Scientific research on the production, quality and potential applications of edible/biodegradable films in food manufacturing has been carried out by several research groups worldwide and has been reported in research publications5-9. The enormous commercial and environmental potential in the area of edible/biodegradable films/coatings has often been stressed5,10,11 and numerous publications have primarily addressed issues relating to mechanical properties, gas migration, and the effects of other factors on these properties, such as type and content of plasticisers, pH, relative humidity and temperature etc.6,8,10-15.
However, research into edible/biodegradable films is still in its infancy and research on industrial application of edible/biodegradable films has received more attention in recent years, however, coverage is still quite limited.
Researchers in the Food Packaging Group, Department of Food and Nutritional Sciences, University College Cork, Ireland, have developed several functional, biopolymer-based, edible/biodegradable films over the last few years.
The limitations of edible packaging
Generally, edible films have limited application primarily because of their inferior physical characteristics. For example, single, lipid-based films have good moisture barrier properties but contain no mechanical strength23. Consequently, laminated films were formed by adhering two or more biopolymer films together. However, laminated films are advantageous to single, emulsion-based biopolymer films due to their possession of enhanced barrier properties. The creation of laminated structures has the potential to overcome these shortcomings by engineering edible/biodegradable films with multiple functional layers.
Edible films and coatings based on water-soluble proteins are often water-soluble themselves but possess excellent oxygen, lipid and flavour barrier properties. Proteins act as a cohesive, structural matrix in multicomponent systems, yielding films and coatings with good mechanical properties. Lipids, on the other hand, act as good moisture barriers, but have poor gas, lipid and flavour barriers. By combining proteins and lipids in emulsion or bilayer (a membrane consisting of two molecular layers), the positive attributes of both can be combined and the negatives minimised.
From the research conducted by the Food Packaging Group at UCC, the general characteristics of developed edible/biodegradable films are as follows:
- Thickness of manufactured edible/biodegradable films range from 25μm to 140μm
- Films can be clear, transparent, and translucent or opaque depending on the ingredients used and the processing technique employed
- Aging specific film types under controlled environmental conditions improved mechanical properties and gas barrier properties
- Storing films at ambient condition (18-23°C, 40- 65 per cent RH) for five years did not significantly alter structural characteristics
- Films formed from various ingredients can be relatively easily laminated together
- Manufactured films can be labeled, printed on or heat sealed
- Small variations in film microstructure (e.g. biopolymer phase separation) affects film properties
Post time: Mar-05-2021