used for this purpose. The aim of this article is to provide an overview of the effects of various treatments on whey, soy, and wheat gluten protein-based films and coatings. These three protein sources have been chosen since they are among the most abundantly used and are well described in the literature. Similar behavior might be expected for other protein sources. Most of the modifications are still not fully understood at a fundamental level, but all the methods discussed change the properties of the proteins and resulting products. Mastering these modifications is an important step towards the industrial implementation of protein-based films.

No MeSH data available.