Each week, food retailers end up ditching as much as 50 percent of their stock of fruit and vegetables. It’s a similar story with consumers. There are two main reasons for this wastage: premature ripening, which in many fruits is triggered by ethylene, a plant hormone; and microbial infestation, often in the form of mold. Yet the use of active packaging can help slow these processes and prolong the shelf life of fresh fruit and vegetables, thereby reducing food waste.
Longer shelf life with active packaging
The FreshInPac project develops packaging that is designed to prolong the shelf life of fresh fruit and vegetables by inhibiting ethylene-induced ripening and microbial spoilage. Active materials are being developed and characterized for both of these purposes. On the basis of these materials, researchers are carrying out shelf-life simulations and storage tests in order to design and trial demonstrators for future packaging systems.
Modified atmosphere packaging and active substances
When packaging fresh fruit and vegetables, materials should be selected that allow the contents to breath and that prevent fermentation under anoxic conditions. Packaging with an overly strong gas barrier is therefore unsuitable for this purpose. Instead, perforated packaging is used to create a protective atmosphere. This is known as equilibrium modified atmosphere packaging (EMAP), in which an elevated concentration of carbon dioxide serves to suppress microbial activity. At the same time, lowered oxygen levels inhibit metabolic processes in the fruit, reducing the release of ethylene and thereby slowing down ripening. Through the incorporation of active substances in packaging, these effects can be reinforced. Ethylene scavengers, for example, in the form of clay particles loaded with catalytic metals or potassium permanganate, serve to bind or break down the ethylene released from fruit and vegetables, thereby delaying the ripening process. Similarly, antimicrobial substances are used to inhibit the growth of bacteria (bacteriostatic) and fungus (fungistatic). Various combinations of essential oils and other substances are currently being investigated for this purpose. Such active substances can be either directly incorporated in plastic foil or applied in the form of a special coating. Here, the recyclability of the packaging materials is also taken into account.
Simulations for development of new packaging
The Fraunhofer Institute for Process Engineering and Packaging IVV has developed mathematical models to describe how such packaging regulates the release of ethylene. On this basis, we are now designing suitable packaging for selected fruit and vegetable varieties based on the ethylene scavengers developed in the FreshInPac project. This work also uses data on the levels of respiratory gas in the packaging, which are derived from an enhanced version of the shelf-life modeling framework developed at Fraunhofer IVV. This model describes the respiratory behavior of the packaged fruit and its production of ethylene, both of which are influenced by the atmosphere within the packaging, by the gas permeability of the packaging, and by the effect of the ethylene scavengers. By combining all these factors, it is possible to simulate EMAP behavior, thereby creating a template for the development of new packaging concepts that enable prolonged shelf life.
The following bodies are involved in the FreshInPac project:
- IVLV (Industry Association for Food Technology and Packaging, Germany) – project coordinator
- CELABOR (Wallonia, Belgium)
- Materia Nova (Wallonia, Belgium)
- ZUT (West Pomeranian University of Technology, Poland)
- ATB (Leibniz Institute for Agricultural Engineering and Bioeconomy, Germany)