Evaluation of Composition on Processability and Water Absorption of Wheat Gluten-Based Bioplastics

The nature of the plasticizer fraction within a bioplastic matrix is of extreme importance. Thus, brittleness has sometimes been observed when water has been used. The goal of the present manuscript has been to assess the effects of the addition of sucrose and trehalose in gluten-based bioplastics either in presence or absence of water. It was found that the role of the disaccharides in the samples studied depended on whether water was present or not in the formulation. Therefore, when water was included in the formulation together with glycerol, sugars were solubilized within the aqueous fraction, and then played a plasticizer role in the bioplastics. In that case, lower torque and temperatures during mixing, as well as lower viscoelastic properties and greater water absorption ability were generally observed in the presence of sugars. On the other hand, when no water was added, sugars acted as fillers, especially sucrose, which reinforced the blends as denoted by lower loss tangents and higher viscoelastic moduli. In this case, a microporous structure is formed after water immersion, observing smaller pore sizes in the positions previously taken by those sugars. The present manuscript highlights the importance of the procedure followed when introducing sugars in the formulation on the eventual properties of the bioplastics.

Automated summary

The addition of sucrose and trehalose in gluten-based bioplastics has different effects depending on the presence of water. When water is present, sugars act as plasticizers; when no water is added, sugars act as fillers that reinforce the blends.