Another deliverable was reached by Quafety scientists, especially the scientists coordinated by Professor Elefterios Drosinos at University of Athens have reached the deliverable on methods of antimicrobial packaging and coating for fresh-cut products.The aim of the work (active and intelligent packaging) was to address two types of packaging: (a) active and (b) intelligent.
Regarding active packaging, it is based on active compounds whose antimicrobial efficacy has been examined and sensorial impact has been taken into consideration. Two different types have been developed and evaluated according to the method of active compound release to the product surface: (i) from the packaging to the product surface and (ii) diffusion via edible coating.
Regarding the first type of active packaging, the initial experiments aimed at the selection of an essential oil able to inhibit the pathogenic microorganisms under study, i.e. L. monocytogenes and E. coli O157:H7. Then, it was applied in rocket and melon that were packaged with a microperforated, polypropylene-based bag (OPP) film in either air or modified atmosphere packaging (MAP) (5% O2, 10% CO2) and stored at 0, 5, 10 and 15 °C in order to assess the effect of the essential oil in situ.
Regarding the second type of active packaging, the performance of various formulations (i.e. chitosan, gelatin, gelatin/chitosan as blended, gelatin/chitosan as Layer-by-Layer, alginate/chitosan as Layer-by-Layer) applied as edible coatings on fresh-cut melons was studied. Moreover, the combined effect of proper process conditions (i.e. accurate washing, proper dipping) and packaging system (OPP40) for the prolongation of fresh-cut melon shelf life was assessed.
Regarding the development of an intelligent packaging, initially a study of the freshness and marketability of the product (rocket) stored at usual and abusive temperatures was performed, then, a study of the growth of selected microorganisms at the same temperatures took place and then growth of the most suitable microorganism was adjusted to match the time/temperature – freshness relationship of the product and a device for the presentation of the Time-Temperature Indicator was made.
The scientists concluded that the Lemongrass essential oil seemed to affect the enterococci and yeast-mould populations and to be dependent on the product, the storage temperature as well as the packaging atmosphere.
The impact on the sensorial properties was more pronounced during the first 4-5 days of storage and faded as storage proceeded, due to the evaporation. During this time the product was not acceptable by all panellists due to the intense odour, but after that time the residual odour was not that intense and the product was more acceptable.
As far as the development and application of edible coating was concerned, performance of various formulations exhibited that films prepared by the Layer-by-Layer approach benefit better mechanical properties, higher permeability and when applied on food models, demonstrated effective microbial spoilage inhibition.
The Layer-by-Layer formulation was superior in preservation of fruit texture and also slightly reduced fruit weight loss, while the blended formulation did not improve these parameters. Both composite coatings do not obstruct fruit gas exchange and do not cause accumulation of off flavour volatiles. Regarding the best combination of process variables, it corresponded to proper washing of the whole melon, dipping treatment in hexanal of the cut pieces, active coating with hexanal and packaging in OPP40. Under these conditions the shelf life reached was of 16 days, compared to that of control melon that accounted for less than one week. A Time-Temperature Indicator was developed based on the microbial activity of lactic acid bacteria and a presentation on the packaging was proposed.
For further info:
Elefterios Drosinos - ehd@aua.gr