Edible Films: Eat Your Food With the Wrappers On!
All these years, we have been buying foodstuffs packed or wrapped in plastic, metal foils or papers, which we usually remove and throw in garbage bins. Although most of the packaging materials have been petroleum-derived polymers, the rising concern with their nonrenewable and non-biodegradable nature paves the route for the development of greener alternatives. Due to the rapid advancements in food technology, now we have food products packed in edible packaging materials. Yes! You can eat the wrappers as well!
What are edible films and coatings?
Edible films and coatings are any type of material used for enrobing various food inorder to extend shelf life of the product, that may be eaten together with food, with or without further removal. They are thin layers on the surface of the food, providing a barrier to moisture, oxygen and microbial contamination. Edible films contain only food-grade components in their composition, including film-forming matrix, solvent, plasticizers and other additives.
What are they made up of?
Diverse biological materials, such as polysaccharides, proteins, lipids and resins can be used in edible packaging formulations. They have two major components: a biomacromolecule-based matrix which forms a cohesive structure and a solvent (usually water). A plasticizer is often required for reducing brittleness and increasing flexibility . Usually, edible films and coatings are supposed to be transparent and flavorless, not interfering with the sensory properties of food. However, specific sensory properties may be desirable for some applications, such as sushi wraps, pouches to be melted on cooking, films between crust and toppings of pizzas or even film snacks.
Current research trend is the exploration of food industry by-products and waste as potential edible packaging materials. For example, whey protein from cheese production, chitosan from crustacean shells, corn zein from ethanol production, potato starch from potato chip waste, mung bean protein from mung bean starch and fruit pomace from beverage production. This can help in preventing competition for food resources as well as reducing environmental impacts and waste disposal costs. New sources of materials and blends have been used in the last few years to formulate edible films and coatings, including fruits and vegetable purees.
Applications of edible films
Edible coatings have been used as a barrier to minimize water loss, delaying the natural senescence of coated fruits and vegetables through selective permeability to gases. They extend the shelf life of minimally-processed fruits and vegetables by reducing moisture and solute migration, gas exchange, respiration and oxidative reaction rates. They can also suppress physiological disorders, delay changes in textural properties and improve mechanical integrity or food handling characteristics. They offer additional advantages in commercial use, such as biocompatibility, nontoxicity, nonpolluting characteristics and low cost.
Another important application of edible coating is the reduction of oil uptake in deep fried products. Excess of fat in the diet has been linked to coronary heart disease, thus coatings applied to food before frying can help in reducing health problems associated with overconsumption of fat. Cellulose derivatives, including methylcellulose and hydroxypropyl- methylcellulose, which exhibit thermal gelation, can be used to reduce oil absorption through film formation.
One important advantage of using edible films and coatings is that several active ingredients can be incorporated into the matrix and consumed with the food, improving safety or nutritional and sensory attributes; the tendencies are to use edible coatings as carriers of functional ingredients by incorporating antimicrobials, antibrownings, and nutraceuticals to improve the quality of fruits and vegetables.
Antioxidant edible films can prevent food oxidation, development of off-flavors and nutritional losses, whereas antimicrobials can prevent spoilage from food-borne bacteria and organoleptic deterioration by microorganism proliferation.
The use of edible films has found a very important niche of applications, including in food packaging and biomedical applications through their good performance as carriers for active compounds. Research in this field has largely increased in the last few years, but some drawbacks are still to be solved to permit their use in massive applications in the packaging of consumer goods. The potential of edible coatings has been recognized as an alternative or synergistic addition to conventional packaging to enhance food quality and protection.
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