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35 Edible Coatings and Films from Agricultural and Marine Food Wastes

drawback of using the extrusion process is that it cannot form a proper film, as the

biopolymers do not have a fixed melting point and they experience decaying on

heat applications [1].

35.5.3

Dipping Method

Membranous film formation takes place over the food surface when it got dipped

into a coating solution. Then it will be removed and air-dried further, and this

method was mainly used on fruits, vegetables, and meat products [1]. The dipping

method is not suitable for fresh-cut fruits as it is difficult to form an adhesion of the

coating on the hydrophilic surface. To overcome this, a multilayer technique called

layer-by-layer electrodeposition is applied. Here, two or more layers are bonded

physically or chemically to each other [4].

35.5.4

Spraying Method

It is a conventional method generally used for a low viscosity coating with a

high-pressure range of 60–80 psi for better coverage [1] and also offers thickness

control and uniform coating. A spray can generate a coating through combined

hydrophilic and hydrophobic interactions, and using an emulsion, directly forms

layer before atomization, or a bilayer formation occurs after two pulverizations.

The classical spray system can produce a spray with a drop size distribution of up

to 20 μm. However, the polymeric coating formation by spraying method can be

affected by other factors like drying rate, temperature, and drying method [4].

35.5.5

Spreading Method

This is otherwise called as brushing and comprises of controlled spreading on the

material surface and drying by the hot air. The brushing method is found to be more

effective than dipping or wrapping in terms of moisture loss [4].

35.6

Conclusion

Large amount of food wastes are generated (peel, pomace, husk, seed, and animal

waste) and this causes very serious issues in the food resources management and

also has a negative environmental impact. Increased interest in environmental con-

servation and valorization of food wastes has encouraged the development of new

products like edible film from food wastes of plant and animal origin. Researchers

have put a lot of efforts in order to optimize and facilitate food wastes into edible

film and coating formation. However, still lot more research need to be done.