Edible Films and Coatings Overview

Study Notes

Edible films and coatings are applied to food after creation of the edible solution.
The solution is cast, dried, and detached for edible films.
Coatings are applied as dips or sprays, then dried.
Preparation of edible solutions involves adding components, homogenization, and degassing.

Polysaccharides like cellulose, chitosan, starch, pectin, and alginate are used.
Cellulose is commonly used as it's tasteless, odorless, transparent, and has a high oxygen, carbon dioxide, and lipid barrier.

Chitosan: Good oxygen barrier and mechanical properties, but low water vapor resistance.
Starch: Good oxygen and carbon dioxide barrier, but poor water vapor barrier.
Proteins (e.g., collagen, gelatin): Good transparency, mechanical, and barrier properties.
Wheat gluten: Transparent, mechanically strong, and insoluble in water.
Whey protein: Creates dense, strong films with good oxygen and water vapor barriers.
Lipids (e.g., waxes, paraffins): Good gas and moisture barriers.

Bioplastics are a type of packaging material made from renewable resources.
Examples include polymers from sugarcane, corn, cellulose, or yeast.
Polylactic acid (PLA) is a common biobased and biodegradable polymer made from corn starch.
PLA packaging for meat showed no significant differences from conventional plastic and modified atmosphere packaging.

Polymer films aren't complete barriers to water and O2 but are good barriers to microorganisms and dirt.

Jute and cotton cloths have been used for packaging food items (e.g., fruits, vegetables, grains, etc).
Paper and plastic bags have largely replaced them.

Composite containers consist of cylindrical bodies made of paperboard/fiberboard and metal/plastic ends.
Where a good barrier is needed, coated board or aluminum foil is incorporated.
Smaller containers (tubes/cans) are used for items like spices, custard powders, etc.
Larger containers (e.g., fiberboard drums) are used as alternatives to paper/plastic sacks/metal drums for products like powdered milk.

Packaging needs vary with food types.
Cereals need moisture resistance. HDPE polymers are commonly used for these. -Snack foods need oxygen barrier, moisture barrier, and light barrier -Meat, poultry, and fish packaging requires a package for oxygen, moisture, odor, and grease barrier. -Shrink bag methods use ethylene-vinyl acetate (EVA), polyvinylidene dichloride (PVDC) and/or PA, which is heat shrunk. -Thermoformed plastic bags using materials like PET are also used to contain meat and produce a tight vacuum.

Cheese packaging depends on type and attribute.
Hard cheeses (e.g., Parmesan, Romano, Grana): 20-25% moisture content
Semi-hard cheeses (e.g., Edam, Gouda, etc): 40-49% moisture content
Rindless cheese can use plastic film to prevent evaporation. PET, LDPE, and PA are typical materials for these cases.

EVOH (ethylene vinyl alcohol) and PVDC (polyvinylidene dichloride) are used when oxygen barrier is required, such as in cheese packaging to prevent mold growth