Comparative effect of different plasticizers on physicochemical properties of hydroxypropyl methyl cellulose (HPMC)- based films appropriate for gilthead seabream packaging

The selection of adequate plasticizers to synthesize biopolymer biodegradable and edible films for food pack- aging is crucial to develop materials with appropriate barriers, mechanical and physicochemical properties. The aim of the study was to develop hydroxypropyl methyl cellulose (HPMC) based films with hydrophilic and hydrophobic plasticizers and evaluate their effectiveness as green packaging materials for gilthead seabream fillets. Mechanical properties, water barrier, surface hydrophobicity, optical and UV–visible barrier properties were determined. The films produced were transparent with excellent optical appearance and good preventive ability against UV radiation. HPMC based films with glycerol as plasticizer were more compact and had lower thickness (45.43±3.33 μm) and higher young’s modulus, indicating stiffer, less flexible films (1613.22±492.88 MPa). In contrast, films plasticized with oleic acid had the highest elongation at break (30.35±4.21 %), indi- cating greater flexibility. The films with glycerol were hydrophilic (contact angle equal to 81.47±6.65◦) while the films with fatty acids (oleic and linoleic acid) were hydrophobic (contact angle > 90◦). The hydrophobic films had also better water barriers compared to films with glycerol. All tested packaging materials resulted in similar preservative effect on packed gilthead seabream fillets, leading in shelf life 7–8 days at 2 ◦ C. The results of the study show the potential of the developed biodegradable films to replace the conventional synthetic pe- troleum based materials in fresh fish packaging