Sorbitol-plasticized jackfruit starch-based films: investigation of the effect of the starch and plasticizer concentration on the film properties

Jackfruit seeds have been explored as one interesting alternative starch source to be used in the production of sustainable bioplastics. In this context, this work aimed to investigate the effect of sorbitol concentration, one alternative plasticizer to glycerol, and the starch properties of the films. A complete factorial experimental study was done based on five different concentrations of starch (2, 3, 4, 5, and 6% w/w) and sorbitol (40, 50, 60, 70, 80 g per 100 g of starch). The films were produced by cast- ing technique and were characterized about thickness, optical properties, moisture resistance, mechanical properties, and morphology. The optical properties revealed opaque films, with opacity values ranging from 16.04 to 21.26%. Regarding mois- ture resistance, the less hydrophilic films showed lower plasticizer content. The water solubility varied from 25.48 to 38.93%; the water vapor permeability ranged from 9.99 to 11.82 × 10 −9 (g/m s Pa) and the free energy of hydrophobic interac- tions varied from − 28.16 to 40.13 mJ  m −1 . Concerning the mechanical properties, the tensile strength of the films ranged from 3.55 to 9.25 MPa, and increasing the sorbitol concentration decreased the tensile strength and increased the elongation at break. The morphology and structure analysis showed that starch granules were not fully gelatinized, with microbubbles and grooves in the film matrix. This study showed the great potential of jackfruit seed starch and sorbitol in the manufacture of biodegradable films as alternative sustainable packaging.

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