Thesis (Ph.D.) - Cairo University - Faculty of Science - Department of Physical Chemistry

Edible coatings have increased attention in the field of food industries due to their outstanding ability to extend the shelf-life of food. Edible coatings could be designed from different components to verify the best desired properties.In this thesis, four systems of edible coatings with different components were prepared, and their ability to extend the shelf-life of green capsicums were evaluated. In the first part, Box-Behnken design was used to optimize the compositions of carboxymethyl starch, alginate and microcrystalline cellulose (MCC) to obtain a composite edible coating of the lowest water vapor permeability (WVP).Thermal and mechanical properties were improved upon increasing the content of MCC.The optimized coatings significantly extended the shelf-life of green capsicums where significant resistance to spoilage and mass loss were obtained. In the second part, chitosan biguanidine (CG) was prepared and used as a multifunctional polymer crosslinker to carboxymethyl starch and alginate. Thermal stability and mechanical properties were significantly improved while the WVP was reduced upon increasing the CG content. Excellent antimicrobial activity was observed due to the presence of CG.The prepared coating significantly inhibited the spoilage of green capsicums and extended their shelf-life. In the third part, a composite edible coating was prepared through the incorporation of gelatin into carboxymethyl starch and alginate. FTIR and XRD data verified the interactions between the film{u2019}s components.Thermal, mechanical and barrier properties of the prepared coatings were improved in the presence of gelatin.

Issued also as CD