Physical, mechanical and water barrier properties of yuba films incorporated with various types of additives.

BACKGROUND

To apply yuba as an edible film, we evaluated film properties after adding various additives, including plasticizer (glycerol and sorbitol), cross-linking agent (oxidized ferulic acid), emulsifier (sodium pyrophosphate), thicker (sodium carboxymethyl cellulose) and lipid (beeswax), alone or in combination (sodium pyrophosphate and sorbitol; sodium carboxymethyl cellulose and glycerol; and beeswax and glycerol).

RESULTS

The addition of beeswax and oxidized ferulic acid enhanced the water resistance of the film, showing a decreased solubility in water and swelling ratio. The results for tensile strength and elongation showed opposite trends, except for sorbitol, sodium pyrophosphate, and sodium carboxymethyl cellulose and glycerol. Tensile strength of sodium carboxymethyl cellulose (9.3 MPa) was increased compared to that of yuba without additive (3.5 MPa). Elongation was increased in glycerol (132%) compared to that in the control (8%). Water vapor permeability decreased in all samples by 0.7 to 8 times compared to that of the control. X-ray diffraction analysis found that blending additives influenced the crystalline degree and second structure of the film. Atomic force microscopy revealed that the control (37 nm) and sodium carboxymethyl cellulose and glycerol (47 nm) exhibited smooth surface and lower roughness values compared to glycerol (84 nm) and sodium carboxymethyl cellulose and glycerol (87 nm).

CONCLUSION

Our results confirmed that yuba could be used as edible film with a wide range of applications depending on types of additive and purpose of use. The results of the present study revealed that sodium carboxymethyl cellulose and glycerol-added yuba film had exceptional edible film properties, including water resistance, elongation and water vapor permeability based on principal component analysis. © 2018 Society of Chemical Industry.